iris/core/src/orientation/align.rs

use crate::util::impl_axis_index;
use crate::{Px, Rel};

use super::*;

#[derive(Debug, Clone, Copy, PartialEq)]
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)
    }
}

/// Where a widget sits in a box longer than it is. The default is the middle,
/// because the two edges are the ones that assume a direction: which of them
/// is the near one depends on the writing system and on which way a container
/// runs, and the middle is the same either way.
#[derive(Debug, Clone, Copy, PartialEq)]
pub struct AxisAlign(Rel);

impl AxisAlign {
    pub const NEG: Self = Self::new(0.0);
    pub const CENTER: Self = Self::new(0.5);
    pub const POS: Self = Self::new(1.0);

    pub const fn new(rel: f32) -> Self {
        Self(Rel::from_f32(rel))
    }

    /// A fraction of the room left over, which is what the layout reads: the
    /// three constants are the familiar places along it, not the only ones.
    pub const fn rel(&self) -> Rel {
        self.0
    }
}

impl Default for AxisAlign {
    fn default() -> Self {
        Self::CENTER
    }
}

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(Debug, Clone, Copy, PartialEq, Default)]
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 }
    }
}

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 Len {
    /// This length placed in the box it is measured in: the alignment names a
    /// point along that box, and the two ends are that point less the part of
    /// the length falling before it and plus the part falling after.
    pub const fn align(&self, align: AxisAlign) -> UiSpan {
        let rel = align.rel();
        let at = Len::from_parts(rel, Px::ZERO);
        UiSpan {
            start: at - self.scale(rel),
            end: at + self.scale(Rel::ONE.sub(rel)),
        }
    }
}

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 },
        }
    }
}

const impl From<RegionAlign> for UiVec2 {
    fn from(align: RegionAlign) -> Self {
        Self::new(
            Len::from_parts(align.x.rel(), Px::ZERO),
            Len::from_parts(align.y.rel(), Px::ZERO),
        )
    }
}

impl RegionAlign {
    pub const fn pos(self) -> UiVec2 {
        UiVec2::from(self)
    }
}

impl_axis_index!(RegionAlign => AxisAlign);
impl_axis_index!(Align => Option<AxisAlign>);