State management cleanup

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

Index: third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h
diff --git a/third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h b/third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h
index a568fd06e4b752ac3ad1cb5ce139dde57c4b2f05..7a32f35c3f8c3b2eeb9fb369e8ed06690ac6daa3 100644
--- a/third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h
+++ b/third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h
@@ -69,6 +69,36 @@ class WebExternalTextureLayer;
 class WebGraphicsContext3DProvider;
 class WebLayer;
 
+// OpenGL state the the DrawingBuffer may modify, which it will need to
+// restore before returning from any of its methods.
+struct PLATFORM_EXPORT DrawingBufferRestoreState {
+  bool scissorEnabled = false;
+
+  GLfloat clearColor[4] = {0, 0, 0, 0};
+  GLfloat clearDepth = 0;
+  GLint clearStencil = 0;
+
+  GLboolean colorMask[4] = {0, 0, 0, 0};
+  GLboolean depthMask = 0;
+  GLuint stencilMask = 0;
+
+  GLint packAlignment = 4;
+
+  // The bound 2D texture for the active texture unit.
+  GLuint activeTexture2DBinding = 0;
+  GLuint renderbufferBinding = 0;
+  GLuint drawFramebufferBinding = 0;
+  GLuint readFramebufferBinding = 0;
+  GLuint pixelUnpackBufferBinding = 0;
+};
+
+// An interface through which DrawingBuffer may query the state that it will
+// need to reset from an object that is tracking this state.
+class PLATFORM_EXPORT DrawingBufferStateTracker {
+ public:
+  virtual void GetDrawingBufferRestoreState(DrawingBufferRestoreState*) = 0;
+};
+
 // Manages a rendering target (framebuffer + attachment) for a canvas.  Can
 // publish its rendering results to a WebLayer for compositing.
 class PLATFORM_EXPORT DrawingBuffer
@@ -93,6 +123,7 @@ class PLATFORM_EXPORT DrawingBuffer
 
   static PassRefPtr<DrawingBuffer> create(
       std::unique_ptr<WebGraphicsContext3DProvider>,
+      DrawingBufferStateTracker*,
       const IntSize&,
       bool premultipliedAlpha,
       bool wantAlphaChannel,
@@ -111,7 +142,7 @@ class PLATFORM_EXPORT DrawingBuffer
 
   // 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.
+  // clear values and masks.
   void clearFramebuffers(GLbitfield clearMask);
 
   // Indicates whether the DrawingBuffer internally allocated a packed
@@ -130,86 +161,21 @@ class PLATFORM_EXPORT DrawingBuffer
                             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;
   }
@@ -246,7 +212,6 @@ class PLATFORM_EXPORT DrawingBuffer
   // DrawingBuffer.
   PassRefPtr<StaticBitmapImage> transferToStaticBitmapImage();
 
-  // Destroys the TEXTURE_2D binding for the owned context
   bool copyToPlatformTexture(gpu::gles2::GLES2Interface*,
                              GLuint texture,
                              GLenum internalFormat,
@@ -256,8 +221,6 @@ class PLATFORM_EXPORT DrawingBuffer
                              bool flipY,
                              SourceDrawingBuffer);
 
-  void setPackAlignment(GLint param);
-
   bool paintRenderingResultsToImageData(int&,
                                         int&,
                                         SourceDrawingBuffer,
@@ -268,14 +231,9 @@ class PLATFORM_EXPORT DrawingBuffer
     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();
-
   void addNewMailboxCallback(std::unique_ptr<WTF::Closure> closure) {
     m_newMailboxCallback = std::move(closure);
   }
@@ -283,6 +241,7 @@ class PLATFORM_EXPORT DrawingBuffer
  protected:  // For unittests
   DrawingBuffer(std::unique_ptr<WebGraphicsContext3DProvider>,
                 std::unique_ptr<Extensions3DUtil>,
+                DrawingBufferStateTracker*,
                 bool discardFramebufferSupported,
                 bool wantAlphaChannel,
                 bool premultipliedAlpha,
@@ -303,9 +262,38 @@ class PLATFORM_EXPORT DrawingBuffer
   Vector<RecycledBitmap> m_recycledBitmaps;
 
