1 files changed, 81 insertions, 0 deletions
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..1ee51b4
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,81 @@
+pub use colour::Colour;
+pub type Point = geometry::Point<i32>;
+pub type Dimensions = geometry::Dimensions<u32>;
+pub type Rect = geometry::Rect<i32, u32>;
+pub use geometry::HasDimensions;
+
+pub struct Buffer {
+    array: Vec<Colour>,
+    dimensions: Dimensions,
+}
+
+impl Buffer {
+    pub const ZERO: Buffer = Buffer { array: Vec::new(), dimensions: Dimensions::ZERO };
+
+    pub fn new(dimensions: Dimensions) -> Self {
+        let array = vec![Colour::BLACK; dimensions.area_usize()];
+        Self { array, dimensions }
+    }
+    pub fn new_with_fill(dimensions: Dimensions, colour: Colour) -> Self {
+        let array = vec![colour; dimensions.area_usize()];
+        Self { array, dimensions }
+    }
+    pub fn fill(&mut self, colour: Colour) {
+        self.array.iter_mut().for_each(|c| *c = colour);
+    }
+    pub fn copy_into(&mut self, coords: Point, other: &Buffer) {
+        let self_rect = Rect::from(self.dimensions);
+        let other_rect = Rect::construct(coords, other.dimensions);
+        let intersection = self_rect.intersect(other_rect);
+        if intersection.dimensions().is_zero() { return }
+
+        // Find where the origin of the intersection rect sits within both buffers.
+        let other_point = intersection.origin - coords;
+        let self_point = intersection.origin;
+        let mut other_i = (other.width() as usize * other_point.y as usize) + other_point.x as usize;
+        let mut self_i = (self.width() as usize * self_point.y as usize) + self_point.x as usize;
+
+        let inter_width = intersection.width() as usize;
+        let other_width = other.width() as usize;
+        let self_width = self.width() as usize;
+        let other_slice = other.as_slice();
+        let self_slice = self.as_mut_slice();
+
+        for _ in 0..intersection.height() {
+            let self_row = &mut self_slice[self_i .. self_i+inter_width];
+            let other_row = &other_slice[other_i .. other_i+inter_width];
+            self_row.copy_from_slice(other_row);
+            other_i += other_width;
+            self_i += self_width;
+        }
+    }
+    pub fn resize(&mut self, dimensions: Dimensions) {
+        self.array.resize(dimensions.area_usize(), Colour::BLACK);
+        self.dimensions = dimensions;
+    }
+    pub fn as_rows(&self) -> std::slice::ChunksExact<Colour> {
+        self.array.chunks_exact(self.dimensions.width as usize)
+    }
+    pub fn as_slice(&self) -> &[Colour] {
+        &self.array
+    }
+    pub fn as_mut_slice(&mut self) -> &mut [Colour] {
+        &mut self.array
+    }
+    pub fn as_u32_slice(&self) -> &[u32] {
+        unsafe { std::mem::transmute::<&[Colour], &[u32]>(&self.array) }
+    }
+}
+
+impl HasDimensions<u32> for Buffer {
+    fn dimensions(&self) -> Dimensions { self.dimensions }
+}
+
+impl std::ops::Index<usize> for Buffer {
+    type Output = Colour;
+    fn index(&self, i: usize) -> &Colour { &self.array[i] }
+}
+
+impl std::ops::IndexMut<usize> for Buffer {
+    fn index_mut(&mut self, i: usize) -> &mut Colour { &mut self.array[i] }
+}