1 files changed, 168 insertions, 0 deletions
diff --git a/gfx/layers/AsyncCanvasRenderer.h b/gfx/layers/AsyncCanvasRenderer.h
new file mode 100644
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+++ b/gfx/layers/AsyncCanvasRenderer.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_LAYERS_ASYNCCANVASRENDERER_H_
+#define MOZILLA_LAYERS_ASYNCCANVASRENDERER_H_
+
+#include "LayersTypes.h"
+#include "mozilla/gfx/Point.h"          // for IntSize
+#include "mozilla/Mutex.h"
+#include "nsCOMPtr.h"                   // for nsCOMPtr
+
+class nsICanvasRenderingContextInternal;
+class nsIInputStream;
+class nsIThread;
+
+namespace mozilla {
+
+namespace gfx {
+class DataSourceSurface;
+}
+
+namespace gl {
+class GLContext;
+}
+
+namespace dom {
+class HTMLCanvasElement;
+}
+
+namespace layers {
+
+class CanvasClient;
+class TextureClient;
+
+/**
+ * Since HTMLCanvasElement and OffscreenCanvas are not thread-safe, we create
+ * AsyncCanvasRenderer which is thread-safe wrapper object for communicating
+ * among main, worker and ImageBridgeChild threads.
+ *
+ * Each HTMLCanvasElement object is responsible for creating
+ * AsyncCanvasRenderer object. Once Canvas is transfered to worker,
+ * OffscreenCanvas will keep reference pointer of this object.
+ *
+ * Sometimes main thread needs AsyncCanvasRenderer's result, such as layers
+ * fallback to BasicLayerManager or calling toDataURL in Javascript. Simply call
+ * GetSurface() in main thread will readback the result to mSurface.
+ *
+ * If layers backend is LAYERS_CLIENT, this object will pass to ImageBridgeChild
+ * for submitting frames to Compositor.
+ */
+class AsyncCanvasRenderer final
+{
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AsyncCanvasRenderer)
+
+public:
+  AsyncCanvasRenderer();
+
+  void NotifyElementAboutAttributesChanged();
+  void NotifyElementAboutInvalidation();
+
+  void SetCanvasClient(CanvasClient* aClient);
+
+  void SetWidth(uint32_t aWidth)
+  {
+    mWidth = aWidth;
+  }
+
+  void SetHeight(uint32_t aHeight)
+  {
+    mHeight = aHeight;
+  }
+
+  void SetIsAlphaPremultiplied(bool aIsAlphaPremultiplied)
+  {
+    mIsAlphaPremultiplied = aIsAlphaPremultiplied;
+  }
+
+  // Active thread means the thread which spawns GLContext.
+  void SetActiveThread();
+  void ResetActiveThread();
+
+  // This will readback surface and return the surface
+  // in the DataSourceSurface.
+  // Can be called in main thread only.
+  already_AddRefed<gfx::DataSourceSurface> GetSurface();
+
+  // For SharedSurface_Basic case, before the frame sending to the compositor,
+  // we readback it to a texture client because SharedSurface_Basic cannot shared.
+  // We don't want to readback it again here, so just copy the content of that
+  // texture client here to avoid readback again.
+  void CopyFromTextureClient(TextureClient *aClient);
+
+  // Readback current WebGL's content and convert it to InputStream. This
+  // function called GetSurface implicitly and GetSurface handles only get
+  // called in the main thread. So this function can be called in main thread.
+  nsresult
+  GetInputStream(const char *aMimeType,
+                 const char16_t *aEncoderOptions,
+                 nsIInputStream **aStream);
+
+  gfx::IntSize GetSize() const
+  {
+    return gfx::IntSize(mWidth, mHeight);
+  }
+
+  uint64_t GetCanvasClientAsyncID() const
+  {
+    return mCanvasClientAsyncID;
+  }
+
+  CanvasClient* GetCanvasClient() const
+  {
+    return mCanvasClient;
+  }
+
+  already_AddRefed<nsIThread> GetActiveThread();
+
+  // The lifetime is controllered by HTMLCanvasElement.
+  // Only accessed in main thread.
+  dom::HTMLCanvasElement* mHTMLCanvasElement;
+
+  // Only accessed in active thread.
+  nsICanvasRenderingContextInternal* mContext;
+
+  // We need to keep a reference to the context around here, otherwise the
+  // canvas' surface texture destructor will deref and destroy it too early
+  // Only accessed in active thread.
+  RefPtr<gl::GLContext> mGLContext;
+private:
+
+  virtual ~AsyncCanvasRenderer();
+
+  // Readback current WebGL's content and return it as DataSourceSurface.
+  already_AddRefed<gfx::DataSourceSurface> UpdateTarget();
+
+  bool mIsAlphaPremultiplied;
+
+  uint32_t mWidth;
+  uint32_t mHeight;
+  uint64_t mCanvasClientAsyncID;
+
+  // The lifetime of this pointer is controlled by OffscreenCanvas
+  // Can be accessed in active thread and ImageBridge thread.
+  // But we never accessed it at the same time on both thread. So no
+  // need to protect this member.
+  CanvasClient* mCanvasClient;
+
+  // When backend is LAYER_BASIC and SharedSurface type is Basic.
+  // CanvasClient will readback the GLContext to a TextureClient
+  // in order to send frame to compositor. To avoid readback again,
+  // we copy from this TextureClient to this mSurfaceForBasic directly
+  // by calling CopyFromTextureClient().
+  RefPtr<gfx::DataSourceSurface> mSurfaceForBasic;
+
+  // Protect non thread-safe objects.
+  Mutex mMutex;
+
+  // Can be accessed in any thread, need protect by mutex.
+  nsCOMPtr<nsIThread> mActiveThread;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif // MOZILLA_LAYERS_ASYNCCANVASRENDERER_H_