fix layer scrolling

    Bug: 5774119

Add support for layer scrolling; also fixes the scrollTop demo
referenced in bug: 5748199

Change-Id: Id04a3d52bb1e75e9ee24a4f1b8aa9b0334369ba1

7 files changed, 42 insertions, 14 deletions

diff --git a/Source/WebCore/platform/graphics/android/GraphicsLayerAndroid.cpp b/Source/WebCore/platform/graphics/android/GraphicsLayerAndroid.cpp
index d466cf3..1369a62 100644
--- a/Source/WebCore/platform/graphics/android/GraphicsLayerAndroid.cpp
+++ b/Source/WebCore/platform/graphics/android/GraphicsLayerAndroid.cpp
@@ -555,6 +555,15 @@ void GraphicsLayerAndroid::updateScrollingLayers()
 #endif
 }
 
+void GraphicsLayerAndroid::updateScrollOffset() {
+    RenderLayer* layer = renderLayerFromClient(m_client);
+    if (!layer || !m_foregroundLayer)
+        return;
+    IntSize scroll = layer->scrolledContentOffset();
+    m_foregroundLayer->setScrollOffset(IntPoint(scroll.width(), scroll.height()));
+    askForSync();
+}
+
 bool GraphicsLayerAndroid::repaint()
 {
     LOG("(%x) repaint(), gPaused(%d) m_needsRepaint(%d) m_haveContents(%d) ",
@@ -610,9 +619,11 @@ bool GraphicsLayerAndroid::repaint()
             if (!layer->renderer()->style()->isLeftToRightDirection()) {
                 rtlOffset = layer->scrollWidth() - clip.width(); // Scroll all the way right.
             }
+            m_foregroundLayer->setScrollOffset(IntPoint(scroll.width() + rtlOffset,
+                    scroll.height()));
             // Need to offset the foreground layer by the clip layer in order
             // for the contents to be in the correct position.
-            m_foregroundLayer->setPosition(-x - rtlOffset, -y);
+            m_foregroundLayer->setPosition(-x, -y);
             // Set the scrollable bounds of the layer.
             m_foregroundLayer->setScrollLimits(-x, -y, m_size.width(), m_size.height());
 
diff --git a/Source/WebCore/platform/graphics/android/GraphicsLayerAndroid.h b/Source/WebCore/platform/graphics/android/GraphicsLayerAndroid.h
index 358f674..e872c91 100644
--- a/Source/WebCore/platform/graphics/android/GraphicsLayerAndroid.h
+++ b/Source/WebCore/platform/graphics/android/GraphicsLayerAndroid.h
@@ -123,6 +123,8 @@ public:
 
     static int instancesCount();
 
+    virtual void updateScrollOffset();
+
 private:
 
     void askForSync();
diff --git a/Source/WebCore/platform/graphics/android/LayerAndroid.cpp b/Source/WebCore/platform/graphics/android/LayerAndroid.cpp
index 25c5e7b..342a541 100644
--- a/Source/WebCore/platform/graphics/android/LayerAndroid.cpp
+++ b/Source/WebCore/platform/graphics/android/LayerAndroid.cpp
@@ -117,6 +117,7 @@ LayerAndroid::LayerAndroid(const LayerAndroid& layer) : Layer(layer),
     m_fixedMarginBottom = layer.m_fixedMarginBottom;
     m_fixedRect = layer.m_fixedRect;
     m_iframeOffset = layer.m_iframeOffset;
+    m_offset = layer.m_offset;
     m_recordingPicture = layer.m_recordingPicture;
     SkSafeRef(m_recordingPicture);
 
@@ -610,7 +611,7 @@ void LayerAndroid::updateGLPositionsAndScale(const TransformationMatrix& parentM
     m_atomicSync.lock();
     IntSize layerSize(getSize().width(), getSize().height());
     FloatPoint anchorPoint(getAnchorPoint().fX, getAnchorPoint().fY);
-    FloatPoint position(getPosition().fX, getPosition().fY);
+    FloatPoint position(getPosition().fX - m_offset.x(), getPosition().fY - m_offset.y());
     float centerOffsetX = (0.5f - anchorPoint.x()) * layerSize.width();
     float centerOffsetY = (0.5f - anchorPoint.y()) * layerSize.height();
     float originX = anchorPoint.x() * layerSize.width();
diff --git a/Source/WebCore/platform/graphics/android/LayerAndroid.h b/Source/WebCore/platform/graphics/android/LayerAndroid.h
index d6e1e9a..578c2ff 100644
--- a/Source/WebCore/platform/graphics/android/LayerAndroid.h
+++ b/Source/WebCore/platform/graphics/android/LayerAndroid.h
@@ -199,6 +199,7 @@ public:
         setShouldInheritFromRootTransform(true);
     }
 