  private:
-  // All parameters necessary to generate the texture that will be passed to
-  // prepareMailbox.
-  struct TextureParameters {
+  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;
@@ -318,7 +306,11 @@ class PLATFORM_EXPORT DrawingBuffer
   };
 
   struct ColorBuffer : public RefCounted<ColorBuffer> {
-    ColorBuffer(DrawingBuffer*, const TextureParameters&, const IntSize&);
+    ColorBuffer(DrawingBuffer*,
+                const ColorBufferParameters&,
+                const IntSize&,
+                GLuint textureId,
+                GLuint imageId);
     ~ColorBuffer();
 
     // The owning DrawingBuffer. Note that DrawingBuffer is explicitly destroyed
@@ -326,11 +318,11 @@ class PLATFORM_EXPORT DrawingBuffer
     // ColorBuffers.
     RefPtr<DrawingBuffer> drawingBuffer;
 
-    const TextureParameters parameters;
+    const ColorBufferParameters parameters;
     const IntSize size;
 
-    GLuint textureId = 0;
-    GLuint imageId = 0;
+    const GLuint textureId = 0;
+    const GLuint imageId = 0;
 
     // The mailbox used to send this buffer to the compositor.
     gpu::Mailbox mailbox;
@@ -346,31 +338,44 @@ class PLATFORM_EXPORT DrawingBuffer
     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);
 
-  // Callbacks for mailboxes given to the compositor from PrepareTextureMailbox.
-  void gpuMailboxReleased(RefPtr<ColorBuffer>,
+  // Helper functions to be called only by prepareTextureMailboxInternal.
+  bool finishPrepareTextureMailboxGpu(
+      cc::TextureMailbox* outMailbox,
+      std::unique_ptr<cc::SingleReleaseCallback>* outReleaseCallback);
+  bool finishPrepareTextureMailboxSoftware(
+      cc::TextureMailbox* outMailbox,
+      std::unique_ptr<cc::SingleReleaseCallback>* outReleaseCallback);
+
+  // Callbacks for mailboxes given to the compositor from
+  // finishPrepareTextureMailboxGpu and finishPrepareTextureMailboxSoftware.
+  void mailboxReleasedGpu(RefPtr<ColorBuffer>,
                           const gpu::SyncToken&,
                           bool lostResource);
-  void softwareMailboxReleased(std::unique_ptr<cc::SharedBitmap>,
+  void mailboxReleasedSoftware(std::unique_ptr<cc::SharedBitmap>,
                                const IntSize&,
                                const gpu::SyncToken&,
                                bool lostResource);
 
   // The texture parameters to use for a texture that will be backed by a
-  // CHROMIUM_image.
-  TextureParameters chromiumImageTextureParameters();
-
-  // The texture parameters to use for a default texture.
-  TextureParameters defaultTextureParameters();
+  // CHROMIUM_image, backed by a GpuMemoryBuffer.
+  ColorBufferParameters gpuMemoryBufferColorBufferParameters();
 
-  // Creates and binds a texture with the given parameters. Returns 0 on
-  // failure, or the newly created texture id on success. The caller takes
-  // ownership of the newly created texture.
-  GLuint createColorTexture(const TextureParameters&);
+  // The texture parameters to use for an ordinary GL texture.
+  ColorBufferParameters textureColorBufferParameters();
 
   // Attempts to allocator storage for, or resize all buffers. Returns whether
   // the operation was successful.
@@ -378,8 +383,6 @@ class PLATFORM_EXPORT DrawingBuffer
 
   void clearPlatformLayer();
 
-  PassRefPtr<ColorBuffer> takeRecycledMailbox();
-
   std::unique_ptr<cc::SharedBitmap> createOrRecycleBitmap();
 
   // Updates the current size of the buffer, ensuring that
@@ -400,16 +403,6 @@ class PLATFORM_EXPORT DrawingBuffer
   // Helper function to flip a bitmap vertically.
   void flipVertically(uint8_t* data, int width, int height);
 
