Remove Deref and DerefMut impls on Buffer

We want to migrate towards exposing either less structured buffers
(`[u8]`, useful for different formats) or more structured buffers
(`[Pixel]`, useful for ergonomics). `[u32]` is kind of in a weird state
in between these and has confusing interactions with endianess.

Since the current impls are not zero-cost on all backends, making them
be a potential invisible performance cliff for users, we'd prefer for
users to instead explicitly access the buffer's data in the format they
desire.

Author: madsmtm

CHANGELOG.md

@@ -4,6 +4,7 @@
 - Added `Buffer::pixel_rows()` for iterating over rows of the buffer data.
 - Added `Buffer::pixels_iter()` for iterating over each pixel with its associated `x`/`y` coordinate.
 - **Breaking:** Removed generic type parameters `D` and `W` from `Buffer<'_>` struct.
+- **Breaking:** Removed `Deref[Mut]` implementation on `Buffer<'_>`. Use `Buffer::pixels()` instead.
 
 # 0.4.7
 

benches/buffer_mut.rs

@@ -40,10 +40,10 @@ fn buffer_mut(c: &mut criterion::Criterion) {
                 });
             });
 
-            c.bench_function("data()", |b| {
+            c.bench_function("pixels()", |b| {
                 let mut buffer = surface.buffer_mut().unwrap();
                 b.iter(|| {
-                    let pixels: &mut [u32] = &mut buffer;
+                    let pixels: &mut [u32] = buffer.pixels();
                     black_box(pixels);
                 });
             });
@@ -52,7 +52,7 @@ fn buffer_mut(c: &mut criterion::Criterion) {
                 let mut buffer = surface.buffer_mut().unwrap();
                 b.iter(|| {
                     let buffer = black_box(&mut buffer);
-                    buffer.fill(0x00000000);
+                    buffer.pixels().fill(0x00000000);
                 });
             });
 

examples/animation.rs

@@ -70,7 +70,7 @@ fn main() {
 
                 let frame = &frames[((elapsed * 60.0).round() as usize).clamp(0, 59)];
 
-                buffer.copy_from_slice(frame);
+                buffer.pixels().copy_from_slice(frame);
                 buffer.present().unwrap();
             }
             WindowEvent::CloseRequested

examples/drm.rs

@@ -128,7 +128,7 @@ mod imple {
 
             // Start drawing.
             let mut buffer = surface.buffer_mut()?;
-            draw_to_buffer(&mut buffer, tick);
+            draw_to_buffer(buffer.pixels(), tick);
             buffer.present()?;
 
             // Wait for the page flip to happen.

examples/fruit.rs

@@ -58,7 +58,7 @@ fn main() {
                     let blue = pixel.0[2] as u32;
 
                     let color = blue | (green << 8) | (red << 16);
-                    buffer[(y * width + x) as usize] = color;
+                    buffer.pixels()[(y * width + x) as usize] = color;
                 }
 
                 buffer.present().unwrap();

src/backend_dispatch.rs

@@ -166,16 +166,6 @@ macro_rules! make_dispatch {
                 }
             }
 
-            #[inline]
-            fn pixels(&self) -> &[u32] {
-                match self {
-                    $(
-                        $(#[$attr])*
-                        Self::$name(inner) => inner.pixels(),
-                    )*
-                }
-            }
-
             #[inline]
             fn pixels_mut(&mut self) -> &mut [u32] {
                 match self {

src/backend_interface.rs

@@ -37,7 +37,6 @@ pub(crate) trait SurfaceInterface<D: HasDisplayHandle + ?Sized, W: HasWindowHand
 pub(crate) trait BufferInterface {
     fn width(&self) -> NonZeroU32;
     fn height(&self) -> NonZeroU32;
-    fn pixels(&self) -> &[u32];
     fn pixels_mut(&mut self) -> &mut [u32];
     fn age(&self) -> u8;
     fn present_with_damage(self, damage: &[Rect]) -> Result<(), SoftBufferError>;

src/backends/android.rs

@@ -131,11 +131,6 @@ impl BufferInterface for BufferImpl<'_> {
         NonZeroU32::new(self.native_window_buffer.height() as u32).unwrap()
     }
 
-    #[inline]
-    fn pixels(&self) -> &[u32] {
-        &self.buffer
-    }
-
     #[inline]
     fn pixels_mut(&mut self) -> &mut [u32] {
         &mut self.buffer

src/backends/cg.rs

@@ -287,11 +287,6 @@ impl BufferInterface for BufferImpl<'_> {
         NonZeroU32::new(self.height as u32).unwrap()
     }
 
-    #[inline]
-    fn pixels(&self) -> &[u32] {
-        &self.buffer
-    }
-
     #[inline]
     fn pixels_mut(&mut self) -> &mut [u32] {
         &mut self.buffer

src/backends/kms.rs

@@ -313,11 +313,6 @@ impl BufferInterface for BufferImpl<'_> {
         self.size.1
     }
 
-    #[inline]
-    fn pixels(&self) -> &[u32] {
-        bytemuck::cast_slice(self.mapping.as_ref())
-    }
-
     #[inline]
     fn pixels_mut(&mut self) -> &mut [u32] {
         bytemuck::cast_slice_mut(self.mapping.as_mut())