Implement Screen in terms of ndarray

Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 
 [dependencies]
 cgmath = "0.16.0"
+ndarray = "0.11.1"
 
 [profile.release]
 opt-level = "s"

src/main.rs

@@ -1,6 +1,7 @@
 #![feature(allocator_api)]
 
 extern crate cgmath;
+extern crate ndarray;
 
 mod core;
 mod screen;
@@ -33,7 +34,12 @@ pub fn fill(
     cx: f64, cy: f64,
     dx: f64, dy: f64
 ) {
-    let screen_buf = unsafe { slice::from_raw_parts_mut(std::mem::transmute(screen_ptr), screen_width * screen_height) };
+    let screen_buf = unsafe {
+        slice::from_raw_parts_mut(
+            std::mem::transmute(screen_ptr),
+            screen_width * screen_height
+        )
+    };
     let mut screen = screen::Screen::new(screen_buf, screen_width, screen_height);
 
     let pos = Vector2::new(cx, cy);

src/screen.rs

@@ -1,3 +1,5 @@
+use ndarray::ArrayViewMut2;
+
 #[repr(C)]
 #[derive(Clone, Copy)]
 pub struct Pixel {
@@ -7,27 +9,20 @@ pub struct Pixel {
     pub a: u8,
 }
 
-pub struct Screen<'a> {
-    buf: &'a mut [Pixel],
-    width: usize,
-    height: usize,
-}
+pub struct Screen<'a>(ArrayViewMut2<'a, Pixel>);
 
 impl<'a> Screen<'a> {
     pub fn new(buf: &mut [Pixel], width: usize, height: usize) -> Screen {
         assert!(buf.len() == width * height);
+        let buf = ArrayViewMut2::from_shape((height, width), buf).unwrap();
 
-        Screen {
-            buf,
-            width,
-            height,
-        }
+        Screen(buf)
     }
 
-    pub fn width(&self) -> usize { self.width }
-    pub fn height(&self) -> usize { self.height }
+    pub fn width(&self) -> usize { self.0.dim().1 }
+    pub fn height(&self) -> usize { self.0.dim().0 }
 
     pub fn px(&mut self, x: usize, y: usize) -> &mut Pixel {
-        &mut self.buf[y * self.width + x]
+        &mut self.0[[y, x]]
     }
 }