DrawingBuffer: Clean up GL state restoration

third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 59 matching lines @@
 class WebLayer;
 
 // Manages a rendering target (framebuffer + attachment) for a canvas.  Can
 // publish its rendering results to a WebLayer for compositing.
 class PLATFORM_EXPORT DrawingBuffer
     : public NON_EXPORTED_BASE(cc::TextureLayerClient),
       public RefCounted<DrawingBuffer> {
   WTF_MAKE_NONCOPYABLE(DrawingBuffer);
 
  public:
+  class Client {
+   public:
+    // Returns true if the DrawingBuffer is currently bound for draw.
+    virtual bool DrawingBufferClientIsBoundForDraw() = 0;
+    virtual void DrawingBufferClientRestoreScissorTest() = 0;
+    // Restores the mask and clear value for color, depth, and stencil buffers.
+    virtual void DrawingBufferClientRestoreMaskAndClearValues() = 0;
+    virtual void DrawingBufferClientRestorePixelPackAlignment() = 0;
+    // Restores the GL_TEXTURE_2D binding for the active texture unit only.
+    virtual void DrawingBufferClientRestoreTexture2DBinding() = 0;
+    virtual void DrawingBufferClientRestoreRenderbufferBinding() = 0;
+    virtual void DrawingBufferClientRestoreFramebufferBinding() = 0;
+    virtual void DrawingBufferClientRestorePixelUnpackBufferBinding() = 0;
+  };
+
   enum PreserveDrawingBuffer {
     Preserve,
     Discard,
   };
   enum WebGLVersion {
     WebGL1,
     WebGL2,
   };
 
   enum ChromiumImageUsage {
     AllowChromiumImage,
     DisallowChromiumImage,
   };
 
   static PassRefPtr<DrawingBuffer> create(
       std::unique_ptr<WebGraphicsContext3DProvider>,
+      Client*,
       const IntSize&,
       bool premultipliedAlpha,
       bool wantAlphaChannel,
       bool wantDepthBuffer,
       bool wantStencilBuffer,
       bool wantAntialiasing,
       PreserveDrawingBuffer,
       WebGLVersion,
       ChromiumImageUsage);
   static void forceNextDrawingBufferCreationToFail();
 
   ~DrawingBuffer() override;
 
   // Destruction will be completed after all mailboxes are released.
   void beginDestruction();
 
   // Issues a glClear() on all framebuffers associated with this DrawingBuffer.
-  // The caller is responsible for making the context current and setting the
-  // clear values and masks. Modifies the framebuffer binding.
   void clearFramebuffers(GLbitfield clearMask);
 
   // Indicates whether the DrawingBuffer internally allocated a packed
   // depth-stencil renderbuffer in the situation where the end user only asked
   // for a depth buffer. In this case, we need to upgrade clears of the depth
   // buffer to clears of the depth and stencil buffers in order to avoid
   // performance problems on some GPUs.
   bool hasImplicitStencilBuffer() const { return m_hasImplicitStencilBuffer; }
   bool hasDepthBuffer() const { return !!m_depthStencilBuffer; }
   bool hasStencilBuffer() const { return !!m_depthStencilBuffer; }
 
   // Given the desired buffer size, provides the largest dimensions that will
   // fit in the pixel budget.
   static IntSize adjustSize(const IntSize& desiredSize,
                             const IntSize& curSize,
                             int maxTextureSize);
 
   // Resizes (or allocates if necessary) all buffers attached to the default
-  // framebuffer. Returns whether the operation was successful. Leaves GL
-  // bindings dirtied.
-  bool reset(const IntSize&);
+  // framebuffer. Returns whether the operation was successful.
+  bool resize(const IntSize&);
 
   // Bind the default framebuffer to |target|. |target| must be
   // GL_FRAMEBUFFER, GL_READ_FRAMEBUFFER, or GL_DRAW_FRAMEBUFFER.
   void bind(GLenum target);
   IntSize size() const { return m_size; }
 
