monolith

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

pub struct Rect {

    pub x: f64,

    pub y: f64,

    pub w: f64,

    pub h: f64,

}

pub(crate) const TOL: f64 = 0.05;

impl Rect {

    pub const fn new(x: f64, y: f64, w: f64, h: f64) -> Self {

        Self { x, y, w, h }

    }

    pub fn right(&self) -> f64 {

        self.x + self.w

    }

    pub fn bottom(&self) -> f64 {

        self.y + self.h

    }

    /// Whether the point lies inside, counting the left and top edges only.

    pub fn contains(&self, x: f64, y: f64) -> bool {

        x >= self.x && y >= self.y && x < self.right() && y < self.bottom()

    }

    pub fn center_x(&self) -> f64 {

        self.x + self.w / 2.0

    }

    pub fn center_y(&self) -> f64 {

        self.y + self.h / 2.0

    }

    pub fn lerp(&self, other: &Rect, s: f64) -> Rect {

        Rect::new(

            self.x + (other.x - self.x) * s,

            self.y + (other.y - self.y) * s,

            self.w + (other.w - self.w) * s,

            self.h + (other.h - self.h) * s,

        )

    }

    pub(crate) fn same_x(&self, o: &Rect) -> bool {

        (self.x - o.x).abs() < TOL && (self.w - o.w).abs() < TOL

    }

    pub(crate) fn same_y(&self, o: &Rect) -> bool {

        (self.y - o.y).abs() < TOL && (self.h - o.h).abs() < TOL

    }

    /// Takes the horizontal extent of `x_from` and the vertical extent of `y_from`.

    pub(crate) fn mixed(x_from: &Rect, y_from: &Rect) -> Rect {

        Rect::new(x_from.x, y_from.y, x_from.w, y_from.h)

    }

    pub(crate) fn bounding<'a>(rects: impl IntoIterator<Item = &'a Rect>) -> Rect {

        let (mut x0, mut y0, mut x1, mut y1) = (

            f64::INFINITY,

            f64::INFINITY,

            f64::NEG_INFINITY,

            f64::NEG_INFINITY,

        );

        for r in rects {

            x0 = x0.min(r.x);

            y0 = y0.min(r.y);

            x1 = x1.max(r.right());

            y1 = y1.max(r.bottom());

        }

        Rect::new(x0, y0, x1 - x0, y1 - y0)

    }

    pub(crate) fn expanded(&self, by: f64) -> Rect {

        Rect::new(

            self.x - by,

            self.y - by,

            self.w + 2.0 * by,

            self.h + 2.0 * by,

        )

    }

    pub(crate) fn intersects(&self, o: &Rect) -> bool {

        self.x < o.right() && o.x < self.right() && self.y < o.bottom() && o.y < self.bottom()

    }

}

/// How a window changes between two keyframes.

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

pub(crate) struct Change {

    pub x: bool,

    pub y: bool,

}

impl Change {

    pub fn between(a: &Rect, b: &Rect) -> Self {

        Self {

            x: !a.same_x(b),

            y: !a.same_y(b),

        }

    }

    pub fn moves(&self) -> bool {

        self.x || self.y

    }

    pub fn both(&self) -> bool {

        self.x && self.y

    }

}