learn how workspaces + proc macros work & restructure everything

core/src/layout/attr.rs

@@ -0,0 +1,20 @@
+use crate::layout::{Ui, WidgetIdFn, WidgetLike, WidgetRef};
+
+pub trait WidgetAttr<W: ?Sized> {
+    type Input;
+    fn run(ui: &mut Ui, id: &WidgetRef<W>, input: Self::Input);
+}
+
+pub trait Attrable<W: ?Sized, Tag> {
+    fn attr<A: WidgetAttr<W>>(self, input: A::Input) -> impl WidgetIdFn<W>;
+}
+
+impl<WL: WidgetLike<Tag>, Tag> Attrable<WL::Widget, Tag> for WL {
+    fn attr<A: WidgetAttr<WL::Widget>>(self, input: A::Input) -> impl WidgetIdFn<WL::Widget> {
+        |ui| {
+            let id = self.add(ui);
+            A::run(ui, &id, input);
+            id
+        }
+    }
+}

core/src/layout/event.rs

@@ -0,0 +1,187 @@
+use std::{hash::Hash, rc::Rc};
+
+use crate::{
+    layout::{IdFnTag, Ui, UiModule, WidgetIdFn, WidgetLike, WidgetRef},
+    util::{HashMap, Id},
+};
+
+pub trait Event: Sized {
+    type Module<Ctx: 'static>: EventModule<Self, Ctx>;
+    type Data: Clone;
+}
+
+pub struct EventCtx<'a, Ctx, Data> {
+    pub ui: &'a mut Ui,
+    pub state: &'a mut Ctx,
+    pub data: Data,
+}
+
+pub type ECtx<'a, Ctx, Data, W> = EventIdCtx<'a, Ctx, Data, W>;
+pub struct EventIdCtx<'a, Ctx, Data, W: ?Sized> {
+    pub widget: &'a WidgetRef<W>,
+    pub ui: &'a mut Ui,
+    pub state: &'a mut Ctx,
+    pub data: Data,
+}
+
+pub trait EventFn<Ctx, Data>: Fn(EventCtx<Ctx, Data>) + 'static {}
+impl<F: Fn(EventCtx<Ctx, Data>) + 'static, Ctx, Data> EventFn<Ctx, Data> for F {}
+
+pub trait WidgetEventFn<Ctx, Data, W: ?Sized>: Fn(EventIdCtx<Ctx, Data, W>) + 'static {}
+impl<F: Fn(EventIdCtx<Ctx, Data, W>) + 'static, Ctx, Data, W: ?Sized> WidgetEventFn<Ctx, Data, W>
+    for F
+{
+}
+
+
+impl Ui {
+    pub fn register_event<W: ?Sized, E: Event, Ctx: 'static>(
+        &mut self,
+        id: &WidgetRef<W>,
+        event: E,
+        f: impl EventFn<Ctx, E::Data>,
+    ) {
+        self.data
+            .modules
+            .get_mut::<E::Module<Ctx>>()
+            .register(id.id(), event, f);
+    }
+
+    pub fn register_widget_event<W: ?Sized + 'static, E: Event, Ctx: 'static>(
+        &mut self,
+        id: &WidgetRef<W>,
+        event: E,
+        f: impl WidgetEventFn<Ctx, E::Data, W>,
+    ) {
+        let id_ = id.weak();
+        self.data
+            .modules
+            .get_mut::<E::Module<Ctx>>()
+            .register(id.id(), event, move |ctx| {
+                f(EventIdCtx {
+                    widget: &id_.expect_strong(),
+                    ui: ctx.ui,
+                    state: ctx.state,
+                    data: ctx.data,
+                })
+            });
+    }
+}
+
+pub trait DefaultEvent: Hash + Eq + 'static {
+    type Data: Clone;
+}
+
+impl<E: DefaultEvent> Event for E {
+    type Module<Ctx: 'static> = DefaultEventModule<E, Ctx>;
+    type Data = E::Data;
+}
+
+pub trait EventModule<E: Event, Ctx>: UiModule + Default {
+    fn register(&mut self, id: Id, event: E, f: impl EventFn<Ctx, E::Data>);
+    fn run<'a>(
+        &self,
+        id: &Id,
+        event: E,
+    ) -> Option<impl Fn(EventCtx<Ctx, E::Data>) + use<'a, Self, E, Ctx>>;
+}
+
+type EventFnMap<Ctx, Data> = HashMap<Id, Vec<Rc<dyn EventFn<Ctx, Data>>>>;
+pub struct DefaultEventModule<E: Event, Ctx> {
+    map: HashMap<E, EventFnMap<Ctx, <E as Event>::Data>>,
+}
+
+impl<E: Event + 'static, Ctx: 'static> UiModule for DefaultEventModule<E, Ctx> {
+    fn on_remove(&mut self, id: &Id) {
+        for map in self.map.values_mut() {
+            map.remove(id);
+        }
+    }
+}
+
+pub trait HashableEvent: Event + Hash + Eq + 'static {}
+impl<E: Event + Hash + Eq + 'static> HashableEvent for E {}
+
+impl<E: HashableEvent, Ctx: 'static> EventModule<E, Ctx> for DefaultEventModule<E, Ctx> {
+    fn register(&mut self, id: Id, event: E, f: impl EventFn<Ctx, <E as Event>::Data>) {
+        self.map
+            .entry(event)
+            .or_default()
+            .entry(id)
+            .or_default()
+            .push(Rc::new(f));
+    }
+
+    fn run<'a>(
+        &self,
+        id: &Id,
+        event: E,
+    ) -> Option<impl Fn(EventCtx<Ctx, E::Data>) + use<'a, E, Ctx>> {
+        if let Some(map) = self.map.get(&event)
+            && let Some(fs) = map.get(id)
+        {
+            let fs = fs.clone();
+            Some(move |ctx: EventCtx<Ctx, <E as Event>::Data>| {
+                for f in &fs {
+                    f(EventCtx {
+                        ui: ctx.ui,
+                        state: ctx.state,
+                        data: ctx.data.clone(),
+                    })
+                }
+            })
+        } else {
+            None
+        }
+    }
+}
+
+impl<E: HashableEvent, Ctx: 'static> DefaultEventModule<E, Ctx> {
+    pub fn run_all(&self, event: E, ctx: EventCtx<Ctx, E::Data>)
+    where
+        E::Data: Clone,
+    {
+        if let Some(map) = self.map.get(&event) {
+            for fs in map.values() {
+                for f in fs {
+                    f(EventCtx {
+                        ui: ctx.ui,
+                        state: ctx.state,
+                        data: ctx.data.clone(),
+                    })
+                }
+            }
+        }
+    }
+}
+
+impl<E: Event + 'static, Ctx: 'static> Default for DefaultEventModule<E, Ctx> {
+    fn default() -> Self {
+        Self {
+            map: Default::default(),
+        }
+    }
+}
+
+impl Ui {
+    pub fn run_event<E: Event, Ctx: 'static, W: ?Sized>(
+        &mut self,
+        ctx: &mut Ctx,
+        id: &WidgetRef<W>,
+        event: E,
+        data: E::Data,
+    ) {
+        if let Some(f) = self
+            .data
+            .modules
+            .get_mut::<E::Module<Ctx>>()
+            .run(&id.id(), event)
+        {
+            f(EventCtx {
+                ui: self,
+                state: ctx,
+                data,
+            });
+        }
+    }
+}

core/src/layout/mod.rs

@@ -0,0 +1,24 @@
+mod attr;
+mod event;
+mod module;
+mod num;
+mod orientation;
+mod painter;
+mod primitive;
+mod ui;
+mod view;
+mod widget;
+
+pub use attr::*;
+pub use event::*;
+pub use module::*;
+pub use num::*;
+pub use orientation::*;
+pub use painter::*;
+pub use primitive::*;
+pub use ui::*;
+pub use view::*;
+pub use widget::*;
+
+pub use crate::util::Vec2;
+pub type UiColor = Color<u8>;

core/src/layout/module.rs

@@ -0,0 +1,35 @@
+use std::any::{Any, TypeId};
+
+use crate::{
+    layout::WidgetInstance,
+    util::{HashMap, Id},
+};
+
+#[allow(unused_variables)]
+pub trait UiModule: Any {
+    fn on_draw(&mut self, inst: &WidgetInstance) {}
+    fn on_undraw(&mut self, inst: &WidgetInstance) {}
+    fn on_remove(&mut self, id: &Id) {}
+    fn on_move(&mut self, inst: &WidgetInstance) {}
+}
+
+#[derive(Default)]
+pub struct Modules {
+    map: HashMap<TypeId, Box<dyn UiModule>>,
+}
+
+impl Modules {
+    pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut (dyn UiModule + 'static)> {
+        self.map.values_mut().map(|m| m.as_mut())
+    }
+
+    pub fn get_mut<M: UiModule + Default>(&mut self) -> &mut M {
+        let rf = self
+            .map
+            .entry(TypeId::of::<M>())
+            .or_insert_with(|| Box::new(M::default()))
+            .as_mut();
+        let any: &mut dyn Any = &mut *rf;
+        any.downcast_mut().unwrap()
+    }
+}

core/src/layout/num.rs

@@ -0,0 +1,49 @@
+use crate::util::Vec2;
+use std::marker::Destruct;
+
+pub const trait UiNum {
+    fn to_f32(self) -> f32;
+}
+
+impl const UiNum for f32 {
+    fn to_f32(self) -> f32 {
+        self
+    }
+}
+
+impl const UiNum for u32 {
+    fn to_f32(self) -> f32 {
+        self as f32
+    }
+}
+
+impl const UiNum for i32 {
+    fn to_f32(self) -> f32 {
+        self as f32
+    }
+}
+
+impl<T: const UiNum, U: const UiNum> const From<(T, U)> for Vec2
+where
+    (T, U): const Destruct,
+{
+    fn from((x, y): (T, U)) -> Self {
+        Self {
+            x: x.to_f32(),
+            y: y.to_f32(),
+        }
+    }
+}
+
+impl<T: const UiNum + Copy> const From<T> for Vec2 {
+    fn from(v: T) -> Self {
+        Self {
+            x: v.to_f32(),
+            y: v.to_f32(),
+        }
+    }
+}
+
+pub const fn vec2(x: impl const UiNum, y: impl const UiNum) -> Vec2 {
+    Vec2::new(x.to_f32(), y.to_f32())
+}

core/src/layout/orientation/align.rs

@@ -0,0 +1,200 @@
+use crate::layout::vec2;
+
+use super::*;
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct Align {
+    pub x: Option<AxisAlign>,
+    pub y: Option<AxisAlign>,
+}
+
+impl Align {
+    pub const TOP_LEFT: RegionAlign = RegionAlign::TOP_LEFT;
+    pub const TOP_CENTER: RegionAlign = RegionAlign::TOP_CENTER;
+    pub const TOP_RIGHT: RegionAlign = RegionAlign::TOP_RIGHT;
+    pub const CENTER_LEFT: RegionAlign = RegionAlign::CENTER_LEFT;
+    pub const CENTER: RegionAlign = RegionAlign::CENTER;
+    pub const CENTER_RIGHT: RegionAlign = RegionAlign::CENTER_RIGHT;
+    pub const BOT_LEFT: RegionAlign = RegionAlign::BOT_LEFT;
+    pub const BOT_CENTER: RegionAlign = RegionAlign::BOT_CENTER;
+    pub const BOT_RIGHT: RegionAlign = RegionAlign::BOT_RIGHT;
+    pub const LEFT: CardinalAlign = CardinalAlign::LEFT;
+    pub const H_CENTER: CardinalAlign = CardinalAlign::H_CENTER;
+    pub const RIGHT: CardinalAlign = CardinalAlign::RIGHT;
+    pub const TOP: CardinalAlign = CardinalAlign::TOP;
+    pub const V_CENTER: CardinalAlign = CardinalAlign::V_CENTER;
+    pub const BOT: CardinalAlign = CardinalAlign::BOT;
+
+    pub fn tuple(&self) -> (Option<AxisAlign>, Option<AxisAlign>) {
+        (self.x, self.y)
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub enum AxisAlign {
+    Neg,
+    Center,
+    Pos,
+}
+
+impl AxisAlign {
+    pub const fn rel(&self) -> f32 {
+        match self {
+            Self::Neg => 0.0,
+            Self::Center => 0.5,
+            Self::Pos => 1.0,
+        }
+    }
+}
+
+pub struct CardinalAlign {
+    axis: Axis,
+    align: AxisAlign,
+}
+
+impl CardinalAlign {
+    pub const LEFT: Self = Self::new(Axis::X, AxisAlign::Neg);
+    pub const H_CENTER: Self = Self::new(Axis::X, AxisAlign::Center);
+    pub const RIGHT: Self = Self::new(Axis::X, AxisAlign::Pos);
+    pub const TOP: Self = Self::new(Axis::Y, AxisAlign::Neg);
+    pub const V_CENTER: Self = Self::new(Axis::Y, AxisAlign::Center);
+    pub const BOT: Self = Self::new(Axis::Y, AxisAlign::Pos);
+
+    pub const fn new(axis: Axis, align: AxisAlign) -> Self {
+        Self { axis, align }
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct RegionAlign {
+    pub x: AxisAlign,
+    pub y: AxisAlign,
+}
+
+impl RegionAlign {
+    pub const TOP_LEFT: Self = Self::new(AxisAlign::Neg, AxisAlign::Neg);
+    pub const TOP_CENTER: Self = Self::new(AxisAlign::Center, AxisAlign::Neg);
+    pub const TOP_RIGHT: Self = Self::new(AxisAlign::Pos, AxisAlign::Neg);
+    pub const CENTER_LEFT: Self = Self::new(AxisAlign::Neg, AxisAlign::Center);
+    pub const CENTER: Self = Self::new(AxisAlign::Center, AxisAlign::Center);
+    pub const CENTER_RIGHT: Self = Self::new(AxisAlign::Pos, AxisAlign::Center);
+    pub const BOT_LEFT: Self = Self::new(AxisAlign::Neg, AxisAlign::Pos);
+    pub const BOT_CENTER: Self = Self::new(AxisAlign::Center, AxisAlign::Pos);
+    pub const BOT_RIGHT: Self = Self::new(AxisAlign::Pos, AxisAlign::Pos);
+
+    pub const fn new(x: AxisAlign, y: AxisAlign) -> Self {
+        Self { x, y }
+    }
+    pub const fn rel(&self) -> Vec2 {
+        vec2(self.x.rel(), self.y.rel())
+    }
+}
+
+impl UiVec2 {
+    pub fn partial_align(&self, align: Align) -> UiRegion {
+        UiRegion {
+            x: if let Some(align) = align.x {
+                self.x.align(align)
+            } else {
+                UiSpan::FULL
+            },
+            y: if let Some(align) = align.y {
+                self.y.align(align)
+            } else {
+                UiSpan::FULL
+            },
+        }
+    }
+
+    pub fn align(&self, align: RegionAlign) -> UiRegion {
+        UiRegion {
+            x: self.x.align(align.x),
+            y: self.y.align(align.y),
+        }
+    }
+}
+
+impl Vec2 {
+    pub fn partial_align(&self, align: Align) -> UiRegion {
+        let s = UiVec2::from(*self);
+        UiRegion {
+            x: if let Some(align) = align.x {
+                s.x.align(align)
+            } else {
+                UiSpan::FULL
+            },
+            y: if let Some(align) = align.y {
+                s.y.align(align)
+            } else {
+                UiSpan::FULL
+            },
+        }
+    }
+
+    pub fn align(&self, align: RegionAlign) -> UiRegion {
+        let s = UiVec2::from(*self);
+        UiRegion {
+            x: s.x.align(align.x),
+            y: s.y.align(align.y),
+        }
+    }
+}
+
+impl UiScalar {
+    pub const fn align(&self, align: AxisAlign) -> UiSpan {
+        let rel = align.rel();
+        let mut start = UiScalar::rel(rel);
+        start.abs -= self.abs * rel;
+        start.rel -= self.rel * rel;
+        let mut end = UiScalar::rel(rel);
+        end.abs += self.abs * (1.0 - rel);
+        end.rel += self.rel * (1.0 - rel);
+        UiSpan { start, end }
+    }
+}
+
+impl From<RegionAlign> for Align {
+    fn from(region: RegionAlign) -> Self {
+        Self {
+            x: Some(region.x),
+            y: Some(region.y),
+        }
+    }
+}
+
+impl From<Align> for RegionAlign {
+    fn from(align: Align) -> Self {
+        Self {
+            x: align.x.unwrap_or(AxisAlign::Center),
+            y: align.y.unwrap_or(AxisAlign::Center),
+        }
+    }
+}
+
+impl From<CardinalAlign> for RegionAlign {
+    fn from(align: CardinalAlign) -> Self {
+        Align::from(align).into()
+    }
+}
+
+impl From<CardinalAlign> for Align {
+    fn from(cardinal: CardinalAlign) -> Self {
+        let align = Some(cardinal.align);
+        match cardinal.axis {
+            Axis::X => Self { x: align, y: None },
+            Axis::Y => Self { x: None, y: align },
+        }
+    }
+}
+
+impl const From<RegionAlign> for UiVec2 {
+    fn from(align: RegionAlign) -> Self {
+        Self::rel(align.rel())
+    }
+}
+
+impl RegionAlign {
+    pub const fn pos(self) -> UiVec2 {
+        UiVec2::from(self)
+    }
+}

