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

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 342 matching lines @@
       m_maximumLegibleScale(1),
       m_doubleTapZoomPageScaleFactor(0),
       m_doubleTapZoomPending(false),
       m_enableFakePageScaleAnimationForTesting(false),
       m_fakePageScaleAnimationPageScaleFactor(0),
       m_fakePageScaleAnimationUseAnchor(false),
       m_compositorDeviceScaleFactorOverride(0),
       m_suppressNextKeypressEvent(false),
       m_imeAcceptEvents(true),
       m_devToolsEmulator(nullptr),
-      m_isTransparent(false),
       m_tabsToLinks(false),
       m_layerTreeView(nullptr),
       m_rootLayer(nullptr),
       m_rootGraphicsLayer(nullptr),
       m_visualViewportContainerLayer(nullptr),
       m_matchesHeuristicsForGpuRasterization(false),
       m_flingModifier(0),
       m_flingSourceDevice(WebGestureDeviceUninitialized),
       m_fullscreenController(FullscreenController::create(this)),
       m_baseBackgroundColor(Color::white),
       m_baseBackgroundColorOverrideEnabled(false),
       m_baseBackgroundColorOverride(Color::transparent),
+      m_backgroundColorOverrideEnabled(false),
       m_backgroundColorOverride(Color::transparent),
       m_zoomFactorOverride(0),
       m_userGestureObserved(false),
       m_shouldDispatchFirstVisuallyNonEmptyLayout(false),
       m_shouldDispatchFirstLayoutAfterFinishedParsing(false),
       m_shouldDispatchFirstLayoutAfterFinishedLoading(false),
       m_displayMode(WebDisplayModeBrowser),
       m_elasticOverscroll(FloatSize()),
       m_mutator(nullptr),
       m_scheduler(WTF::wrapUnique(Platform::current()
@@ skipping 2052 matching lines @@
 
   FrameSelection& selection = frame->selection();
   if (!selection.isAvailable()) {
     // plugins/mouse-capture-inside-shadow.html reaches here.
     return false;
   }
   return selection.computeVisibleSelectionInDOMTreeDeprecated().isBaseFirst();
 }
 
 WebColor WebViewImpl::backgroundColor() const {
-  if (isTransparent())
-    return Color::transparent;
+  if (m_backgroundColorOverrideEnabled)
+    return m_backgroundColorOverride;
   if (!m_page)
     return baseBackgroundColor().rgb();
   if (!m_page->mainFrame())
     return baseBackgroundColor().rgb();
   if (!m_page->mainFrame()->isLocalFrame())
     return baseBackgroundColor().rgb();
   FrameView* view = m_page->deprecatedLocalMainFrame()->view();
+  if (!view)
+    return baseBackgroundColor().rgb();
   return view->documentBackgroundColor().rgb();
 }
 
 WebPagePopup* WebViewImpl::pagePopup() const {
   return m_pagePopup.get();
 }
 
 // TODO(ekaramad):This method is almost duplicated in WebFrameWidgetImpl as
 // well. This code needs to be refactored  (http://crbug.com/629721).
 WebRange WebViewImpl::caretOrSelectionRange() {
@@ skipping 1042 matching lines @@
 void WebViewImpl::didCloseContextMenu() {
   LocalFrame* frame = m_page->focusController().focusedFrame();
   if (frame)
     frame->selection().setCaretBlinkingSuspended(false);
 }
 
 void WebViewImpl::hidePopups() {
   cancelPagePopup();
 }
 
-void WebViewImpl::setIsTransparent(bool isTransparent) {
-  // Set any existing frames to be transparent.
-  Frame* frame = m_page->mainFrame();
-  while (frame) {
-    if (frame->isLocalFrame())
-      toLocalFrame(frame)->view()->setTransparent(isTransparent);
-    frame = frame->tree().traverseNext();
-  }
-
-  // Future frames check this to know whether to be transparent.
-  m_isTransparent = isTransparent;
-
-  if (m_layerTreeView)
-    m_layerTreeView->setHasTransparentBackground(this->isTransparent());
-}
-
-bool WebViewImpl::isTransparent() const {
-  return m_isTransparent;
-}
-
 WebInputMethodControllerImpl* WebViewImpl::getActiveWebInputMethodController()
     const {
   return WebInputMethodControllerImpl::fromFrame(focusedLocalFrameInWidget());
 }
 
