Bug 745177 - Retain and re-use uploaded GL tiles. r=ajuma

Rather than discarding uploaded tiles once they fall outside of the valid region, shuffle them off into a separate tile-store with all the metadata they need to render them, and render them in the areas that our current valid region doesn't cover in TiledThebesLayerOGL::RenderLayer.
2012-04-24 22:48:33 -04:00 · 2012-04-24 22:48:33 -04:00 · a459a00ba8
--- a/gfx/layers/Layers.h
+++ b/gfx/layers/Layers.h
@ -110,6 +110,7 @@ public:
    , mViewportScrollOffset(0, 0)
    , mScrollId(NULL_SCROLL_ID)
    , mCSSContentSize(0, 0)
+    , mResolution(1, 1)
  {}

  // Default copy ctor and operator= are fine
@ -151,6 +152,10 @@ public:
  // Consumers often want to know the size before scaling to pixels
  // so we record this size as well.
  gfx::Size mCSSContentSize;
+
+  // This represents the resolution at which the associated layer
+  // will been rendered.
+  gfxSize mResolution;
 };

 #define MOZ_LAYER_DECL_NAME(n, e)                           \
--- a/gfx/layers/Makefile.in
+++ b/gfx/layers/Makefile.in
@ -86,6 +86,7 @@ CPPSRCS = \
        LayerManagerOGL.cpp \
        ThebesLayerOGL.cpp \
        TiledThebesLayerOGL.cpp \
+        ReusableTileStoreOGL.cpp \
        LayerSorter.cpp \
        ImageLayers.cpp \
        $(NULL)
--- a/gfx/layers/TiledLayerBuffer.h
+++ b/gfx/layers/TiledLayerBuffer.h
@ -87,8 +87,20 @@ public:
  // (x*GetTileLength(), y*GetTileLength(), GetTileLength(), GetTileLength())
  Tile GetTile(int x, int y) const;

+  // This operates the same as GetTile(aTileOrigin), but will also replace the
+  // specified tile with the placeholder tile. This does not call ReleaseTile
+  // on the removed tile.
+  bool RemoveTile(const nsIntPoint& aTileOrigin, Tile& aRemovedTile);
+
+  // This operates the same as GetTile(x, y), but will also replace the
+  // specified tile with the placeholder tile. This does not call ReleaseTile
+  // on the removed tile.
+  bool RemoveTile(int x, int y, Tile& aRemovedTile);
+
  uint16_t GetTileLength() const { return TILEDLAYERBUFFER_TILE_SIZE; }

+  unsigned int GetTileCount() const { return mRetainedTiles.Length(); }
+
  const nsIntRegion& GetValidRegion() const { return mValidRegion; }
  const nsIntRegion& GetLastPaintRegion() const { return mLastPaintRegion; }
  void SetLastPaintRegion(const nsIntRegion& aLastPaintRegion) {
@ -161,6 +173,30 @@ TiledLayerBuffer<Derived, Tile>::GetTile(int x, int y) const
  return mRetainedTiles.SafeElementAt(index, AsDerived().GetPlaceholderTile());
 }

+template<typename Derived, typename Tile> bool
+TiledLayerBuffer<Derived, Tile>::RemoveTile(const nsIntPoint& aTileOrigin,
+                                            Tile& aRemovedTile)
+{
+  int firstTileX = mValidRegion.GetBounds().x / GetTileLength();
+  int firstTileY = mValidRegion.GetBounds().y / GetTileLength();
+  return RemoveTile(aTileOrigin.x / GetTileLength() - firstTileX,
+                    aTileOrigin.y / GetTileLength() - firstTileY,
+                    aRemovedTile);
+}
+
+template<typename Derived, typename Tile> bool
+TiledLayerBuffer<Derived, Tile>::RemoveTile(int x, int y, Tile& aRemovedTile)
+{
+  int index = x * mRetainedHeight + y;
+  const Tile& tileToRemove = mRetainedTiles.SafeElementAt(index, AsDerived().GetPlaceholderTile());
+  if (!IsPlaceholder(tileToRemove)) {
+    aRemovedTile = tileToRemove;
+    mRetainedTiles[index] = AsDerived().GetPlaceholderTile();
+    return true;
+  }
+  return false;
+}
+
 template<typename Derived, typename Tile> void
 TiledLayerBuffer<Derived, Tile>::Update(const nsIntRegion& aNewValidRegion,
                                        const nsIntRegion& aPaintRegion)
@ -209,14 +245,16 @@ TiledLayerBuffer<Derived, Tile>::Update(const nsIntRegion& aNewValidRegion,
        int tileY = (y - oldBufferOrigin.y) / GetTileLength();
        int index = tileX * oldRetainedHeight + tileY;

-        NS_ABORT_IF_FALSE(!IsPlaceholder(oldRetainedTiles.
-                                         SafeElementAt(index, AsDerived().GetPlaceholderTile())),
-                          "Expected tile");
+        // The tile may have been removed, skip over it in this case.
+        if (IsPlaceholder(oldRetainedTiles.
+                          SafeElementAt(index, AsDerived().GetPlaceholderTile()))) {
+          newRetainedTiles.AppendElement(AsDerived().GetPlaceholderTile());
+        } else {
+          Tile tileWithPartialValidContent = oldRetainedTiles[index];
+          newRetainedTiles.AppendElement(tileWithPartialValidContent);
+          oldRetainedTiles[index] = AsDerived().GetPlaceholderTile();
+        }

-        Tile tileWithPartialValidContent = oldRetainedTiles[index];
-        newRetainedTiles.AppendElement(tileWithPartialValidContent);
-
-        oldRetainedTiles[index] = AsDerived().GetPlaceholderTile();
      } else {
        // This tile is either:
        // 1) Outside the new valid region and will simply be an empty
--- a/gfx/layers/ipc/ShadowLayerUtils.h
+++ b/gfx/layers/ipc/ShadowLayerUtils.h
@ -73,6 +73,7 @@ struct ParamTraits<mozilla::layers::FrameMetrics>
    WriteParam(aMsg, aParam.mViewportScrollOffset);
    WriteParam(aMsg, aParam.mDisplayPort);
    WriteParam(aMsg, aParam.mScrollId);
+    WriteParam(aMsg, aParam.mResolution);
  }

  static bool Read(const Message* aMsg, void** aIter, paramType* aResult)
@ -82,7 +83,8 @@ struct ParamTraits<mozilla::layers::FrameMetrics>
            ReadParam(aMsg, aIter, &aResult->mContentSize) &&
            ReadParam(aMsg, aIter, &aResult->mViewportScrollOffset) &&
            ReadParam(aMsg, aIter, &aResult->mDisplayPort) &&
-            ReadParam(aMsg, aIter, &aResult->mScrollId));
+            ReadParam(aMsg, aIter, &aResult->mScrollId) &&
+            ReadParam(aMsg, aIter, &aResult->mResolution));
  }
 };