core/src/layout/orientation/axis.rs

@@ -0,0 +1,73 @@
+use super::*;
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum Axis {
+    X,
+    Y,
+}
+
+pub trait Axis_ {
+}
+
+impl std::ops::Not for Axis {
+    type Output = Self;
+
+    fn not(self) -> Self::Output {
+        match self {
+            Self::X => Self::Y,
+            Self::Y => Self::X,
+        }
+    }
+}
+
+#[derive(Clone, Copy, Eq, PartialEq)]
+pub struct Dir {
+    pub axis: Axis,
+    pub sign: Sign,
+}
+
+impl Dir {
+    pub const fn new(axis: Axis, dir: Sign) -> Self {
+        Self { axis, sign: dir }
+    }
+
+    pub const LEFT: Self = Self::new(Axis::X, Sign::Neg);
+    pub const RIGHT: Self = Self::new(Axis::X, Sign::Pos);
+    pub const UP: Self = Self::new(Axis::Y, Sign::Neg);
+    pub const DOWN: Self = Self::new(Axis::Y, Sign::Pos);
+}
+
+#[derive(Clone, Copy, Eq, PartialEq)]
+pub enum Sign {
+    Neg,
+    Pos,
+}
+
+impl Vec2 {
+    pub fn axis(&self, axis: Axis) -> f32 {
+        match axis {
+            Axis::X => self.x,
+            Axis::Y => self.y,
+        }
+    }
+
+    pub fn axis_mut(&mut self, axis: Axis) -> &mut f32 {
+        match axis {
+            Axis::X => &mut self.x,
+            Axis::Y => &mut self.y,
+        }
+    }
+
+    pub const fn from_axis(axis: Axis, aligned: f32, ortho: f32) -> Self {
+        Self {
+            x: match axis {
+                Axis::X => aligned,
+                Axis::Y => ortho,
+            },
+            y: match axis {
+                Axis::Y => aligned,
+                Axis::X => ortho,
+            },
+        }
+    }
+}

core/src/layout/orientation/len.rs

@@ -0,0 +1,198 @@
+use super::*;
+use crate::{layout::UiNum, util::impl_op};
+
+#[derive(Debug, Default, Clone, Copy, PartialEq)]
+pub struct Size {
+    pub x: Len,
+    pub y: Len,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Len {
+    pub abs: f32,
+    pub rel: f32,
+    pub rest: f32,
+}
+
+impl<N: UiNum> From<N> for Len {
+    fn from(value: N) -> Self {
+        Len::abs(value.to_f32())
+    }
+}
+
+impl<Nx: UiNum, Ny: UiNum> From<(Nx, Ny)> for Size {
+    fn from((x, y): (Nx, Ny)) -> Self {
+        Self {
+            x: x.into(),
+            y: y.into(),
+        }
+    }
+}
+
+impl From<Len> for Size {
+    fn from(value: Len) -> Self {
+        Self { x: value, y: value }
+    }
+}
+
+impl Size {
+    pub const ZERO: Self = Self {
+        x: Len::ZERO,
+        y: Len::ZERO,
+    };
+
+    pub const REST: Self = Self {
+        x: Len::REST,
+        y: Len::REST,
+    };
+
+    pub fn abs(v: Vec2) -> Self {
+        Self {
+            x: Len::abs(v.x),
+            y: Len::abs(v.y),
+        }
+    }
+
+    pub fn rel(v: Vec2) -> Self {
+        Self {
+            x: Len::rel(v.x),
+            y: Len::rel(v.y),
+        }
+    }
+
+    pub fn rest(v: Vec2) -> Self {
+        Self {
+            x: Len::rest(v.x),
+            y: Len::rest(v.y),
+        }
+    }
+
+    pub fn to_uivec2(self) -> UiVec2 {
+        UiVec2 {
+            x: self.x.apply_rest(),
+            y: self.y.apply_rest(),
+        }
+    }
+
+    pub fn from_axis(axis: Axis, aligned: Len, ortho: Len) -> Self {
+        match axis {
+            Axis::X => Self {
+                x: aligned,
+                y: ortho,
+            },
+            Axis::Y => Self {
+                x: ortho,
+                y: aligned,
+            },
+        }
+    }
+
+    pub fn axis(&self, axis: Axis) -> Len {
+        match axis {
+            Axis::X => self.x,
+            Axis::Y => self.y,
+        }
+    }
+}
+
+impl Len {
+    pub const ZERO: Self = Self {
+        abs: 0.0,
+        rel: 0.0,
+        rest: 0.0,
+    };
+
+    pub const REST: Self = Self {
+        abs: 0.0,
+        rel: 0.0,
+        rest: 1.0,
+    };
+
+    pub fn apply_rest(&self) -> UiScalar {
+        UiScalar {
+            rel: self.rel + if self.rest > 0.0 { 1.0 } else { 0.0 },
+            abs: self.abs,
+        }
+    }
+
+    pub fn abs(abs: impl UiNum) -> Self {
+        Self {
+            abs: abs.to_f32(),
+            rel: 0.0,
+            rest: 0.0,
+        }
+    }
+    pub fn rel(rel: impl UiNum) -> Self {
+        Self {
+            abs: 0.0,
+            rel: rel.to_f32(),
+            rest: 0.0,
+        }
+    }
+    pub fn rest(ratio: impl UiNum) -> Self {
+        Self {
+            abs: 0.0,
+            rel: 0.0,
+            rest: ratio.to_f32(),
+        }
+    }
+}
+
+pub mod len_fns {
+    use super::*;
+
+    pub fn abs(abs: impl UiNum) -> Len {
+        Len {
+            abs: abs.to_f32(),
+            rel: 0.0,
+            rest: 0.0,
+        }
+    }
+    pub fn rel(rel: impl UiNum) -> Len {
+        Len {
+            abs: 0.0,
+            rel: rel.to_f32(),
+            rest: 0.0,
+        }
+    }
+    pub fn rest(ratio: impl UiNum) -> Len {
+        Len {
+            abs: 0.0,
+            rel: 0.0,
+            rest: ratio.to_f32(),
+        }
+    }
+}
+
+impl_op!(Len Add add; abs rel rest);
+impl_op!(Len Sub sub; abs rel rest);
+
+impl_op!(Size Add add; x y);
+impl_op!(Size Sub sub; x y);
+
+impl Default for Len {
+    fn default() -> Self {
+        Self::rest(1.0)
+    }
+}
+
+impl std::fmt::Display for Size {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "({}, {})", self.x, self.y)
+    }
+}
+
+impl std::fmt::Display for Len {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.abs != 0.0 {
+            write!(f, "{} abs;", self.abs)?;
+        }
+        if self.rel != 0.0 {
+            write!(f, "{} rel;", self.rel)?;
+        }
+        if self.rest != 0.0 {
+            write!(f, "{} rest;", self.rest)?;
+        }
+        Ok(())
+    }
+}

core/src/layout/orientation/mod.rs

@@ -0,0 +1,10 @@
+mod align;
+mod axis;
+mod len;
+mod pos;
+
+use super::Vec2;
+pub use align::*;
+pub use axis::*;
+pub use len::*;
+pub use pos::*;

core/src/layout/orientation/pos.rs

@@ -0,0 +1,464 @@
+use std::{fmt::Display, hash::Hash, marker::Destruct};
+
+use super::*;
+use crate::{
+    layout::UiNum,
+    util::{LerpUtil, impl_op},
+};
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, bytemuck::Pod, bytemuck::Zeroable, Default)]
+pub struct UiVec2 {
+    pub x: UiScalar,
+    pub y: UiScalar,
+}
+
+impl UiVec2 {
+    pub const ZERO: Self = Self {
+        x: UiScalar::ZERO,
+        y: UiScalar::ZERO,
+    };
+
+    pub const fn new(x: UiScalar, y: UiScalar) -> Self {
+        Self { x, y }
+    }
+
+    pub const fn abs(abs: impl const Into<Vec2>) -> Self {
+        let abs = abs.into();
+        Self {
+            x: UiScalar::abs(abs.x),
+            y: UiScalar::abs(abs.y),
+        }
+    }
+
+    pub const fn rel(rel: impl const Into<Vec2>) -> Self {
+        let rel = rel.into();
+        Self {
+            x: UiScalar::rel(rel.x),
+            y: UiScalar::rel(rel.y),
+        }
+    }
+
+    pub const fn shift(&mut self, offset: impl const Into<UiVec2>) {
+        let offset = offset.into();
+        *self += offset;
+    }
+
+    pub const fn offset(mut self, offset: impl const Into<UiVec2>) -> Self {
+        self.shift(offset);
+        self
+    }
+
+    pub const fn within(&self, region: &UiRegion) -> UiVec2 {
+        UiVec2 {
+            x: self.x.within(&region.x),
+            y: self.y.within(&region.y),
+        }
+    }
+
+    pub const fn outside(&self, region: &UiRegion) -> UiVec2 {
+        UiVec2 {
+            x: self.x.outside(&region.x),
+            y: self.y.outside(&region.y),
+        }
+    }
+
+    pub fn axis_mut(&mut self, axis: Axis) -> &mut UiScalar {
+        match axis {
+            Axis::X => &mut self.x,
+            Axis::Y => &mut self.y,
+        }
+    }
+
+    pub fn axis(&self, axis: Axis) -> UiScalar {
+        match axis {
+            Axis::X => self.x,
+            Axis::Y => self.y,
+        }
+    }
+
+    pub fn to_abs(&self, rel: Vec2) -> Vec2 {
+        Vec2 {
+            x: self.x.to_abs(rel.x),
+            y: self.y.to_abs(rel.y),
+        }
+    }
+
+    pub const FULL_SIZE: Self = Self::rel(Vec2::ONE);
+
+    pub const fn from_axis(axis: Axis, aligned: UiScalar, ortho: UiScalar) -> Self {
+        match axis {
+            Axis::X => Self {
+                x: aligned,
+                y: ortho,
+            },
+            Axis::Y => Self {
+                x: ortho,
+                y: aligned,
+            },
+        }
+    }
+
+    pub fn get_abs(&self) -> Vec2 {
+        (self.x.abs, self.y.abs).into()
+    }
+
+    pub fn get_rel(&self) -> Vec2 {
+        (self.x.rel, self.y.rel).into()
+    }
+
+    pub fn abs_mut(&mut self) -> Vec2View<'_> {
+        Vec2View {
+            x: &mut self.x.abs,
+            y: &mut self.y.abs,
+        }
+    }
+}
+
+impl Display for UiVec2 {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "rel{};abs{}", self.get_rel(), self.get_abs())
+    }
+}
+
+impl_op!(UiVec2 Add add; x y);
+impl_op!(UiVec2 Sub sub; x y);
+
+impl const From<Vec2> for UiVec2 {
+    fn from(abs: Vec2) -> Self {
+        Self::abs(abs)
+    }
+}
+
+impl<T: const UiNum, U: const UiNum> const From<(T, U)> for UiVec2
+where
+    (T, U): const Destruct,
+{
+    fn from(abs: (T, U)) -> Self {
+        Self::abs(abs)
+    }
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, PartialEq, bytemuck::Pod, Default, bytemuck::Zeroable)]
+pub struct UiScalar {
+    pub rel: f32,
+    pub abs: f32,
+}
+
+impl Eq for UiScalar {}
+impl Hash for UiScalar {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        state.write_u32(self.rel.to_bits());
+        state.write_u32(self.abs.to_bits());
+    }
+}
+
+impl_op!(UiScalar Add add; rel abs);
+impl_op!(UiScalar Sub sub; rel abs);
+
+impl UiScalar {
+    pub const ZERO: Self = Self { rel: 0.0, abs: 0.0 };
+    pub const FULL: Self = Self { rel: 1.0, abs: 0.0 };
+
+    pub const fn new(rel: f32, abs: f32) -> Self {
+        Self { rel, abs }
+    }
+
+    pub const fn rel(rel: f32) -> Self {
+        Self { rel, abs: 0.0 }
+    }
+
+    pub const fn abs(abs: f32) -> Self {
+        Self { rel: 0.0, abs }
+    }
+
+    pub const fn rel_min() -> Self {
+        Self::new(0.0, 0.0)
+    }
+
+    pub const fn rel_max() -> Self {
+        Self::new(1.0, 0.0)
+    }
+
+    pub const fn max(&self, other: Self) -> Self {
+        Self {
+            rel: self.rel.max(other.rel),
+            abs: self.abs.max(other.abs),
+        }
+    }
+
+    pub const fn min(&self, other: Self) -> Self {
+        Self {
+            rel: self.rel.min(other.rel),
+            abs: self.abs.min(other.abs),
+        }
+    }
+
+    pub const fn offset(mut self, amt: f32) -> Self {
+        self.abs += amt;
+        self
+    }
+
+    pub const fn within(&self, span: &UiSpan) -> Self {
+        let anchor = self.rel.lerp(span.start.rel, span.end.rel);
+        let offset = self.abs + self.rel.lerp(span.start.abs, span.end.abs);
+        Self {
+            rel: anchor,
+            abs: offset,
+        }
+    }
+
+    pub const fn outside(&self, span: &UiSpan) -> Self {
+        let rel = self.rel.lerp_inv(span.start.rel, span.end.rel);
+        let abs = self.abs - rel.lerp(span.start.abs, span.end.abs);
+        Self { rel, abs }
+    }
+
+    pub fn within_len(&self, len: UiScalar) -> Self {
+        self.within(&UiSpan {
+            start: UiScalar::ZERO,
+            end: len,
+        })
+    }
+
+    pub fn select_len(&self, len: UiScalar) -> Self {
+        len.within_len(*self)
+    }
+
+    pub const fn flip(&mut self) {
+        self.rel = 1.0 - self.rel;
+        self.abs = -self.abs;
+    }
+
+    pub const fn to(&self, end: Self) -> UiSpan {
+        UiSpan { start: *self, end }
+    }
+
+    pub const fn to_abs(&self, rel: f32) -> f32 {
+        self.rel * rel + self.abs
+    }
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, PartialEq, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct UiSpan {
+    pub start: UiScalar,
+    pub end: UiScalar,
+}
+
+impl UiSpan {
+    pub const FULL: Self = Self {
+        start: UiScalar::ZERO,
+        end: UiScalar::FULL,
+    };
+
+    pub const fn rel(rel: f32) -> Self {
+        Self {
+            start: UiScalar::rel(rel),
+            end: UiScalar::rel(rel),
+        }
+    }
+
+    pub const fn new(start: UiScalar, end: UiScalar) -> Self {
+        Self { start, end }
+    }
+
+    pub const fn flip(&mut self) {
+        self.start.flip();
+        self.end.flip();
+        std::mem::swap(&mut self.start.rel, &mut self.end.rel);
+        std::mem::swap(&mut self.start.abs, &mut self.end.abs);
+    }
+
+    pub const fn shift(&mut self, offset: UiScalar) {
+        self.start += offset;
+        self.end += offset;
+    }
+
+    pub const fn within(&self, parent: &Self) -> Self {
+        Self {
+            start: self.start.within(parent),
+            end: self.end.within(parent),
+        }
+    }
+
+    pub const fn outside(&self, parent: &Self) -> Self {
+        Self {
+            start: self.start.outside(parent),
+            end: self.end.outside(parent),
+        }
+    }
+
+    pub const fn len(&self) -> UiScalar {
+        self.end - self.start
+    }
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, PartialEq, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct UiRegion {
+    pub x: UiSpan,
+    pub y: UiSpan,
+}
+
+impl UiRegion {
+    pub const FULL: Self = Self {
+        x: UiSpan::FULL,
+        y: UiSpan::FULL,
+    };
+
+    pub const fn new(x: UiSpan, y: UiSpan) -> Self {
+        Self { x, y }
+    }
+
+    pub const fn rel(rel: Vec2) -> Self {
+        Self {
+            x: UiSpan::rel(rel.x),
+            y: UiSpan::rel(rel.y),
+        }
+    }
+    pub const fn within(&self, parent: &Self) -> Self {
+        Self {
+            x: self.x.within(&parent.x),
+            y: self.y.within(&parent.y),
+        }
+    }
+    pub const fn outside(&self, parent: &Self) -> Self {
+        Self {
+            x: self.x.outside(&parent.x),
+            y: self.y.outside(&parent.y),
+        }
+    }
+
+    pub const fn axis(&mut self, axis: Axis) -> &UiSpan {
+        match axis {
+            Axis::X => &self.x,
+            Axis::Y => &self.y,
+        }
+    }
+
+    pub const fn axis_mut(&mut self, axis: Axis) -> &mut UiSpan {
+        match axis {
+            Axis::X => &mut self.x,
+            Axis::Y => &mut self.y,
+        }
+    }
+
+    pub const fn flip(&mut self, axis: Axis) {
+        match axis {
+            Axis::X => self.x.flip(),
+            Axis::Y => self.y.flip(),
+        }
+    }
+
+    pub fn shift(&mut self, offset: impl Into<UiVec2>) {
+        let offset = offset.into();
+        self.x.shift(offset.x);
+        self.y.shift(offset.y);
+    }
+
+    pub fn offset(mut self, offset: impl Into<UiVec2>) -> Self {
+        self.shift(offset);
+        self
+    }
+
+    pub fn to_px(&self, size: Vec2) -> PixelRegion {
+        PixelRegion {
+            top_left: self.top_left().get_rel() * size + self.top_left().get_abs(),
+            bot_right: self.bot_right().get_rel() * size + self.bot_right().get_abs(),
+        }
+    }
+
+    pub const fn center(&self) -> UiVec2 {
+        Align::CENTER.pos().within(self)
+    }
+
+    pub const fn size(&self) -> UiVec2 {
+        UiVec2 {
+            x: self.x.len(),
+            y: self.y.len(),
+        }
+    }
+
+    pub const fn top_left(&self) -> UiVec2 {
+        UiVec2 {
+            x: self.x.start,
+            y: self.y.start,
+        }
+    }
+
+    pub const fn bot_right(&self) -> UiVec2 {
+        UiVec2 {
+            x: self.x.end,
+            y: self.y.end,
+        }
+    }
+
+    pub const fn from_axis(axis: Axis, aligned: UiSpan, ortho: UiSpan) -> Self {
+        Self {
+            x: match axis {
+                Axis::X => aligned,
+                Axis::Y => ortho,
+            },
+            y: match axis {
+                Axis::X => ortho,
+                Axis::Y => aligned,
+            },
+        }
+    }
+}
+
+impl Display for UiRegion {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{} -> {} (size: {})",
+            self.top_left(),
+            self.bot_right(),
+            self.size()
+        )
+    }
+}
+
+#[derive(Debug)]
+pub struct PixelRegion {
+    pub top_left: Vec2,
+    pub bot_right: Vec2,
+}
+
+impl PixelRegion {
+    pub fn contains(&self, pos: Vec2) -> bool {
+        pos.x >= self.top_left.x
+            && pos.x <= self.bot_right.x
+            && pos.y >= self.top_left.y
+            && pos.y <= self.bot_right.y
+    }
+
+    pub fn size(&self) -> Vec2 {
+        self.bot_right - self.top_left
+    }
+}
+
+impl Display for PixelRegion {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} -> {}", self.top_left, self.bot_right)
+    }
+}
+
+pub struct Vec2View<'a> {
+    pub x: &'a mut f32,
+    pub y: &'a mut f32,
+}
+
+impl Vec2View<'_> {
+    pub fn set(&mut self, other: Vec2) {
+        *self.x = other.x;
+        *self.y = other.y;
+    }
+
+    pub fn add(&mut self, other: Vec2) {
+        *self.x += other.x;
+        *self.y += other.y;
+    }
+}

