Single source of truth for preferred canvas format

Author: MendyBerger

crates/wasi-webgpu-wasmtime/src/lib.rs

@@ -29,6 +29,14 @@ pub mod reexports {
     pub use wgpu_types;
 }
 
+// https://searchfox.org/mozilla-central/source/dom/webgpu/Instance.h#68
+#[cfg(target_os = "android")]
+const PREFERRED_CANVAS_FORMAT: wasi::webgpu::webgpu::GpuTextureFormat =
+    wasi::webgpu::webgpu::GpuTextureFormat::Rgba8unorm;
+#[cfg(not(target_os = "android"))]
+const PREFERRED_CANVAS_FORMAT: wasi::webgpu::webgpu::GpuTextureFormat =
+    wasi::webgpu::webgpu::GpuTextureFormat::Bgra8unorm;
+
 #[cfg(all(
     not(target_os = "linux"),
     not(target_os = "android"),
@@ -184,10 +192,7 @@ where
     fn display_api_ready(&mut self, display: &Arc<dyn DisplayApi + Send + Sync>) {
         let surface_id = (self.create_surface)(display);
         // TODO: fix this once user can pass in configuration options. For now just taking from `gpu.get-preferred-canvas-format()`.
-        #[cfg(target_os = "android")]
-        let swapchain_format = wgpu_types::TextureFormat::Rgba8Unorm;
-        #[cfg(not(target_os = "android"))]
-        let swapchain_format = wgpu_types::TextureFormat::Bgra8Unorm;
+        let swapchain_format = PREFERRED_CANVAS_FORMAT.into();
 
         // https://www.w3.org/TR/webgpu/#dictdef-gpucanvasconfiguration
         let config = wgpu_types::SurfaceConfiguration {

crates/wasi-webgpu-wasmtime/src/trait_impls.rs

@@ -16,6 +16,7 @@ use crate::{
     wasi::{io::poll, webgpu::webgpu},
     wrapper_types::{Buffer, ComputePassEncoder, Device, RenderBundleEncoder, RenderPassEncoder},
     AbstractBuffer, MainThreadSpawner, WasiWebGpuImpl, WasiWebGpuView, WebGpuSurface,
+    PREFERRED_CANVAS_FORMAT,
 };
 
 impl<T: WasiWebGpuView> webgpu::Host for WasiWebGpuImpl<T> {
@@ -2375,11 +2376,7 @@ impl<T: WasiWebGpuView> webgpu::HostGpu for WasiWebGpuImpl<T> {
         &mut self,
         _gpu: Resource<webgpu::Gpu>,
     ) -> webgpu::GpuTextureFormat {
-        // https://searchfox.org/mozilla-central/source/dom/webgpu/Instance.h#68
-        #[cfg(target_os = "android")]
-        return webgpu::GpuTextureFormat::Rgba8unorm;
-        #[cfg(not(target_os = "android"))]
-        return webgpu::GpuTextureFormat::Bgra8unorm;
+        PREFERRED_CANVAS_FORMAT
     }
 
     fn wgsl_language_features(