 Color WebViewImpl::baseBackgroundColor() const {
   return m_baseBackgroundColorOverrideEnabled ? m_baseBackgroundColorOverride
                                               : m_baseBackgroundColor;
 }
 
@@ skipping 27 matching lines @@
     mainFrameImpl()
         ->frame()
         ->view()
         ->updateLifecycleToCompositingCleanPlusScrolling();
   }
   updateBaseBackgroundColor();
 }
 
 void WebViewImpl::updateBaseBackgroundColor() {
   Color color = baseBackgroundColor();
-  if (m_page->mainFrame() && m_page->mainFrame()->isLocalFrame())
-    m_page->deprecatedLocalMainFrame()->view()->setBaseBackgroundColor(color);
+  if (m_page->mainFrame() && m_page->mainFrame()->isLocalFrame()) {
+    FrameView* view = m_page->deprecatedLocalMainFrame()->view();
+    view->setBaseBackgroundColor(color);
+    view->updateBaseBackgroundColorRecursively(color);

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

Why this new line?

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

setIsTransparent was previously setting the transparency bit on all existing
FrameViews. It needed to do that, because it was called when some FrameViews may
already exist.

Now that we are using the baseBackgroundColor(Override) to enable transparency,
setBaseBackgroundColor may be called when some FrameViews already exist. (I
don't think the baseBackgroundColor was previously intended to change after
initial WebViewImpl creation.) In any case, we now need to pass on the
baseBackgroundColor update to all existing FrameViews, so that we preserve a
behavior similar to what setIsTransparent did previously.

[chrishtr, 2017/03/29 15:36:41]

Ok.

+  }
 }
 
 void WebViewImpl::setIsActive(bool active) {
   if (page())
     page()->focusController().setActive(active);
 }
 
 bool WebViewImpl::isActive() const {
   return page() ? page()->focusController().isActive() : false;
 }
@@ skipping 105 matching lines @@
 
 void WebViewImpl::mainFrameScrollOffsetChanged() {
   m_devToolsEmulator->mainFrameScrollOrScaleChanged();
 }
 
 bool WebViewImpl::useExternalPopupMenus() {
   return shouldUseExternalPopupMenus;
 }
 
 void WebViewImpl::setBackgroundColorOverride(WebColor color) {
+  m_backgroundColorOverrideEnabled = true;
   m_backgroundColorOverride = color;
   updateLayerTreeBackgroundColor();
 }
 
+void WebViewImpl::clearBackgroundColorOverride() {
+  m_backgroundColorOverrideEnabled = false;
+  updateLayerTreeBackgroundColor();
+}
+
 void WebViewImpl::setZoomFactorOverride(float zoomFactor) {
   m_zoomFactorOverride = zoomFactor;
   setZoomLevel(zoomLevel());
 }
 
 void WebViewImpl::setPageOverlayColor(WebColor color) {
   if (m_pageColorOverlay)
     m_pageColorOverlay.reset();
 
   if (color == Color::transparent)
@@ skipping 289 matching lines @@
   if (!page() || !m_layerTreeView)
     return;
 
   m_layerTreeView->setPageScaleFactorAndLimits(
       pageScaleFactor(), minimumPageScaleFactor(), maximumPageScaleFactor());
 }
 
 void WebViewImpl::updateLayerTreeBackgroundColor() {
   if (!m_layerTreeView)
     return;
-
-  m_layerTreeView->setBackgroundColor(alphaChannel(m_backgroundColorOverride)
-                                          ? m_backgroundColorOverride
-                                          : backgroundColor());
+  m_layerTreeView->setBackgroundColor(backgroundColor());
 }
 
 void WebViewImpl::updateLayerTreeDeviceScaleFactor() {
   DCHECK(page());
   DCHECK(m_layerTreeView);
 
   float deviceScaleFactor = m_compositorDeviceScaleFactorOverride
                                 ? m_compositorDeviceScaleFactorOverride
                                 : page()->deviceScaleFactorDeprecated();
   m_layerTreeView->setDeviceScaleFactor(deviceScaleFactor);
@@ skipping 133 matching lines @@
   if (focusedFrame->localFrameRoot() != mainFrameImpl()->frame())
     return nullptr;
   return focusedFrame;
 }
 
 LocalFrame* WebViewImpl::focusedLocalFrameAvailableForIme() const {
   return m_imeAcceptEvents ? focusedLocalFrameInWidget() : nullptr;
 }
 
 }  // namespace blink