core/src/layout/painter.rs

@@ -0,0 +1,609 @@
+use std::{cell::Ref, marker::Unsize, sync::mpsc::Sender};
+
+use crate::{
+    layout::{
+        Axis, Len, Modules, PrimitiveLayers, RenderedText, Size, TextAttrs, TextBuffer, TextData,
+        TextureHandle, Textures, UiRegion, UiVec2, Vec2, Widget, WidgetRef, WidgetUpdate, Widgets,
+    },
+    render::{Mask, MaskIdx, Primitive, PrimitiveHandle, PrimitiveInst},
+    util::{HashMap, HashSet, Id, TrackedArena},
+};
+
+/// makes your surfaces look pretty
+pub struct Painter<'a, 'c> {
+    ctx: &'a mut PainterCtx<'c>,
+    widget: WidgetRef,
+    id: Id,
+    region: UiRegion,
+    mask: MaskIdx,
+    textures: Vec<TextureHandle>,
+    primitives: Vec<PrimitiveHandle>,
+    children: Vec<Id>,
+    children_width: HashMap<Id, (UiVec2, Len)>,
+    children_height: HashMap<Id, (UiVec2, Len)>,
+    pub layer: usize,
+}
+
+/// context for a painter; lets you draw and redraw widgets
+struct PainterCtx<'a> {
+    pub widgets: &'a Widgets,
+    pub active: &'a mut HashMap<Id, WidgetInstance>,
+    pub layers: &'a mut PrimitiveLayers,
+    pub textures: &'a mut Textures,
+    pub masks: &'a mut TrackedArena<Mask, u32>,
+    pub text: &'a mut TextData,
+    pub output_size: Vec2,
+    pub modules: &'a mut Modules,
+    pub cache_width: HashMap<Id, (UiVec2, Len)>,
+    pub cache_height: HashMap<Id, (UiVec2, Len)>,
+    pub needs_redraw: HashSet<Id>,
+    draw_started: HashSet<Id>,
+}
+
+/// stores information for children about the highest level parent that needed their size
+/// so that they can redraw the parent if their size changes
+#[derive(Clone, Copy, Debug, Default)]
+pub struct ResizeRef {
+    x: Option<(Id, (UiVec2, Len))>,
+    y: Option<(Id, (UiVec2, Len))>,
+}
+
+/// important non rendering data for retained drawing
+#[derive(Debug)]
+pub struct WidgetInstance {
+    pub id: Id,
+    pub region: UiRegion,
+    pub parent: Option<Id>,
+    pub textures: Vec<TextureHandle>,
+    pub primitives: Vec<PrimitiveHandle>,
+    pub children: Vec<Id>,
+    pub resize: ResizeRef,
+    pub mask: MaskIdx,
+    pub layer: usize,
+}
+
+/// data to be stored in Ui to create PainterCtxs easily
+pub struct PainterData {
+    pub widgets: Widgets,
+    pub active: HashMap<Id, WidgetInstance>,
+    pub layers: PrimitiveLayers,
+    pub textures: Textures,
+    pub text: TextData,
+    pub output_size: Vec2,
+    pub modules: Modules,
+    pub px_dependent: HashSet<Id>,
+    pub masks: TrackedArena<Mask, u32>,
+}
+
+impl PainterData {
+    pub fn new(send: Sender<WidgetUpdate>) -> Self {
+        Self {
+            widgets: Widgets::new(send),
+            active: Default::default(),
+            layers: Default::default(),
+            textures: Default::default(),
+            text: Default::default(),
+            output_size: Default::default(),
+            modules: Default::default(),
+            px_dependent: Default::default(),
+            masks: Default::default(),
+        }
+    }
+}
+
+impl<'a> PainterCtx<'a> {
+    /// redraws a widget that's currently active (drawn)
+    /// can be called on something already drawn or removed,
+    /// will just return if so
+    pub fn redraw<W: Widget + ?Sized + Unsize<dyn Widget>>(&mut self, widget: &WidgetRef<W>) {
+        let id = widget.id();
+        self.needs_redraw.remove(&id);
+        if self.draw_started.contains(&id) {
+            return;
+        }
+        let Some(active) = self.active.get(&id) else {
+            return;
+        };
+        let mut resize = active.resize;
+
+        // set resize back after redrawing
+        let finish = |s: &mut Self, resize| {
+            if let Some(active) = s.active.get_mut(&id) {
+                // might need to get_or_insert here instead of just assuming
+                active.resize = resize;
+            }
+        };
+
+        // check if a parent depends on the desired size of this, if so then redraw it first
+        // TODO: this is stupid having 2 of these, don't ask me what the consequences are
+        let mut ret = false;
+        if let Some((rid, (outer, old_desired))) = &mut resize.x {
+            let new_desired = SizeCtx {
+                source: id,
+                cache_width: &mut self.cache_width,
+                cache_height: &mut self.cache_height,
+                text: self.text,
+                textures: self.textures,
+                outer: *outer,
+                output_size: self.output_size,
+                checked_width: &mut Default::default(),
+                checked_height: &mut Default::default(),
+                id,
+            }
+            .width(widget);
+            if new_desired != *old_desired {
+                // unsure if I need to walk down the tree here
+                self.redraw(&self.widgets.get(*rid));
+                *old_desired = new_desired;
+                if self.draw_started.contains(&id) {
+                    ret = true;
+                }
+            }
+        }
+
+        if let Some((rid, (outer, old_desired))) = &mut resize.y {
+            // NOTE: might need hack in Span here (or also do it properly here)
+            let new_desired = SizeCtx {
+                source: id,
+                cache_width: &mut self.cache_width,
+                cache_height: &mut self.cache_height,
+                text: self.text,
+                textures: self.textures,
+                outer: *outer,
+                output_size: self.output_size,
+                checked_width: &mut Default::default(),
+                checked_height: &mut Default::default(),
+                id,
+            }
+            .height(widget);
+            if new_desired != *old_desired {
+                self.redraw(&self.widgets.get(*rid));
+                *old_desired = new_desired;
+                if self.draw_started.contains(&id) {
+                    ret = true;
+                }
+            }
+        }
+
+        if ret {
+            return finish(self, resize);
+        }
+
+        let Some(active) = self.remove(id) else {
+            return;
+        };
+
+        self.draw_inner(
+            active.layer,
+            widget,
+            active.region,
+            active.parent,
+            active.mask,
+            Some(active.children),
+        );
+        finish(self, resize);
+    }
+
+    fn draw_inner<W: Widget + ?Sized + Unsize<dyn Widget>>(
+        &mut self,
+        layer: usize,
+        widget: &WidgetRef<W>,
+        region: UiRegion,
+        parent: Option<Id>,
+        mask: MaskIdx,
+        old_children: Option<Vec<Id>>,
+    ) {
+        let id = widget.id();
+        // I have no idea if these checks work lol
+        // the idea is u can't redraw stuff u already drew,
+        // and if parent is different then there's another copy with a different parent
+        // but this has a very weird issue where you can't move widgets unless u remove first
+        // so swapping is impossible rn I think?
+        // there's definitely better solutions like a counter (>1 = panic) but don't care rn
+        // if self.draw_started.contains(&id) {
+        //     panic!(
+        //         "Cannot draw the same widget ({}) twice (1)",
+        //         self.widgets.data(&id).unwrap().label
+        //     );
+        // }
+        let mut old_children = old_children.unwrap_or_default();
+        let mut resize = ResizeRef::default();
+        if let Some(active) = self.active.get_mut(&id)
+            && !self.needs_redraw.contains(&id)
+        {
+            // check to see if we can skip drawing first
+            if active.parent != parent {
+                panic!("Cannot draw the same widget twice (2)");
+            }
+            if active.region == region {
+                return;
+            } else if active.region.size() == region.size() {
+                // TODO: epsilon?
+                let from = active.region;
+                self.mov(id, from, region);
+                return;
+            }
+            // if not, then maintain resize and track old children to remove unneeded
+            let active = self.remove(id).unwrap();
+            old_children = active.children;
+            resize = active.resize;
+        }
+
+        // draw widget
+        self.draw_started.insert(id);
+
+        let mut painter = Painter {
+            region,
+            mask,
+            layer,
+            widget: widget.as_any(),
+            id,
+            textures: Vec::new(),
+            primitives: Vec::new(),
+            ctx: self,
+            children: Vec::new(),
+            children_width: Default::default(),
+            children_height: Default::default(),
+        };
+
+        widget.get_mut_quiet().draw(&mut painter);
+
+        let children_width = painter.children_width;
+        let children_height = painter.children_height;
+
+        // add to active
+        let instance = WidgetInstance {
+            id,
+            region,
+            parent,
+            textures: painter.textures,
+            primitives: painter.primitives,
+            children: painter.children,
+            resize,
+            mask: painter.mask,
+            layer,
+        };
+        // set resize for children who's size this widget depends on
+        for (cid, outer) in children_width {
+            if let Some(w) = self.active.get_mut(&cid)
+                && w.resize.x.is_none()
+            {
+                w.resize.x = Some((id, outer))
+            }
+        }
+        for (cid, outer) in children_height {
+            if let Some(w) = self.active.get_mut(&cid)
+                && w.resize.y.is_none()
+            {
+                w.resize.y = Some((id, outer))
+            }
+        }
+
+        // remove old children that weren't kept
+        for c in &old_children {
+            if !instance.children.contains(c) {
+                self.remove_rec(*c);
+            }
+        }
+
+        // update modules
+        for m in self.modules.iter_mut() {
+            m.on_draw(&instance);
+        }
+        self.active.insert(id, instance);
+    }
+
+    fn mov(&mut self, id: Id, from: UiRegion, to: UiRegion) {
+        let active = self.active.get_mut(&id).unwrap();
+        for h in &active.primitives {
+            let region = self.layers[h.layer].region_mut(h);
+            *region = region.outside(&from).within(&to);
+        }
+        active.region = active.region.outside(&from).within(&to);
+        for m in self.modules.iter_mut() {
+            m.on_move(active);
+        }
+        // children will not be changed, so this technically should not be needed
+        // probably need unsafe
+        let children = active.children.clone();
+        for child in children {
+            self.mov(child, from, to);
+        }
+    }
+
+    /// NOTE: instance textures are cleared and self.textures freed
+    fn remove(&mut self, id: Id) -> Option<WidgetInstance> {
+        let mut inst = self.active.remove(&id);
+        if let Some(inst) = &mut inst {
+            for h in &inst.primitives {
+                let mask = self.layers.free(h);
+                if mask != MaskIdx::NONE {
+                    self.masks.remove(mask);
+                }
+            }
+            inst.textures.clear();
+            self.textures.free();
+            for m in self.modules.iter_mut() {
+                m.on_undraw(inst);
+            }
+        }
+        inst
+    }
+
+    fn remove_rec(&mut self, id: Id) -> Option<WidgetInstance> {
+        let inst = self.remove(id);
+        if let Some(inst) = &inst {
+            for c in &inst.children {
+                self.remove_rec(*c);
+            }
+        }
+        inst
+    }
+}
+
+impl PainterData {
+    fn ctx(&mut self, needs_redraw: HashSet<Id>) -> PainterCtx<'_> {
+        PainterCtx {
+            widgets: &self.widgets,
+            active: &mut self.active,
+            layers: &mut self.layers,
+            textures: &mut self.textures,
+            text: &mut self.text,
+            output_size: self.output_size,
+            modules: &mut self.modules,
+            masks: &mut self.masks,
+            cache_width: Default::default(),
+            cache_height: Default::default(),
+            draw_started: Default::default(),
+            needs_redraw,
+        }
+    }
+
+    pub fn draw<W: Widget + ?Sized + Unsize<dyn Widget>>(&mut self, id: &WidgetRef<W>) {
+        let mut ctx = self.ctx(Default::default());
+        ctx.draw_started.clear();
+        ctx.layers.clear();
+        ctx.draw_inner(0, id, UiRegion::FULL, None, MaskIdx::NONE, None);
+    }
+
+    pub fn redraw(&mut self, ids: HashSet<Id>) {
+        let mut ctx = self.ctx(ids);
+        while let Some(&id) = ctx.needs_redraw.iter().next() {
+            ctx.redraw(&ctx.widgets.get(id));
+        }
+    }
+}
+
+impl<'a, 'c> Painter<'a, 'c> {
+    fn primitive_at<P: Primitive>(&mut self, primitive: P, region: UiRegion) {
+        let h = self.ctx.layers.write(
+            self.layer,
+            PrimitiveInst {
+                id: self.id(),
+                primitive,
+                region,
+                mask_idx: self.mask,
+            },
+        );
+        if self.mask != MaskIdx::NONE {
+            // TODO: I have no clue if this works at all :joy:
+            self.ctx.masks.push_ref(self.mask);
+        }
+        self.primitives.push(h);
+    }
+
+    /// Writes a primitive to be rendered
+    pub fn primitive<P: Primitive>(&mut self, primitive: P) {
+        self.primitive_at(primitive, self.region)
+    }
+
+    pub fn primitive_within<P: Primitive>(&mut self, primitive: P, region: UiRegion) {
+        self.primitive_at(primitive, region.within(&self.region));
+    }
+
+    pub fn set_mask(&mut self, region: UiRegion) {
+        assert!(self.mask == MaskIdx::NONE);
+        self.mask = self.ctx.masks.push(Mask { region });
+    }
+
+    /// Draws a widget within this widget's region.
+    pub fn widget<W: Widget + ?Sized + Unsize<dyn Widget>>(&mut self, id: &WidgetRef<W>) {
+        self.widget_at(id, self.region);
+    }
+
+    /// Draws a widget somewhere within this one.
+    /// Useful for drawing child widgets in select areas.
+    pub fn widget_within<W: Widget + ?Sized + Unsize<dyn Widget>>(
+        &mut self,
+        id: &WidgetRef<W>,
+        region: UiRegion,
+    ) {
+        self.widget_at(id, region.within(&self.region));
+    }
+
+    fn widget_at<W: Widget + ?Sized + Unsize<dyn Widget>>(
+        &mut self,
+        id: &WidgetRef<W>,
+        region: UiRegion,
+    ) {
+        self.children.push(id.id());
+        self.ctx
+            .draw_inner(self.layer, id, region, Some(self.id()), self.mask, None);
+    }
+
+    pub fn texture_within(&mut self, handle: &TextureHandle, region: UiRegion) {
+        self.textures.push(handle.clone());
+        self.primitive_at(handle.primitive(), region.within(&self.region));
+    }
+
+    pub fn texture(&mut self, handle: &TextureHandle) {
+        self.textures.push(handle.clone());
+        self.primitive(handle.primitive());
+    }
+
+    pub fn texture_at(&mut self, handle: &TextureHandle, region: UiRegion) {
+        self.textures.push(handle.clone());
+        self.primitive_at(handle.primitive(), region);
+    }
+
+    /// returns (handle, offset from top left)
+    pub fn render_text(&mut self, buffer: &mut TextBuffer, attrs: &TextAttrs) -> RenderedText {
+        self.ctx
+            .text
+            .get_mut()
+            .draw(buffer, attrs, self.ctx.textures)
+    }
+
+    pub fn region(&self) -> UiRegion {
+        self.region
+    }
+
+    pub fn size<W: Widget + ?Sized>(&mut self, id: &WidgetRef<W>) -> Size {
+        self.size_ctx().size(id)
+    }
+
+    pub fn len_axis<W: Widget + ?Sized>(&mut self, id: &WidgetRef<W>, axis: Axis) -> Len {
+        match axis {
+            Axis::X => self.size_ctx().width(id),
+            Axis::Y => self.size_ctx().height(id),
+        }
+    }
+
+    pub fn size_ctx(&mut self) -> SizeCtx<'_> {
+        SizeCtx {
+            source: self.id(),
+            id: self.id(),
+            text: self.ctx.text,
+            textures: self.ctx.textures,
+            output_size: self.ctx.output_size,
+            checked_width: &mut self.children_width,
+            checked_height: &mut self.children_height,
+            cache_width: &mut self.ctx.cache_width,
+            cache_height: &mut self.ctx.cache_height,
+            outer: self.region.size(),
+        }
+    }
+
+    pub fn output_size(&self) -> Vec2 {
+        self.ctx.output_size
+    }
+
+    pub fn px_size(&mut self) -> Vec2 {
+        self.region.size().to_abs(self.ctx.output_size)
+    }
+
+    pub fn text_data(&mut self) -> &mut TextData {
+        self.ctx.text
+    }
+
+    pub fn child_layer(&mut self) {
+        self.layer = self.ctx.layers.child(self.layer);
+    }
+
+    pub fn next_layer(&mut self) {
+        self.layer = self.ctx.layers.next(self.layer);
+    }
+
+    pub fn label(&self) -> Ref<'_, String> {
+        self.widget.get_label()
+    }
+
+    pub fn id(&self) -> Id {
+        self.id
+    }
+}
+
+pub struct SizeCtx<'a> {
+    pub text: &'a mut TextData,
+    pub textures: &'a mut Textures,
+    source: Id,
+    cache_width: &'a mut HashMap<Id, (UiVec2, Len)>,
+    cache_height: &'a mut HashMap<Id, (UiVec2, Len)>,
+    checked_width: &'a mut HashMap<Id, (UiVec2, Len)>,
+    checked_height: &'a mut HashMap<Id, (UiVec2, Len)>,
+    /// TODO: should this be pub? rn used for sized
+    pub outer: UiVec2,
+    output_size: Vec2,
+    id: Id,
+}
+
+impl SizeCtx<'_> {
+    pub fn id(&self) -> &Id {
+        &self.id
+    }
+
+    pub fn source(&self) -> &Id {
+        &self.source
+    }
+
+    pub fn width<W: Widget + ?Sized>(&mut self, widget: &WidgetRef<W>) -> Len {
+        // first check cache
+        // TODO: is this needed? broken rn bc does not store children during upper size check,
+        // so if something actually using check_* hits cache it fails to add them
+        // if let Some(&(outer, len)) = self.cache_width.get(&id)
+        //     && outer == self.outer
+        // {
+        //     self.checked_width.insert(id, (self.outer, len));
+        //     return len;
+        // }
+        // store self vars that need to be maintained
+        let id = widget.id();
+        let self_outer = self.outer;
+        let self_id = self.id;
+        // get size of input id
+        self.id = id;
+        let len = widget.get_mut_quiet().desired_width(self);
+        // restore vars & update cache + checked
+        self.outer = self_outer;
+        self.id = self_id;
+        self.cache_width.insert(id, (self.outer, len));
+        self.checked_width.insert(id, (self.outer, len));
+        len
+    }
+
+    // TODO: should be refactored to share code w width_inner
+    pub fn height<W: Widget + ?Sized>(&mut self, widget: &WidgetRef<W>) -> Len {
+        // if let Some(&(outer, len)) = self.cache_height.get(&id)
+        //     && outer == self.outer
+        // {
+        //     self.checked_height.insert(id, (self.outer, len));
+        //     return len;
+        // }
+        let id = widget.id();
+        let self_outer = self.outer;
+        let self_id = self.id;
+        self.id = id;
+        let len = widget.get_mut_quiet().desired_height(self);
+        self.outer = self_outer;
+        self.id = self_id;
+        self.cache_height.insert(id, (self.outer, len));
+        self.checked_height.insert(id, (self.outer, len));
+        len
+    }
+
+    pub fn len_axis<W: Widget + ?Sized>(&mut self, id: &WidgetRef<W>, axis: Axis) -> Len {
+        match axis {
+            Axis::X => self.width(id),
+            Axis::Y => self.height(id),
+        }
+    }
+
+    pub fn size<W: Widget + ?Sized>(&mut self, id: &WidgetRef<W>) -> Size {
+        Size {
+            x: self.width(id),
+            y: self.height(id),
+        }
+    }
+
+    pub fn px_size(&mut self) -> Vec2 {
+        self.outer.to_abs(self.output_size)
+    }
+
+    pub fn output_size(&mut self) -> Vec2 {
+        self.output_size
+    }
+
+    pub fn draw_text(&mut self, buffer: &mut TextBuffer, attrs: &TextAttrs) -> RenderedText {
+        self.text.get_mut().draw(buffer, attrs, self.textures)
+    }
+}

