Add pixel formats and transparency

Cargo.toml

@@ -40,13 +40,19 @@ x11 = [
     "winit/x11",
 ]
 x11-dlopen = ["tiny-xlib/dlopen", "x11rb/dl-libxcb"]
+f16 = ["half"]
 
 [dependencies]
 raw_window_handle = { package = "raw-window-handle", version = "0.6", features = [
     "std",
 ] }
 tracing = { version = "0.1.41", default-features = false }
 
+# For f16 support in pixel conversions.
+# TODO: Use standard library's f16 once stable:
+# https://github.com/rust-lang/rust/issues/116909
+half = { version = "2.7.1", optional = true }
+
 [target.'cfg(target_os = "android")'.dependencies]
 bytemuck = "1.12.3"
 ndk = "0.9.0"

src/backend_interface.rs

@@ -1,6 +1,6 @@
 //! Interface implemented by backends
 
-use crate::{InitError, Rect, SoftBufferError};
+use crate::{AlphaMode, InitError, PixelFormat, Rect, SoftBufferError};
 
 use raw_window_handle::{HasDisplayHandle, HasWindowHandle};
 use std::num::NonZeroU32;
@@ -22,12 +22,26 @@ pub(crate) trait SurfaceInterface<D: HasDisplayHandle + ?Sized, W: HasWindowHand
     where
         W: Sized,
         Self: Sized;
+
     /// Get the inner window handle.
     fn window(&self) -> &W;
-    /// Resize the internal buffer to the given width and height.
-    fn resize(&mut self, width: NonZeroU32, height: NonZeroU32) -> Result<(), SoftBufferError>;
+
+    fn alpha_mode(&self) -> AlphaMode;
+
+    /// Reconfigure the internal buffer(s).
+    ///
+    /// Returns `Some(byte_stride)` if the buffer was successfully resized, or `None` if the surface does not support the given pixel format.
+    fn configure(
+        &mut self,
+        width: NonZeroU32,
+        height: NonZeroU32,
+        alpha_mode: AlphaMode,
+        pixel_format: PixelFormat,
+    ) -> Result<Option<u32>, SoftBufferError>;
+
     /// Get a mutable reference to the buffer.
     fn buffer_mut(&mut self) -> Result<Self::Buffer<'_>, SoftBufferError>;
+
     /// Fetch the buffer from the window.
     fn fetch(&mut self) -> Result<Vec<u32>, SoftBufferError> {
         Err(SoftBufferError::Unimplemented)

src/backends/cg.rs

@@ -252,7 +252,7 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for CGImpl<
         &self.window_handle
     }
 
-    fn resize(&mut self, width: NonZeroU32, height: NonZeroU32) -> Result<(), SoftBufferError> {
+    fn configure(&mut self, width: NonZeroU32, height: NonZeroU32) -> Result<(), SoftBufferError> {
         self.width = width.get() as usize;
         self.height = height.get() as usize;
         Ok(())

src/backends/wayland/buffer.rs

@@ -82,7 +82,13 @@ pub(super) struct WaylandBuffer {
 }
 
 impl WaylandBuffer {
-    pub fn new(shm: &wl_shm::WlShm, width: i32, height: i32, qh: &QueueHandle<State>) -> Self {
+    pub fn new(
+        shm: &wl_shm::WlShm,
+        width: i32,
+        height: i32,
+        format: wl_shm::Format,
+        qh: &QueueHandle<State>,
+    ) -> Self {
         // Calculate size to use for shm pool
         let pool_size = get_pool_size(width, height);
 
@@ -94,15 +100,7 @@ impl WaylandBuffer {
         // Create wayland shm pool and buffer
         let pool = shm.create_pool(tempfile.as_fd(), pool_size, qh, ());
         let released = Arc::new(AtomicBool::new(true));
-        let buffer = pool.create_buffer(
-            0,
-            width,
-            height,
-            width * 4,
-            wl_shm::Format::Xrgb8888,
-            qh,
-            released.clone(),
-        );
+        let buffer = pool.create_buffer(0, width, height, width * 4, format, qh, released.clone());
 
         Self {
             qh: qh.clone(),
@@ -118,7 +116,7 @@ impl WaylandBuffer {
         }
     }
 