--- a/gfx/layers/opengl/ReusableTileStoreOGL.cpp
+++ b/gfx/layers/opengl/ReusableTileStoreOGL.cpp
@ -0,0 +1,188 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ReusableTileStoreOGL.h"
+
+namespace mozilla {
+namespace layers {
+
+ReusableTileStoreOGL::~ReusableTileStoreOGL()
+{
+  if (mTiles.Length() == 0)
+    return;
+
+  mContext->MakeCurrent();
+  for (int i = 0; i < mTiles.Length(); i++)
+    mContext->fDeleteTextures(1, &mTiles[i]->mTexture.mTextureHandle);
+  mTiles.Clear();
+}
+
+void
+ReusableTileStoreOGL::HarvestTiles(TiledLayerBufferOGL* aVideoMemoryTiledBuffer,
+                                   const nsIntRegion& aOldValidRegion,
+                                   const nsIntRegion& aNewValidRegion,
+                                   const gfxSize& aOldResolution,
+                                   const gfxSize& aNewResolution)
+{
+  gfxSize scaleFactor = gfxSize(aNewResolution.width / aOldResolution.width,
+                                aNewResolution.height / aOldResolution.height);
+
+#ifdef GFX_TILEDLAYER_PREF_WARNINGS
+  printf_stderr("Seeing if there are any tiles we can reuse\n");
+#endif
+
+  // Iterate over existing harvested tiles and release any that are contained
+  // within the new valid region.
+  mContext->MakeCurrent();
+  for (int i = 0; i < mTiles.Length();) {
+    ReusableTiledTextureOGL* tile = mTiles[i];
+
+    bool release = false;
+    if (tile->mResolution == aNewResolution) {
+      if (aNewValidRegion.Contains(tile->mTileRegion))
+        release = true;
+    } else {
+      nsIntRegion transformedTileRegion(tile->mTileRegion);
+      transformedTileRegion.ScaleRoundOut(tile->mResolution.width / aNewResolution.width,
+                                          tile->mResolution.height / aNewResolution.height);
+      if (aNewValidRegion.Contains(transformedTileRegion))
+        release = true;
+    }
+
+    if (release) {
+#ifdef GFX_TILEDLAYER_PREF_WARNINGS
+      nsIntRect tileBounds = tile->mTileRegion.GetBounds();
+      printf_stderr("Releasing obsolete reused tile at %d,%d, x%f\n",
+                    tileBounds.x, tileBounds.y, tile->mResolution.width);
+#endif
+      mContext->fDeleteTextures(1, &tile->mTexture.mTextureHandle);
+      mTiles.RemoveElementAt(i);
+      continue;
+    }
+
+    i++;
+  }
+
+  // Iterate over the tiles and decide which ones we're going to harvest.
+  // We harvest any tile that is entirely outside of the new valid region, or
+  // any tile that is partially outside of the valid region and whose
+  // resolution has changed.
+  // XXX Tile iteration needs to be abstracted, or have some utility functions
+  //     to make it simpler.
+  uint16_t tileSize = aVideoMemoryTiledBuffer->GetTileLength();
+  nsIntRect validBounds = aOldValidRegion.GetBounds();
+  for (int x = validBounds.x; x < validBounds.XMost();) {
+    int w = tileSize - x % tileSize;
+    if (x + w > validBounds.x + validBounds.width)
+      w = validBounds.x + validBounds.width - x;
+
+    for (int y = validBounds.y; y < validBounds.YMost();) {
+      int h = tileSize - y % tileSize;
+      if (y + h > validBounds.y + validBounds.height)
+        h = validBounds.y + validBounds.height - y;
+
+      // If the new valid region doesn't contain this tile region,
+      // harvest the tile.
+      nsIntRegion tileRegion;
+      tileRegion.And(aOldValidRegion, nsIntRect(x, y, w, h));
+
+      nsIntRegion intersectingRegion;
+      bool retainTile = false;
+      if (aNewResolution != aOldResolution) {
+        // Reconcile resolution changes.
+        // If the resolution changes, we know the backing layer will have been
+        // invalidated, so retain tiles that are partially encompassed by the
+        // new valid area, instead of just tiles that don't intersect at all.
+        nsIntRegion transformedTileRegion(tileRegion);
+        transformedTileRegion.ScaleRoundOut(scaleFactor.width, scaleFactor.height);
+        if (!aNewValidRegion.Contains(transformedTileRegion))
+          retainTile = true;
+      } else if (intersectingRegion.And(tileRegion, aNewValidRegion).IsEmpty()) {
+        retainTile = true;
+      }
+
+      if (retainTile) {
+#ifdef GFX_TILEDLAYER_PREF_WARNINGS
+        printf_stderr("Retaining tile at %d,%d, x%f for reuse\n", x, y, aOldResolution.width);
+#endif
+        TiledTexture removedTile;
+        if (aVideoMemoryTiledBuffer->RemoveTile(nsIntPoint(x, y), removedTile)) {
+          ReusableTiledTextureOGL* reusedTile =
+            new ReusableTiledTextureOGL(removedTile, tileRegion, tileSize,
+                                        aOldResolution);
+          mTiles.AppendElement(reusedTile);
+        }
+#ifdef GFX_TILEDLAYER_PREF_WARNINGS
+        else
+          printf_stderr("Failed to retain tile for reuse\n");
+#endif
+      }
+
+      y += h;
+    }
+
+    x += w;
+  }
+
+  // Now prune our reused tile store of its oldest tiles if it gets too large.
+  while (mTiles.Length() > aVideoMemoryTiledBuffer->GetTileCount() * mSizeLimit) {
+#ifdef GFX_TILEDLAYER_PREF_WARNINGS
+    nsIntRect tileBounds = mTiles[0]->mTileRegion.GetBounds();
+    printf_stderr("Releasing old reused tile at %d,%d, x%f\n",
+                  tileBounds.x, tileBounds.y, mTiles[0]->mResolution.width);
+#endif
+    mContext->fDeleteTextures(1, &mTiles[0]->mTexture.mTextureHandle);
+    mTiles.RemoveElementAt(0);
+  }
+
+#ifdef GFX_TILEDLAYER_PREF_WARNINGS
+  printf_stderr("Retained %d tiles\n", mTiles.Length());
+#endif
+}
+
+void
+ReusableTileStoreOGL::DrawTiles(TiledThebesLayerOGL* aLayer,