core/src/layout/primitive/color.rs

@@ -0,0 +1,165 @@
+#![allow(clippy::multiple_bound_locations)]
+
+use std::marker::Destruct;
+
+/// stored in linear for sane manipulation
+#[repr(C)]
+#[derive(Clone, Copy, Hash, PartialEq, Eq, bytemuck::Zeroable, Debug)]
+pub struct Color<T: ColorNum> {
+    pub r: T,
+    pub g: T,
+    pub b: T,
+    pub a: T,
+}
+
+impl<T: ColorNum> Color<T> {
+    pub const BLACK: Self = Self::rgb(T::MIN, T::MIN, T::MIN);
+    pub const WHITE: Self = Self::rgb(T::MAX, T::MAX, T::MAX);
+    pub const GRAY: Self = Self::rgb(T::MID, T::MID, T::MID);
+
+    pub const RED: Self = Self::rgb(T::MAX, T::MIN, T::MIN);
+    pub const ORANGE: Self = Self::rgb(T::MAX, T::MID, T::MIN);
+    pub const YELLOW: Self = Self::rgb(T::MAX, T::MAX, T::MIN);
+    pub const LIME: Self = Self::rgb(T::MID, T::MAX, T::MIN);
+    pub const GREEN: Self = Self::rgb(T::MIN, T::MAX, T::MIN);
+    pub const TURQUOISE: Self = Self::rgb(T::MIN, T::MAX, T::MID);
+    pub const CYAN: Self = Self::rgb(T::MIN, T::MAX, T::MAX);
+    pub const SKY: Self = Self::rgb(T::MIN, T::MID, T::MAX);
+    pub const BLUE: Self = Self::rgb(T::MIN, T::MIN, T::MAX);
+    pub const PURPLE: Self = Self::rgb(T::MID, T::MIN, T::MAX);
+    pub const MAGENTA: Self = Self::rgb(T::MAX, T::MIN, T::MAX);
+
+    pub const NONE: Self = Self::new(T::MIN, T::MIN, T::MIN, T::MIN);
+
+    pub const fn new(r: T, g: T, b: T, a: T) -> Self {
+        Self { r, g, b, a }
+    }
+    pub const fn rgb(r: T, g: T, b: T) -> Self {
+        Self { r, g, b, a: T::MAX }
+    }
+    pub fn alpha(mut self, a: T) -> Self {
+        self.a = a;
+        self
+    }
+
+    pub fn as_arr(self) -> [T; 4] {
+        [self.r, self.g, self.b, self.a]
+    }
+}
+
+pub const trait F32Conversion {
+    fn to(self) -> f32;
+    fn from(x: f32) -> Self;
+}
+
+pub trait ColorNum {
+    const MIN: Self;
+    const MID: Self;
+    const MAX: Self;
+}
+
+macro_rules! map_rgb {
+    ($x:ident,$self:ident, $e:tt) => {
+        #[allow(unused_braces)]
+        Self {
+            r: {
+                let $x = $self.r;
+                $e
+            },
+            g: {
+                let $x = $self.g;
+                $e
+            },
+            b: {
+                let $x = $self.b;
+                $e
+            },
+            a: $self.a,
+        }
+    };
+}
+
+impl<T: ColorNum + const F32Conversion> Color<T>
+where
+    Self: const Destruct,
+{
+    pub const fn mul_rgb(self, amt: impl const F32Conversion) -> Self {
+        let amt = amt.to();
+        map_rgb!(x, self, { T::from(x.to() * amt) })
+    }
+
+    pub const fn add_rgb(self, amt: impl const F32Conversion) -> Self {
+        let amt = amt.to();
+        map_rgb!(x, self, { T::from(x.to() + amt) })
+    }
+
+    pub const fn darker(self, amt: f32) -> Self {
+        self.mul_rgb(1.0 - amt)
+    }
+
+    pub const fn brighter(self, amt: f32) -> Self {
+        map_rgb!(x, self, {
+            let x = x.to();
+            T::from(x + (1.0 - x) * amt)
+        })
+    }
+
+    pub fn map_rgb(self, f: impl Fn(T) -> T) -> Self {
+        Self {
+            r: f(self.r),
+            g: f(self.g),
+            b: f(self.b),
+            a: self.a,
+        }
+    }
+
+    pub fn srgb(r: T, g: T, b: T) -> Self {
+        Self {
+            r: s_to_l(r),
+            g: s_to_l(g),
+            b: s_to_l(b),
+            a: T::MAX,
+        }
+    }
+}
+
+fn s_to_l<T: F32Conversion>(x: T) -> T {
+    let x = x.to();
+    T::from(if x <= 0.0405 {
+        x / 12.92
+    } else {
+        ((x + 0.055) / 1.055).powf(2.4)
+    })
+}
+
+impl ColorNum for u8 {
+    const MIN: Self = u8::MIN;
+    const MID: Self = u8::MAX / 2;
+    const MAX: Self = u8::MAX;
+}
+
+impl ColorNum for f32 {
+    const MIN: Self = 0.0;
+    const MID: Self = 0.5;
+    const MAX: Self = 1.0;
+}
+
+unsafe impl bytemuck::Pod for Color<u8> {}
+
+impl const F32Conversion for f32 {
+    fn to(self) -> f32 {
+        self
+    }
+    fn from(x: f32) -> Self {
+        x
+    }
+}
+
+impl const F32Conversion for u8 {
+    fn to(self) -> f32 {
+        self as f32 / 255.0
+    }
+    fn from(x: f32) -> Self {
+        (x * 255.0).clamp(0.0, 255.0) as Self
+    }
+}

core/src/layout/primitive/layer.rs

@@ -0,0 +1,268 @@
+use std::ops::{Index, IndexMut};
+
+use crate::render::{MaskIdx, Primitive, PrimitiveHandle, PrimitiveInst, Primitives};
+
+struct LayerNode<T> {
+    next: Ptr,
+    prev: Ptr,
+    child: Option<Child>,
+    depth: usize,
+    data: T,
+}
+
+#[derive(Clone, Copy, Debug)]
+enum Ptr {
+    /// continue on same level
+    Next(usize),
+    /// go back to parent
+    Parent(usize),
+    /// end
+    None,
+}
+
+/// TODO: currently this does not ever free layers
+/// is that realistically desired?
+pub struct Layers<T> {
+    vec: Vec<LayerNode<T>>,
+    /// index of last layer at top level (start at first = 0)
+    last: usize,
+}
+
+#[derive(Clone, Copy)]
+struct Child {
+    head: usize,
+    tail: usize,
+}
+
+pub type PrimitiveLayers = Layers<Primitives>;
+
+impl<T: Default> Layers<T> {
+    pub fn new() -> Layers<T> {
+        Self {
+            vec: vec![LayerNode::head()],
+            last: 0,
+        }
+    }
+
+    pub fn clear(&mut self) {
+        self.vec.clear();
+        self.vec.push(LayerNode::head());
+    }
+
+    fn push(&mut self, node: LayerNode<T>) -> usize {
+        let i = self.vec.len();
+        self.vec.push(node);
+        i
+    }
+
+    pub fn next(&mut self, i: usize) -> usize {
+        if let Ptr::Next(i) = self.vec[i].next {
+            return i;
+        }
+        let i_new = self.push(LayerNode::new(
+            T::default(),
+            self.vec[i].next,
+            Ptr::Next(i),
+            self.vec[i].depth,
+        ));
+        self.vec[i].next = Ptr::Next(i_new);
+        self.vec[i_new].prev = Ptr::Next(i);
+        match self.vec[i_new].next {
+            Ptr::Next(i) => self.vec[i].prev = Ptr::Next(i_new),
+            Ptr::Parent(i) => self.vec[i].child.as_mut().unwrap().tail = i_new,
+            Ptr::None => self.last = i_new,
+        }
+        i_new
+    }
+
+    pub fn child(&mut self, i: usize) -> usize {
+        if let Some(c) = self.vec[i].child {
+            return c.head;
+        }
+        let i_child = self.push(LayerNode::new(
+            T::default(),
+            Ptr::Parent(i),
+            Ptr::Parent(i),
+            self.vec[i].depth + 1,
+        ));
+        self.vec[i].child = Some(Child {
+            head: i_child,
+            tail: i_child,
+        });
+        i_child
+    }
+
+    pub fn iter_mut(&mut self) -> LayerIteratorMut<'_, T> {
+        LayerIteratorMut::new(&mut self.vec, self.last)
+    }
+
+    pub fn iter_orderless_mut(&mut self) -> impl Iterator<Item = (usize, &mut T)> {
+        self.vec.iter_mut().map(|n| &mut n.data).enumerate()
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = (usize, &T)> {
+        self.indices().map(|i| (i, &self.vec[i].data))
+    }
+
+    pub fn iter_depth(&self) -> impl Iterator<Item = ((usize, usize), &T)> {
+        self.indices()
+            .map(|i| ((i, self.vec[i].depth), &self.vec[i].data))
+    }
+
+    pub fn indices(&self) -> LayerIndexIterator<'_, T> {
+        LayerIndexIterator::new(&self.vec, self.last)
+    }
+}
+
+impl PrimitiveLayers {
+    pub fn write<P: Primitive>(&mut self, layer: usize, info: PrimitiveInst<P>) -> PrimitiveHandle {
+        self[layer].write(layer, info)
+    }
+
+    pub fn free(&mut self, h: &PrimitiveHandle) -> MaskIdx {
+        self[h.layer].free(h)
+    }
+}
+
+impl<T: Default> Default for Layers<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T> Index<usize> for Layers<T> {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.vec[index].data
+    }
+}
+
+impl<T> IndexMut<usize> for Layers<T> {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        &mut self.vec[index].data
+    }
+}
+
+impl<T: Default> LayerNode<T> {
+    pub fn new(data: T, next: Ptr, prev: Ptr, depth: usize) -> Self {
+        Self {
+            next,
+            prev,
+            child: None,
+            data,
+            depth,
+        }
+    }
+
+    pub fn head() -> Self {
+        Self::new(T::default(), Ptr::None, Ptr::None, 0)
+    }
+}
+
+pub struct LayerIteratorMut<'a, T> {
+    inner: LayerIndexIterator<'a, T>,
+}
+
+impl<'a, T> Iterator for LayerIteratorMut<'a, T> {
+    type Item = (usize, &'a mut T);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let i = self.inner.next()?;
+        // SAFETY: requires index iterator to work properly
+        #[allow(mutable_transmutes)]
+        let layer = unsafe { std::mem::transmute::<&T, &mut T>(&self.inner.vec[i].data) };
+        Some((i, layer))
+    }
+}
+
+impl<'a, T> DoubleEndedIterator for LayerIteratorMut<'a, T> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        let i = self.inner.next_back()?;
+        // SAFETY: requires index iterator to work properly
+        #[allow(mutable_transmutes)]
+        let layer = unsafe { std::mem::transmute::<&T, &mut T>(&self.inner.vec[i].data) };
+        Some((i, layer))
+    }
+}
+
+impl<'a, T> LayerIteratorMut<'a, T> {
+    fn new(vec: &'a mut Vec<LayerNode<T>>, last: usize) -> Self {
+        Self {
+            inner: LayerIndexIterator::new(vec, last),
+        }
+    }
+}
+
+pub struct LayerIndexIterator<'a, T> {
+    next: Option<usize>,
+    next_back: Option<usize>,
+    vec: &'a Vec<LayerNode<T>>,
+}
+
+impl<'a, T> Iterator for LayerIndexIterator<'a, T> {
+    type Item = usize;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let ret_i = self.next?;
+        let node = &self.vec[ret_i];
+        self.next = if let Some(c) = node.child {
+            Some(c.head)
+        } else if let Ptr::Next(i) = node.next {
+            Some(i)
+        } else if let Ptr::Parent(i) = node.next {
+            let mut node = &self.vec[i];
+            while let Ptr::Parent(i) = node.next {
+                node = &self.vec[i];
+            }
+            if let Ptr::Next(i) = node.next {
+                Some(i)
+            } else {
+                None
+            }
+        } else {
+            None
+        };
+        if self.next_back.unwrap() == ret_i {
+            self.next = None;
+            self.next_back = None;
+        }
+        Some(ret_i)
+    }
+}
+
+impl<'a, T> DoubleEndedIterator for LayerIndexIterator<'a, T> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        let ret_i = self.next_back?;
+        let node = &self.vec[ret_i];
+        self.next_back = if let Ptr::Next(mut i) = node.prev {
+            while let Some(c) = self.vec[i].child {
+                i = c.tail
+            }
+            Some(i)
+        } else if let Ptr::Parent(i) = node.prev {
+            Some(i)
+        } else {
+            None
+        };
+        if self.next.unwrap() == ret_i {
+            self.next = None;
+            self.next_back = None;
+        }
+        Some(ret_i)
+    }
+}
+
+impl<'a, T> LayerIndexIterator<'a, T> {
+    fn new(vec: &'a Vec<LayerNode<T>>, last: usize) -> Self {
+        let mut last = last;
+        while let Some(c) = vec[last].child {
+            last = c.tail;
+        }
+        Self {
+            next: Some(0),
+            next_back: Some(last),
+            vec,
+        }
+    }
+}

core/src/layout/primitive/mask.rs

@@ -0,0 +1,46 @@
+//! tree structure for masking
+
+use crate::layout::UiRegion;
+
+pub struct Masks {
+    data: Vec<MaskNode>,
+}
+
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub struct MaskPtr(u32);
+
+#[repr(C)]
+pub struct MaskNode {
+    /// TODO: this is just a rect for now,
+    /// but would like to support arbitrary masks
+    /// at some point; custom shader
+    /// would probably handle that case
+    /// bc you'd need to render to a special target
+    /// anyways
+    region: UiRegion,
+    prev: MaskPtr,
+}
+
+impl MaskPtr {
+    const NONE: Self = Self(u32::MAX);
+}
+
+impl Masks {
+    pub fn push(&mut self, parent: MaskPtr, region: UiRegion) -> MaskPtr {
+        match parent.0 {
+            _ => {
+            }
+            u32::MAX => {
+                let i = self.data.len();
+                self.data.push(MaskNode {
+                    region,
+                    prev: parent,
+                });
+                MaskPtr(i as u32)
+            }
+        }
+    }
+
+    pub fn pop(&mut self, i: usize) {}
+}

core/src/layout/primitive/mod.rs

@@ -0,0 +1,9 @@
+mod color;
+mod layer;
+mod text;
+mod texture;
+
+pub use color::*;
+pub use layer::*;
+pub use text::*;
+pub use texture::*;

