made painter actually how I wanted it (draw now takes in an owned painter)

src/core/frame.rs

@@ -6,9 +6,8 @@ pub struct Regioned {
 }
 
 impl<Ctx: 'static> Widget<Ctx> for Regioned {
-    fn draw(&self, painter: &mut Painter<Ctx>) {
-        painter.region.select(&self.region);
-        painter.draw_inner(&self.inner);
+    fn draw(&self, mut painter: Painter<Ctx>) {
+        painter.draw_within(&self.inner, self.region);
     }
 }
 

src/core/image.rs

@@ -1,13 +1,13 @@
 use image::DynamicImage;
 
-use crate::{Color, TextureHandle, Widget, WidgetFnRet, render::RectPrimitive};
+use crate::{Color, Painter, TextureHandle, Widget, WidgetFnRet, render::RectPrimitive};
 
 pub struct Image {
     handle: Option<TextureHandle>,
 }
 
 impl<Ctx> Widget<Ctx> for Image {
-    fn draw(&self, painter: &mut crate::Painter<Ctx>) {
+    fn draw(&self, mut painter: Painter<Ctx>) {
         if let Some(handle) = &self.handle {
             painter.draw_texture(handle);
         } else {

src/core/rect.rs

@@ -28,7 +28,7 @@ impl Rect {
 }
 
 impl<Ctx> Widget<Ctx> for Rect {
-    fn draw(&self, painter: &mut Painter<Ctx>) {
+    fn draw(&self, mut painter: Painter<Ctx>) {
         painter.write(RectPrimitive {
             color: self.color,
             radius: self.radius,

src/core/span.rs

@@ -6,7 +6,7 @@ pub struct Span {
 }
 
 impl<Ctx: 'static> Widget<Ctx> for Span {
-    fn draw(&self, painter: &mut Painter<Ctx>) {
+    fn draw(&self, mut painter: Painter<Ctx>) {
         let total = self.sums();
         let mut start = UIScalar::min();
         for (child, length) in &self.children {

src/core/stack.rs

@@ -1,11 +1,11 @@
-use crate::{Widget, WidgetId};
+use crate::{Painter, Widget, WidgetId};
 
 pub struct Stack {
     pub children: Vec<WidgetId>,
 }
 
 impl<Ctx> Widget<Ctx> for Stack {
-    fn draw(&self, painter: &mut crate::Painter<Ctx>) {
+    fn draw(&self, mut painter: Painter<Ctx>) {
         for child in &self.children {
             painter.draw(child);
         }

src/layout/painter.rs

@@ -6,17 +6,18 @@ use crate::{
 pub struct Painter<'a, Ctx: 'static> {
     nodes: &'a Widgets<Ctx>,
     ctx: &'a mut Ctx,
-    sensors_map: &'a mut SensorMap<Ctx>,
+    sensors_map: &'a SensorMap<Ctx>,
     active_sensors: &'a mut ActiveSensors,
-    primitives: Primitives,
-    pub region: UiRegion,
+    primitives: &'a mut Primitives,
+    region: UiRegion,
 }
 
 impl<'a, Ctx> Painter<'a, Ctx> {
     pub fn new(
         nodes: &'a Widgets<Ctx>,
+        primitives: &'a mut Primitives,
         ctx: &'a mut Ctx,
-        sensors_map: &'a mut SensorMap<Ctx>,
+        sensors_map: &'a SensorMap<Ctx>,
         active_sensors: &'a mut ActiveSensors,
     ) -> Self {
         Self {
@@ -24,59 +25,56 @@ impl<'a, Ctx> Painter<'a, Ctx> {
             ctx,
             active_sensors,
             sensors_map,
-            primitives: Primitives::default(),
+            primitives,
             region: UiRegion::full(),
         }
     }
+
+    /// Writes a primitive to be rendered
     pub fn write<P: Primitive>(&mut self, data: P) {
         self.primitives.write(data, self.region);
     }
 
-    /// Draws a widget but does NOT maintain the region.
-    /// Useful if you only have a single widget to draw.
-    pub fn draw_inner<W>(&mut self, id: &WidgetId<W>)
-    where
-        Ctx: 'static,
-    {
-        if self.sensors_map.get(&id.id).is_some() {
-            self.active_sensors.push((self.region, id.id.duplicate()));
-        }
-        self.nodes.get_dyn(id).draw(self);
-    }
-
-    /// Draws a widget and maintains the original region.
-    /// Useful if you need to draw multiple overlapping child widgets.
+    /// Draws a widget within this widget's region.
     pub fn draw<W>(&mut self, id: &WidgetId<W>)
     where
         Ctx: 'static,
     {
-        let old = self.region;
-        self.draw_inner(id);
-        self.region = old;
+        self.draw_at(id, self.region);
     }
 
