Disable clipping on the base surface

Base surface can expand dynamically (see BaseLayerAndroid::updatePosition) to
fill the viewport, so disable clipping on it.

bug:6593707
Change-Id: I3afafb28fbe95d3162c76f8e835932577ded65ce

2 files changed, 14 insertions, 11 deletions

diff --git a/Source/WebCore/platform/graphics/android/layers/BaseLayerAndroid.cpp b/Source/WebCore/platform/graphics/android/layers/BaseLayerAndroid.cpp
index 82af3bf..8069778 100644
--- a/Source/WebCore/platform/graphics/android/layers/BaseLayerAndroid.cpp
+++ b/Source/WebCore/platform/graphics/android/layers/BaseLayerAndroid.cpp
@@ -84,7 +84,12 @@ void BaseLayerAndroid::updatePositionsRecursive(const SkRect& visibleContentRect
 
     updateLayerPositions(visibleContentRect);
     TransformationMatrix ident;
-    FloatRect clip(0, 0, getWidth(), getHeight());
+
+    // Start with an unnecessarily large clip, since the base layer can
+    // dynamically increase in size to cover the viewport, and we cache its draw
+    // clip. This way the base layer will never have it's visible area clipped
+    // by its m_clippingRect, only the viewport.
+    FloatRect clip(0, 0, 1e10, 1e10);
 
     bool forcePositionCalculation = !m_positionsCalculated;
     float scale = 1.0f;
diff --git a/Source/WebCore/platform/graphics/android/rendering/Surface.cpp b/Source/WebCore/platform/graphics/android/rendering/Surface.cpp
index 9df1a7a..d68051d 100644
--- a/Source/WebCore/platform/graphics/android/rendering/Surface.cpp
+++ b/Source/WebCore/platform/graphics/android/rendering/Surface.cpp
@@ -230,17 +230,15 @@ bool Surface::drawGL(bool layerTilesDisabled)
     if (singleLayer() && !getFirstLayer()->visible())
         return false;
 
-    bool isBaseLayer = isBase()
-        || getFirstLayer()->subclassType() == LayerAndroid::FixedBackgroundImageLayer
-        || getFirstLayer()->subclassType() == LayerAndroid::ForegroundBaseLayer;
-
-    FloatRect drawClip = getFirstLayer()->drawClip();
-    if (!singleLayer()) {
-        for (unsigned int i = 1; i < m_layers.size(); i++)
-            drawClip.unite(m_layers[i]->drawClip());
+    if (!isBase()) {
+        FloatRect drawClip = getFirstLayer()->drawClip();
+        if (!singleLayer()) {
+            for (unsigned int i = 1; i < m_layers.size(); i++)
+                drawClip.unite(m_layers[i]->drawClip());
+        }
+        FloatRect clippingRect = TilesManager::instance()->shader()->rectInInvViewCoord(drawClip);
+        TilesManager::instance()->shader()->clip(clippingRect);
     }
-    FloatRect clippingRect = TilesManager::instance()->shader()->rectInInvViewCoord(drawClip);
-    TilesManager::instance()->shader()->clip(clippingRect);
 
     bool askRedraw = false;
     if (m_surfaceBacking && !tilesDisabled) {