-  // Copies the multisample color buffer to the normal color buffer and leaves
-  // m_fbo bound.
-  void commit();
-
-  // commit should copy the full multisample buffer, and not respect the
-  // current scissor bounds. Track the state of the scissor test so that it
-  // can be disabled during calls to commit.
-  void setScissorEnabled(bool scissorEnabled) {
-    m_scissorEnabled = scissorEnabled;
-  }
-
-  // The DrawingBuffer needs to track the texture bound to texture unit 0.
-  // The bound texture is tracked to avoid costly queries during rendering.
-  void setTexture2DBinding(GLuint texture) { m_texture2DBinding = texture; }
-
-  void setPixelUnpackBufferBinding(GLuint buffer) {
-    DCHECK(m_webGLVersion > WebGL1);
-    m_pixelUnpackBufferBinding = buffer;
-  }
-
-  void notifyBufferDeleted(GLuint buffer) {
-    if (m_webGLVersion > WebGL1 && buffer == m_pixelUnpackBufferBinding) {
-      setPixelUnpackBufferBinding(0);
-    }
-  }
-
-  // The DrawingBuffer needs to track the currently bound framebuffer so it
-  // restore the binding when needed.
-  void setFramebufferBinding(GLenum target, GLuint fbo) {
-    switch (target) {
-      case GL_FRAMEBUFFER:
-        m_drawFramebufferBinding = fbo;
-        m_readFramebufferBinding = fbo;
-        break;
-      case GL_DRAW_FRAMEBUFFER:
-        m_drawFramebufferBinding = fbo;
-        break;
-      case GL_READ_FRAMEBUFFER:
-        m_readFramebufferBinding = fbo;
-        break;
-      default:
-        ASSERT(0);
-    }
-  }
-
-  // The DrawingBuffer needs to track the color mask and clear color so that
-  // it can restore it when needed.
-  void setClearColor(GLfloat* clearColor) {
-    memcpy(m_clearColor, clearColor, 4 * sizeof(GLfloat));
-  }
-
-  void setColorMask(GLboolean* colorMask) {
-    memcpy(m_colorMask, colorMask, 4 * sizeof(GLboolean));
-  }
-
-  // The DrawingBuffer needs to track the currently bound renderbuffer so it
-  // restore the binding when needed.
-  void setRenderbufferBinding(GLuint renderbuffer) {
-    m_renderbufferBinding = renderbuffer;
-  }
-
-  // Track the currently active texture unit. Texture unit 0 is used as host for
-  // a scratch texture.
-  void setActiveTextureUnit(GLint textureUnit) {
-    m_activeTextureUnit = textureUnit;
-  }
+  // Resolves the multisample color buffer to the normal color buffer and leaves
+  // the resolved color buffer bound to GL_READ_FRAMEBUFFER and
+  // GL_DRAW_FRAMEBUFFER.
+  void resolveAndBindForReadAndDraw();
 
   bool multisample() const;
 
-  GLuint framebuffer() const;
-
   bool discardFramebufferSupported() const {
     return m_discardFramebufferSupported;
   }
 
   void markContentsChanged();
   void setBufferClearNeeded(bool);
   bool bufferClearNeeded() const;
   void setIsHidden(bool);
   void setFilterQuality(SkFilterQuality);
 
@@ skipping 16 matching lines @@
   bool PrepareTextureMailbox(
       cc::TextureMailbox* outMailbox,
       std::unique_ptr<cc::SingleReleaseCallback>* outReleaseCallback) override;
 
   // Returns a StaticBitmapImage backed by a texture containing the current
   // contents of the front buffer. This is done without any pixel copies. The
   // texture in the ImageBitmap is from the active ContextProvider on the
   // DrawingBuffer.
   PassRefPtr<StaticBitmapImage> transferToStaticBitmapImage();
 
-  // Destroys the TEXTURE_2D binding for the owned context
   bool copyToPlatformTexture(gpu::gles2::GLES2Interface*,
                              GLuint texture,
                              GLenum internalFormat,
                              GLenum destType,
                              GLint level,
                              bool premultiplyAlpha,
                              bool flipY,
                              SourceDrawingBuffer);
 
-  void setPackAlignment(GLint param);
-
   bool paintRenderingResultsToImageData(int&,
                                         int&,
                                         SourceDrawingBuffer,
                                         WTF::ArrayBufferContents&);
 
   int sampleCount() const { return m_sampleCount; }
   bool explicitResolveOfMultisampleData() const {
     return m_antiAliasingMode == MSAAExplicitResolve;
   }
 
