Visual viewport API initial implementation.

third_party/WebKit/Source/core/frame/VisualViewport.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 69 matching lines @@
 {
     sendUMAMetrics();
 }
 
 DEFINE_TRACE(VisualViewport)
 {
     visitor->trace(m_frameHost);
     ScrollableArea::trace(visitor);
 }
 
+void VisualViewport::updateLayoutIgnorePendingStylesheets()
+{
+    if (!mainFrame())
+        return;
+
+    Document* document = mainFrame()->document();
+    if (!document)
+        return;
+
+    document->updateLayoutIgnorePendingStylesheets();
+    return;
+}
+
 void VisualViewport::setSize(const IntSize& size)
 {
     if (m_size == size)
         return;
 
     TRACE_EVENT2("blink", "VisualViewport::setSize", "width", size.width(), "height", size.height());
     bool widthDidChange = size.width() != m_size.width();
     m_size = size;
 
     if (m_innerViewportContainerLayer) {
@@ skipping 84 matching lines @@
 void VisualViewport::move(const FloatSize& delta)
 {
     setLocation(m_offset + delta);
 }
 
 void VisualViewport::setScale(float scale)
 {
     setScaleAndLocation(scale, m_offset);
 }
 
+double VisualViewport::scrollLeft()
+{
+    updateLayoutIgnorePendingStylesheets();

[ymalik, 2016/03/18 13:30:57]

@bokan, I am not sure whether we need to call
updateLayoutIgnorePendingStylesheets(). I think it makes sense and I see it
being called from Element::scrollLeft and friends. WDYT?

[bokan, 2016/03/18 16:05:07]

I think we need it. The reason being that the visual viewport's scroll position
depends on the size of the layout viewport. The layout viewport's size depends
on the layout since it's calculated based on the minimum possible page scale and
the minimum page scale depends on content width. This means that a really wide
element can increase/decrease the layout viewport's width which means the max
scroll position will change.

[ymalik, 2016/03/22 16:35:06]

Acknowledged.

+
+    return visibleRect().x();
+}
+
+double VisualViewport::scrollTop()
+{
+    updateLayoutIgnorePendingStylesheets();
+
+    return visibleRect().y();
+}
+
+void VisualViewport::setScrollLeft(double x)
+{
+    updateLayoutIgnorePendingStylesheets();
+
+    DoublePoint layoutPos(x, visibleRect().y());
+    setScrollPosition(layoutPos, ProgrammaticScroll, ScrollBehaviorAuto);
+}
+
+void VisualViewport::setScrollTop(double y)
+{
+    updateLayoutIgnorePendingStylesheets();
+
+    DoublePoint layoutPos(visibleRect().x(), y);
+    setScrollPosition(layoutPos, ProgrammaticScroll, ScrollBehaviorAuto);
+}
+
+double VisualViewport::clientWidth()
+{
+    updateLayoutIgnorePendingStylesheets();
+
+    return visibleRect().width();
+}
+
+double VisualViewport::clientHeight()
+{
+    updateLayoutIgnorePendingStylesheets();
+
+    return visibleRect().height();
+}
+
+double VisualViewport::pageScale()
+{
+    updateLayoutIgnorePendingStylesheets();
+
+    return m_scale;
+}
+
 void VisualViewport::setScaleAndLocation(float scale, const FloatPoint& location)
 {
     if (!mainFrame())
         return;
 
     bool valuesChanged = false;
 
     if (scale != m_scale) {
         m_scale = scale;
         valuesChanged = true;
@@ skipping 15 matching lines @@
                 document->enqueueScrollEventForNode(document);
         }
 
         mainFrame()->loader().client()->didChangeScrollOffset();
         valuesChanged = true;
     }
 
     if (!valuesChanged)
         return;
 
+    if (RuntimeEnabledFeatures::visualViewportAPIEnabled()) {
+        if (Document* document = mainFrame()->document()) {
+            if (document->documentElement())
+                document->documentElement()->dispatchViewportChangedEvent();
+        }
+    }
+
     InspectorInstrumentation::didUpdateLayout(mainFrame());
     mainFrame()->loader().saveScrollState();
 
     clampToBoundaries();
 }
 
 bool VisualViewport::magnifyScaleAroundAnchor(float magnifyDelta, const FloatPoint& anchor)
 {
     const float oldPageScale = scale();
     const float newPageScale = frameHost().chromeClient().clampPageScaleFactorToLimits(
@@ skipping 500 matching lines @@
     } else if (graphicsLayer == m_rootTransformLayer) {
         name =  "Root Transform Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink