From 0e864b60c73d4f9bc196e56ef557735d6ef504e1 Mon Sep 17 00:00:00 2001
From: Diego Wilson <dwilson@codeaurora.org>
Date: Thu, 10 Jan 2013 11:51:43 +0100
Subject: [PATCH] Bug 810501: Get buffer offset from ThebesLayer when composing
 with hwc. r=cjones a=blocking-basecamp

---
 gfx/layers/opengl/LayerManagerOGL.h  | 13 ++++++++++++-
 gfx/layers/opengl/ThebesLayerOGL.cpp | 14 ++++++--------
 widget/gonk/HwcComposer2D.cpp        | 26 +++++++++++++++-----------
 3 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/gfx/layers/opengl/LayerManagerOGL.h b/gfx/layers/opengl/LayerManagerOGL.h
index 4a54edf87a0..4bba11eca6d 100644
--- a/gfx/layers/opengl/LayerManagerOGL.h
+++ b/gfx/layers/opengl/LayerManagerOGL.h
@@ -10,6 +10,7 @@
 
 #include "mozilla/layers/ShadowLayers.h"
 #include "mozilla/TimeStamp.h"
+#include "nsPoint.h"
 
 #ifdef XP_WIN
 #include <windows.h>
@@ -435,12 +436,20 @@ enum LayerRenderStateFlags {
 };
 
 struct LayerRenderState {
-  LayerRenderState() : mSurface(nullptr), mFlags(0)
+  LayerRenderState() : mSurface(nullptr), mFlags(0), mHasOwnOffset(false)
   {}
 
   LayerRenderState(SurfaceDescriptor* aSurface, uint32_t aFlags = 0)
     : mSurface(aSurface)
     , mFlags(aFlags)
+    , mHasOwnOffset(false)
+  {}
+
+  LayerRenderState(SurfaceDescriptor* aSurface, nsIntPoint aOffset, uint32_t aFlags = 0)
+    : mSurface(aSurface)
+    , mFlags(aFlags)
+    , mOffset(aOffset)
+    , mHasOwnOffset(true)
   {}
 
   bool YFlipped() const
@@ -451,6 +460,8 @@ struct LayerRenderState {
 
   SurfaceDescriptor* mSurface;
   uint32_t mFlags;
+  nsIntPoint mOffset;
+  bool mHasOwnOffset;
 };
 
 /**
diff --git a/gfx/layers/opengl/ThebesLayerOGL.cpp b/gfx/layers/opengl/ThebesLayerOGL.cpp
index 5147120ee80..432ada089aa 100644
--- a/gfx/layers/opengl/ThebesLayerOGL.cpp
+++ b/gfx/layers/opengl/ThebesLayerOGL.cpp
@@ -98,8 +98,8 @@ public:
 
   bool Initialised() { return mInitialised; }
 
-protected:
   virtual nsIntPoint GetOriginOffset() = 0;
+protected:
 
   GLContext* gl() const { return mOGLLayer->gl(); }
 
@@ -343,7 +343,6 @@ public:
     return mTexImage ? mTexImage->GetBackingSurface() : nullptr;
   }
 
-protected:
   virtual nsIntPoint GetOriginOffset() {
     return BufferRect().TopLeft() - BufferRotation();
   }
@@ -366,6 +365,10 @@ public:
 
   virtual PaintState BeginPaint(ContentType aContentType,
                                 uint32_t aFlags);
+  virtual nsIntPoint GetOriginOffset() {
+    return mBufferRect.TopLeft() - mBufferRotation;
+  }
+
 
 protected:
   enum XSide {
@@ -376,10 +379,6 @@ protected:
   };
   nsIntRect GetQuadrantRectangle(XSide aXSide, YSide aYSide);
 
-  virtual nsIntPoint GetOriginOffset() {
-    return mBufferRect.TopLeft() - mBufferRotation;
-  }
-
 private:
   nsIntRect mBufferRect;
   nsIntPoint mBufferRotation;
@@ -947,7 +946,6 @@ public:
     return mBufferRotation;
   }
 
