Implement difference clip rects with window rectangles

src/gpu/gl/GrGLGpu.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLGpu_DEFINED
 #define GrGLGpu_DEFINED
 
@@ skipping 296 matching lines @@
 
     // flushes the scissor. see the note on flushBoundTextureAndParams about
     // flushing the scissor after that function is called.
     void flushScissor(const GrScissorState&,
                       const GrGLIRect& rtViewport,
                       GrSurfaceOrigin rtOrigin);
 
     // disables the scissor
     void disableScissor();
 
+    void flushWindowRectangles(const GrWindowRectangles&, const GrGLRenderTarget*);
+    void disableWindowRectangles();
+
     void initFSAASupport();
 
     // determines valid stencil formats
     void initStencilFormats();
 
     // sets a texture unit to use for texture operations other than binding a texture to a program.
     // ensures that such operations don't negatively interact with tracking bound textures.
     void setScratchTextureUnit();
 
     // bounds is region that may be modified.
@@ skipping 85 matching lines @@
     // last scissor / viewport scissor state seen by the GL.
     struct {
         TriState    fEnabled;
         GrGLIRect   fRect;
         void invalidate() {
             fEnabled = kUnknown_TriState;
             fRect.invalidate();
         }
     } fHWScissorSettings;
 
+    class {
+    public:
+        bool valid() const { return kInvalidOrigin != fOrigin; }
+        void invalidate() { fOrigin = kInvalidOrigin; }
+
+        bool disabled() const {
+            return this->valid() && Mode::kExclusive == fWindows.mode() && !fWindows.count();
+        }
+        void setDisabled() { fOrigin = kDefault_GrSurfaceOrigin, fWindows.reset(); }
+
+        bool equal(GrSurfaceOrigin org, const GrGLIRect& viewp,
+                   const GrWindowRectangles& windows) const {
+            if (!this->valid()) {
+                return false;
+            }
+            if (fWindows.count() && (fOrigin != org || fViewport != viewp)) {
+                return false;
+            }
+            return fWindows == windows;
+        }
+
+        void set(GrSurfaceOrigin org, const GrGLIRect& viewp, const GrWindowRectangles& windows) {
+            fOrigin = org;
+            fViewport = viewp;
+            fWindows = windows;
+        }
+
+    private:
+        typedef GrWindowRectangles::Mode Mode;
+        enum { kInvalidOrigin = -1 };
+
+        int                  fOrigin;
+        GrGLIRect            fViewport;
+        GrWindowRectangles   fWindows;
+    } fHWWindowRects;
+
     GrGLIRect                   fHWViewport;
 
     /**
      * Tracks vertex attrib array state.
      */
     class HWVertexArrayState {
     public:
         HWVertexArrayState() : fCoreProfileVertexArray(nullptr) { this->invalidate(); }
 
         ~HWVertexArrayState() { delete fCoreProfileVertexArray; }
@@ skipping 164 matching lines @@
     bool fPLSHasBeenUsed;
 
     float fHWMinSampleShading;
 
     typedef GrGpu INHERITED;
     friend class GrGLPathRendering; // For accessing setTextureUnit.
     friend class gr_instanced::GLInstancedRendering; // For accessing flushGLState.
 };
 
 #endif