+                                const nsIntRegion& aValidRegion,
+                                const gfxSize& aResolution,
+                                const gfx3DMatrix& aTransform,
+                                const nsIntPoint& aRenderOffset)
+{
+  // Render old tiles to fill in gaps we haven't had the time to render yet.
+  for (size_t i = 0; i < mTiles.Length(); i++) {
+    ReusableTiledTextureOGL* tile = mTiles[i];
+
+    // Work out the scaling factor in case of resolution differences.
+    gfxSize scaleFactor = gfxSize(aResolution.width / tile->mResolution.width,
+                                  aResolution.height / tile->mResolution.height);
+
+    // Get the valid tile region, in the given coordinate space.
+    nsIntRegion transformedTileRegion(tile->mTileRegion);
+    if (aResolution != tile->mResolution)
+      transformedTileRegion.ScaleRoundOut(scaleFactor.width, scaleFactor.height);
+
+    // Skip drawing tiles that will be completely drawn over.
+    if (aValidRegion.Contains(transformedTileRegion))
+      continue;
+
+    // Reconcile the resolution difference by adjusting the transform.
+    gfx3DMatrix transform = aTransform;
+    if (aResolution != tile->mResolution)
+      transform.Scale(scaleFactor.width, scaleFactor.height, 1);
+
+    // XXX We should clip here to make sure we don't overlap with the valid
+    //     region, otherwise we may end up with rendering artifacts on
+    //     semi-transparent layers.
+    //     Similarly, if we have multiple tiles covering the same area, we will
+    //     end up with rendering artifacts if the aLayer isn't opaque.
+    nsIntRect tileRect = tile->mTileRegion.GetBounds();
+    uint16_t tileStartX = tileRect.x % tile->mTileSize;
+    uint16_t tileStartY = tileRect.y % tile->mTileSize;
+    nsIntRect textureRect(tileStartX, tileStartY, tileRect.width, tileRect.height);
+    nsIntSize textureSize(tile->mTileSize, tile->mTileSize);
+    aLayer->RenderTile(tile->mTexture, transform, aRenderOffset, tileRect, textureRect, textureSize);
+  }
+}
+
+} // mozilla
+} // layers
--- a/gfx/layers/opengl/ReusableTileStoreOGL.h
+++ b/gfx/layers/opengl/ReusableTileStoreOGL.h
@ -0,0 +1,96 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_REUSABLETILESTOREOGL_H
+#define GFX_REUSABLETILESTOREOGL_H
+
+#include "TiledThebesLayerOGL.h"
+#include "nsTArray.h"
+#include "nsAutoPtr.h"
+
+namespace mozilla {
+
+namespace gl {
+class GLContext;
+}
+
+namespace layers {
+
+// A storage class for the information required to render a single tile from
+// a TiledLayerBufferOGL.
+class ReusableTiledTextureOGL
+{
+public:
+  ReusableTiledTextureOGL(TiledTexture aTexture,
+                          const nsIntRegion& aTileRegion,
+                          uint16_t aTileSize,
+                          gfxSize aResolution)
+    : mTexture(aTexture)
+    , mTileRegion(aTileRegion)
+    , mTileSize(aTileSize)
+    , mResolution(aResolution)
+  {}
+
+  ~ReusableTiledTextureOGL() {}
+
+  TiledTexture mTexture;
+  const nsIntRegion mTileRegion;
+  uint16_t mTileSize;
+  gfxSize mResolution;
+};
+
+// This class will operate on a TiledLayerBufferOGL to harvest tiles that have
+// rendered content that is about to become invalid. We do this so that in the
+// situation that we need to render an area of a TiledThebesLayerOGL that hasn't
+// been updated quickly enough, we can still display something (and hopefully
+// it'll be the same as the valid rendered content). While this may end up
+// showing invalid data, it should only be momentarily.
+class ReusableTileStoreOGL
+{
+public:
+  ReusableTileStoreOGL(gl::GLContext* aContext, float aSizeLimit)
+    : mContext(aContext)
+    , mSizeLimit(aSizeLimit)
+  {}
+
+  ~ReusableTileStoreOGL();
+
+  // Harvests tiles from a TiledLayerBufferOGL that are about to become
+  // invalid. aOldValidRegion and aOldResolution should be the valid region
+  // and resolution of the data currently in aVideoMemoryTiledBuffer, and
+  // aNewValidRegion and aNewResolution should be the valid region and
+  // resolution of the data that is about to update aVideoMemoryTiledBuffer.
+  void HarvestTiles(TiledLayerBufferOGL* aVideoMemoryTiledBuffer,
+                    const nsIntRegion& aOldValidRegion,
+                    const nsIntRegion& aNewValidRegion,
+                    const gfxSize& aOldResolution,
+                    const gfxSize& aNewResolution);
+
+  // Draws all harvested tiles that don't intersect with the given valid region.
+  // Differences in resolution will be reconciled via altering the given
+  // transformation.
+  void DrawTiles(TiledThebesLayerOGL* aLayer,
+                 const nsIntRegion& aValidRegion,
+                 const gfxSize& aResolution,
+                 const gfx3DMatrix& aTransform,
+                 const nsIntPoint& aRenderOffset);
+
+private:
+  // This GLContext should correspond to the one used in any TiledLayerBufferOGL
+  // that is passed into HarvestTiles and DrawTiles.
+  nsRefPtr<gl::GLContext> mContext;
+
+  // This determines the maximum number of tiles stored in this tile store,
+  // as a fraction of the amount of tiles stored in the TiledLayerBufferOGL
+  // given to HarvestTiles.
+  float mSizeLimit;
+
+  // This stores harvested tiles, in the order in which they were harvested.
+  nsTArray< nsAutoPtr<ReusableTiledTextureOGL> > mTiles;
+};
+
+} // layers
+} // mozilla
+
+#endif // GFX_REUSABLETILESTOREOGL_H
--- a/gfx/layers/opengl/TiledThebesLayerOGL.cpp
+++ b/gfx/layers/opengl/TiledThebesLayerOGL.cpp
@ -4,6 +4,7 @@