core/src/layout/primitive/text.rs

@@ -0,0 +1,193 @@
+use std::simd::{Simd, num::SimdUint};
+
+use crate::{
+    layout::{Align, RegionAlign, TextureHandle, Textures, UiColor, Vec2},
+    util::Handle,
+};
+use cosmic_text::{
+    Attrs, AttrsList, Buffer, CacheKey, Color, Family, FontSystem, Metrics, Placement, SwashCache,
+    SwashContent,
+};
+use image::{GenericImageView, RgbaImage};
+
+/// TODO: properly wrap this
+pub mod text_lib {
+    pub use cosmic_text::*;
+}
+
+pub type TextData = Handle<TextDataInner>;
+
+pub struct TextDataInner {
+    pub font_system: FontSystem,
+    pub swash_cache: SwashCache,
+    glyph_cache: Vec<(Placement, CacheKey, Color)>,
+}
+
+impl Default for TextDataInner {
+    fn default() -> Self {
+        Self {
+            font_system: FontSystem::new(),
+            swash_cache: SwashCache::new(),
+            glyph_cache: Default::default(),
+        }
+    }
+}
+
+#[derive(Clone, Copy)]
+pub struct TextAttrs {
+    pub color: UiColor,
+    pub font_size: f32,
+    pub line_height: f32,
+    pub family: Family<'static>,
+    pub wrap: bool,
+    /// inner alignment of text region (within where it's drawn)
+    pub align: RegionAlign,
+}
+
+impl TextAttrs {
+    pub fn apply(&self, font_system: &mut FontSystem, buf: &mut Buffer, width: Option<f32>) {
+        buf.set_metrics_and_size(
+            font_system,
+            Metrics::new(self.font_size, self.line_height),
+            width,
+            None,
+        );
+        let attrs = Attrs::new().family(self.family);
+        let list = AttrsList::new(&attrs);
+        for line in &mut buf.lines {
+            line.set_attrs_list(list.clone());
+        }
+    }
+}
+
+pub type TextBuffer = Buffer;
+
+impl Default for TextAttrs {
+    fn default() -> Self {
+        let size = 14.0;
+        Self {
+            color: UiColor::WHITE,
+            font_size: size,
+            line_height: size * LINE_HEIGHT_MULT,
+            family: Family::SansSerif,
+            wrap: false,
+            align: Align::CENTER_LEFT,
+        }
+    }
+}
+
+pub const LINE_HEIGHT_MULT: f32 = 1.1;
+
+impl TextDataInner {
+    pub fn draw(
+        &mut self,
+        buffer: &mut TextBuffer,
+        attrs: &TextAttrs,
+        textures: &mut Textures,
+    ) -> RenderedText {
+        // TODO: either this or the layout stuff (or both) is super slow,
+        // should probably do texture packing and things if possible.
+        // very visible if you add just a couple of wrapping texts and resize window
+        // should also be timed to figure out exactly what points need to be sped up
+        // let mut pixels = HashMap::<_, [u8; 4]>::default();
+        let mut min_x = 0;
+        let mut min_y = 0;
+        let mut max_x = 0;
+        let mut max_y = 0;
+        let text_color = {
+            let c = attrs.color;
+            cosmic_text::Color::rgba(c.r, c.g, c.b, c.a)
+        };
+        let mut max_width = 0.0f32;
+        let mut height = 0.0;
+
+        for run in buffer.layout_runs() {
+            for glyph in run.glyphs.iter() {
+                let physical_glyph = glyph.physical((0., 0.), 1.0);
+
+                let glyph_color = match glyph.color_opt {
+                    Some(some) => some,
+                    None => text_color,
+                };
+
+                if let Some(img) = self
+                    .swash_cache
+                    .get_image(&mut self.font_system, physical_glyph.cache_key)
+                {
+                    let mut pos = img.placement;
+                    pos.left += physical_glyph.x;
+                    pos.top = physical_glyph.y + run.line_y as i32 - pos.top;
+                    min_x = min_x.min(pos.left);
+                    min_y = min_y.min(pos.top);
+                    max_x = max_x.max(pos.left + pos.width as i32);
+                    max_y = max_y.max(pos.top + pos.height as i32);
+                    self.glyph_cache
+                        .push((pos, physical_glyph.cache_key, glyph_color));
+                }
+            }
+            max_width = max_width.max(run.line_w);
+            height += run.line_height;
+        }
+        let img_width = (max_x - min_x + 1) as u32;
+        let img_height = (max_y - min_y + 1) as u32;
+        let mut image = RgbaImage::new(img_width, img_height);
+
+        for (pos, key, color) in self.glyph_cache.drain(..) {
+            let img = self
+                .swash_cache
+                .get_image(&mut self.font_system, key)
+                .as_ref()
+                .unwrap();
+            let mut merge = |i, color: [u8; 4]| {
+                let i = i as i32;
+                let x = (i % pos.width as i32 + pos.left - min_x) as u32;
+                let y = (i / pos.width as i32 + pos.top - min_y) as u32;
+                let pixel = &mut image[(x, y)].0;
+                // TODO: no clue if proper alpha blending should be done
+                *pixel = Simd::from(color).saturating_add(Simd::from(*pixel)).into();
+            };
+
+            match img.content {
+                SwashContent::Mask => {
+                    for (i, a) in img.data.iter().enumerate() {
+                        let mut color = color.as_rgba();
+                        color[3] = ((color[3] as u32 * *a as u32) / u8::MAX as u32) as u8;
+                        merge(i, color);
+                    }
+                }
+                SwashContent::SubpixelMask => todo!("subpixel mask text rendering"),
+                SwashContent::Color => {
+                    let (colors, _) = img.data.as_chunks::<4>();
+                    for (i, color) in colors.iter().enumerate() {
+                        merge(i, *color);
+                    }
+                }
+            }
+        }
+
+        let max_dim = 8192;
+        if image.width() > max_dim || image.height() > max_dim {
+            let width = image.width().min(max_dim);
+            let height = image.height().min(max_dim);
+            eprintln!(
+                "WARNING: image of size {:?} cropped to {:?} (texture too big)",
+                image.dimensions(),
+                (width, height)
+            );
+            image = image.view(0, 0, width, height).to_image();
+        }
+
+        RenderedText {
+            handle: textures.add(image),
+            top_left_offset: Vec2::new(min_x as f32, min_y as f32),
+            size: Vec2::new(max_width, height),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub struct RenderedText {
+    pub handle: TextureHandle,
+    pub top_left_offset: Vec2,
+    pub size: Vec2,
+}

core/src/layout/primitive/texture.rs

@@ -0,0 +1,135 @@
+use std::{
+    ops::Index,
+    sync::mpsc::{Receiver, Sender, channel},
+};
+
+use image::{DynamicImage, GenericImageView};
+
+use crate::{layout::Vec2, render::TexturePrimitive, util::RefCounter};
+
+#[derive(Debug, Clone)]
+pub struct TextureHandle {
+    inner: TexturePrimitive,
+    size: Vec2,
+    counter: RefCounter,
+    send: Sender<u32>,
+}
+
+/// a texture manager for a ui
+/// note that this is heavily oriented towards wgpu's renderer so the primitives don't need mapped
+pub struct Textures {
+    free: Vec<u32>,
+    images: Vec<Option<DynamicImage>>,
+    updates: Vec<Update>,
+    send: Sender<u32>,
+    recv: Receiver<u32>,
+}
+
+pub enum TextureUpdate<'a> {
+    Push(&'a DynamicImage),
+    Set(u32, &'a DynamicImage),
+    Free(u32),
+    PushFree,
+    SetFree,
+}
+
+enum Update {
+    Push(u32),
+    Set(u32),
+    Free(u32),
+}
+
+impl Textures {
+    pub fn new() -> Self {
+        let (send, recv) = channel();
+        Self {
+            free: Vec::new(),
+            images: Vec::new(),
+            updates: Vec::new(),
+            send,
+            recv,
+        }
+    }
+    pub fn add(&mut self, image: impl Into<DynamicImage>) -> TextureHandle {
+        let image = image.into();
+        let size = image.dimensions().into();
+        let view_idx = self.push(image);
+        // 0 == default in renderer; TODO: actually create samplers here
+        let sampler_idx = 0;
+        TextureHandle {
+            inner: TexturePrimitive {
+                view_idx,
+                sampler_idx,
+            },
+            size,
+            counter: RefCounter::new(),
+            send: self.send.clone(),
+        }
+    }
+
+    fn push(&mut self, image: DynamicImage) -> u32 {
+        if let Some(i) = self.free.pop() {
+            self.images[i as usize] = Some(image);
+            self.updates.push(Update::Set(i));
+            i
+        } else {
+            let i = self.images.len() as u32;
+            self.images.push(Some(image));
+            self.updates.push(Update::Push(i));
+            i
+        }
+    }
+
+    pub fn free(&mut self) {
+        for idx in self.recv.try_iter() {
+            self.images[idx as usize] = None;
+            self.updates.push(Update::Free(idx));
+            self.free.push(idx);
+        }
+    }
+
+    pub fn updates(&mut self) -> impl Iterator<Item = TextureUpdate<'_>> {
+        self.updates.drain(..).map(|u| match u {
+            Update::Push(i) => self.images[i as usize]
+                .as_ref()
+                .map(TextureUpdate::Push)
+                .unwrap_or(TextureUpdate::PushFree),
+            Update::Set(i) => self.images[i as usize]
+                .as_ref()
+                .map(|img| TextureUpdate::Set(i, img))
+                .unwrap_or(TextureUpdate::SetFree),
+            Update::Free(i) => TextureUpdate::Free(i),
+        })
+    }
+}
+
+impl TextureHandle {
+    pub fn primitive(&self) -> TexturePrimitive {
+        self.inner
+    }
+    pub fn size(&self) -> Vec2 {
+        self.size
+    }
+}
+
+impl Drop for TextureHandle {
+    fn drop(&mut self) {
+        if self.counter.drop() {
+            let _ = self.send.send(self.inner.view_idx);
+        }
+    }
+}
+
+impl Index<&TextureHandle> for Textures {
+    type Output = DynamicImage;
+
+    fn index(&self, index: &TextureHandle) -> &Self::Output {
+        self.images[index.inner.view_idx as usize].as_ref().unwrap()
+    }
+}
+
+impl Default for Textures {
+    fn default() -> Self {
+        Self::new()
+    }
+}

core/src/layout/ui.rs

@@ -0,0 +1,167 @@
+use image::DynamicImage;
+
+use crate::{
+    layout::{
+        IdLike, PainterData, PixelRegion, TextureHandle, Vec2, Widget, WidgetInstance, WidgetLike,
+        WidgetRef, WidgetUpdate,
+    },
+    util::{HashSet, Id},
+};
+use std::sync::mpsc::{Receiver, channel};
+
+pub struct Ui {
+    pub(crate) data: PainterData,
+    root: Option<WidgetRef>,
+    updates: HashSet<Id>,
+    free: Vec<Id>,
+    recv: Receiver<WidgetUpdate>,
+    full_redraw: bool,
+    resized: bool,
+}
+
+impl Ui {
+    pub fn add<W: Widget, Tag>(&mut self, w: impl WidgetLike<Tag, Widget = W>) -> WidgetRef<W> {
+        w.add(self)
+    }
+
+    pub fn add_widget<W: Widget>(&mut self, w: W) -> WidgetRef<W> {
+        self.data.widgets.insert(w)
+    }
+
+    pub fn set_root<Tag>(&mut self, w: impl WidgetLike<Tag>) {
+        self.root = Some(w.add(self));
+        self.full_redraw = true;
+    }
+
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn add_texture(&mut self, image: DynamicImage) -> TextureHandle {
+        self.data.textures.add(image)
+    }
+
+    pub fn resize(&mut self, size: impl Into<Vec2>) {
+        self.data.output_size = size.into();
+        self.resized = true;
+    }
+
+    fn redraw_all(&mut self) {
+        for (_, inst) in self.data.active.drain() {
+            for m in self.data.modules.iter_mut() {
+                m.on_undraw(&inst);
+            }
+        }
+        // free before bc nothing should exist
+        self.free();
+        if let Some(root) = &self.root {
+            self.data.draw(root);
+        }
+    }
+
+    pub fn update(&mut self) -> bool {
+        for update in self.recv.try_iter() {
+            match update {
+                WidgetUpdate::Drop(id) => {
+                    self.free.push(id);
+                }
+                WidgetUpdate::Mutate(id) => {
+                    self.updates.insert(id);
+                }
+            }
+        }
+        if self.full_redraw {
+            self.redraw_all();
+            self.full_redraw = false;
+            true
+        } else if self.resized {
+            self.resized = false;
+            self.redraw_all();
+            true
+        } else if !self.updates.is_empty() {
+            self.redraw_updates();
+            true
+        } else {
+            false
+        }
+    }
+
+    fn redraw_updates(&mut self) {
+        self.data.redraw(std::mem::take(&mut self.updates));
+        self.free();
+    }
+
+    /// free any resources that don't have references anymore
+    fn free(&mut self) {
+        for id in self.free.drain(..) {
+            for m in self.data.modules.iter_mut() {
+                m.on_remove(&id);
+            }
+            self.data.widgets.delete(id);
+        }
+        self.data.textures.free();
+    }
+
+    pub fn needs_redraw(&self) -> bool {
+        self.full_redraw || !self.updates.is_empty()
+    }
+
+    pub fn num_widgets(&self) -> usize {
+        self.data.widgets.len()
+    }
+
+    pub fn active_widgets(&self) -> usize {
+        self.data.active.len()
+    }
+
+    pub fn debug_layers(&self) {
+        for ((idx, depth), primitives) in self.data.layers.iter_depth() {
+            let indent = " ".repeat(depth * 2);
+            let len = primitives.instances().len();
+            print!("{indent}{idx}: {len} primitives");
+            if len >= 1 {
+                print!(" ({})", primitives.instances()[0].binding);
+            }
+            println!();
+        }
+    }
+
+    pub fn window_region<W>(&self, id: &impl IdLike<W>) -> Option<PixelRegion> {
+        let region = self.data.active.get(&id.id())?.region;
+        Some(region.to_px(self.data.output_size))
+    }
+
+    pub fn debug(&self, label: &str) -> impl Iterator<Item = &WidgetInstance> {
+        self.data.active.iter().filter_map(move |(id, inst)| {
+            let widget = &self.data.widgets.get(*id);
+            if widget.get_label().as_str() == label {
+                Some(inst)
+            } else {
+                None
+            }
+        })
+    }
+
+    pub fn data(&self) -> &PainterData {
+        &self.data
+    }
+
+    pub fn data_mut(&mut self) -> &mut PainterData {
+        &mut self.data
+    }
+}
+
+impl Default for Ui {
+    fn default() -> Self {
+        let (send, recv) = channel();
+        Self {
+            data: PainterData::new(send),
+            root: Default::default(),
+            updates: Default::default(),
+            free: Default::default(),
+            full_redraw: false,
+            recv,
+            resized: false,
+        }
+    }
+}

core/src/layout/view.rs

@@ -0,0 +1,17 @@
+use crate::layout::{Widget, WidgetLike, WidgetRef};
+use std::marker::Unsize;
+
+pub trait WidgetView {
+    type Widget: Widget + ?Sized + Unsize<dyn Widget> = dyn Widget;
+    fn view(&self) -> &WidgetRef<Self::Widget>;
+}
+
+pub struct ViewTag;
+
+impl<WV: WidgetView> WidgetLike<ViewTag> for WV {
+    type Widget = WV::Widget;
+
+    fn add(self, _ui: &mut super::Ui) -> WidgetRef<Self::Widget> {
+        self.view().clone()
+    }
+}

core/src/layout/widget/handle.rs

@@ -0,0 +1,163 @@
+use std::{
+    cell::{Ref, RefMut},
+    marker::Unsize,
+    ops::CoerceUnsized,
+    sync::mpsc::Sender,
+};
+
+use crate::{
+    layout::{IdFnTag, IdTag, Ui, Widget, WidgetLike},
+    util::{Handle, Id, WeakHandle},
+};
+
+/// An handle for a widget in a UI.
+///
+/// TODO: ergonomic clones when they get put in rust-analyzer & don't cause ICEs?
+pub struct WidgetRef<W: ?Sized = dyn Widget>(Handle<Inner<W>>);
+pub struct WeakWidgetRef<W: ?Sized = dyn Widget>(WeakHandle<Inner<W>>);
+
+struct Inner<W: ?Sized> {
+    id: Id,
+    send: Sender<WidgetUpdate>,
+    label: String,
+    widget: W,
+}
+
+pub enum WidgetUpdate {
+    Drop(Id),
+    Mutate(Id),
+}
+
+impl<W> PartialEq for WidgetRef<W> {
+    fn eq(&self, other: &Self) -> bool {
+        self.id() == other.id()
+    }
+}
+
+impl<W> std::fmt::Debug for WidgetRef<W> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.id().fmt(f)
+    }
+}
+
+impl<W: ?Sized> Clone for WidgetRef<W> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<W: Widget> WidgetRef<W> {
+    pub(super) fn new(id: Id, widget: W, send: Sender<WidgetUpdate>) -> Self {
+        let mut label = std::any::type_name::<W>().to_string();
+        if let (Some(first), Some(last)) = (label.find(":"), label.rfind(":")) {
+            label = label.split_at(first).0.to_string() + "::" + label.split_at(last + 1).1;
+        }
+        Self(
+            Inner {
+                widget,
+                id,
+                send,
+                label,
+            }
+            .into(),
+        )
+    }
+}
+
+impl<W: Widget + ?Sized + Unsize<dyn Widget>> WidgetRef<W> {
+    pub fn any(self) -> WidgetRef<dyn Widget> {
+        WidgetRef(self.0)
+    }
+    pub fn as_any(&self) -> WidgetRef<dyn Widget> {
+        WidgetRef(self.0.clone())
+    }
+}
+
+impl<W: ?Sized> WidgetRef<W> {
+    pub fn id(&self) -> Id {
+        self.0.get().id
+    }
+
+    pub fn get(&self) -> Ref<'_, W> {
+        Ref::map(self.0.get(), |i| &i.widget)
+    }
+
+    pub fn get_mut(&self) -> RefMut<'_, W> {
+        let inner = self.0.get_mut();
+        let _ = inner.send.send(WidgetUpdate::Mutate(inner.id));
+        RefMut::map(inner, |i| &mut i.widget)
+    }
+
+    pub fn get_mut_quiet(&self) -> RefMut<'_, W> {
+        RefMut::map(self.0.get_mut(), |i| &mut i.widget)
+    }
+
+    pub fn get_label(&self) -> Ref<'_, String> {
+        Ref::map(self.0.get(), |i| &i.label)
+    }
+
+    pub fn set_label(&self, label: impl Into<String>) {
+        self.0.get_mut().label = label.into();
+    }
+
+    pub fn refs(&self) -> usize {
+        self.0.refs()
+    }
+
+    pub fn weak(&self) -> WeakWidgetRef<W> {
+        WeakWidgetRef(self.0.weak())
+    }
+}
+
+impl<W: ?Sized> WeakWidgetRef<W> {
+    /// should guarantee that widget is still valid to prevent indexing failures
+    pub(crate) fn expect_strong(&self) -> WidgetRef<W> {
+        WidgetRef(self.0.strong().expect("widget should not be dropped"))
+    }
+}
+
+impl<W: Widget + ?Sized + Unsize<dyn Widget>> WeakWidgetRef<W> {
+    pub fn any(self) -> WeakWidgetRef<dyn Widget> {
+        WeakWidgetRef(self.0.clone())
+    }
+}
+
+impl<W: ?Sized> Drop for Inner<W> {
+    fn drop(&mut self) {
+        let _ = self.send.send(WidgetUpdate::Drop(self.id));
+    }
+}
+
+pub trait WidgetIdFn<W: ?Sized = dyn Widget>: FnOnce(&mut Ui) -> WidgetRef<W> {}
+impl<W: ?Sized, F: FnOnce(&mut Ui) -> WidgetRef<W>> WidgetIdFn<W> for F {}
+
+pub trait WidgetRet: FnOnce(&mut Ui) -> WidgetRef {}
+impl<F: FnOnce(&mut Ui) -> WidgetRef> WidgetRet for F {}
+
+impl<W: Widget + ?Sized + Unsize<dyn Widget> + 'static> WidgetLike<IdTag> for WidgetRef<W> {
+    type Widget = W;
+    fn add(self, _: &mut Ui) -> WidgetRef<W> {
+        self
+    }
+}
+
+impl<W: Widget + ?Sized + Unsize<dyn Widget> + 'static, F: FnOnce(&mut Ui) -> WidgetRef<W>>
+    WidgetLike<IdFnTag> for F
+{
+    type Widget = W;
+    fn add(self, ui: &mut Ui) -> WidgetRef<W> {
+        self(ui)
+    }
+}
+
+pub trait IdLike<W> {
+    fn id(&self) -> Id;
+}
+
+impl<W> IdLike<W> for WidgetRef<W> {
+    fn id(&self) -> Id {
+        self.id()
+    }
+}
+
+impl<W: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<WidgetRef<U>> for WidgetRef<W> {}