-  void restorePixelUnpackBufferBindings();
-
-  // Bind to m_drawFramebufferBinding or m_readFramebufferBinding if it's not 0.
-  // Otherwise, bind to the default FBO.
+  // Rebind the read and draw framebuffers that WebGL is expecting.
   void restoreFramebufferBindings();
 
-  void restoreTextureBindings();
+  // Restore all state that may have been dirtied by any call.
+  void restoreAllState();
 
   void addNewMailboxCallback(std::unique_ptr<WTF::Closure> closure) {
     m_newMailboxCallback = std::move(closure);
   }
 
  protected:  // For unittests
   DrawingBuffer(std::unique_ptr<WebGraphicsContext3DProvider>,
                 std::unique_ptr<Extensions3DUtil>,
+                Client*,
                 bool discardFramebufferSupported,
                 bool wantAlphaChannel,
                 bool premultipliedAlpha,
                 PreserveDrawingBuffer,
                 WebGLVersion,
                 bool wantsDepth,
                 bool wantsStencil,
                 ChromiumImageUsage);
 
   bool initialize(const IntSize&, bool useMultisampling);
 
   // Shared memory bitmaps that were released by the compositor and can be used
   // again by this DrawingBuffer.
   struct RecycledBitmap {
     std::unique_ptr<cc::SharedBitmap> bitmap;
     IntSize size;
   };
   Vector<RecycledBitmap> m_recycledBitmaps;
 
  private:
+  friend class ScopedStateRestorer;
+  friend class ColorBuffer;
+
+  // This structure should wrap all public entrypoints that may modify GL state.
+  // It will restore all state when it drops out of scope.
+  class ScopedStateRestorer {
+   public:
+    ScopedStateRestorer(DrawingBuffer*);
+    ~ScopedStateRestorer();
+
+    // Mark parts of the state that are dirty and need to be restored.
+    void setClearStateDirty() { m_clearStateDirty = true; }
+    void setPixelPackAlignmentDirty() { m_pixelPackAlignmentDirty = true; }
+    void setTextureBindingDirty() { m_textureBindingDirty = true; }
+    void setRenderbufferBindingDirty() { m_renderbufferBindingDirty = true; }
+    void setFramebufferBindingDirty() { m_framebufferBindingDirty = true; }
+    void setPixelUnpackBufferBindingDirty() {
+      m_pixelUnpackBufferBindingDirty = true;
+    }
+
+   private:
+    RefPtr<DrawingBuffer> m_drawingBuffer;
+    bool m_clearStateDirty = false;
+    bool m_pixelPackAlignmentDirty = false;
+    bool m_textureBindingDirty = false;
+    bool m_renderbufferBindingDirty = false;
+    bool m_framebufferBindingDirty = false;
+    bool m_pixelUnpackBufferBindingDirty = false;
+  };
+
   // All parameters necessary to generate the texture for the ColorBuffer.
   struct ColorBufferParameters {
     DISALLOW_NEW();
     GLenum target = 0;
     GLenum internalColorFormat = 0;
 
     // The internal color format used when allocating storage for the
     // texture. This may be different from internalColorFormat if RGB
     // emulation is required.
     GLenum creationInternalColorFormat = 0;
@@ skipping 26 matching lines @@
     gpu::SyncToken produceSyncToken;
 
     // The sync token for when this buffer was received back from the
     // compositor.
     gpu::SyncToken receiveSyncToken;
 
    private:
     WTF_MAKE_NONCOPYABLE(ColorBuffer);
   };
 
+  // The same as clearFramebuffers(), but leaves GL state dirty.
+  void clearFramebuffersInternal(GLbitfield clearMask);
+
+  // The same as reset(), but leaves GL state dirty.
+  bool resizeFramebufferInternal(const IntSize&);
+
+  // The same as commit(), but leaves GL state dirty.
+  void resolveMultisampleFramebufferInternal();
+
   bool prepareTextureMailboxInternal(
       cc::TextureMailbox* outMailbox,
       std::unique_ptr<cc::SingleReleaseCallback>* outReleaseCallback,
       bool forceGpuResult);
 
