Implement overlay scrollbar fade out for non-composited scrollers.

third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2008, 2011 Apple 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.
@@ skipping 26 matching lines @@
 #include "platform/scroll/ProgrammaticScrollAnimator.h"
 #include "platform/scroll/ScrollbarTheme.h"
 
 #include "platform/tracing/TraceEvent.h"
 
 static const int kPixelsPerLineStep = 40;
 static const float kMinFractionToStepWhenPaging = 0.875f;
 
 namespace blink {
 
-struct SameSizeAsScrollableArea {
-  virtual ~SameSizeAsScrollableArea();
-#if ENABLE(ASSERT)
-  VerifyEagerFinalization verifyEager;
-#endif
-  Member<void*> pointer[2];
-  unsigned bitfields : 17;
-  IntPoint origin;
-};
-
-static_assert(sizeof(ScrollableArea) == sizeof(SameSizeAsScrollableArea),
-              "ScrollableArea should stay small");
-
 int ScrollableArea::pixelsPerLineStep(HostWindow* host) {
   if (!host)
     return kPixelsPerLineStep;
   return host->windowToViewportScalar(kPixelsPerLineStep);
 }
 
 float ScrollableArea::minFractionToStepWhenPaging() {
   return kMinFractionToStepWhenPaging;
 }
 
 int ScrollableArea::maxOverlapBetweenPages() {
   static int maxOverlapBetweenPages =
       ScrollbarTheme::theme().maxOverlapBetweenPages();
   return maxOverlapBetweenPages;
 }
 
 ScrollableArea::ScrollableArea()
     : m_scrollbarOverlayColorTheme(ScrollbarOverlayColorThemeDark),
       m_scrollOriginChanged(false),
       m_horizontalScrollbarNeedsPaintInvalidation(false),
       m_verticalScrollbarNeedsPaintInvalidation(false),
       m_scrollCornerNeedsPaintInvalidation(false),
-      m_scrollbarsHidden(false) {}
+      m_scrollbarsHidden(false),
+      m_scrollbarCaptured(false) {}
 
 ScrollableArea::~ScrollableArea() {}
 
-void ScrollableArea::clearScrollAnimators() {
+void ScrollableArea::clearScrollableArea() {
 #if OS(MACOSX)
   if (m_scrollAnimator)
     m_scrollAnimator->dispose();
 #endif
   m_scrollAnimator.clear();
   m_programmaticScrollAnimator.clear();
+  if (m_fadeOverlayScrollbarsTimer)
+    m_fadeOverlayScrollbarsTimer->stop();
 }
 
 ScrollAnimatorBase& ScrollableArea::scrollAnimator() const {
   if (!m_scrollAnimator)
     m_scrollAnimator =
         ScrollAnimatorBase::create(const_cast<ScrollableArea*>(this));
 
   return *m_scrollAnimator;
 }
 
@@ skipping 222 matching lines @@
 void ScrollableArea::mouseExitedContentArea() const {
   if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator())
     scrollAnimator->mouseEnteredContentArea();
 }
 
 void ScrollableArea::mouseMovedInContentArea() const {
   if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator())
     scrollAnimator->mouseMovedInContentArea();
 }
 
-void ScrollableArea::mouseEnteredScrollbar(Scrollbar& scrollbar) const {
+void ScrollableArea::mouseEnteredScrollbar(Scrollbar& scrollbar) {
   scrollAnimator().mouseEnteredScrollbar(scrollbar);
+  // Restart the fade out timer.
+  showOverlayScrollbars();
 }
 
-void ScrollableArea::mouseExitedScrollbar(Scrollbar& scrollbar) const {
+void ScrollableArea::mouseExitedScrollbar(Scrollbar& scrollbar) {
   scrollAnimator().mouseExitedScrollbar(scrollbar);
 }
 