-protected:
   virtual nsIntPoint GetOriginOffset() {
     return mBufferRect.TopLeft() - mBufferRotation;
   }
@@ -1156,7 +1154,7 @@ ShadowThebesLayerOGL::GetRenderState()
   }
   uint32_t flags = (mBuffer->Rotation() != nsIntPoint()) ?
                    LAYER_RENDER_STATE_BUFFER_ROTATION : 0;
-  return LayerRenderState(&mBufferDescriptor, flags);
+  return LayerRenderState(&mBufferDescriptor, mBuffer->GetOriginOffset(), flags);
 }
 
 bool
diff --git a/widget/gonk/HwcComposer2D.cpp b/widget/gonk/HwcComposer2D.cpp
index 3d9e9ee75b6..4d08cfa903f 100644
--- a/widget/gonk/HwcComposer2D.cpp
+++ b/widget/gonk/HwcComposer2D.cpp
@@ -174,13 +174,13 @@ HwcComposer2D::GetRotation()
  * Sets hwc layer rectangles required for hwc composition
  *
  * @param aVisible Input. Layer's unclipped visible rectangle
- *        The origin is the layer's buffer
+ *        The origin is the top-left corner of the layer
  * @param aTransform Input. Layer's transformation matrix
  *        It transforms from layer space to screen space
  * @param aClip Input. A clipping rectangle.
  *        The origin is the top-left corner of the screen
  * @param aBufferRect Input. The layer's buffer bounds
- *        The origin is the buffer itself and hence always (0,0)
+ *        The origin is the top-left corner of the layer
  * @param aSurceCrop Output. Area of the source to consider,
  *        the origin is the top-left corner of the buffer
  * @param aVisibleRegionScreen Output. Visible region in screen space.
@@ -207,9 +207,7 @@ PrepareLayerRects(nsIntRect aVisible, const gfxMatrix& aTransform,
     gfxMatrix inverse(aTransform);
     inverse.Invert();
     gfxRect crop = inverse.TransformBounds(visibleRectScreen);
-    // Map to buffer space
-    crop -= visibleRect.TopLeft();
-    gfxRect bufferRect(aBufferRect);
+
     //clip to buffer size
     crop.IntersectRect(crop, aBufferRect);
     crop.RoundOut();
@@ -219,11 +217,13 @@ PrepareLayerRects(nsIntRect aVisible, const gfxMatrix& aTransform,
         return false;
     }
 
-
     //propagate buffer clipping back to visible rect
-    visibleRectScreen = aTransform.TransformBounds(crop + visibleRect.TopLeft());
+    visibleRectScreen = aTransform.TransformBounds(crop);
     visibleRectScreen.RoundOut();
 
+    // Map from layer space to buffer space
+    crop -= aBufferRect.TopLeft();
+
     aSourceCrop->left = crop.x;
     aSourceCrop->top  = crop.y;
     aSourceCrop->right  = crop.x + crop.width;
@@ -326,11 +326,15 @@ HwcComposer2D::PrepareLayerList(Layer* aLayer,
 
     nsIntRect bufferRect;
     if (fillColor) {
-        bufferRect = nsIntRect(0, 0, visibleRect.width,
-            visibleRect.height);
+        bufferRect = nsIntRect(visibleRect);
     } else {
-        bufferRect = nsIntRect(0, 0, int(buffer->getWidth()),
-            int(buffer->getHeight()));
+        if(state.mHasOwnOffset) {
+            bufferRect = nsIntRect(state.mOffset.x, state.mOffset.y,
+                int(buffer->getWidth()), int(buffer->getHeight()));
+        } else {
+            bufferRect = nsIntRect(visibleRect.x, visibleRect.y,
+                int(buffer->getWidth()), int(buffer->getHeight()));
+        }
     }
 
     hwc_layer_t& hwcLayer = mList->hwLayers[current];