   // Helper functions to be called only by prepareTextureMailboxInternal.
   bool finishPrepareTextureMailboxGpu(
       cc::TextureMailbox* outMailbox,
       std::unique_ptr<cc::SingleReleaseCallback>* outReleaseCallback);
   bool finishPrepareTextureMailboxSoftware(
@@ skipping 65 matching lines @@
   // implemented by forwarding all draw operations to a multisample
   // renderbuffer, which is resolved before any read operations or swaps.
   bool wantExplicitResolve();
 
   // Whether the WebGL client wants a depth or stencil buffer.
   bool wantDepthOrStencil();
 
   // The format to use when creating a multisampled renderbuffer.
   GLenum getMultisampledRenderbufferFormat();
 
+  // Weak, reset by beginDestruction.
+  Client* m_client = nullptr;
+
   const PreserveDrawingBuffer m_preserveDrawingBuffer;
   const WebGLVersion m_webGLVersion;
-  bool m_scissorEnabled = false;
-  GLuint m_texture2DBinding = 0;
-  GLuint m_pixelUnpackBufferBinding = 0;
-  GLuint m_drawFramebufferBinding = 0;
-  GLuint m_readFramebufferBinding = 0;
-  GLuint m_renderbufferBinding = 0;
-  GLenum m_activeTextureUnit = GL_TEXTURE0;
-  GLfloat m_clearColor[4];
-  GLboolean m_colorMask[4];
 
   std::unique_ptr<WebGraphicsContext3DProvider> m_contextProvider;
   // Lifetime is tied to the m_contextProvider.
   gpu::gles2::GLES2Interface* m_gl;
   std::unique_ptr<Extensions3DUtil> m_extensionsUtil;
   IntSize m_size = {-1, -1};
   const bool m_discardFramebufferSupported;
   const bool m_wantAlphaChannel;
   const bool m_premultipliedAlpha;
   const bool m_softwareRendering;
   bool m_hasImplicitStencilBuffer = false;
   bool m_storageTextureSupported = false;
 
   std::unique_ptr<WTF::Closure> m_newMailboxCallback;
 
+  // The current state restorer, which is used to track state dirtying. It is in
+  // error to dirty state shared with WebGL while there is no existing state
+  // restorer. It is also in error to instantiate two state restorers at once.
+  ScopedStateRestorer* m_stateRestorer = nullptr;
+
   // This is used when the user requests either a depth or stencil buffer.
   GLuint m_depthStencilBuffer = 0;
 
   // When wantExplicitResolve() returns true, the target of all draw
   // operations.
   GLuint m_multisampleFBO = 0;
 
   // The id of the renderbuffer storage for |m_multisampleFBO|.
   GLuint m_multisampleRenderbuffer = 0;
 
@@ skipping 26 matching lines @@
     None,
     MSAAImplicitResolve,
     MSAAExplicitResolve,
     ScreenSpaceAntialiasing,
   };
 
   AntialiasingMode m_antiAliasingMode = None;
 
   int m_maxTextureSize = 0;
   int m_sampleCount = 0;
-  int m_packAlignment = 4;
   bool m_destructionInProgress = false;
   bool m_isHidden = false;
   SkFilterQuality m_filterQuality = kLow_SkFilterQuality;
 
   std::unique_ptr<WebExternalTextureLayer> m_layer;
 
   // Mailboxes that were released by the compositor can be used again by this
   // DrawingBuffer.
   Deque<RefPtr<ColorBuffer>> m_recycledColorBufferQueue;
 
   // If the width and height of the Canvas's backing store don't
   // match those that we were given in the most recent call to
   // reshape(), then we need an intermediate bitmap to read back the
   // frame buffer into. This seems to happen when CSS styles are
   // used to resize the Canvas.
   SkBitmap m_resizingBitmap;
 
   // In the case of OffscreenCanvas, we do not want to enable the
   // WebGLImageChromium flag, so we replace all the
   // RuntimeEnabledFeatures::webGLImageChromiumEnabled() call with
   // shouldUseChromiumImage() calls, and set m_chromiumImageUsage to
   // DisallowChromiumImage in the case of OffscreenCanvas.
   ChromiumImageUsage m_chromiumImageUsage;
   bool shouldUseChromiumImage();
 };
 
 }  // namespace blink
 
 #endif  // DrawingBuffer_h