core/src/layout/widget/like.rs

@@ -0,0 +1,79 @@
+use super::*;
+use std::marker::Unsize;
+
+pub trait WidgetLike<Tag> {
+    type Widget: Widget + ?Sized + Unsize<dyn Widget> + 'static;
+
+    fn add(self, ui: &mut Ui) -> WidgetRef<Self::Widget>;
+
+    fn with_id<W2>(
+        self,
+        f: impl FnOnce(&mut Ui, WidgetRef<Self::Widget>) -> WidgetRef<W2>,
+    ) -> impl WidgetIdFn<W2>
+    where
+        Self: Sized,
+    {
+        move |ui| {
+            let id = self.add(ui);
+            f(ui, id)
+        }
+    }
+
+    fn set_root(self, ui: &mut Ui)
+    where
+        Self: Sized,
+    {
+        ui.set_root(self);
+    }
+}
+
+pub struct WidgetArr<const LEN: usize> {
+    pub arr: [WidgetRef; LEN],
+}
+
+impl<const LEN: usize> WidgetArr<LEN> {
+    pub fn new(arr: [WidgetRef; LEN]) -> Self {
+        Self { arr }
+    }
+}
+
+pub trait WidgetArrLike<const LEN: usize, Tag> {
+    fn ui(self, ui: &mut Ui) -> WidgetArr<LEN>;
+}
+
+impl<const LEN: usize> WidgetArrLike<LEN, ArrTag> for WidgetArr<LEN> {
+    fn ui(self, _: &mut Ui) -> WidgetArr<LEN> {
+        self
+    }
+}
+
+// I hate this language it's so bad why do I even use it
+macro_rules! impl_widget_arr {
+    ($n:expr;$($W:ident)*) => {
+        impl_widget_arr!($n;$($W)*;$(${concat($W,Tag)})*);
+    };
+    ($n:expr;$($W:ident)*;$($Tag:ident)*) => {
+        impl<$($W: WidgetLike<$Tag>,$Tag,)*> WidgetArrLike<$n, ($($Tag,)*)> for ($($W,)*) {
+            fn ui(self, ui: &mut Ui) -> WidgetArr<$n> {
+                #[allow(non_snake_case)]
+                let ($($W,)*) = self;
+                WidgetArr::new(
+                    [$($W.add(ui),)*],
+                )
+            }
+        }
+    };
+}
+
+impl_widget_arr!(1;A);
+impl_widget_arr!(2;A B);
+impl_widget_arr!(3;A B C);
+impl_widget_arr!(4;A B C D);
+impl_widget_arr!(5;A B C D E);
+impl_widget_arr!(6;A B C D E F);
+impl_widget_arr!(7;A B C D E F G);
+impl_widget_arr!(8;A B C D E F G H);
+impl_widget_arr!(9;A B C D E F G H I);
+impl_widget_arr!(10;A B C D E F G H I J);
+impl_widget_arr!(11;A B C D E F G H I J K);
+impl_widget_arr!(12;A B C D E F G H I J K L);

core/src/layout/widget/mod.rs

@@ -0,0 +1,63 @@
+mod handle;
+mod like;
+mod tag;
+mod widgets;
+
+pub use handle::*;
+pub use like::*;
+pub use tag::*;
+pub use widgets::*;
+
+use crate::layout::{Len, Painter, SizeCtx, Ui};
+
+pub trait Widget: 'static {
+    fn draw(&mut self, painter: &mut Painter);
+    fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len;
+    fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len;
+}
+
+impl Widget for () {
+    fn draw(&mut self, _: &mut Painter) {}
+    fn desired_width(&mut self, _: &mut SizeCtx) -> Len {
+        Len::ZERO
+    }
+    fn desired_height(&mut self, _: &mut SizeCtx) -> Len {
+        Len::ZERO
+    }
+}
+
+/// A function that returns a widget given a UI.
+/// Useful for defining trait functions on widgets that create a parent widget so that the children
+/// don't need to be IDs yet
+pub trait WidgetFn<W: Widget + ?Sized>: FnOnce(&mut Ui) -> W {}
+impl<W: Widget, F: FnOnce(&mut Ui) -> W> WidgetFn<W> for F {}
+
+impl<W: Widget, F: FnOnce(&mut Ui) -> W> WidgetLike<FnTag> for F {
+    type Widget = W;
+    fn add(self, ui: &mut Ui) -> WidgetRef<W> {
+        self(ui).add(ui)
+    }
+}
+
+impl<W: Widget> WidgetLike<WidgetTag> for W {
+    type Widget = W;
+    fn add(self, ui: &mut Ui) -> WidgetRef<W> {
+        ui.add_widget(self)
+    }
+}
+
+pub trait WidgetOption {
+    fn get(self, ui: &mut Ui) -> Option<WidgetRef>;
+}
+
+impl WidgetOption for () {
+    fn get(self, _: &mut Ui) -> Option<WidgetRef> {
+        None
+    }
+}
+
+impl<F: FnOnce(&mut Ui) -> Option<WidgetRef>> WidgetOption for F {
+    fn get(self, ui: &mut Ui) -> Option<WidgetRef> {
+        self(ui)
+    }
+}

core/src/layout/widget/tag.rs

@@ -0,0 +1,5 @@
+pub struct WidgetTag;
+pub struct FnTag;
+pub struct IdTag;
+pub struct IdFnTag;
+pub struct ArrTag;

core/src/layout/widget/widgets.rs

@@ -0,0 +1,50 @@
+use std::sync::mpsc::Sender;
+
+use crate::{
+    layout::{WeakWidgetRef, Widget, WidgetRef, WidgetUpdate},
+    util::{HashMap, Id, IdTracker},
+};
+
+pub struct Widgets {
+    ids: IdTracker,
+    map: HashMap<Id, WeakWidgetRef>,
+    send: Sender<WidgetUpdate>,
+}
+
+impl Widgets {
+    pub fn new(send: Sender<WidgetUpdate>) -> Self {
+        Self {
+            ids: IdTracker::default(),
+            map: HashMap::default(),
+            send,
+        }
+    }
+
+    pub fn get(&self, id: Id) -> WidgetRef {
+        self.map.get(&id).unwrap().expect_strong()
+    }
+
+    pub fn insert<W: Widget>(&mut self, widget: W) -> WidgetRef<W> {
+        let id = self.ids.next();
+        let rf = WidgetRef::new(id, widget, self.send.clone());
+        self.map.insert(id, rf.weak().any());
+        rf
+    }
+
+    pub fn delete(&mut self, id: Id) {
+        self.map.remove(&id);
+        self.ids.free(id);
+    }
+
+    pub fn reserve(&mut self) -> Id {
+        self.ids.next()
+    }
+
+    pub fn len(&self) -> usize {
+        self.map.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.map.is_empty()
+    }
+}

core/src/lib.rs

@@ -0,0 +1,19 @@
+#![feature(macro_metavar_expr_concat)]
+#![feature(const_ops)]
+#![feature(const_trait_impl)]
+#![feature(const_convert)]
+#![feature(map_try_insert)]
+#![feature(unboxed_closures)]
+#![feature(fn_traits)]
+#![feature(const_cmp)]
+#![feature(const_destruct)]
+#![feature(portable_simd)]
+#![feature(associated_type_defaults)]
+#![feature(unsize)]
+#![feature(coerce_unsized)]
+
+pub mod layout;
+pub mod render;
+pub mod util;
+
+pub use image;

core/src/render/data.rs

@@ -0,0 +1,50 @@
+use crate::{layout::UiRegion, util::Id};
+use wgpu::*;
+
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable, Default)]
+pub struct WindowUniform {
+    pub width: f32,
+    pub height: f32,
+}
+
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct PrimitiveInstance {
+    pub region: UiRegion,
+    pub binding: u32,
+    pub idx: u32,
+    pub mask_idx: MaskIdx,
+}
+
+impl PrimitiveInstance {
+    const ATTRIBS: [VertexAttribute; 7] = vertex_attr_array![
+        0 => Float32x2,
+        1 => Float32x2,
+        2 => Float32x2,
+        3 => Float32x2,
+        4 => Uint32,
+        5 => Uint32,
+        6 => Uint32,
+    ];
+
+    pub fn desc() -> VertexBufferLayout<'static> {
+        VertexBufferLayout {
+            array_stride: std::mem::size_of::<Self>() as BufferAddress,
+            step_mode: VertexStepMode::Instance,
+            attributes: &Self::ATTRIBS,
+        }
+    }
+}
+
+pub type MaskIdx = Id<u32>;
+
+impl MaskIdx {
+    pub const NONE: Self = Self::preset(u32::MAX);
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct Mask {
+    pub region: UiRegion,
+}

core/src/render/mod.rs

@@ -0,0 +1,356 @@
+use std::num::NonZero;
+
+use crate::{
+    layout::Ui,
+    render::{data::PrimitiveInstance, texture::GpuTextures, util::ArrBuf},
+    util::HashMap,
+};
+use data::WindowUniform;
+use wgpu::{
+    util::{BufferInitDescriptor, DeviceExt},
+    *,
+};
+use winit::dpi::PhysicalSize;
+
+mod data;
+mod primitive;
+mod texture;
+mod util;
+
+pub use data::{Mask, MaskIdx};
+pub use primitive::*;
+
+const SHAPE_SHADER: &str = include_str!("./shader.wgsl");
+
+pub struct UiRenderNode {
+    uniform_group: BindGroup,
+    primitive_layout: BindGroupLayout,
+    rsc_layout: BindGroupLayout,
+    rsc_group: BindGroup,
+
+    pipeline: RenderPipeline,
+
+    layers: HashMap<usize, RenderLayer>,
+    active: Vec<usize>,
+    window_buffer: Buffer,
+    textures: GpuTextures,
+    masks: ArrBuf<Mask>,
+}
+
+struct RenderLayer {
+    instance: ArrBuf<PrimitiveInstance>,
+    primitives: PrimitiveBuffers,
+    primitive_group: BindGroup,
+}
+
+impl UiRenderNode {
+    pub fn draw<'a>(&'a self, pass: &mut RenderPass<'a>) {
+        pass.set_pipeline(&self.pipeline);
+        pass.set_bind_group(0, &self.uniform_group, &[]);
+        pass.set_bind_group(2, &self.rsc_group, &[]);
+        for i in &self.active {
+            let layer = &self.layers[i];
+            if layer.instance.len() == 0 {
+                continue;
+            }
+            pass.set_bind_group(1, &layer.primitive_group, &[]);
+            pass.set_vertex_buffer(0, layer.instance.buffer.slice(..));
+            pass.draw(0..4, 0..layer.instance.len() as u32);
+        }
+    }
+
+    pub fn update(&mut self, device: &Device, queue: &Queue, ui: &mut Ui) {
+        self.active.clear();
+        for (i, primitives) in ui.data.layers.iter_mut() {
+            self.active.push(i);
+            for change in primitives.apply_free() {
+                if let Some(inst) = ui.data.active.get_mut(&change.id) {
+                    for h in &mut inst.primitives {
+                        if h.layer == i && h.inst_idx == change.old {
+                            h.inst_idx = change.new;
+                            break;
+                        }
+                    }
+                }
+            }
+            let rlayer = self.layers.entry(i).or_insert_with(|| {
+                let primitives = PrimitiveBuffers::new(device);
+                let primitive_group =
+                    Self::primitive_group(device, &self.primitive_layout, primitives.buffers());
+                RenderLayer {
+                    instance: ArrBuf::new(
+                        device,
+                        BufferUsages::VERTEX | BufferUsages::COPY_DST,
+                        "instance",
+                    ),
+                    primitives,
+                    primitive_group,
+                }
+            });
+            if primitives.updated {
+                rlayer
+                    .instance
+                    .update(device, queue, primitives.instances());
+                rlayer.primitives.update(device, queue, primitives.data());
+                rlayer.primitive_group = Self::primitive_group(
+                    device,
+                    &self.primitive_layout,
+                    rlayer.primitives.buffers(),
+                );
+                primitives.updated = false;
+            }
+        }
+        let mut changed = false;
+        changed |= self.textures.update(&mut ui.data.textures);
+        if ui.data.masks.changed {
+            ui.data.masks.changed = false;
+            self.masks.update(device, queue, &ui.data.masks[..]);
+            changed = true;
+        }
+        if changed {
+            self.rsc_group = Self::rsc_group(device, &self.rsc_layout, &self.textures, &self.masks);
+        }
+    }
+
+    pub fn resize(&mut self, size: &PhysicalSize<u32>, queue: &Queue) {
+        let slice = &[WindowUniform {
+            width: size.width as f32,
+            height: size.height as f32,
+        }];
+        queue.write_buffer(&self.window_buffer, 0, bytemuck::cast_slice(slice));
+    }
+
+    pub fn new(
+        device: &Device,
+        queue: &Queue,
+        config: &SurfaceConfiguration,
+        limits: UiLimits,
+    ) -> Self {
+        let shader = device.create_shader_module(ShaderModuleDescriptor {
+            label: Some("UI Shape Shader"),
+            source: ShaderSource::Wgsl(SHAPE_SHADER.into()),
+        });
+
+        let window_uniform = WindowUniform::default();
+        let window_buffer = device.create_buffer_init(&BufferInitDescriptor {
+            label: Some("window"),
+            contents: bytemuck::cast_slice(&[window_uniform]),
+            usage: BufferUsages::UNIFORM | BufferUsages::COPY_DST,
+        });
+
+        let uniform_layout = device.create_bind_group_layout(&BindGroupLayoutDescriptor {
+            entries: &[BindGroupLayoutEntry {
+                binding: 0,
+                visibility: ShaderStages::VERTEX | ShaderStages::FRAGMENT,
+                ty: BindingType::Buffer {
+                    ty: BufferBindingType::Uniform,
+                    has_dynamic_offset: false,
+                    min_binding_size: None,
+                },
+                count: None,
+            }],
+            label: Some("window"),
+        });
+
+        let uniform_group = Self::bind_group_0(device, &uniform_layout, &window_buffer);
+
+        let primitive_layout = device.create_bind_group_layout(&BindGroupLayoutDescriptor {
+            entries: &core::array::from_fn::<_, { PrimitiveBuffers::LEN }, _>(|i| {
+                BindGroupLayoutEntry {
+                    binding: i as u32,
+                    visibility: ShaderStages::FRAGMENT,
+                    ty: BindingType::Buffer {
+                        ty: BufferBindingType::Storage { read_only: true },
+                        has_dynamic_offset: false,
+                        min_binding_size: None,
+                    },
+                    count: None,
+                }
+            }),
+            label: Some("primitive"),
+        });
+
+        let tex_manager = GpuTextures::new(device, queue);
+        let masks = ArrBuf::new(
+            device,
+            BufferUsages::STORAGE | BufferUsages::COPY_DST,
+            "ui masks",
+        );
+
+        let rsc_layout = Self::rsc_layout(device, &limits);
+        let rsc_group = Self::rsc_group(device, &rsc_layout, &tex_manager, &masks);
+
+        let pipeline_layout = device.create_pipeline_layout(&PipelineLayoutDescriptor {
+            label: Some("UI Shape Pipeline Layout"),
+            bind_group_layouts: &[&uniform_layout, &primitive_layout, &rsc_layout],
+            push_constant_ranges: &[],
+        });
+        let pipeline = device.create_render_pipeline(&RenderPipelineDescriptor {
+            label: Some("UI Shape Pipeline"),
+            layout: Some(&pipeline_layout),
+            vertex: VertexState {
+                module: &shader,
+                entry_point: Some("vs_main"),
+                buffers: &[PrimitiveInstance::desc()],
+                compilation_options: Default::default(),
+            },
+            fragment: Some(FragmentState {
+                module: &shader,
+                entry_point: Some("fs_main"),
+                targets: &[Some(ColorTargetState {
+                    format: config.format,
+                    blend: Some(BlendState::ALPHA_BLENDING),
+                    write_mask: ColorWrites::ALL,
+                })],
+                compilation_options: Default::default(),
+            }),
+            primitive: PrimitiveState {
+                topology: PrimitiveTopology::TriangleStrip,
+                strip_index_format: None,
+                front_face: FrontFace::Cw,
+                cull_mode: Some(Face::Back),
+                polygon_mode: PolygonMode::Fill,
+                unclipped_depth: false,
+                conservative: false,
+            },
+            depth_stencil: None,
+            multisample: MultisampleState {
+                count: 1,
+                mask: !0,
+                alpha_to_coverage_enabled: false,
+            },
+            multiview: None,
+            cache: None,
+        });
+
+        Self {
+            uniform_group,
+            primitive_layout,
+            rsc_layout,
+            rsc_group,
+            pipeline,
+            window_buffer,
+            layers: HashMap::default(),
+            active: Vec::new(),
+            textures: tex_manager,
+            masks,
+        }
+    }
+
+    fn bind_group_0(
+        device: &Device,
+        layout: &BindGroupLayout,
+        window_buffer: &Buffer,
+    ) -> BindGroup {
+        device.create_bind_group(&BindGroupDescriptor {
+            layout,
+            entries: &[BindGroupEntry {
+                binding: 0,
+                resource: window_buffer.as_entire_binding(),
+            }],
+            label: Some("ui window"),
+        })
+    }
+
+    fn primitive_group(
+        device: &Device,
+        layout: &BindGroupLayout,
+        buffers: [(u32, &Buffer); PrimitiveBuffers::LEN],
+    ) -> BindGroup {
+        device.create_bind_group(&BindGroupDescriptor {
+            layout,
+            entries: &buffers.map(|(binding, buf)| BindGroupEntry {
+                binding,
+                resource: buf.as_entire_binding(),
+            }),
+            label: Some("ui primitives"),
+        })
+    }
+
+    fn rsc_layout(device: &Device, limits: &UiLimits) -> BindGroupLayout {
+        device.create_bind_group_layout(&BindGroupLayoutDescriptor {
+            entries: &[
+                BindGroupLayoutEntry {
+                    binding: 0,
+                    visibility: ShaderStages::FRAGMENT,
+                    ty: BindingType::Texture {
+                        sample_type: TextureSampleType::Float { filterable: false },
+                        view_dimension: TextureViewDimension::D2,
+                        multisampled: false,
+                    },
+                    count: Some(NonZero::new(limits.max_textures).unwrap()),
+                },
+                BindGroupLayoutEntry {
+                    binding: 1,
+                    visibility: ShaderStages::FRAGMENT,
+                    ty: BindingType::Sampler(SamplerBindingType::NonFiltering),
+                    count: Some(NonZero::new(limits.max_samplers).unwrap()),
+                },
+                BindGroupLayoutEntry {
+                    binding: 2,
+                    visibility: ShaderStages::FRAGMENT,
+                    ty: BindingType::Buffer {
+                        ty: BufferBindingType::Storage { read_only: true },
+                        has_dynamic_offset: false,
+                        min_binding_size: None,
+                    },
+                    count: None,
+                },
+            ],
+            label: Some("ui rsc"),
+        })
+    }
+
+    fn rsc_group(
+        device: &Device,
+        layout: &BindGroupLayout,
+        tex_manager: &GpuTextures,
+        masks: &ArrBuf<Mask>,
+    ) -> BindGroup {
+        device.create_bind_group(&BindGroupDescriptor {
+            layout,
+            entries: &[
+                BindGroupEntry {
+                    binding: 0,
+                    resource: BindingResource::TextureViewArray(&tex_manager.views()),
+                },
+                BindGroupEntry {
+                    binding: 1,
+                    resource: BindingResource::SamplerArray(&tex_manager.samplers()),
+                },
+                BindGroupEntry {
+                    binding: 2,
+                    resource: masks.buffer.as_entire_binding(),
+                },
+            ],
+            label: Some("ui rsc"),
+        })
+    }
+
+    pub fn view_count(&self) -> usize {
+        self.textures.view_count()
+    }
+}
+
+pub struct UiLimits {
+    max_textures: u32,
+    max_samplers: u32,
+}
+
+impl Default for UiLimits {
+    fn default() -> Self {
+        Self {
+            max_textures: 100000,
+            max_samplers: 1000,
+        }
+    }
+}
+
+impl UiLimits {
+    pub fn max_binding_array_elements_per_shader_stage(&self) -> u32 {
+        self.max_textures + self.max_samplers
+    }
+    pub fn max_binding_array_sampler_elements_per_shader_stage(&self) -> u32 {
+        self.max_samplers
+    }
+}