+    void setScrollOffset(IntPoint offset) { m_offset = offset; }
     void setBackgroundColor(SkColor color);
     void setMaskLayer(LayerAndroid*);
     void setMasksToBounds(bool masksToBounds)
@@ -315,7 +316,7 @@ public:
 
 protected:
     virtual void onDraw(SkCanvas*, SkScalar opacity);
-
+    IntPoint m_offset;
     TransformationMatrix m_drawTransform;
 
 private:
diff --git a/Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.cpp b/Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.cpp
index 3c2ced5..55692be 100644
--- a/Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.cpp
+++ b/Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.cpp
@@ -9,27 +9,34 @@ namespace WebCore {
 
 bool ScrollableLayerAndroid::scrollTo(int x, int y)
 {
-    SkIRect scrollBounds;
-    getScrollRect(&scrollBounds);
-    if (!scrollBounds.fRight && !scrollBounds.fBottom)
+    IntRect scrollBounds;
+    getScrollBounds(&scrollBounds);
+    if (!scrollBounds.width() && !scrollBounds.height())
         return false;
-
-    SkScalar newX = SkScalarPin(x, 0, scrollBounds.fRight);
-    SkScalar newY = SkScalarPin(y, 0, scrollBounds.fBottom);
+    SkScalar newX = SkScalarPin(x, scrollBounds.x(), scrollBounds.width());
+    SkScalar newY = SkScalarPin(y, scrollBounds.y(), scrollBounds.height());
     // Check for no change.
-    if (newX == scrollBounds.fLeft && newY == scrollBounds.fTop)
+    if (newX == m_offset.x() && newY == m_offset.y())
         return false;
+    setScrollOffset(IntPoint(newX, newY));
+    return true;
+}
 
-    setPosition(m_scrollLimits.fLeft - newX, m_scrollLimits.fTop - newY);
+void ScrollableLayerAndroid::getScrollBounds(IntRect* out) const
+{
+    const SkPoint& pos = getPosition();
+    out->setX(m_scrollLimits.fLeft - pos.fX);
+    out->setY(m_scrollLimits.fTop - pos.fY);
+    out->setWidth(getSize().width() - m_scrollLimits.width());
+    out->setHeight(getSize().height() - m_scrollLimits.height());
 
-    return true;
 }
 
 void ScrollableLayerAndroid::getScrollRect(SkIRect* out) const
 {
     const SkPoint& pos = getPosition();
-    out->fLeft = m_scrollLimits.fLeft - pos.fX;
-    out->fTop = m_scrollLimits.fTop - pos.fY;
+    out->fLeft = m_scrollLimits.fLeft - pos.fX + m_offset.x();
+    out->fTop = m_scrollLimits.fTop - pos.fY + m_offset.y();
     out->fRight = getSize().width() - m_scrollLimits.width();
     out->fBottom = getSize().height() - m_scrollLimits.height();
 }
diff --git a/Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.h b/Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.h
index 5cba5d9..b8ff299 100644
--- a/Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.h
+++ b/Source/WebCore/platform/graphics/android/ScrollableLayerAndroid.h
@@ -71,6 +71,9 @@ public:
     friend LayerAndroid* android::deserializeLayer(SkStream* stream);
 
 private:
+
+    void getScrollBounds(IntRect*) const;
+
     // The position of the visible area of the layer, relative to the parent
     // layer. This is fixed during scrolling. We acheive scrolling by modifying
     // the position of the layer.
diff --git a/Source/WebCore/rendering/RenderLayer.cpp b/Source/WebCore/rendering/RenderLayer.cpp
index cdc4c05..0932224 100644
--- a/Source/WebCore/rendering/RenderLayer.cpp
+++ b/Source/WebCore/rendering/RenderLayer.cpp
@@ -64,6 +64,7 @@
 #include "HTMLNames.h"
 #if ENABLE(ANDROID_OVERFLOW_SCROLL)
 #include "HTMLTextAreaElement.h"
+#include "GraphicsLayerAndroid.h"
 #endif
 #include "HitTestRequest.h"
 #include "HitTestResult.h"
@@ -1424,6 +1425,8 @@ void RenderLayer::scrollTo(int x, int y)
     // do not need to repaint simply because we are scrolling
     if (view && !hasOverflowScroll())
         renderer()->repaintUsingContainer(repaintContainer, rectForRepaint);
+    if (view && hasOverflowScroll() && backing() && backing()->graphicsLayer())
+        static_cast<GraphicsLayerAndroid*>(backing()->graphicsLayer())->updateScrollOffset();
 #else
     if (view)
         renderer()->repaintUsingContainer(repaintContainer, rectForRepaint);