Trigger style recalc when the window's active state change

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 323 matching lines @@
         m_verticalScrollbar->styleChanged();
         didStyleChange = true;
     }
     if (didStyleChange) {
         updateScrollbarGeometry();
         updateScrollCorner();
         positionScrollbarLayers();
     }
 }
 
+void FrameView::invalidateAllCustomScrollbarsOnActiveChanged()
+{
+    const ChildrenWidgetSet* viewChildren = children();
+    bool didStyleChange = false;
+    for (const RefPtrWillBeMember<Widget>& child : *viewChildren) {
+        Widget* widget = child.get();
+        if (widget->isFrameView()) {
+            toFrameView(widget)->recalculateCustomScrollbarStyle();
+            if (toFrameView(widget)->hasCustomScrollbars())

[rune, 2014/12/10 08:29:32]

hasCustomScrollbars() is traversing the whole widget sub-tree in the case where
you have no custom scrollbars. In the case where you find a custom scrollbar and
return from hasCustomScrollbars(), you'll enter and traverse the same widgets
again. This if-check only makes this code more expensive.


How about doing this instead? (I haven't tested that it works):

void FrameView::invalidateAllCustomScrollbarsOnActiveChanged()
{
    const ChildrenWidgetSet* viewChildren = children();
    for (const RefPtrWillBeMember<Widget>& child : *viewChildren) {
        Widget* widget = child.get();
        if (widget->isFrameView())
            toFrameView(widget)->invalidateAllCustomScrollbarsOnActiveChanged();
        else if (widget->isScrollbar())
            toScrollbar(widget)->styleChanged();
    }

    recalculateCustomScrollbarStyle();
}

[MuVen, 2014/12/10 08:44:33]

yes this is much simpler, I have verified all the test, its passing. PTAL of
updated patch with these changes.

+                toFrameView(widget)->invalidateAllCustomScrollbarsOnActiveChanged();
+        } else if (widget->isScrollbar() && toScrollbar(widget)->isCustomScrollbar()) {
+            toScrollbar(widget)->styleChanged();
+            didStyleChange = true;
+        }
+    }
+    if (didStyleChange) {
+        updateScrollbarGeometry();
+        updateScrollCorner();
+        positionScrollbarLayers();
+    }
+}
+
 void FrameView::recalculateScrollbarOverlayStyle()
 {
     ScrollbarOverlayStyle oldOverlayStyle = scrollbarOverlayStyle();
     ScrollbarOverlayStyle overlayStyle = ScrollbarOverlayStyleDefault;
 
     Color backgroundColor = documentBackgroundColor();
     // Reduce the background color from RGB to a lightness value
     // and determine which scrollbar style to use based on a lightness
     // heuristic.
     double hue, saturation, lightness;
@@ skipping 3602 matching lines @@
         return;
 
     ScrollableArea::setScrollOrigin(origin);
 
     // Update if the scroll origin changes, since our position will be different if the content size did not change.
     if (updatePositionAtAll && updatePositionSynchronously)
         updateScrollbars(scrollOffsetDouble());
 }
 
 } // namespace blink