 #include "mozilla/layers/PLayersChild.h"
 #include "TiledThebesLayerOGL.h"
+#include "ReusableTileStoreOGL.h"
 #include "BasicTiledThebesLayer.h"
 #include "gfxImageSurface.h"

@ -37,12 +38,15 @@ TiledLayerBufferOGL::ReleaseTile(TiledTexture aTile)
 void
 TiledLayerBufferOGL::Upload(const BasicTiledLayerBuffer* aMainMemoryTiledBuffer,
                            const nsIntRegion& aNewValidRegion,
-                            const nsIntRegion& aInvalidateRegion)
+                            const nsIntRegion& aInvalidateRegion,
+                            const gfxSize& aResolution)
 {
 #ifdef GFX_TILEDLAYER_PREF_WARNINGS
  printf_stderr("Upload %i, %i, %i, %i\n", aInvalidateRegion.GetBounds().x, aInvalidateRegion.GetBounds().y, aInvalidateRegion.GetBounds().width, aInvalidateRegion.GetBounds().height);
  long start = PR_IntervalNow();
 #endif
+
+  mResolution = aResolution;
  mMainMemoryTiledBuffer = aMainMemoryTiledBuffer;
  mContext->MakeCurrent();
  Update(aNewValidRegion, aInvalidateRegion);
@ -113,6 +117,15 @@ TiledThebesLayerOGL::TiledThebesLayerOGL(LayerManagerOGL *aManager)
  , mVideoMemoryTiledBuffer(aManager->gl())
 {
  mImplData = static_cast<LayerOGL*>(this);
+  // XXX Add a pref for reusable tile store size
+  mReusableTileStore = new ReusableTileStoreOGL(aManager->gl(), 1);
+}
+
+TiledThebesLayerOGL::~TiledThebesLayerOGL()
+{
+  mMainMemoryTiledBuffer.ReadUnlock();
+  if (mReusableTileStore)
+    delete mReusableTileStore;
 }

