Use Surface areas to compute tile usage

Previously we used the surface's first layer's area, which is often incorrect in
the case of significant layer merging.

bug:6545187
Change-Id: Ied3e5e3cd894b145ed905f8ba83649b3c4f3b1dd

5 files changed, 30 insertions, 20 deletions

diff --git a/Source/WebCore/platform/graphics/android/rendering/Surface.cpp b/Source/WebCore/platform/graphics/android/rendering/Surface.cpp
index be1e176..94b7b6e 100644
--- a/Source/WebCore/platform/graphics/android/rendering/Surface.cpp
+++ b/Source/WebCore/platform/graphics/android/rendering/Surface.cpp
@@ -341,7 +341,13 @@ void Surface::computeTexturesAmount(TexturesResult* result)
     if (!m_surfaceBacking || isBase())
         return;
 
-    m_surfaceBacking->computeTexturesAmount(result, getFirstLayer());
+
+    LayerAndroid* layer = 0;
+    if (singleLayer())
+        layer = getFirstLayer();
+
+    m_surfaceBacking->computeTexturesAmount(result, visibleContentArea(),
+                                            fullContentArea(), layer);
 }
 
 bool Surface::isBase()
diff --git a/Source/WebCore/platform/graphics/android/rendering/SurfaceBacking.cpp b/Source/WebCore/platform/graphics/android/rendering/SurfaceBacking.cpp
index fcd9655..6d26aa8 100644
--- a/Source/WebCore/platform/graphics/android/rendering/SurfaceBacking.cpp
+++ b/Source/WebCore/platform/graphics/android/rendering/SurfaceBacking.cpp
@@ -161,36 +161,37 @@ bool SurfaceBacking::swapTiles()
     return swap;
 }
 
-void SurfaceBacking::computeTexturesAmount(TexturesResult* result, LayerAndroid* layer)
+void SurfaceBacking::computeTexturesAmount(TexturesResult* result,
+                                           const IntRect& visibleContentArea,
+                                           const IntRect& fullContentArea,
+                                           LayerAndroid* layer)
 {
-    // TODO: shouldn't use layer, as this SB may paint multiple layers
-    if (!layer)
-        return;
-
-    IntRect fullContentArea = layer->fullContentArea();
-    IntRect clippedVisibleArea = layer->visibleContentArea();
 
     // get two numbers here:
     // - textures needed for a clipped area
     // - textures needed for an un-clipped area
     TileGrid* tileGrid = m_zooming ? m_backTileGrid : m_frontTileGrid;
     int nbTexturesUnclipped = tileGrid->nbTextures(fullContentArea, m_scale);
-    int nbTexturesClipped = tileGrid->nbTextures(clippedVisibleArea, m_scale);
+    int nbTexturesClipped = tileGrid->nbTextures(visibleContentArea, m_scale);
+
+    if (layer) {
+        // TODO: should handle multi-layer case better
 
-    // Set kFixedLayers level
-    if (layer->isPositionFixed())
-        result->fixed += nbTexturesClipped;
+        // Set kFixedLayers level
+        if (layer->isPositionFixed())
+            result->fixed += nbTexturesClipped;
 
-    // Set kScrollableAndFixedLayers level
-    if (layer->contentIsScrollable()
-        || layer->isPositionFixed())
-        result->scrollable += nbTexturesClipped;
+        // Set kScrollableAndFixedLayers level
+        if (layer->contentIsScrollable()
+            || layer->isPositionFixed())
+            result->scrollable += nbTexturesClipped;
+    }
 
     // Set kClippedTextures level
     result->clipped += nbTexturesClipped;
 
     // Set kAllTextures level
-    if (layer->contentIsScrollable())
+    if (layer && layer->contentIsScrollable())
         result->full += nbTexturesClipped;
     else
         result->full += nbTexturesUnclipped;
diff --git a/Source/WebCore/platform/graphics/android/rendering/SurfaceBacking.h b/Source/WebCore/platform/graphics/android/rendering/SurfaceBacking.h
index 137a25b..5709f2a 100644
--- a/Source/WebCore/platform/graphics/android/rendering/SurfaceBacking.h
+++ b/Source/WebCore/platform/graphics/android/rendering/SurfaceBacking.h
@@ -49,7 +49,10 @@ public:
                 const TransformationMatrix* transform, bool aggressiveRendering,
                 const Color* background);
     void markAsDirty(const SkRegion& dirtyArea);
-    void computeTexturesAmount(TexturesResult* result, LayerAndroid* layer);
+    void computeTexturesAmount(TexturesResult* result,
+                               const IntRect& visibleContentArea,
+                               const IntRect& fullContentArea,
+                               LayerAndroid* layer);
     void discardTextures()
     {
         m_frontTileGrid->discardTextures();
diff --git a/Source/WebCore/platform/graphics/android/rendering/TileGrid.cpp b/Source/WebCore/platform/graphics/android/rendering/TileGrid.cpp
index 9cd904e..f8510bb 100644
--- a/Source/WebCore/platform/graphics/android/rendering/TileGrid.cpp
+++ b/Source/WebCore/platform/graphics/android/rendering/TileGrid.cpp
@@ -275,7 +275,7 @@ Tile* TileGrid::getTile(int x, int y)
     return 0;
 }
 
-int TileGrid::nbTextures(IntRect& area, float scale)
+int TileGrid::nbTextures(const IntRect& area, float scale)
 {
     IntRect tileBounds = computeTilesArea(area, scale);
     int numberTextures = tileBounds.width() * tileBounds.height();
diff --git a/Source/WebCore/platform/graphics/android/rendering/TileGrid.h b/Source/WebCore/platform/graphics/android/rendering/TileGrid.h
index 665f4ec..2879dd9 100644
--- a/Source/WebCore/platform/graphics/android/rendering/TileGrid.h
+++ b/Source/WebCore/platform/graphics/android/rendering/TileGrid.h
@@ -67,7 +67,7 @@ public:
     bool isMissingContent();
     bool isDirty() { return !m_dirtyRegion.isEmpty(); }
 
-    int nbTextures(IntRect& area, float scale);
+    int nbTextures(const IntRect& area, float scale);
 
 private:
     void prepareTile(int x, int y, TilePainter* painter,