Improve the fixed element position calculation

In the previous WAR, we get the screen size from UI thread at every draw call.
That is awkward.

Now with Java side fix, we can get the screen size from setSize call now.
However, forcing a full re-layout seems like an expensive operation.
What we need to make the webkit to know the update can be done by just
updating the fixed position elements only.

So I have done these:
1. Take away the WAR by forcing the update at the convertToLayerCoord.
2. Get rid of the UI thread stuff used to tell WebViewCore the screen size.
And get rid of the redundant variables, too.
3. update the fixed element at the setSize time.

BTW, I also rename the PlatformBridge functions name.

bug: 3397602

Change-Id: I0c422ecdb570de89aecb6e568d5067acf18ecfc6

4 files changed, 31 insertions, 4 deletions

diff --git a/WebCore/page/FrameView.cpp b/WebCore/page/FrameView.cpp
index 5314a32..1f03599 100644
--- a/WebCore/page/FrameView.cpp
+++ b/WebCore/page/FrameView.cpp
@@ -1067,6 +1067,29 @@ void FrameView::removeFixedObject()
         updateCanBlitOnScrollRecursively();
 }
 
+#if PLATFORM(ANDROID)
+// When the screen size change, fixed positioned element should be updated.
+void FrameView::updatePositionedObjects()
+{
+    RenderBlock::PositionedObjectsListHashSet* positionedObjects = 0;
+    if (RenderView* root = m_frame->contentRenderer())
+        positionedObjects = root->positionedObjects();
+
+    if (!positionedObjects || positionedObjects->isEmpty())
+        return;
+
+    RenderBlock::PositionedObjectsListHashSet::const_iterator end = positionedObjects->end();
+    for (RenderBlock::PositionedObjectsListHashSet::const_iterator it = positionedObjects->begin(); it != end; ++it) {
+        RenderBox* renderBox = *it;
+        if (renderBox->style()->position() != FixedPosition)
+            continue;
+
+        renderBox->computeLogicalWidth();
+        renderBox->computeLogicalHeight();
+    }
+}
+#endif
+
 bool FrameView::scrollContentsFastPath(const IntSize& scrollDelta, const IntRect& rectToScroll, const IntRect& clipRect)
 {
     const size_t fixedObjectThreshold = 5;
diff --git a/WebCore/page/FrameView.h b/WebCore/page/FrameView.h
index 1b5b322..4135045 100644
--- a/WebCore/page/FrameView.h
+++ b/WebCore/page/FrameView.h
@@ -97,6 +97,10 @@ public:
 
     bool needsFullRepaint() const { return m_doFullRepaint; }
 
+#if PLATFORM(ANDROID)
+    void updatePositionedObjects();
+#endif
+
 #if USE(ACCELERATED_COMPOSITING)
     void updateCompositingLayers();
 
diff --git a/WebCore/platform/android/PlatformBridge.h b/WebCore/platform/android/PlatformBridge.h
index 3f559d5..faa823e 100644
--- a/WebCore/platform/android/PlatformBridge.h
+++ b/WebCore/platform/android/PlatformBridge.h
@@ -149,8 +149,8 @@ public:
     static int memoryUsageMB();
     static int actualMemoryUsageMB();
 
-    static int visibleScreenWidth(const FrameView*);
-    static int visibleScreenHeight(const FrameView*);
+    static int screenWidthInDocCoord(const FrameView*);
+    static int screenHeightInDocCoord(const FrameView*);
 };
 
 }
diff --git a/WebCore/rendering/RenderBox.cpp b/WebCore/rendering/RenderBox.cpp
index 3c8e2ca..ebd7d54 100644
--- a/WebCore/rendering/RenderBox.cpp
+++ b/WebCore/rendering/RenderBox.cpp
@@ -2085,7 +2085,7 @@ int RenderBox::containingBlockWidthForPositioned(const RenderBoxModelObject* con
     // That is in the doc coordindate.
     if (style()->position() == FixedPosition && containingBlock->isRenderView()) {
         const RenderView* view = toRenderView(containingBlock);
-        return PlatformBridge::visibleScreenWidth(view->frameView());
+        return PlatformBridge::screenWidthInDocCoord(view->frameView());
     }
 #endif
     if (containingBlock->isBox()) {
@@ -2123,7 +2123,7 @@ int RenderBox::containingBlockHeightForPositioned(const RenderBoxModelObject* co
     // That is in the doc coordindate.
     if (style()->position() == FixedPosition && containingBlock->isRenderView()) {
         const RenderView* view = toRenderView(containingBlock);
-        return PlatformBridge::visibleScreenHeight(view->frameView());
+        return PlatformBridge::screenHeightInDocCoord(view->frameView());
     }
 #endif
     int heightResult = 0;