-  // Allocate a storage texture if possible. Otherwise, allocate a regular
-  // texture.
-  void allocateConditionallyImmutableTexture(GLenum target,
-                                             GLenum internalformat,
-                                             GLsizei width,
-                                             GLsizei height,
-                                             GLint border,
-                                             GLenum format,
-                                             GLenum type);
-
   // If RGB emulation is required, then the CHROMIUM image's alpha channel
   // must be immediately cleared after it is bound to a texture. Nothing
   // should be allowed to change the alpha channel after this.
@@ -417,11 +410,12 @@ class PLATFORM_EXPORT DrawingBuffer
 
   // Tries to create a CHROMIUM_image backed texture if
   // RuntimeEnabledFeatures::webGLImageChromiumEnabled() is true. On failure,
-  // or if the flag is false, creates a default texture.
-  RefPtr<ColorBuffer> createTextureAndAllocateMemory(const IntSize&);
+  // or if the flag is false, creates a default texture. Always returns a valid
+  // ColorBuffer.
+  RefPtr<ColorBuffer> createColorBuffer(const IntSize&);
 
-  // Creates and allocates space for a default texture.
-  RefPtr<ColorBuffer> createDefaultTextureAndAllocateMemory(const IntSize&);
+  // Creates or recycles a ColorBuffer of size |m_size|.
+  PassRefPtr<ColorBuffer> createOrRecycleColorBuffer();
 
   // Attaches |m_backColorBuffer| to |m_fbo|, which is always the source for
   // read operations.
@@ -438,17 +432,11 @@ class PLATFORM_EXPORT DrawingBuffer
   // The format to use when creating a multisampled renderbuffer.
   GLenum getMultisampledRenderbufferFormat();
 
+  // Weak, reset by beginDestruction.
+  DrawingBufferStateTracker* m_stateTracker = 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.
@@ -462,12 +450,13 @@ class PLATFORM_EXPORT DrawingBuffer
   bool m_hasImplicitStencilBuffer = false;
   bool m_storageTextureSupported = false;
 
-  // This is the ColorBuffer that was most recently presented to the compositor
-  // by prepareTextureMailboxInternal.
-  RefPtr<ColorBuffer> m_frontColorBuffer;
-
   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;
 
@@ -480,13 +469,16 @@ class PLATFORM_EXPORT DrawingBuffer
 
   // When wantExplicitResolve() returns false, the target of all draw and
   // read operations. When wantExplicitResolve() returns true, the target of
-  // all read operations. A swap is performed by exchanging |m_backColorBuffer|
-  // with |m_frontColorBuffer|.
+  // all read operations.
   GLuint m_fbo = 0;
 
-  // All information about the texture storage for |m_fbo|.
+  // The ColorBuffer that backs |m_fbo|.
   RefPtr<ColorBuffer> m_backColorBuffer;
 
+  // The ColorBuffer that was most recently presented to the compositor by
+  // prepareTextureMailboxInternal.
+  RefPtr<ColorBuffer> m_frontColorBuffer;
+
   // True if our contents have been modified since the last presentation of this
   // buffer.
   bool m_contentsChanged = true;
@@ -511,7 +503,6 @@ class PLATFORM_EXPORT DrawingBuffer
 
   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;
@@ -520,7 +511,7 @@ class PLATFORM_EXPORT DrawingBuffer
 
   // Mailboxes that were released by the compositor can be used again by this
   // DrawingBuffer.
-  Deque<RefPtr<ColorBuffer>> m_recycledMailboxQueue;
+  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
@@ -529,9 +520,6 @@ class PLATFORM_EXPORT DrawingBuffer
   // used to resize the Canvas.
   SkBitmap m_resizingBitmap;
 
-  // Used to flip a bitmap vertically.
-  Vector<uint8_t> m_scanline;
-
   // In the case of OffscreenCanvas, we do not want to enable the
   // WebGLImageChromium flag, so we replace all the
   // RuntimeEnabledFeatures::webGLImageChromiumEnabled() call with