core/src/render/primitive.rs

@@ -0,0 +1,283 @@
+use std::ops::{Deref, DerefMut};
+
+use crate::{
+    layout::{Color, UiRegion},
+    render::{
+        ArrBuf,
+        data::{MaskIdx, PrimitiveInstance},
+    },
+    util::Id,
+};
+use bytemuck::Pod;
+use wgpu::*;
+
+pub struct Primitives {
+    instances: Vec<PrimitiveInstance>,
+    assoc: Vec<Id>,
+    data: PrimitiveData,
+    free: Vec<usize>,
+    pub updated: bool,
+}
+
+impl Default for Primitives {
+    fn default() -> Self {
+        Self {
+            instances: Default::default(),
+            assoc: Default::default(),
+            data: Default::default(),
+            free: Vec::new(),
+            updated: true,
+        }
+    }
+}
+
+pub trait Primitive: Pod {
+    const BINDING: u32;
+    fn vec(data: &mut PrimitiveData) -> &mut PrimitiveVec<Self>;
+}
+
+macro_rules! primitives {
+    ($($name:ident: $ty:ty => $binding:expr,)*) => {
+        #[derive(Default)]
+        pub struct PrimitiveData {
+            $(pub(crate) $name: PrimitiveVec<$ty>,)*
+        }
+
+        pub struct PrimitiveBuffers {
+            $($name: ArrBuf<$ty>,)*
+        }
+
+        impl PrimitiveBuffers {
+            pub fn update(&mut self, device: &Device, queue: &Queue, data: &PrimitiveData) {
+                $(self.$name.update(device, queue, &data.$name);)*
+            }
+        }
+
+        impl PrimitiveBuffers {
+            pub const LEN: usize = primitives!(@count $($name)*);
+            pub fn buffers(&self) -> [(u32, &Buffer); Self::LEN] {
+                [
+                    $((<$ty>::BINDING, &self.$name.buffer),)*
+                ]
+            }
+            pub fn new(device: &Device) -> Self {
+                Self {
+                    $($name: ArrBuf::new(
+                        device,
+                        BufferUsages::STORAGE | BufferUsages::COPY_DST,
+                        stringify!($name),
+                    ),)*
+                }
+            }
+        }
+
+        impl PrimitiveData {
+            pub fn clear(&mut self) {
+                $(self.$name.clear();)*
+            }
+            pub fn free(&mut self, binding: u32, idx: usize) {
+                match binding {
+                    $(<$ty>::BINDING => self.$name.free(idx),)*
+                    _ => unreachable!()
+                }
+            }
+        }
+
+        $(
+            unsafe impl bytemuck::Pod for $ty {}
+            unsafe impl bytemuck::Zeroable for $ty {}
+            impl Primitive for $ty {
+                const BINDING: u32 = $binding;
+                fn vec(data: &mut PrimitiveData) -> &mut PrimitiveVec<Self> {
+                    &mut data.$name
+                }
+            }
+        )*
+    };
+    (@count $t1:tt $($t:tt)+) => { 1 + primitives!(@count $($t),+) };
+    (@count $t:tt) => { 1 };
+}
+
+pub struct PrimitiveInst<P> {
+    pub id: Id,
+    pub primitive: P,
+    pub region: UiRegion,
+    pub mask_idx: MaskIdx,
+}
+
+impl Primitives {
+    pub fn write<P: Primitive>(
+        &mut self,
+        layer: usize,
+        PrimitiveInst {
+            id,
+            primitive,
+            region,
+            mask_idx,
+        }: PrimitiveInst<P>,
+    ) -> PrimitiveHandle {
+        self.updated = true;
+        let vec = P::vec(&mut self.data);
+        let i = vec.add(primitive);
+        let inst = PrimitiveInstance {
+            region,
+            idx: i as u32,
+            mask_idx,
+            binding: P::BINDING,
+        };
+        let inst_i = if let Some(i) = self.free.pop() {
+            self.instances[i] = inst;
+            self.assoc[i] = id;
+            i
+        } else {
+            let i = self.instances.len();
+            self.instances.push(inst);
+            self.assoc.push(id);
+            i
+        };
+        PrimitiveHandle::new::<P>(layer, inst_i, i)
+    }
+
+    /// returns (old index, new index)
+    pub fn apply_free(&mut self) -> impl Iterator<Item = PrimitiveChange> {
+        self.free.sort_by(|a, b| b.cmp(a));
+        self.free.drain(..).filter_map(|i| {
+            self.instances.swap_remove(i);
+            self.assoc.swap_remove(i);
+            if i == self.instances.len() {
+                return None;
+            }
+            let id = self.assoc[i];
+            let old = self.instances.len();
+            Some(PrimitiveChange { id, old, new: i })
+        })
+    }
+
+    pub fn free(&mut self, h: &PrimitiveHandle) -> MaskIdx {
+        self.updated = true;
+        self.data.free(h.binding, h.data_idx);
+        self.free.push(h.inst_idx);
+        self.instances[h.inst_idx].mask_idx
+    }
+
+    pub fn data(&self) -> &PrimitiveData {
+        &self.data
+    }
+
+    pub fn instances(&self) -> &Vec<PrimitiveInstance> {
+        &self.instances
+    }
+
+    pub fn region_mut(&mut self, h: &PrimitiveHandle) -> &mut UiRegion {
+        self.updated = true;
+        &mut self.instances[h.inst_idx].region
+    }
+}
+
+pub struct PrimitiveChange {
+    pub id: Id,
+    pub old: usize,
+    pub new: usize,
+}
+
+#[derive(Debug)]
+pub struct PrimitiveHandle {
+    pub layer: usize,
+    pub inst_idx: usize,
+    pub data_idx: usize,
+    pub binding: u32,
+}
+
+impl PrimitiveHandle {
+    fn new<P: Primitive>(layer: usize, inst_idx: usize, data_idx: usize) -> Self {
+        Self {
+            layer,
+            inst_idx,
+            data_idx,
+            binding: P::BINDING,
+        }
+    }
+}
+
+primitives!(
+    rects: RectPrimitive => 0,
+    textures: TexturePrimitive => 1,
+);
+
+#[repr(C)]
+#[derive(Copy, Clone)]
+pub struct RectPrimitive {
+    pub color: Color<u8>,
+    pub radius: f32,
+    pub thickness: f32,
+    pub inner_radius: f32,
+}
+
+impl RectPrimitive {
+    pub fn color(color: Color<u8>) -> Self {
+        Self {
+            color,
+            radius: 0.0,
+            thickness: 0.0,
+            inner_radius: 0.0,
+        }
+    }
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct TexturePrimitive {
+    pub view_idx: u32,
+    pub sampler_idx: u32,
+}
+
+pub struct PrimitiveVec<T> {
+    vec: Vec<T>,
+    free: Vec<usize>,
+}
+
+impl<T> PrimitiveVec<T> {
+    pub fn new() -> Self {
+        Self {
+            vec: Vec::new(),
+            free: Vec::new(),
+        }
+    }
+    pub fn add(&mut self, t: T) -> usize {
+        if let Some(i) = self.free.pop() {
+            self.vec[i] = t;
+            i
+        } else {
+            let i = self.vec.len();
+            self.vec.push(t);
+            i
+        }
+    }
+    pub fn free(&mut self, i: usize) {
+        self.free.push(i);
+    }
+    pub fn clear(&mut self) {
+        self.free.clear();
+        self.vec.clear();
+    }
+}
+
+impl<T> Default for PrimitiveVec<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T> Deref for PrimitiveVec<T> {
+    type Target = Vec<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.vec
+    }
+}
+
+impl<T> DerefMut for PrimitiveVec<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.vec
+    }
+}

core/src/render/shader.wgsl

@@ -0,0 +1,178 @@
+const RECT: u32 = 0u;
+const TEXTURE: u32 = 1u;
+
+@group(0) @binding(0)
+var<uniform> window: WindowUniform;
+@group(1) @binding(RECT)
+var<storage> rects: array<Rect>;
+@group(1) @binding(TEXTURE)
+var<storage> textures: array<TextureInfo>;
+
+struct Rect {
+    color: u32,
+    radius: f32,
+    thickness: f32,
+    inner_radius: f32,
+}
+
+struct TextureInfo {
+    view_idx: u32,
+    sampler_idx: u32,
+}
+
+struct Mask {
+    x: UiSpan,
+    y: UiSpan,
+}
+
+struct UiSpan {
+    start: UiScalar,
+    end: UiScalar,
+}
+
+struct UiScalar {
+    rel: f32,
+    abs: f32,
+}
+
+struct UiVec2 {
+    rel: vec2<f32>,
+    abs: vec2<f32>,
+}
+
+@group(2) @binding(0)
+var views: binding_array<texture_2d<f32>>;
+@group(2) @binding(1)
+var samplers: binding_array<sampler>;
+@group(2) @binding(2)
+var<storage> masks: array<Mask>;
+
+struct WindowUniform {
+    dim: vec2<f32>,
+};
+
+struct InstanceInput {
+    @location(0) x_start: vec2<f32>,
+    @location(1) x_end: vec2<f32>,
+    @location(2) y_start: vec2<f32>,
+    @location(3) y_end: vec2<f32>,
+    @location(4) binding: u32,
+    @location(5) idx: u32,
+    @location(6) mask_idx: u32,
+}
+
+struct VertexOutput {
+    @location(0) top_left: vec2<f32>,
+    @location(1) bot_right: vec2<f32>,
+    @location(2) uv: vec2<f32>,
+    @location(3) binding: u32,
+    @location(4) idx: u32,
+    @location(5) mask_idx: u32,
+    @builtin(position) clip_position: vec4<f32>,
+};
+
+struct Region {
+    pos: vec2<f32>,
+    uv: vec2<f32>,
+    top_left: vec2<f32>,
+    bot_right: vec2<f32>,
+}
+
+@vertex
+fn vs_main(
+    @builtin(vertex_index) vi: u32,
+    in: InstanceInput,
+) -> VertexOutput {
+    var out: VertexOutput;
+
+    let top_left_rel = vec2(in.x_start.x, in.y_start.x);
+    let top_left_abs = vec2(in.x_start.y, in.y_start.y);
+    let bot_right_rel = vec2(in.x_end.x, in.y_end.x);
+    let bot_right_abs = vec2(in.x_end.y, in.y_end.y);
+
+    let top_left = floor(top_left_rel * window.dim) + floor(top_left_abs);
+    let bot_right = floor(bot_right_rel * window.dim) + floor(bot_right_abs);
+    let size = bot_right - top_left;
+
+    let uv = vec2<f32>(
+        f32(vi % 2u),
+        f32(vi / 2u)
+    );
+    let pos = (top_left + uv * size) / window.dim * 2.0 - 1.0;
+    out.clip_position = vec4<f32>(pos.x, -pos.y, 0.0, 1.0);
+    out.uv = uv;
+    out.binding = in.binding;
+    out.idx = in.idx;
+    out.top_left = top_left;
+    out.bot_right = bot_right;
+    out.mask_idx = in.mask_idx;
+
+    return out;
+}
+
+@fragment
+fn fs_main(
+    in: VertexOutput
+) -> @location(0) vec4<f32> {
+    let pos = in.clip_position.xy;
+    let region = Region(pos, in.uv, in.top_left, in.bot_right);
+    let i = in.idx;
+    var color: vec4<f32>;
+    switch in.binding {
+        case RECT: {
+            color = draw_rounded_rect(region, rects[i]);
+        }
+        case TEXTURE: {
+            color = draw_texture(region, textures[i]);
+        }
+        default: {
+            color = vec4(1.0, 0.0, 1.0, 1.0);
+        }
+    }
+    if in.mask_idx != 4294967295u {
+        let mask = masks[in.mask_idx];
+        let tl = UiVec2(vec2(mask.x.start.rel, mask.y.start.rel), vec2(mask.x.start.abs, mask.y.start.abs));
+        let br = UiVec2(vec2(mask.x.end.rel, mask.y.end.rel), vec2(mask.x.end.abs, mask.y.end.abs));
+
+        let top_left = floor(tl.rel * window.dim) + floor(tl.abs);
+        let bot_right = floor(br.rel * window.dim) + floor(br.abs);
+        if pos.x < top_left.x || pos.x > bot_right.x || pos.y < top_left.y || pos.y > bot_right.y {
+            color *= 0.0;
+        }
+    }
+    return color;
+}
+
+// TODO: this seems really inefficient (per frag indexing)?
+fn draw_texture(region: Region, info: TextureInfo) -> vec4<f32> {
+    return textureSample(views[info.view_idx], samplers[info.sampler_idx], region.uv);
+}
+
+fn draw_rounded_rect(region: Region, rect: Rect) -> vec4<f32> {
+    var color = unpack4x8unorm(rect.color);
+
+    let edge = 0.5;
+
+    let size = region.bot_right - region.top_left;
+    let corner = size / 2.0;
+    let center = region.top_left + corner;
+
+    let dist = distance_from_rect(region.pos, center, corner, rect.radius);
+    color.a *= 1.0 - smoothstep(-min(edge, rect.radius), edge, dist);
+
+    if rect.thickness > 0.0 {
+        let dist2 = distance_from_rect(region.pos, center, corner - rect.thickness, rect.inner_radius);
+        color.a *= smoothstep(-min(edge, rect.inner_radius), edge, dist2);
+    }
+
+    return color;
+}
+
+fn distance_from_rect(pixel_pos: vec2<f32>, rect_center: vec2<f32>, rect_corner: vec2<f32>, radius: f32) -> f32 {
+    // vec from center to pixel
+    let p = pixel_pos - rect_center;
+    // vec from inner rect corner to pixel
+    let q = abs(p) - (rect_corner - radius);
+    return length(max(q, vec2(0.0))) - radius;
+}
+