-    pub fn resize(&mut self, width: i32, height: i32) {
+    pub fn configure(&mut self, width: i32, height: i32, format: wl_shm::Format) {
         // If size is the same, there's nothing to do
         if self.width != width || self.height != height {
             // Destroy old buffer
@@ -139,7 +137,7 @@ impl WaylandBuffer {
                 width,
                 height,
                 width * 4,
-                wl_shm::Format::Xrgb8888,
+                format,
                 &self.qh,
                 self.released.clone(),
             );

src/backends/wayland/mod.rs

@@ -1,7 +1,7 @@
 use crate::{
     backend_interface::*,
     error::{InitError, SwResultExt},
-    Rect, SoftBufferError,
+    AlphaMode, Rect, SoftBufferError,
 };
 use raw_window_handle::{HasDisplayHandle, HasWindowHandle, RawDisplayHandle, RawWindowHandle};
 use std::{
@@ -81,6 +81,7 @@ pub struct WaylandImpl<D: ?Sized, W: ?Sized> {
     surface: Option<wl_surface::WlSurface>,
     buffers: Option<(WaylandBuffer, WaylandBuffer)>,
     size: Option<(NonZeroI32, NonZeroI32)>,
+    format: wl_shm::Format,
 
     /// The pointer to the window object.
     ///
@@ -128,7 +129,12 @@ impl<D: HasDisplayHandle + ?Sized, W: HasWindowHandle> SurfaceInterface<D, W>
         &self.window_handle
     }
 
-    fn resize(&mut self, width: NonZeroU32, height: NonZeroU32) -> Result<(), SoftBufferError> {
+    fn configure(
+        &mut self,
+        width: NonZeroU32,
+        height: NonZeroU32,
+        alpha_mode: AlphaMode,
+    ) -> Result<AlphaMode, SoftBufferError> {
         self.size = Some(
             (|| {
                 let width = NonZeroI32::try_from(width).ok()?;
@@ -137,7 +143,13 @@ impl<D: HasDisplayHandle + ?Sized, W: HasWindowHandle> SurfaceInterface<D, W>
             })()
             .ok_or(SoftBufferError::SizeOutOfRange { width, height })?,
         );
-        Ok(())
+        let (format, chosen_alpha_mode) = match alpha_mode {
+            AlphaMode::Opaque => (wl_shm::Format::Xrgb8888, AlphaMode::Opaque),
+            AlphaMode::PreMultiplied => (wl_shm::Format::Argb8888, AlphaMode::PreMultiplied),
+            AlphaMode::PostMultiplied => (wl_shm::Format::Argb8888, AlphaMode::PostMultiplied),
+        };
+        self.format = format;
+        Ok(chosen_alpha_mode)
     }
 
     fn buffer_mut(&mut self) -> Result<BufferImpl<'_>, SoftBufferError> {
@@ -164,20 +176,22 @@ impl<D: HasDisplayHandle + ?Sized, W: HasWindowHandle> SurfaceInterface<D, W>
             }
 
             // Resize, if buffer isn't large enough
-            back.resize(width.get(), height.get());
+            back.configure(width.get(), height.get(), self.format);
         } else {
             // Allocate front and back buffer
             self.buffers = Some((
                 WaylandBuffer::new(
                     &self.display.shm,
                     width.get(),
                     height.get(),
+                    self.format,
                     &self.display.qh,
                 ),
                 WaylandBuffer::new(
                     &self.display.shm,
                     width.get(),
                     height.get(),
+                    self.format,
                     &self.display.qh,
                 ),
             ));

src/backends/web.rs

@@ -10,6 +10,7 @@ use web_sys::{CanvasRenderingContext2d, HtmlCanvasElement};
 use web_sys::{OffscreenCanvas, OffscreenCanvasRenderingContext2d};
 
 use crate::backend_interface::*;
+use crate::convert::FALLBACK_FORMAT;
 use crate::error::{InitError, SwResultExt};
 use crate::{util, NoDisplayHandle, NoWindowHandle, Rect, SoftBufferError};
 use std::marker::PhantomData;
@@ -231,6 +232,8 @@ impl SurfaceExtWeb for crate::Surface<NoDisplayHandle, NoWindowHandle> {
         let imple = crate::SurfaceDispatch::Web(WebImpl::from_canvas(canvas, NoWindowHandle(()))?);
 
         Ok(Self {
+            pixel_format: FALLBACK_FORMAT,
+            fallback_buffer: None,
             surface_impl: Box::new(imple),
             _marker: PhantomData,
         })
@@ -243,6 +246,8 @@ impl SurfaceExtWeb for crate::Surface<NoDisplayHandle, NoWindowHandle> {
         )?);
 
         Ok(Self {
+            pixel_format: FALLBACK_FORMAT,
+            fallback_buffer: None,
             surface_impl: Box::new(imple),
             _marker: PhantomData,
         })