 void
@ -132,7 +145,29 @@ TiledThebesLayerOGL::ProcessUploadQueue()
  if (mRegionToUpload.IsEmpty())
    return;

-  mVideoMemoryTiledBuffer.Upload(&mMainMemoryTiledBuffer, mMainMemoryTiledBuffer.GetValidRegion(), mRegionToUpload);
+  gfxSize resolution(1, 1);
+  if (mReusableTileStore) {
+    // Work out render resolution by multiplying the resolution of our ancestors.
+    // Only container layers can have frame metrics, so we start off with a
+    // resolution of 1, 1.
+    // XXX For large layer trees, it would be faster to do this once from the
+    //     root node upwards and store the value on each layer.
+    for (ContainerLayer* parent = GetParent(); parent; parent = parent->GetParent()) {
+      const FrameMetrics& metrics = parent->GetFrameMetrics();
+      resolution.width *= metrics.mResolution.width;
+      resolution.height *= metrics.mResolution.height;
+    }
+
+    mReusableTileStore->HarvestTiles(&mVideoMemoryTiledBuffer,
+                                     mVideoMemoryTiledBuffer.GetValidRegion(),
+                                     mMainMemoryTiledBuffer.GetValidRegion(),
+                                     mVideoMemoryTiledBuffer.GetResolution(),
+                                     resolution);
+  }
+
+  mVideoMemoryTiledBuffer.Upload(&mMainMemoryTiledBuffer,
+                                 mMainMemoryTiledBuffer.GetValidRegion(),
+                                 mRegionToUpload, resolution);
  mValidRegion = mVideoMemoryTiledBuffer.GetValidRegion();

  mMainMemoryTiledBuffer.ReadUnlock();
@ -146,12 +181,46 @@ TiledThebesLayerOGL::ProcessUploadQueue()