-    /// Draws a widget within an inner region and maintains the original region.
-    /// Useful if you need to draw multiple child widgets in select areas within the original
-    /// region.
-    pub fn draw_within(&mut self, id: &WidgetId, region: UiRegion)
+    /// Draws a widget somewhere within this one.
+    /// Useful for drawing child widgets in select areas.
+    pub fn draw_within<W>(&mut self, id: &WidgetId<W>, region: UiRegion)
     where
         Ctx: 'static,
     {
-        let old = self.region;
-        self.region.select(&region);
-        self.draw_inner(id);
-        self.region = old;
+        self.draw_at(id, region.within(&self.region));
+    }
+
+    /// Draws a widget in an arbitrary region.
+    pub fn draw_at<W>(&mut self, id: &WidgetId<W>, region: UiRegion)
+    where
+        Ctx: 'static,
+    {
+        if self.sensors_map.get(&id.id).is_some() {
+            self.active_sensors.push((region, id.id.duplicate()));
+        }
+        self.nodes.get_dyn(id).draw(Painter {
+            nodes: self.nodes,
+            ctx: self.ctx,
+            sensors_map: self.sensors_map,
+            active_sensors: self.active_sensors,
+            primitives: self.primitives,
+            region,
+        });
     }
 
     pub fn draw_texture(&mut self, handle: &TextureHandle) {
         self.write(handle.inner);
     }
 
-    pub fn finish(self) -> Primitives {
-        self.primitives
-    }
-
-    pub fn ctx_mut(&mut self) -> &mut Ctx {
+    pub fn ctx(&mut self) -> &mut Ctx {
         self.ctx
     }
 }

src/layout/ui.rs

@@ -93,16 +93,17 @@ impl<Ctx> Ui<Ctx> {
         Ctx: 'static,
     {
         self.active_sensors.clear();
+        self.primitives.clear();
         let mut painter = Painter::new(
             &self.widgets,
+            &mut self.primitives,
             ctx,
-            &mut self.sensor_map,
+            &self.sensor_map,
             &mut self.active_sensors,
         );
         if let Some(base) = &self.base {
-            painter.draw_inner(base);
+            painter.draw(base);
         }
-        self.primitives = painter.finish();
     }
 
     pub fn update(&mut self, ctx: &mut Ctx)

src/layout/widget.rs

@@ -2,7 +2,7 @@ use crate::{Painter, Ui, WidgetId, WidgetIdFnRet};
 use std::{any::Any, marker::PhantomData};
 
 pub trait Widget<Ctx>: Any {
-    fn draw(&self, painter: &mut Painter<Ctx>);
+    fn draw(&self, painter: Painter<Ctx>);
 }
 
 pub struct WidgetTag;

src/render/primitive.rs

@@ -61,6 +61,12 @@ macro_rules! primitives {
             }
         }
 
+        impl PrimitiveData {
+            pub fn clear(&mut self) {
+                $(self.$name.clear();)*
+            }
+        }
+
         $(
             unsafe impl bytemuck::Pod for $ty {}
             unsafe impl bytemuck::Zeroable for $ty {}
@@ -87,6 +93,12 @@ impl Primitives {
         });
         vec.push(data);
     }
+
+    pub(crate) fn clear(&mut self) {
+        self.updated = true;
+        self.instances.clear();
+        self.data.clear();
+    }
 }
 
 primitives!(

src/testing/mod.rs

@@ -89,10 +89,10 @@ impl Client {
                     ctx.ui[id].color = color.add_rgb(-0.2);
                 })
                 .edit_on(Sense::HoverStart, move |r, _| {
-                    r.color = color.add_rgb(0.1);
+                    r.color = color.add_rgb(0.4);
                 })
                 .edit_on(Sense::PressEnd, move |r, _| {
-                    r.color = color.add_rgb(0.1);
+                    r.color = color.add_rgb(0.4);
                 })
                 .edit_on(Sense::HoverEnd, move |r, _| {
                     r.color = color;