Add back get_preferred_format and sRGB preference

wgpu/examples/framework.rs

@@ -269,11 +269,7 @@ fn start<E: Example>(
     let spawner = Spawner::new();
     let mut config = wgpu::SurfaceConfiguration {
         usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
-        format: *surface
-            .get_supported_formats(&adapter)
-            .unwrap()
-            .first()
-            .unwrap(),
+        format: surface.get_preferred_format(&adapter).unwrap(),
         width: size.width,
         height: size.height,
         present_mode: wgpu::PresentMode::Mailbox,

wgpu/examples/hello-triangle/main.rs

@@ -46,11 +46,7 @@ async fn run(event_loop: EventLoop<()>, window: Window) {
         push_constant_ranges: &[],
     });
 
-    let swapchain_format = *surface
-        .get_supported_formats(&adapter)
-        .unwrap()
-        .first()
-        .unwrap();
+    let swapchain_format = surface.get_preferred_format(&adapter).unwrap();
 
     let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
         label: None,

wgpu/examples/hello-windows/main.rs

@@ -33,12 +33,7 @@ impl ViewportDesc {
 
         let config = wgpu::SurfaceConfiguration {
             usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
-            format: *self
-                .surface
-                .get_supported_formats(adapter)
-                .unwrap()
-                .first()
-                .unwrap(),
+            format: self.surface.get_preferred_format(adapter).unwrap(),
             width: size.width,
             height: size.height,
             present_mode: wgpu::PresentMode::Fifo,

wgpu/src/lib.rs

@@ -3447,13 +3447,32 @@ impl Drop for SurfaceTexture {
 
 impl Surface {
     /// Returns a vec of supported texture formats to use for the [`Surface`] with this adapter.
-    /// Note: The first format in the vector is preferred
     ///
     /// Returns None if the surface is incompatible with the adapter.
     pub fn get_supported_formats(&self, adapter: &Adapter) -> Option<Vec<TextureFormat>> {
         Context::surface_get_supported_formats(&*self.context, &self.id, &adapter.id)
     }
 
+    /// Returns an optimal texture format to use for the [`Surface`] with this adapter.
+    pub fn get_preferred_format(&self, adapter: &Adapter) -> Option<wgt::TextureFormat> {
+        // Check the four formats mentioned in the WebGPU spec.
+        // Also, prefer sRGB over linear as it is better in
+        // representing perceived colors.
+        let preferred_formats = [
+            wgt::TextureFormat::Bgra8UnormSrgb,
+            wgt::TextureFormat::Rgba8UnormSrgb,
+            wgt::TextureFormat::Bgra8Unorm,
+            wgt::TextureFormat::Rgba8Unorm,
+            wgt::TextureFormat::Rgba16Float,
+        ];
+
+        let formats = self.get_supported_formats(adapter)?;
+        preferred_formats
+            .iter()
+            .cloned()
+            .find(|preferred| formats.contains(preferred))
+    }
+
     /// Initializes [`Surface`] for presentation.
     ///
     /// # Panics