Fixed Inconsistent behaviour of custom-scrollbar

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 1680 matching lines @@
 {
     if (m_frame->isMainFrame() && m_frame->document()) {
         if (TextAutosizer* textAutosizer = m_frame->document()->textAutosizer())
             textAutosizer->updatePageInfoInAllFrames();
     }
 
     ScrollableArea::contentsResized();
     setNeedsLayout();
 }
 
-void FrameView::scrollbarExistenceDidChange()
+void FrameView::scrollbarNeedsLayout()
 {
     // We check to make sure the view is attached to a frame() as this method can
     // be triggered before the view is attached by LocalFrame::createView(...) setting
     // various values such as setScrollBarModes(...) for example.  An ASSERT is
     // triggered when a view is layout before being attached to a frame().
     if (!frame().view())
         return;
 
     // Note that simply having overlay scrollbars is not sufficient to be
     // certain that scrollbars' presence does not impact layout. This should
@@ skipping 1591 matching lines @@
         int clientWidth = visibleWidth();
         IntRect oldRect(m_horizontalScrollbar->frameRect());
         IntRect hBarRect((shouldPlaceVerticalScrollbarOnLeft() && m_verticalScrollbar) ? m_verticalScrollbar->width() : 0,
             height() - m_horizontalScrollbar->height(),
             width() - (m_verticalScrollbar ? m_verticalScrollbar->width() : 0),
             m_horizontalScrollbar->height());
         m_horizontalScrollbar->setFrameRect(adjustScrollbarRectForResizer(hBarRect, m_horizontalScrollbar.get()));
         if (!m_scrollbarsSuppressed && oldRect != m_horizontalScrollbar->frameRect())
             m_horizontalScrollbar->invalidate();
 
+        oldRect = m_horizontalScrollbar->frameRect();
+
         if (m_scrollbarsSuppressed)
             m_horizontalScrollbar->setSuppressInvalidation(true);
         m_horizontalScrollbar->setEnabled(contentsWidth() > clientWidth);
         m_horizontalScrollbar->setProportion(clientWidth, contentsWidth());
         m_horizontalScrollbar->offsetDidChange();
         if (m_scrollbarsSuppressed)
             m_horizontalScrollbar->setSuppressInvalidation(false);
+
+        if (!m_scrollbarsSuppressed && oldRect != m_horizontalScrollbar->frameRect() && m_horizontalScrollbar->isCustomScrollbar()) {
+            IntRect hBarRect((shouldPlaceVerticalScrollbarOnLeft() && m_verticalScrollbar) ? m_verticalScrollbar->width() : 0,
+                height() - m_horizontalScrollbar->height(),
+                width() - (m_verticalScrollbar ? m_verticalScrollbar->width() : 0),
+                m_horizontalScrollbar->height());
+            m_horizontalScrollbar->setFrameRect(adjustScrollbarRectForResizer(hBarRect, m_horizontalScrollbar.get()));
+            if (oldRect.height() != m_horizontalScrollbar->frameRect().height())
+                scrollbarNeedsLayout();
+            m_horizontalScrollbar->invalidate();
+        }
     }
 
     if (m_verticalScrollbar) {
         int clientHeight = visibleHeight();
         IntRect oldRect(m_verticalScrollbar->frameRect());
         IntRect vBarRect(shouldPlaceVerticalScrollbarOnLeft() ? 0 : (width() - m_verticalScrollbar->width()),
             0,
             m_verticalScrollbar->width(),
             height() - (m_horizontalScrollbar ? m_horizontalScrollbar->height() : 0));
         m_verticalScrollbar->setFrameRect(adjustScrollbarRectForResizer(vBarRect, m_verticalScrollbar.get()));
         if (!m_scrollbarsSuppressed && oldRect != m_verticalScrollbar->frameRect())
             m_verticalScrollbar->invalidate();
 
+        oldRect = m_verticalScrollbar->frameRect();
+
         if (m_scrollbarsSuppressed)
             m_verticalScrollbar->setSuppressInvalidation(true);
         m_verticalScrollbar->setEnabled(contentsHeight() > clientHeight);
         m_verticalScrollbar->setProportion(clientHeight, contentsHeight());
         m_verticalScrollbar->offsetDidChange();
         if (m_scrollbarsSuppressed)
             m_verticalScrollbar->setSuppressInvalidation(false);
+
+        if (!m_scrollbarsSuppressed && oldRect != m_verticalScrollbar->frameRect() && m_verticalScrollbar->isCustomScrollbar()) {
+            IntRect vBarRect(shouldPlaceVerticalScrollbarOnLeft() ? 0 : (width() - m_verticalScrollbar->width()),
+                0,
+                m_verticalScrollbar->width(),
+                height() - (m_horizontalScrollbar ? m_horizontalScrollbar->height() : 0));
+            m_verticalScrollbar->setFrameRect(adjustScrollbarRectForResizer(vBarRect, m_verticalScrollbar.get()));
+            if (oldRect.width() != m_verticalScrollbar->frameRect().width())
+                scrollbarNeedsLayout();
+            m_verticalScrollbar->invalidate();
+        }
     }
 }
 
 IntRect FrameView::adjustScrollbarRectForResizer(const IntRect& rect, Scrollbar* scrollbar)
 {
     // Get our window resizer rect and see if we overlap. Adjust to avoid the overlap
     // if necessary.
     IntRect adjustedRect(rect);
     bool overlapsResizer = false;
     if (!rect.isEmpty() && !windowResizerRect().isEmpty()) {
@@ skipping 22 matching lines @@
 }
 
 bool FrameView::adjustScrollbarExistence(ComputeScrollbarExistenceOption option)
 {
     ASSERT(m_inUpdateScrollbars);
 
     // If we came in here with the view already needing a layout, then go ahead and do that
     // first.  (This will be the common case, e.g., when the page changes due to window resizing for example).
     // This layout will not re-enter updateScrollbars and does not count towards our max layout pass total.
     if (!m_scrollbarsSuppressed)
-        scrollbarExistenceDidChange();
+        scrollbarNeedsLayout();
 
     bool hasHorizontalScrollbar = m_horizontalScrollbar;
     bool hasVerticalScrollbar = m_verticalScrollbar;
 
     bool newHasHorizontalScrollbar = false;
     bool newHasVerticalScrollbar = false;
     computeScrollbarExistence(newHasHorizontalScrollbar, newHasVerticalScrollbar, contentsSize(), option);
 
     bool scrollbarExistenceChanged = hasHorizontalScrollbar != newHasHorizontalScrollbar || hasVerticalScrollbar != newHasVerticalScrollbar;
     if (!scrollbarExistenceChanged)
         return false;
 
     setHasHorizontalScrollbar(newHasHorizontalScrollbar);
     setHasVerticalScrollbar(newHasVerticalScrollbar);
 
     if (m_scrollbarsSuppressed)
         return true;
 
     if (!useOverlayScrollbars())
         contentsResized();
-    scrollbarExistenceDidChange();
+    scrollbarNeedsLayout();
     return true;
 }
 
 void FrameView::updateScrollbars(const DoubleSize& desiredOffset)
 {
     if (scrollbarsDisabled()) {
         setScrollOffsetFromUpdateScrollbars(desiredOffset);
         return;
     }
 
@@ skipping 515 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