utils: move damage algorithms to algorithm crate

algorithms/src/rect.rs

@@ -0,0 +1,35 @@
+pub mod region;
+
+use {
+    smallvec::SmallVec,
+    std::fmt::{Debug, Formatter},
+};
+
+#[derive(Copy, Clone, Eq, PartialEq, Default)]
+pub struct RectRaw {
+    pub x1: i32,
+    pub y1: i32,
+    pub x2: i32,
+    pub y2: i32,
+}
+
+impl Debug for RectRaw {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Rect")
+            .field("x1", &self.x1)
+            .field("y1", &self.y1)
+            .field("x2", &self.x2)
+            .field("y2", &self.y2)
+            .field("width", &(self.x2 - self.x1))
+            .field("height", &(self.y2 - self.y1))
+            .finish()
+    }
+}
+
+impl RectRaw {
+    fn is_empty(&self) -> bool {
+        self.x1 == self.x2 || self.y1 == self.y2
+    }
+}
+
+type Container = SmallVec<[RectRaw; 1]>;