[blink] Support (semi-)transparent background colors in WebView/Frame.

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

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 156 matching lines @@
       m_hasPendingLayout(false),
       m_inSynchronousPostLayout(false),
       m_postLayoutTasksTimer(
           TaskRunnerHelper::get(TaskType::UnspecedTimer, &frame),
           this,
           &FrameView::postLayoutTimerFired),
       m_updatePluginsTimer(
           TaskRunnerHelper::get(TaskType::UnspecedTimer, &frame),
           this,
           &FrameView::updatePluginsTimerFired),
-      m_isTransparent(false),
       m_baseBackgroundColor(Color::white),
       m_mediaType(MediaTypeNames::screen),
       m_safeToPropagateScrollToParent(true),
       m_scrollCorner(nullptr),
       m_stickyPositionObjectCount(0),
       m_inputEventsScaleFactorForEmulation(1),
       m_layoutSizeFixedToFrameSize(true),
       m_didScrollTimer(TaskRunnerHelper::get(TaskType::UnspecedTimer, &frame),
                        this,
                        &FrameView::didScrollTimerFired),
@@ skipping 2133 matching lines @@
   LayoutViewItem layoutViewItem = this->layoutViewItem();
   if (layoutViewItem.isNull())
     return;
   // TODO(crbug.com/590856): It's still broken if we choose not to crash when
   // the check fails.
   if (!checkLayoutInvalidationIsAllowed())
     return;
   layoutViewItem.setNeedsLayout(LayoutInvalidationReason::Unknown);
 }
 
-bool FrameView::isTransparent() const {
-  return m_isTransparent;
-}
-
-void FrameView::setTransparent(bool isTransparent) {
-  m_isTransparent = isTransparent;
-  DisableCompositingQueryAsserts disabler;
-  if (!layoutViewItem().isNull() &&
-      layoutViewItem().layer()->hasCompositedLayerMapping())
-    layoutViewItem().layer()->compositedLayerMapping()->updateContentsOpaque();
-}
-
 bool FrameView::hasOpaqueBackground() const {
-  return !m_isTransparent && !m_baseBackgroundColor.hasAlpha();
+  return !m_baseBackgroundColor.hasAlpha();
 }
 
 Color FrameView::baseBackgroundColor() const {
   return m_baseBackgroundColor;
 }
 
 void FrameView::setBaseBackgroundColor(const Color& backgroundColor) {
   m_baseBackgroundColor = backgroundColor;
 
   if (!layoutViewItem().isNull() &&
       layoutViewItem().layer()->hasCompositedLayerMapping()) {
     CompositedLayerMapping* compositedLayerMapping =
         layoutViewItem().layer()->compositedLayerMapping();
     compositedLayerMapping->updateContentsOpaque();
     if (compositedLayerMapping->mainGraphicsLayer())
       compositedLayerMapping->mainGraphicsLayer()->setNeedsDisplay();
   }
   recalculateScrollbarOverlayColorTheme(documentBackgroundColor());
 
   if (!shouldThrottleRendering())
     page()->animator().scheduleVisualUpdate(m_frame.get());
 }
 
-void FrameView::updateBackgroundRecursively(const Color& backgroundColor,
-                                            bool transparent) {
-  forAllNonThrottledFrameViews(
-      [backgroundColor, transparent](FrameView& frameView) {
-        frameView.setTransparent(transparent);
-        frameView.setBaseBackgroundColor(backgroundColor);
-      });
+void FrameView::updateBaseBackgroundColorRecursively(
+    const Color& baseBackgroundColor) {
+  forAllNonThrottledFrameViews([baseBackgroundColor](FrameView& frameView) {

[dcheng, 2017/03/31 01:21:15]

Btw, I'm wondering something: we only call this from LocalFrame::createView. But
at that point, we have a new LocalFrame/FrameView, right? So how is it possible
there are any children here?

[Eric Seckler, 2017/03/31 08:32:28]

I'm not sure if there is a way for children to be around in createView - I'm not
familiar enough with when we actually (re)create a view and if we're guaranteed
no children at those times.

But we're also calling this from WebViewImpl::updateBaseBackgroundColor now, so
that the WebView's overrides (for transparency in particular) are applied in all
children too.

So since there's some need for the method anyway, I'll play it safe and keep the
call in createView, too, for now. :)

+    frameView.setBaseBackgroundColor(baseBackgroundColor);
+  });
 }
 
 void FrameView::scrollToFragmentAnchor() {
   Node* anchorNode = m_fragmentAnchor;
   if (!anchorNode)
     return;
 
   // Scrolling is disabled during updateScrollbars (see
   // isProgrammaticallyScrollable).  Bail now to avoid clearing m_fragmentAnchor
   // before we actually have a chance to scroll.
@@ skipping 2877 matching lines @@
 void FrameView::setAnimationHost(
     std::unique_ptr<CompositorAnimationHost> host) {
   m_animationHost = std::move(host);
 }
 
 LayoutUnit FrameView::caretWidth() const {
   return LayoutUnit(getHostWindow()->windowToViewportScalar(1));
 }
 
 }  // namespace blink