core/src/render/texture.rs

@@ -0,0 +1,129 @@
+use image::{DynamicImage, EncodableLayout};
+use wgpu::{util::DeviceExt, *};
+
+use crate::layout::{TextureUpdate, Textures};
+
+pub struct GpuTextures {
+    device: Device,
+    queue: Queue,
+    views: Vec<TextureView>,
+    view_count: usize,
+    samplers: Vec<Sampler>,
+    null_view: TextureView,
+    no_views: Vec<TextureView>,
+}
+
+impl GpuTextures {
+    pub fn update(&mut self, textures: &mut Textures) -> bool {
+        let mut changed = false;
+        for update in textures.updates() {
+            changed = true;
+            match update {
+                TextureUpdate::Push(image) => self.push(image),
+                TextureUpdate::Set(i, image) => self.set(i, image),
+                TextureUpdate::SetFree => self.view_count += 1,
+                TextureUpdate::Free(i) => self.free(i),
+                TextureUpdate::PushFree => self.push_free(),
+            }
+        }
+        changed
+    }
+    fn set(&mut self, i: u32, image: &DynamicImage) {
+        self.view_count += 1;
+        let view = self.create_view(image);
+        self.views[i as usize] = view;
+    }
+    fn free(&mut self, i: u32) {
+        self.view_count -= 1;
+        self.views[i as usize] = self.null_view.clone();
+    }
+    fn push(&mut self, image: &DynamicImage) {
+        self.view_count += 1;
+        let view = self.create_view(image);
+        self.views.push(view);
+    }
+    fn push_free(&mut self) {
+        self.view_count += 1;
+        self.views.push(self.null_view.clone());
+    }
+
+    fn create_view(&self, image: &DynamicImage) -> TextureView {
+        let image = image.to_rgba8();
+        let (width, height) = image.dimensions();
+        let texture = self.device.create_texture_with_data(
+            &self.queue,
+            &TextureDescriptor {
+                label: None,
+                size: Extent3d {
+                    width,
+                    height,
+                    depth_or_array_layers: 1,
+                },
+                mip_level_count: 1,
+                sample_count: 1,
+                dimension: TextureDimension::D2,
+                format: TextureFormat::Rgba8Unorm,
+                usage: TextureUsages::TEXTURE_BINDING,
+                view_formats: &[],
+            },
+            wgt::TextureDataOrder::MipMajor,
+            image.as_bytes(),
+        );
+        texture.create_view(&TextureViewDescriptor::default())
+    }
+
+    pub fn new(device: &Device, queue: &Queue) -> Self {
+        let null_view = null_texture_view(device);
+        Self {
+            device: device.clone(),
+            queue: queue.clone(),
+            views: Vec::new(),
+            samplers: vec![default_sampler(device)],
+            no_views: vec![null_view.clone()],
+            null_view,
+            view_count: 0,
+        }
+    }
+
+    pub fn views(&self) -> Vec<&TextureView> {
+        if self.views.is_empty() {
+            &self.no_views
+        } else {
+            &self.views
+        }
+        .iter()
+        .by_ref()
+        .collect()
+    }
+
+    pub fn samplers(&self) -> Vec<&Sampler> {
+        self.samplers.iter().by_ref().collect()
+    }
+
+    pub fn view_count(&self) -> usize {
+        self.view_count
+    }
+}
+
+pub fn null_texture_view(device: &Device) -> TextureView {
+    device
+        .create_texture(&TextureDescriptor {
+            label: Some("null"),
+            size: Extent3d {
+                width: 1,
+                height: 1,
+                depth_or_array_layers: 1,
+            },
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: TextureDimension::D2,
+            format: TextureFormat::Rgba8Unorm,
+            usage: TextureUsages::TEXTURE_BINDING,
+            view_formats: &[],
+        })
+        .create_view(&TextureViewDescriptor::default())
+}
+
+pub fn default_sampler(device: &Device) -> Sampler {
+    device.create_sampler(&SamplerDescriptor::default())
+}

core/src/render/util/mod.rs

@@ -0,0 +1,48 @@
+use std::marker::PhantomData;
+
+use bytemuck::Pod;
+use wgpu::*;
+
+pub struct ArrBuf<T: Pod> {
+    label: &'static str,
+    usage: BufferUsages,
+    pub buffer: Buffer,
+    len: usize,
+    _pd: PhantomData<T>,
+}
+
+impl<T: Pod> ArrBuf<T> {
+    pub fn new(device: &Device, usage: BufferUsages, label: &'static str) -> Self {
+        Self {
+            label,
+            usage,
+            buffer: Self::init_buf(device, 0, usage, label),
+            len: 0,
+            _pd: PhantomData,
+        }
+    }
+    pub fn update(&mut self, device: &Device, queue: &Queue, data: &[T]) {
+        if self.len != data.len() {
+            self.len = data.len();
+            self.buffer =
+                Self::init_buf(device, std::mem::size_of_val(data), self.usage, self.label);
+        }
+        queue.write_buffer(&self.buffer, 0, bytemuck::cast_slice(data));
+    }
+    fn init_buf(device: &Device, size: usize, usage: BufferUsages, label: &'static str) -> Buffer {
+        let mut size = size as u64;
+        if usage.contains(BufferUsages::STORAGE) {
+            size = size.max(std::mem::size_of::<T>() as u64);
+        }
+        device.create_buffer(&BufferDescriptor {
+            label: Some(label),
+            size,
+            mapped_at_creation: false,
+            usage,
+        })
+    }
+    #[allow(clippy::len_without_is_empty)]
+    pub fn len(&self) -> usize {
+        self.len
+    }
+}

core/src/util/arena.rs

@@ -0,0 +1,109 @@
+use std::ops::Deref;
+
+use crate::util::{Id, IdNum, IdTracker};
+
+pub struct Arena<T, I> {
+    data: Vec<T>,
+    tracker: IdTracker<I>,
+}
+
+impl<T, I: IdNum> Arena<T, I> {
+    pub fn new() -> Self {
+        Self {
+            data: Vec::new(),
+            tracker: IdTracker::default(),
+        }
+    }
+
+    pub fn push(&mut self, value: T) -> Id<I> {
+        let id = self.tracker.next();
+        let i = id.idx();
+        if i == self.data.len() {
+            self.data.push(value);
+        } else {
+            self.data[i] = value;
+        }
+        id
+    }
+
+    pub fn remove(&mut self, id: Id<I>) -> T
+    where
+        T: Copy,
+    {
+        let i = id.idx();
+        self.tracker.free(id);
+        self.data[i]
+    }
+}
+
+impl<T, I: IdNum> Default for Arena<T, I> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+pub struct TrackedArena<T, I> {
+    inner: Arena<T, I>,
+    refs: Vec<u32>,
+    pub changed: bool,
+}
+
+impl<T, I: IdNum> TrackedArena<T, I> {
+    pub fn new() -> Self {
+        Self {
+            inner: Arena::default(),
+            refs: Vec::new(),
+            changed: true,
+        }
+    }
+
+    pub fn push(&mut self, value: T) -> Id<I> {
+        self.changed = true;
+        let id = self.inner.push(value);
+        let i = id.idx();
+        if i == self.refs.len() {
+            self.refs.push(0);
+        }
+        id
+    }
+
+    pub fn push_ref(&mut self, i: Id<I>) {
+        self.refs[i.idx()] += 1;
+    }
+
+    pub fn remove(&mut self, id: Id<I>) -> T
+    where
+        T: Copy,
+    {
+        let i = id.idx();
+        self.refs[i] -= 1;
+        if self.refs[i] == 0 {
+            self.changed = true;
+            self.inner.remove(id)
+        } else {
+            self[i]
+        }
+    }
+}
+
+impl<T, I: IdNum> Default for TrackedArena<T, I> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T, I> Deref for TrackedArena<T, I> {
+    type Target = Vec<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner.data
+    }
+}
+
+impl<T, I> Deref for Arena<T, I> {
+    type Target = Vec<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.data
+    }
+}

core/src/util/change.rs

@@ -0,0 +1,30 @@
+use std::ops::{Deref, DerefMut};
+
+pub struct MutDetect<T> {
+    inner: T,
+    pub changed: bool,
+}
+
+impl<T> Deref for MutDetect<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+impl<T> DerefMut for MutDetect<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        self.changed = true;
+        &mut self.inner
+    }
+}
+
+impl<T> From<T> for MutDetect<T> {
+    fn from(inner: T) -> Self {
+        MutDetect {
+            inner,
+            changed: true,
+        }
+    }
+}

core/src/util/handle.rs

@@ -0,0 +1,60 @@
+use std::{
+    cell::{Ref, RefCell, RefMut},
+    marker::Unsize,
+    ops::CoerceUnsized,
+    rc::{Rc, Weak},
+};
+
+pub struct Handle<T: ?Sized>(Rc<RefCell<T>>);
+pub struct WeakHandle<T: ?Sized>(Weak<RefCell<T>>);
+
+impl<T: ?Sized> Handle<T> {
+    pub fn get(&self) -> Ref<'_, T> {
+        self.0.borrow()
+    }
+
+    pub fn get_mut(&self) -> RefMut<'_, T> {
+        self.0.borrow_mut()
+    }
+
+    pub fn refs(&self) -> usize {
+        Rc::strong_count(&self.0)
+    }
+
+    pub fn weak(&self) -> WeakHandle<T> {
+        WeakHandle(Rc::downgrade(&self.0))
+    }
+}
+
+impl<T: ?Sized> WeakHandle<T> {
+    pub fn strong(&self) -> Option<Handle<T>> {
+        Some(Handle(self.0.upgrade()?))
+    }
+}
+
+impl<T: ?Sized> Clone for Handle<T> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<T: ?Sized> Clone for WeakHandle<T> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<T: Default> Default for Handle<T> {
+    fn default() -> Self {
+        Self(Default::default())
+    }
+}
+
+impl<T> From<T> for Handle<T> {
+    fn from(value: T) -> Self {
+        Self(Rc::new(RefCell::new(value)))
+    }
+}
+
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Handle<U>> for Handle<T> {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<WeakHandle<U>> for WeakHandle<T> {}

core/src/util/id.rs

@@ -0,0 +1,87 @@
+#[repr(C)]
+#[derive(Eq, Hash, PartialEq, Debug, Clone, Copy, bytemuck::Zeroable)]
+pub struct Id<I = u64>(I);
+
+unsafe impl<I: Copy + bytemuck::Zeroable + 'static> bytemuck::Pod for Id<I> {}
+
+pub struct IdTracker<I = u64> {
+    free: Vec<Id<I>>,
+    cur: Id<I>,
+}
+
+impl<I: IdNum> IdTracker<I> {
+    #[allow(clippy::should_implement_trait)]
+    pub fn next(&mut self) -> Id<I> {
+        if let Some(id) = self.free.pop() {
+            return id;
+        }
+        let next = self.cur.next();
+        std::mem::replace(&mut self.cur, next)
+    }
+
+    #[allow(dead_code)]
+    pub fn free(&mut self, id: Id<I>) {
+        self.free.push(id);
+    }
+}
+
+impl<I: IdNum> Id<I> {
+    #[allow(dead_code)]
+    /// for debug purposes; should this be exposed?
+    /// generally you want to use labels with widgets
+    pub(crate) fn raw(id: I) -> Self {
+        Self(id)
+    }
+    pub fn idx(&self) -> usize {
+        self.0.idx()
+    }
+    pub fn next(&self) -> Id<I> {
+        Self(self.0.next())
+    }
+    pub const fn preset(value: I) -> Self {
+        Self(value)
+    }
+}
+
+impl<I: IdNum> Default for IdTracker<I> {
+    fn default() -> Self {
+        Self {
+            free: Vec::new(),
+            cur: Id(I::first()),
+        }
+    }
+}
+
+pub trait IdNum {
+    fn first() -> Self;
+    fn next(&self) -> Self;
+    fn idx(&self) -> usize;
+}
+
+impl IdNum for u64 {
+    fn first() -> Self {
+        0
+    }
+
+    fn next(&self) -> Self {
+        self + 1
+    }
+
+    fn idx(&self) -> usize {
+        *self as usize
+    }
+}
+
+impl IdNum for u32 {
+    fn first() -> Self {
+        0
+    }
+
+    fn next(&self) -> Self {
+        self + 1
+    }
+
+    fn idx(&self) -> usize {
+        *self as usize
+    }
+}

core/src/util/math.rs

@@ -0,0 +1,87 @@
+use std::ops::*;
+
+pub const trait LerpUtil {
+    fn lerp(self, from: Self, to: Self) -> Self;
+    fn lerp_inv(self, from: Self, to: Self) -> Self;
+}
+
+pub const trait DivOr {
+    fn div_or(self, rhs: Self, other: Self) -> Self;
+}
+
+impl const DivOr for f32 {
+    fn div_or(self, rhs: Self, other: Self) -> Self {
+        let res = self / rhs;
+        if res.is_nan() { other } else { res }
+    }
+}
+
+impl<T: const Add<Output = T> + const Sub<Output = T> + const Mul<Output = T> + const DivOr + Copy> const
+    LerpUtil for T
+{
+    /// linear interpolation
+    /// from * (1.0 - self) + to * self
+    fn lerp(self, from: Self, to: Self) -> Self {
+        from + (to - from) * self
+    }
+    /// inverse of lerp
+    fn lerp_inv(self, from: Self, to: Self) -> Self {
+        (self - from).div_or(to - from, from)
+    }
+}
+
+macro_rules! impl_op {
+    ($T:ident $op:ident $fn:ident $opa:ident $fna:ident; $($field:ident)*) => {
+        #[allow(non_snake_case)]
+        mod ${concat($T, _op_, $fn, _impl)} {
+            use super::*;
+            #[allow(unused_imports)]
+            use std::ops::*;
+            impl const $op for $T {
+                type Output = Self;
+
+                fn $fn(self, rhs: Self) -> Self::Output {
+                    Self {
+                        $($field: self.$field.$fn(rhs.$field),)*
+                    }
+                }
+            }
+            impl const $opa for $T {
+                fn $fna(&mut self, rhs: Self) {
+                    *self = self.$fn(rhs);
+                }
+            }
+            impl const $op<f32> for $T {
+                type Output = Self;
+
+                fn $fn(self, rhs: f32) -> Self::Output {
+                    Self {
+                        $($field: self.$field.$fn(rhs),)*
+                    }
+                }
+            }
+            impl const $op<$T> for f32 {
+                type Output = $T;
+
+                fn $fn(self, rhs: $T) -> Self::Output {
+                    $T {
+                        $($field: self.$fn(rhs.$field),)*
+                    }
+                }
+            }
+            impl const $opa<f32> for $T {
+                fn $fna(&mut self, rhs: f32) {
+                    *self = self.$fn(rhs);
+                }
+            }
+        }
+    };
+    ($T:ident $op:ident $fn:ident; $($field:ident)*) => {
+        impl_op!($T $op $fn ${concat($op,Assign)} ${concat($fn,_assign)}; $($field)*);
+    };
+    (impl $op:ident for $T:ident: $fn:ident $($field:ident)*) => {
+        impl_op!($T $op $fn ${concat($op,Assign)} ${concat($fn,_assign)}; $($field)*);
+    };
+}
+
+pub(crate) use impl_op;

core/src/util/mod.rs

@@ -0,0 +1,18 @@
+mod arena;
+mod change;
+mod handle;
+mod id;
+mod math;
+mod refcount;
+mod vec2;
+
+pub use arena::*;
+pub use change::*;
+pub use handle::*;
+pub use id::*;
+pub use math::*;
+pub use refcount::*;
+pub use vec2::*;
+
+pub type HashMap<K, V> = fxhash::FxHashMap<K, V>;
+pub type HashSet<K> = fxhash::FxHashSet<K>;

core/src/util/refcount.rs

@@ -0,0 +1,32 @@
+use std::sync::{
+    Arc,
+    atomic::{AtomicU32, Ordering},
+};
+
+#[derive(Debug)]
+pub struct RefCounter(Arc<AtomicU32>);
+
+impl RefCounter {
+    pub fn new() -> Self {
+        Self(Arc::new(0.into()))
+    }
+    #[allow(unused)]
+    pub fn refs(&self) -> u32 {
+        self.0.load(Ordering::Acquire)
+    }
+    pub fn drop(&mut self) -> bool {
+        let refs = self.0.fetch_sub(1, Ordering::Release);
+        refs == 0
+    }
+    #[allow(unused)]
+    pub fn quiet_clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl Clone for RefCounter {
+    fn clone(&self) -> Self {
+        self.0.fetch_add(1, Ordering::Release);
+        Self(self.0.clone())
+    }
+}

core/src/util/vec2.rs

@@ -0,0 +1,99 @@
+use crate::util::{DivOr, impl_op};
+use std::{hash::Hash, ops::*};
+
+#[repr(C)]
+#[derive(Clone, Copy, PartialEq, Default, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct Vec2 {
+    pub x: f32,
+    pub y: f32,
+}
+
+impl Eq for Vec2 {}
+
+impl Hash for Vec2 {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        state.write_u32(self.x.to_bits());
+        state.write_u32(self.y.to_bits());
+    }
+}
+
+impl Vec2 {
+    pub const ZERO: Self = Self::new(0.0, 0.0);
+    pub const ONE: Self = Self::new(1.0, 1.0);
+
+    pub const fn new(x: f32, y: f32) -> Self {
+        Self { x, y }
+    }
+
+    pub const fn round(self) -> Self {
+        Self {
+            x: self.x.round(),
+            y: self.y.round(),
+        }
+    }
+
+    pub const fn floor(self) -> Self {
+        Self {
+            x: self.x.floor(),
+            y: self.y.floor(),
+        }
+    }
+
+    pub const fn ceil(self) -> Self {
+        Self {
+            x: self.x.ceil(),
+            y: self.y.ceil(),
+        }
+    }
+
+    pub const fn tuple(&self) -> (f32, f32) {
+        (self.x, self.y)
+    }
+
+    pub const fn with_x(mut self, x: f32) -> Self {
+        self.x = x;
+        self
+    }
+
+    pub const fn with_y(mut self, y: f32) -> Self {
+        self.y = y;
+        self
+    }
+}
+
+// this version looks kinda cool... is it more readable? more annoying to copy and change though
+impl_op!(impl Add for Vec2: add x y);
+impl_op!(Vec2 Sub sub; x y);
+impl_op!(Vec2 Mul mul; x y);
+impl_op!(Vec2 Div div; x y);
+
+impl const DivOr for Vec2 {
+    fn div_or(self, rhs: Self, other: Self) -> Self {
+        Self {
+            x: self.x.div_or(rhs.x, other.x),
+            y: self.y.div_or(rhs.y, other.y),
+        }
+    }
+}
+
+impl Neg for Vec2 {
+    type Output = Self;
+
+    fn neg(mut self) -> Self::Output {
+        self.x = -self.x;
+        self.y = -self.y;
+        self
+    }
+}
+
+impl std::fmt::Debug for Vec2 {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "({}, {})", self.x, self.y)
+    }
+}
+
+impl std::fmt::Display for Vec2 {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "({}, {})", self.x, self.y)
+    }
+}