+void ScrollableArea::mouseCapturedScrollbar() {
+  m_scrollbarCaptured = true;
+  showOverlayScrollbars();
+  if (m_fadeOverlayScrollbarsTimer)
+    m_fadeOverlayScrollbarsTimer->stop();
+}
+
+void ScrollableArea::mouseReleasedScrollbar() {
+  m_scrollbarCaptured = false;
+  // This will kick off the fade out timer.
+  showOverlayScrollbars();
+}
+
 void ScrollableArea::contentAreaDidShow() const {
   if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator())
     scrollAnimator->contentAreaDidShow();
 }
 
 void ScrollableArea::contentAreaDidHide() const {
   if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator())
     scrollAnimator->contentAreaDidHide();
 }
 
@@ skipping 18 matching lines @@
                                          ScrollbarOrientation orientation) {
   if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator()) {
     if (orientation == VerticalScrollbar)
       scrollAnimator->willRemoveVerticalScrollbar(scrollbar);
     else
       scrollAnimator->willRemoveHorizontalScrollbar(scrollbar);
   }
 }
 
 void ScrollableArea::contentsResized() {
+  showOverlayScrollbars();
   if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator())
     scrollAnimator->contentsResized();
 }
 
 bool ScrollableArea::hasOverlayScrollbars() const {
   Scrollbar* vScrollbar = verticalScrollbar();
   if (vScrollbar && vScrollbar->isOverlayScrollbar())
     return true;
   Scrollbar* hScrollbar = horizontalScrollbar();
   return hScrollbar && hScrollbar->isOverlayScrollbar();
@@ skipping 140 matching lines @@
   return true;
 }
 
 bool ScrollableArea::scrollbarsHidden() const {
   return hasOverlayScrollbars() && m_scrollbarsHidden;
 }
 
 void ScrollableArea::setScrollbarsHidden(bool hidden) {
   if (m_scrollbarsHidden == static_cast<unsigned>(hidden))
     return;
+
   m_scrollbarsHidden = hidden;
-  didChangeScrollbarsHidden();
+  scrollbarVisibilityChanged();
+}
+
+void ScrollableArea::fadeOverlayScrollbarsTimerFired(TimerBase*) {
+  setScrollbarsHidden(true);
+}
+
+void ScrollableArea::showOverlayScrollbars() {
+  if (!ScrollbarTheme::theme().usesOverlayScrollbars())
+    return;
+
+  setScrollbarsHidden(false);
+
+  const double timeUntilDisable =
+      ScrollbarTheme::theme().overlayScrollbarFadeOutDelaySeconds() +
+      ScrollbarTheme::theme().overlayScrollbarFadeOutDurationSeconds();
+
+  // If the overlay scrollbars don't fade out, don't do anything. This is the
+  // case for the mock overlays used in tests and on Mac, where the fade-out is
+  // animated in ScrollAnimatorMac.
+  if (!timeUntilDisable)
+    return;
+
+  if (!m_fadeOverlayScrollbarsTimer) {
+    m_fadeOverlayScrollbarsTimer.reset(new Timer<ScrollableArea>(
+        this, &ScrollableArea::fadeOverlayScrollbarsTimerFired));
+  }
+
+  if (!m_scrollbarCaptured) {
+    m_fadeOverlayScrollbarsTimer->startOneShot(timeUntilDisable,
+                                               BLINK_FROM_HERE);
+  }
 }
 
 IntRect ScrollableArea::visibleContentRect(
     IncludeScrollbarsInRect scrollbarInclusion) const {
   int scrollbarWidth =
       scrollbarInclusion == IncludeScrollbars ? verticalScrollbarWidth() : 0;
   int scrollbarHeight =
       scrollbarInclusion == IncludeScrollbars ? horizontalScrollbarHeight() : 0;
 
   return enclosingIntRect(
@@ skipping 51 matching lines @@
   return IntSize(std::max(0, size.width() - verticalScrollbarWidth()),
                  std::max(0, size.height() - horizontalScrollbarHeight()));
 }
 
 DEFINE_TRACE(ScrollableArea) {
   visitor->trace(m_scrollAnimator);
   visitor->trace(m_programmaticScrollAnimator);
 }
 
 }  // namespace blink