 }

+void
+TiledThebesLayerOGL::RenderTile(TiledTexture aTile,
+                                const gfx3DMatrix& aTransform,
+                                const nsIntPoint& aOffset,
+                                nsIntRect aScreenRect,
+                                nsIntRect aTextureRect,
+                                nsIntSize aTextureBounds)
+{
+    gl()->fBindTexture(LOCAL_GL_TEXTURE_2D, aTile.mTextureHandle);
+    ColorTextureLayerProgram *program;
+    if (aTile.mFormat == LOCAL_GL_RGB) {
+      program = mOGLManager->GetRGBXLayerProgram();
+    } else {
+      program = mOGLManager->GetBGRALayerProgram();
+    }
+    program->Activate();
+    program->SetTextureUnit(0);
+    program->SetLayerOpacity(GetEffectiveOpacity());
+    program->SetLayerTransform(aTransform);
+    program->SetRenderOffset(aOffset);
+    program->SetLayerQuadRect(aScreenRect);
+
+    mOGLManager->BindAndDrawQuadWithTextureRect(program,
+                                                aTextureRect,
+                                                aTextureBounds);
+}
+
 void
 TiledThebesLayerOGL::RenderLayer(int aPreviousFrameBuffer, const nsIntPoint& aOffset)
 {
  gl()->MakeCurrent();
  ProcessUploadQueue();

+  // Render old tiles to fill in gaps we haven't had the time to render yet.
+  if (mReusableTileStore)
+    mReusableTileStore->DrawTiles(this, mVideoMemoryTiledBuffer.GetValidRegion(),
+                                  mVideoMemoryTiledBuffer.GetResolution(),
+                                  GetEffectiveTransform(), aOffset);
+
+  // Render valid tiles.
  const nsIntRegion& visibleRegion = GetEffectiveVisibleRegion();
  const nsIntRect visibleRect = visibleRegion.GetBounds();
  unsigned int rowCount = 0;
@ -173,22 +242,9 @@ TiledThebesLayerOGL::RenderLayer(int aPreviousFrameBuffer, const nsIntPoint& aOf
        GetTile(nsIntPoint(mVideoMemoryTiledBuffer.RoundDownToTileEdge(x),
                           mVideoMemoryTiledBuffer.RoundDownToTileEdge(y)));
      if (tileTexture != mVideoMemoryTiledBuffer.GetPlaceholderTile()) {
-
-        gl()->fBindTexture(LOCAL_GL_TEXTURE_2D, tileTexture.mTextureHandle);
-        ColorTextureLayerProgram *program;
-        if (tileTexture.mFormat == LOCAL_GL_RGB) {
-          program = mOGLManager->GetRGBXLayerProgram();
-        } else {
-          program = mOGLManager->GetBGRALayerProgram();
-        }
-        program->Activate();
-        program->SetTextureUnit(0);
-        program->SetLayerOpacity(GetEffectiveOpacity());
-        program->SetLayerTransform(GetEffectiveTransform());
-        program->SetRenderOffset(aOffset);
-        program->SetLayerQuadRect(nsIntRect(x,y,w,h)); // screen
-        mOGLManager->BindAndDrawQuadWithTextureRect(program, nsIntRect(tileStartX, tileStartY, w, h), nsIntSize(mVideoMemoryTiledBuffer.GetTileLength(), mVideoMemoryTiledBuffer.GetTileLength())); // texture bounds
-
+        uint16_t tileSize = mVideoMemoryTiledBuffer.GetTileLength();
+        RenderTile(tileTexture, GetEffectiveTransform(), aOffset, nsIntRect(x,y,w,h),
+                   nsIntRect(tileStartX, tileStartY, w, h), nsIntSize(tileSize, tileSize));
      }
      tileY++;
      y += h;
--- a/gfx/layers/opengl/TiledThebesLayerOGL.h
+++ b/gfx/layers/opengl/TiledThebesLayerOGL.h
@ -20,6 +20,8 @@ class GLContext;

 namespace layers {

+class ReusableTileStoreOGL;
+
 class TiledTexture {
 public:
  // Constructs a placeholder TiledTexture. See the comments above
@ -73,10 +75,13 @@ public:

  void Upload(const BasicTiledLayerBuffer* aMainMemoryTiledBuffer,
              const nsIntRegion& aNewValidRegion,
-              const nsIntRegion& aInvalidateRegion);
+              const nsIntRegion& aInvalidateRegion,
+              const gfxSize& aResolution);

