Bug 1637972 - WebGPU handle canvas resize r=aosmond

we recreate the swapchain on the size change

Differential Revision: https://phabricator.services.mozilla.com/D113172

dom/webgpu/CanvasContext.cpp

@@ -115,14 +115,34 @@ wr::ImageKey CanvasContext::CreateImageKey(
 
 bool CanvasContext::UpdateWebRenderLocalCanvasData(
     layers::WebRenderLocalCanvasData* aCanvasData) {
-  if (!mSwapChain || !mSwapChain->GetGpuBridge()) {
+  if (!mSwapChain || !mSwapChain->GetParent()) {
     return false;
   }
 
-  aCanvasData->mGpuBridge = mSwapChain->GetGpuBridge();
+  const auto size =
+      nsIntSize(AssertedCast<int>(mWidth), AssertedCast<int>(mHeight));
+  if (mSwapChain->mSize != size) {
+    const auto gfxFormat = mSwapChain->mGfxFormat;
+    dom::GPUSwapChainDescriptor desc;
+    desc.mFormat = static_cast<dom::GPUTextureFormat>(mSwapChain->mFormat);
+    desc.mUsage = mSwapChain->mUsage;
+    desc.mDevice = mSwapChain->GetParent();
+
+    mSwapChain->Destroy(mExternalImageId);
+    mExternalImageId =
+        layers::CompositorManagerChild::GetInstance()->GetNextExternalImageId();
+
+    dom::GPUExtent3DDict extent;
+    extent.mWidth = size.width;
+    extent.mHeight = size.height;
+    extent.mDepthOrArrayLayers = 1;
+    mSwapChain = new SwapChain(desc, extent, mExternalImageId, gfxFormat);
+  }
+
+  aCanvasData->mGpuBridge = mSwapChain->GetParent()->GetBridge().get();
   aCanvasData->mGpuTextureId = mSwapChain->GetCurrentTexture()->mId;
   aCanvasData->mExternalImageId = mExternalImageId;
-  aCanvasData->mFormat = mSwapChain->mFormat;
+  aCanvasData->mFormat = mSwapChain->mGfxFormat;
   return true;
 }
 

dom/webgpu/CanvasContext.h

@@ -48,7 +48,7 @@ class CanvasContext final : public nsICanvasRenderingContextInternal,
   bool UpdateWebRenderLocalCanvasData(
       layers::WebRenderLocalCanvasData* aCanvasData);
 
-  const wr::ExternalImageId mExternalImageId;
+  wr::ExternalImageId mExternalImageId;
 
  public:  // nsICanvasRenderingContextInternal
   int32_t GetWidth() override { return mWidth; }

dom/webgpu/SwapChain.cpp

@@ -19,7 +19,10 @@ SwapChain::SwapChain(const dom::GPUSwapChainDescriptor& aDesc,
                      wr::ExternalImageId aExternalImageId,
                      gfx::SurfaceFormat aFormat)
     : ChildOf(aDesc.mDevice),
-      mFormat(aFormat),
+      mGfxFormat(aFormat),
+      mFormat(static_cast<uint8_t>(aDesc.mFormat)),
+      mUsage(aDesc.mUsage),
+      mSize(aExtent3D.mWidth, aExtent3D.mHeight),
       mTexture(aDesc.mDevice->InitSwapChain(aDesc, aExtent3D, aExternalImageId,
                                             aFormat)) {}
 
@@ -31,9 +34,7 @@ void SwapChain::Cleanup() {
   }
 }
 
-WebGPUChild* SwapChain::GetGpuBridge() const {
-  return mParent ? mParent->GetBridge().get() : nullptr;
-}
+RefPtr<Device> SwapChain::GetParent() const { return mParent; }
 
 void SwapChain::Destroy(wr::ExternalImageId aExternalImageId) {
   if (mValid && mParent && mParent->GetBridge()) {

dom/webgpu/SwapChain.h

@@ -29,10 +29,14 @@ class SwapChain final : public ObjectBase, public ChildOf<Device> {
             const dom::GPUExtent3DDict& aExtent3D,
             wr::ExternalImageId aExternalImageId, gfx::SurfaceFormat aFormat);
 
-  WebGPUChild* GetGpuBridge() const;
+  RefPtr<Device> GetParent() const;
   void Destroy(wr::ExternalImageId aExternalImageId);
 
-  const gfx::SurfaceFormat mFormat;
+  const gfx::SurfaceFormat mGfxFormat;
+  const uint8_t
+      mFormat;  // This is `dom::GPUTextureFormat` but without the includes
+  const uint32_t mUsage;
+  const nsIntSize mSize;
 
  private:
   virtual ~SwapChain();

dom/webgpu/ipc/WebGPUParent.cpp

@@ -525,11 +525,15 @@ static void PresentCallback(ffi::WGPUBufferMapAsyncStatus status,
     const auto bufferSize = data->mRowCount * data->mSourcePitch;
     const uint8_t* ptr = ffi::wgpu_server_buffer_get_mapped_range(
         req->mContext, bufferId, 0, bufferSize);
-    uint8_t* dst = data->mTextureHost->GetBuffer();
-    for (uint32_t row = 0; row < data->mRowCount; ++row) {
-      memcpy(dst, ptr, data->mTargetPitch);
-      dst += data->mTargetPitch;
-      ptr += data->mSourcePitch;
+    if (data->mTextureHost) {
+      uint8_t* dst = data->mTextureHost->GetBuffer();
+      for (uint32_t row = 0; row < data->mRowCount; ++row) {
+        memcpy(dst, ptr, data->mTargetPitch);
+        dst += data->mTargetPitch;
+        ptr += data->mSourcePitch;
+      }
+    } else {
+      NS_WARNING("WebGPU present skipped: the swapchain is resized!");
     }
     wgpu_server_buffer_unmap(req->mContext, bufferId);
   } else {