Add Rect

showbits-common/src/rect.rs

@@ -0,0 +1,118 @@
+use std::ops::{Add, Sub};
+
+use crate::Vec2;
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct Rect {
+    north: i32,
+    south: i32,
+    west: i32,
+    east: i32,
+}
+
+impl Rect {
+    /// Whenever a `Rect` is constructed, this function must be used. This
+    /// ensures invariants are always checked.
+    fn new(north: i32, south: i32, west: i32, east: i32) -> Self {
+        let result = Self {
+            north,
+            south,
+            west,
+            east,
+        };
+
+        let size = result.size();
+        assert!(size.x >= 0);
+        assert!(size.y >= 0);
+
+        result
+    }
+
+    /// Construct a `Rect` that is a bounding box around two points.
+    ///
+    /// It is not possible to construct a `Rect` with a width or height of 0
+    /// through this method. Use one of the other constructor functions instead.
+    pub fn from_points(a: Vec2, b: Vec2) -> Self {
+        Self::new(a.y.min(b.y), a.y.max(b.y), a.x.min(b.x), a.x.max(b.x))
+    }
+
+    /// Construct a `Rect` from its north-west and south-east corners.
+    pub fn from_nw_se(nw: Vec2, se: Vec2) -> Self {
+        Self::new(nw.y, se.y, nw.x, se.x)
+    }
+
+    /// Construct a `Rect` from its north-east and south-west corners.
+    pub fn from_ne_sw(ne: Vec2, sw: Vec2) -> Self {
+        Self::new(ne.y, sw.y, sw.x, ne.x)
+    }
+
+    /// Construct a `Rect` from its north-west corner and size.
+    pub fn from_nw(nw: Vec2, size: Vec2) -> Self {
+        let se = nw + (size - 1);
+        Self::from_nw_se(nw, se)
+    }
+
+    /// Construct a `Rect` from its north-east corner and size.
+    pub fn from_corner_ne(ne: Vec2, size: Vec2) -> Self {
+        let sw = ne + (size - 1).neg_x();
+        Self::from_ne_sw(ne, sw)
+    }
+
+    /// Construct a `Rect` from its south-west corner and size.
+    pub fn from_corner_sw(sw: Vec2, size: Vec2) -> Self {
+        let ne = sw + (size - 1).neg_y();
+        Self::from_ne_sw(ne, sw)
+    }
+
+    /// Construct a `Rect` from its south-east corner and size.
+    pub fn from_corner_se(se: Vec2, size: Vec2) -> Self {
+        let nw = se - (size - 1);
+        Self::from_nw_se(nw, se)
+    }
+
+    pub fn corner_nw(&self) -> Vec2 {
+        Vec2::new(self.west, self.north)
+    }
+
+    pub fn corner_ne(&self) -> Vec2 {
+        Vec2::new(self.east, self.north)
+    }
+
+    pub fn corner_sw(&self) -> Vec2 {
+        Vec2::new(self.west, self.south)
+    }
+
+    pub fn corner_se(&self) -> Vec2 {
+        Vec2::new(self.east, self.south)
+    }
+
+    pub fn size(&self) -> Vec2 {
+        Vec2::new(self.east - self.west + 1, self.south - self.north + 1)
+    }
+}
+
+impl Add<Vec2> for Rect {
+    type Output = Self;
+
+    fn add(self, rhs: Vec2) -> Self::Output {
+        Self::new(
+            self.north + rhs.y,
+            self.south + rhs.y,
+            self.west + rhs.x,
+            self.east + rhs.x,
+        )
+    }
+}
+
+impl Sub<Vec2> for Rect {
+    type Output = Self;
+
+    fn sub(self, rhs: Vec2) -> Self::Output {
+        Self::new(
+            self.north - rhs.y,
+            self.south - rhs.y,
+            self.west - rhs.x,
+            self.east - rhs.x,
+        )
+    }
+}