Bug 1031494 - Move the FBO texture clamping code so that the OGL CompositingRenderTarget gets the unclamped size. r=BenWa

gfx/layers/composite/ContainerLayerComposite.cpp

@@ -302,15 +302,6 @@ ContainerRender(ContainerT* aContainer,
     SurfaceInitMode mode = INIT_MODE_CLEAR;
     gfx::IntRect surfaceRect = gfx::IntRect(visibleRect.x, visibleRect.y,
                                             visibleRect.width, visibleRect.height);
-    // we're about to create a framebuffer backed by textures to use as an intermediate
-    // surface. What to do if its size (as given by framebufferRect) would exceed the
-    // maximum texture size supported by the GL? The present code chooses the compromise
-    // of just clamping the framebuffer's size to the max supported size.
-    // This gives us a lower resolution rendering of the intermediate surface (children layers).
-    // See bug 827170 for a discussion.
-    int32_t maxTextureSize = compositor->GetMaxTextureSize();
-    surfaceRect.width = std::min(maxTextureSize, surfaceRect.width);
-    surfaceRect.height = std::min(maxTextureSize, surfaceRect.height);
     if (aContainer->GetEffectiveVisibleRegion().GetNumRects() == 1 &&
         (aContainer->GetContentFlags() & Layer::CONTENT_OPAQUE))
     {

gfx/layers/opengl/CompositorOGL.cpp

@@ -800,6 +800,17 @@ CompositorOGL::CreateFBOWithTexture(const IntRect& aRect, bool aCopyFromSource,
                                     GLuint aSourceFrameBuffer,
                                     GLuint *aFBO, GLuint *aTexture)
 {
+  // we're about to create a framebuffer backed by textures to use as an intermediate
+  // surface. What to do if its size (as given by aRect) would exceed the
+  // maximum texture size supported by the GL? The present code chooses the compromise
+  // of just clamping the framebuffer's size to the max supported size.
+  // This gives us a lower resolution rendering of the intermediate surface (children layers).
+  // See bug 827170 for a discussion.
+  IntRect clampedRect = aRect;
+  int32_t maxTexSize = GetMaxTextureSize();
+  clampedRect.width = std::min(clampedRect.width, maxTexSize);
+  clampedRect.height = std::min(clampedRect.height, maxTexSize);
+
   GLuint tex, fbo;
 
   mGLContext->fActiveTexture(LOCAL_GL_TEXTURE0);
@@ -828,25 +839,25 @@ CompositorOGL::CreateFBOWithTexture(const IntRect& aRect, bool aCopyFromSource,
       mGLContext->fCopyTexImage2D(mFBOTextureTarget,
                                   0,
                                   LOCAL_GL_RGBA,
-                                  aRect.x, FlipY(aRect.y + aRect.height),
-                                  aRect.width, aRect.height,
+                                  clampedRect.x, FlipY(clampedRect.y + clampedRect.height),
+                                  clampedRect.width, clampedRect.height,
                                   0);
     } else {
       // Curses, incompatible formats.  Take a slow path.
 
       // RGBA
-      size_t bufferSize = aRect.width * aRect.height * 4;
+      size_t bufferSize = clampedRect.width * clampedRect.height * 4;
       nsAutoArrayPtr<uint8_t> buf(new uint8_t[bufferSize]);
 
-      mGLContext->fReadPixels(aRect.x, aRect.y,
-                              aRect.width, aRect.height,
+      mGLContext->fReadPixels(clampedRect.x, clampedRect.y,
+                              clampedRect.width, clampedRect.height,
                               LOCAL_GL_RGBA,
                               LOCAL_GL_UNSIGNED_BYTE,
                               buf);
       mGLContext->fTexImage2D(mFBOTextureTarget,
                               0,
                               LOCAL_GL_RGBA,
-                              aRect.width, aRect.height,
+                              clampedRect.width, clampedRect.height,
                               0,
                               LOCAL_GL_RGBA,
                               LOCAL_GL_UNSIGNED_BYTE,
@@ -863,7 +874,7 @@ CompositorOGL::CreateFBOWithTexture(const IntRect& aRect, bool aCopyFromSource,
     mGLContext->fTexImage2D(mFBOTextureTarget,
                             0,
                             LOCAL_GL_RGBA,
-                            aRect.width, aRect.height,
+                            clampedRect.width, clampedRect.height,
                             0,
                             LOCAL_GL_RGBA,
                             LOCAL_GL_UNSIGNED_BYTE,