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

third_party/WebKit/Source/web/FullscreenController.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 134 matching lines @@
   // since by the time the latter is called, a Resize has already occured,
   // clamping the scroll offset. Don't save values if we're still waiting to
   // restore a previous set. This can happen if we exit and quickly reenter
   // fullscreen without performing a layout.
   if (m_state == State::Initial) {
     m_initialPageScaleFactor = m_webViewImpl->pageScaleFactor();
     m_initialScrollOffset = m_webViewImpl->mainFrame()->isWebLocalFrame()
                                 ? m_webViewImpl->mainFrame()->getScrollOffset()
                                 : WebSize();
     m_initialVisualViewportOffset = m_webViewImpl->visualViewportOffset();
+    m_initialBackgroundColorOverrideEnabled =
+        m_webViewImpl->backgroundColorOverrideEnabled();
+    m_initialBackgroundColorOverride = m_webViewImpl->backgroundColorOverride();
   }
 
   // If already entering fullscreen, just wait.
   if (m_state == State::EnteringFullscreen)
     return;
 
   DCHECK(m_state == State::Initial ||
          m_state == State::NeedsScrollAndScaleRestore);
   webFrameClient(frame).enterFullscreen();
 
@@ skipping 10 matching lines @@
 
   webFrameClient(frame).exitFullscreen();
 
   m_state = State::ExitingFullscreen;
 }
 
 void FullscreenController::fullscreenElementChanged(Element* fromElement,
                                                     Element* toElement) {
   DCHECK_NE(fromElement, toElement);
 
+  // We only override the WebView's background color for overlay fullscreen
+  // video elements, so have to restore the override when the element changes.
+  restoreBackgroundColorOverride();

[chrishtr, 2017/03/28 19:45:56]

Are the code changes in this file tested by a layout test or unittest?

[Eric Seckler, 2017/03/29 10:50:18]

Yeah, there's a unit test [1], which fails if we don't set transparency
correctly here [2].

[1]
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/web/tests/WebF...
[2] https://codereview.chromium.org/2784783002/#ps20001

+
   if (toElement) {
     DCHECK(Fullscreen::isCurrentFullScreenElement(*toElement));
 
     if (isHTMLVideoElement(*toElement)) {
       HTMLVideoElement& videoElement = toHTMLVideoElement(*toElement);
       videoElement.didEnterFullscreen();
 
       // If the video uses overlay fullscreen mode, make the background
       // transparent.
-      if (videoElement.usesOverlayFullscreenVideo() &&
-          m_webViewImpl->layerTreeView()) {
-        m_webViewImpl->layerTreeView()->setHasTransparentBackground(true);
-      }
+      if (videoElement.usesOverlayFullscreenVideo())
+        m_webViewImpl->setBackgroundColorOverride(Color::transparent);
     }
   }
 
   if (fromElement) {
     DCHECK(!Fullscreen::isCurrentFullScreenElement(*fromElement));
 
     if (isHTMLVideoElement(*fromElement)) {
-      // If the video used overlay fullscreen mode, restore the transparency.
-      if (m_webViewImpl->layerTreeView()) {
-        m_webViewImpl->layerTreeView()->setHasTransparentBackground(
-            m_webViewImpl->isTransparent());
-      }
-
       HTMLVideoElement& videoElement = toHTMLVideoElement(*fromElement);
       videoElement.didExitFullscreen();
     }
   }
 }
 
+void FullscreenController::restoreBackgroundColorOverride() {
+  if (m_webViewImpl->backgroundColorOverrideEnabled() !=
+          m_initialBackgroundColorOverrideEnabled ||
+      m_webViewImpl->backgroundColorOverride() !=
+          m_initialBackgroundColorOverride) {
+    if (m_initialBackgroundColorOverrideEnabled) {
+      m_webViewImpl->setBackgroundColorOverride(
+          m_initialBackgroundColorOverride);
+    } else {
+      m_webViewImpl->clearBackgroundColorOverride();
+    }
+  }
+}
+
 void FullscreenController::updateSize() {
   DCHECK(m_webViewImpl->page());
 
   if (m_state != State::Fullscreen && m_state != State::ExitingFullscreen)
     return;
 
   updatePageScaleConstraints(false);
 
   // Traverse all local frames and notify the LayoutFullScreen object, if any.
   for (Frame* frame = m_webViewImpl->page()->mainFrame(); frame;
@@ skipping 11 matching lines @@
 }
 
 void FullscreenController::didUpdateLayout() {
   if (m_state != State::NeedsScrollAndScaleRestore)
     return;
 
   m_webViewImpl->setPageScaleFactor(m_initialPageScaleFactor);
   if (m_webViewImpl->mainFrame()->isWebLocalFrame())
     m_webViewImpl->mainFrame()->setScrollOffset(WebSize(m_initialScrollOffset));
   m_webViewImpl->setVisualViewportOffset(m_initialVisualViewportOffset);
+  // Background color override was already restored when
+  // fullscreenElementChanged([..], nullptr) was called while exiting.
 
   m_state = State::Initial;
 }
 
 void FullscreenController::updatePageScaleConstraints(bool removeConstraints) {
   PageScaleConstraints fullscreenConstraints;
   if (!removeConstraints) {
     fullscreenConstraints = PageScaleConstraints(1.0, 1.0, 1.0);
     fullscreenConstraints.layoutSize = FloatSize(m_webViewImpl->size());
   }
   m_webViewImpl->pageScaleConstraintsSet().setFullscreenConstraints(
       fullscreenConstraints);
   m_webViewImpl->pageScaleConstraintsSet().computeFinalConstraints();
 
   // Although we called |computedFinalConstraints()| above, the "final"
   // constraints are not actually final. They are still subject to scale factor
   // clamping by contents size. Normally they should be dirtied due to contents
   // size mutation after layout, however the contents size is not guaranteed to
   // mutate, and the scale factor may remain unclamped. Just fire the event
   // again to ensure the final constraints pick up the latest contents size.
   m_webViewImpl->didChangeContentsSize();
   if (m_webViewImpl->mainFrameImpl() &&
       m_webViewImpl->mainFrameImpl()->frameView())
     m_webViewImpl->mainFrameImpl()->frameView()->setNeedsLayout();
 
   m_webViewImpl->updateMainFrameLayoutSize();
 }
 
 }  // namespace blink