  TiledTexture GetPlaceholderTile() const { return TiledTexture(); }

+  const gfxSize& GetResolution() { return mResolution; }
+
 protected:
  TiledTexture ValidateTile(TiledTexture aTile,
                            const nsIntPoint& aTileRect,
@ -91,6 +96,7 @@ protected:
 private:
  nsRefPtr<gl::GLContext> mContext;
  const BasicTiledLayerBuffer* mMainMemoryTiledBuffer;
+  gfxSize mResolution;

  void GetFormatAndTileForImageFormat(gfxASurface::gfxImageFormat aFormat,
                                      GLenum& aOutFormat,
@ -103,10 +109,7 @@ class TiledThebesLayerOGL : public ShadowThebesLayer,
 {
 public:
  TiledThebesLayerOGL(LayerManagerOGL *aManager);
-  virtual ~TiledThebesLayerOGL()
-  {
-    mMainMemoryTiledBuffer.ReadUnlock();
-  }
+  virtual ~TiledThebesLayerOGL();

  // LayerOGL impl
  void Destroy() {}
@ -126,10 +129,22 @@ public:
  }
  void PaintedTiledLayerBuffer(const BasicTiledLayerBuffer* mTiledBuffer);
  void ProcessUploadQueue();
+
+  // Renders a single given tile.
+  // XXX This currently takes an nsIntRect, but should actually take an
+  //     nsIntRegion and iterate over each rectangle in the region.
+  void RenderTile(TiledTexture aTile,
+                  const gfx3DMatrix& aTransform,
+                  const nsIntPoint& aOffset,
+                  nsIntRect aScreenRect,
+                  nsIntRect aTextureRect,
+                  nsIntSize aTextureBounds);
+
 private:
  nsIntRegion                  mRegionToUpload;
  BasicTiledLayerBuffer        mMainMemoryTiledBuffer;
  TiledLayerBufferOGL          mVideoMemoryTiledBuffer;
+  ReusableTileStoreOGL*        mReusableTileStore;
 };

 } // layers
--- a/ipc/glue/IPCMessageUtils.h
+++ b/ipc/glue/IPCMessageUtils.h
@ -53,6 +53,7 @@
 #include "gfxColor.h"
 #include "gfxMatrix.h"
 #include "gfxPattern.h"
+#include "gfxPoint.h"
 #include "nsRect.h"
 #include "nsRegion.h"
 #include "gfxASurface.h"
@ -458,6 +459,27 @@ struct ParamTraits<gfxMatrix>
  }
 };

+template<>
+struct ParamTraits<gfxSize>
+{
+  typedef gfxSize paramType;
+
+  static void Write(Message* aMsg, const paramType& aParam)
+  {
+    WriteParam(aMsg, aParam.width);
+    WriteParam(aMsg, aParam.height);
+  }
+
+  static bool Read(const Message* aMsg, void** aIter, paramType* aResult)
+  {
+    if (ReadParam(aMsg, aIter, &aResult->width) &&
+        ReadParam(aMsg, aIter, &aResult->height))
+      return true;
+
+    return false;
+  }
+};
+
 template<>
 struct ParamTraits<gfx3DMatrix>
 {
--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@ -250,6 +250,10 @@ static void RecordFrameMetrics(nsIFrame* aForFrame,
  }

  metrics.mScrollId = aScrollId;
+
+  nsIPresShell* presShell = presContext->GetPresShell();
+  metrics.mResolution = gfxSize(presShell->GetXResolution(), presShell->GetYResolution());
+
  aRoot->SetFrameMetrics(metrics);
 }