Improve tracking of bound FBOs in GrGLGpu.

src/gpu/gl/GrGLGpu.h

Index: src/gpu/gl/GrGLGpu.h
diff --git a/src/gpu/gl/GrGLGpu.h b/src/gpu/gl/GrGLGpu.h
index b93080b70037d2b5a624b0b9996dc7b798adad12..74e955eed6ff07210e040390b10a1c12767f28d5 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -50,6 +50,15 @@ public:
         return static_cast<GrGLPathRendering*>(pathRendering());
     }
 
+    // On older GLs there may not be separate FBO bindings for draw and read. In that case these
+    // alias each other.
+    enum FBOBinding {
+        kDraw_FBOBinding, // drawing or dst of blit
+        kRead_FBOBinding, // src of blit, read pixels.
+    };
+
+    void willDeleteOrAbandonFramebuffer(GrGLFBO* fbo);
+
     void discard(GrRenderTarget*) SK_OVERRIDE;
 
     // Used by GrGLProgram and GrGLPathTexGenProgramEffects to configure OpenGL
@@ -246,9 +255,18 @@ private:
     // ensures that such operations don't negatively interact with tracking bound textures.
     void setScratchTextureUnit();
 
-    // bounds is region that may be modified and therefore has to be resolved.
-    // NULL means whole target. Can be an empty rect.
-    void flushRenderTarget(GrGLRenderTarget*, const SkIRect* bounds);
+    // Binds the render target, sets the viewport, tracks dirty are for resolve, and tracks whether
+    // mip maps need rebuilding.
+    // bounds is region that may be modified by the draw. NULL means whole target. Can be an empty
+    // rect.
+    void prepareToDrawToRenderTarget(GrGLRenderTarget*, const SkIRect* bounds);
+
+    static const FBOBinding kInvalidFBOBinding = static_cast<FBOBinding>(-1);
+
+    // binds the FBO and returns the GL enum of the framebuffer target it was bound to.
+    GrGLenum bindFBO(FBOBinding, const GrGLFBO*);
+
+    void setViewport(const GrGLIRect& viewport);
 
     void flushStencil(const GrStencilSettings&);
     void flushHWAAState(GrRenderTarget* rt, bool useHWAA, bool isLineDraw);
@@ -281,15 +299,12 @@ private:
     bool createRenderTargetObjects(const GrSurfaceDesc&, bool budgeted, GrGLuint texID, 
                                    GrGLRenderTarget::IDDesc*);
 
-    enum TempFBOTarget {
-        kSrc_TempFBOTarget,
-        kDst_TempFBOTarget
-    };
-
-    GrGLuint bindSurfaceAsFBO(GrSurface* surface, GrGLenum fboTarget, GrGLIRect* viewport,
-                              TempFBOTarget tempFBOTarget);
+    // Binds a surface as an FBO. A temporary FBO ID may be used if the surface is not already
+    // a render target. Afterwards unbindSurfaceforCopy must be called with the value returned.
+    FBOBinding bindSurfaceAsFBOForCopy(GrSurface*, FBOBinding, GrGLIRect* viewport);
 
-    void unbindTextureFromFBO(GrGLenum fboTarget);
+    // Must be matched with bindSurfaceAsFBOForCopy.
+    void unbindSurfaceAsFBOForCopy(FBOBinding);
 
     GrGLContext fGLContext;
 
@@ -309,10 +324,9 @@ private:
         kUnknown_TriState
     };
 
-    GrGLuint                    fTempSrcFBOID;
-    GrGLuint                    fTempDstFBOID;
-
-    GrGLuint                    fStencilClearFBOID;
+    SkAutoTUnref<GrGLFBO> fTempSrcFBO;
+    SkAutoTUnref<GrGLFBO> fTempDstFBO;
+    SkAutoTUnref<GrGLFBO> fStencilClearFBO;
 
     // last scissor / viewport scissor state seen by the GL.
     struct {
@@ -458,9 +472,18 @@ private:
     GrPipelineBuilder::DrawFace fHWDrawFace;
     TriState                    fHWWriteToColor;
     TriState                    fHWDitherEnabled;
-    uint32_t                    fHWBoundRenderTargetUniqueID;
     SkTArray<uint32_t, true>    fHWBoundTextureUniqueIDs;
 
+    // Track read/draw fbo binding state.
+    struct HWFBOBinding {
+        uint32_t    fGenID;
+        bool        fIsDefaultFBO;
+        void invalidate() {
+            fGenID = SK_InvalidGenID;
+            fIsDefaultFBO = false;
+        }
+    } fHWFBOBinding[2];

[egdaniel, 2015/02/24 18:47:01]

Do we want to distinguish these as 0 is draw and 1 is read? Or is safe to just
use them internally as such without really forcing anything?

[bsalomon, 2015/02/24 21:00:52]

I added a cnt value and used it here. In the impl I used the enum values to
index the array.

+
     ///@}
 
     // we record what stencil format worked last time to hopefully exit early