From b01db32e07d7f19cd3a7219ec39ba26893057d26 Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Wed, 15 Feb 2012 16:03:05 -0500
Subject: [PATCH] Bug 725209 - Mark TextureImage as valid when self copying,
 and correctly mark the region needing to be redrawn. r=joe

---
 gfx/gl/GLContext.h                   |  8 ++++++++
 gfx/layers/opengl/ThebesLayerOGL.cpp | 29 ++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/gfx/gl/GLContext.h b/gfx/gl/GLContext.h
index 0fa1da06e326..38bf03944a13 100644
--- a/gfx/gl/GLContext.h
+++ b/gfx/gl/GLContext.h
@@ -247,6 +247,12 @@ public:
         EndUpdate();
     }
 
+    /**
+     * Mark this texture as having valid contents. Call this after modifying
+     * the texture contents externally.
+     */
+    virtual void MarkValid() {}
+
     /**
      * aSurf - the source surface to update from
      * aRegion - the region in this image to update
@@ -392,6 +398,8 @@ public:
     virtual already_AddRefed<gfxASurface>
       GetSurfaceForUpdate(const gfxIntSize& aSize, ImageFormat aFmt);
 
+    virtual void MarkValid() { mTextureState = Valid; }
+
     // Call when drawing into the update surface is complete.
     // Returns true if textures should be upload with a relative 
     // offset - See UploadSurfaceToTexture.
diff --git a/gfx/layers/opengl/ThebesLayerOGL.cpp b/gfx/layers/opengl/ThebesLayerOGL.cpp
index 7e6889ed27bb..76801f6513c5 100644
--- a/gfx/layers/opengl/ThebesLayerOGL.cpp
+++ b/gfx/layers/opengl/ThebesLayerOGL.cpp
@@ -591,15 +591,44 @@ BasicBufferOGL::BeginPaint(ContentType aContentType,
         nsIntRect srcRect(overlap), dstRect(overlap);
         srcRect.MoveBy(- mBufferRect.TopLeft() + mBufferRotation);
         dstRect.MoveBy(- destBufferRect.TopLeft());
+        
+        if (mBufferRotation != nsIntPoint(0, 0)) {
+        // If mBuffer is rotated, then BlitTextureImage will only be copying the bottom-right section
+        // of the buffer. We need to invalidate the remaining sections so that they get redrawn too.
+        // Alternatively we could teach BlitTextureImage to rearrange the rotated segments onto
+        // the new buffer.
+          
+        // When the rotated buffer is reorganised, the bottom-right section will be drawn in the top left.
+        // Find the point where this content ends.
+          nsIntPoint rotationPoint(mBufferRect.x + mBufferRect.width - mBufferRotation.x, 
+                                   mBufferRect.y + mBufferRect.height - mBufferRotation.y);
+
+          // Mark the remaining quadrants (bottom-left&right, top-right) as invalid.
+          nsIntRect bottom(mBufferRect.x, rotationPoint.y, mBufferRect.width, mBufferRotation.y);
+          nsIntRect topright(rotationPoint.x, mBufferRect.y, mBufferRotation.x, rotationPoint.y - mBufferRect.y);
+
+          if (!bottom.IsEmpty()) {
+            nsIntRegion temp;
+            temp.And(destBufferRect, bottom);
+            result.mRegionToDraw.Or(result.mRegionToDraw, temp);
+          }
+          if (!topright.IsEmpty()) {
+            nsIntRegion temp;
+            temp.And(destBufferRect, topright);
+            result.mRegionToDraw.Or(result.mRegionToDraw, temp);
+          }
+        }
 
         destBuffer->Resize(destBufferRect.Size());
 
         gl()->BlitTextureImage(mTexImage, srcRect,
                                destBuffer, dstRect);
+        destBuffer->MarkValid();
         if (mode == Layer::SURFACE_COMPONENT_ALPHA) {
           destBufferOnWhite->Resize(destBufferRect.Size());
           gl()->BlitTextureImage(mTexImageOnWhite, srcRect,
                                  destBufferOnWhite, dstRect);
+          destBufferOnWhite->MarkValid();
         }
       } else {
         // can't blit, just draw everything