Allow objects without scrollbars to be scrollable

Source/core/platform/ScrollView.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 25 matching lines @@
 
 using namespace std;
 
 namespace WebCore {
 
 ScrollView::ScrollView()
     : m_horizontalScrollbarMode(ScrollbarAuto)
     , m_verticalScrollbarMode(ScrollbarAuto)
     , m_horizontalScrollbarLock(false)
     , m_verticalScrollbarLock(false)
-    , m_prohibitsScrolling(false)
     , m_canBlitOnScroll(true)
     , m_scrollbarsAvoidingResizer(0)
     , m_scrollbarsSuppressed(false)
     , m_inUpdateScrollbars(false)
     , m_updateScrollbarsPass(0)
     , m_drawPanScrollIcon(false)
     , m_useFixedLayout(false)
     , m_paintsEntireContents(false)
     , m_clipsRepaints(true)
 {
@@ skipping 220 matching lines @@
     if (!constrainsScrollingToContentEdge())
         return scrollPoint;
 
     IntPoint newScrollPosition = scrollPoint.shrunkTo(maximumScrollPosition());
     newScrollPosition = newScrollPosition.expandedTo(minimumScrollPosition());
     return newScrollPosition;
 }
 
 int ScrollView::scrollSize(ScrollbarOrientation orientation) const
 {
+    Scrollbar* scrollbar = ((orientation == HorizontalScrollbar) ? m_horizontalScrollbar : m_verticalScrollbar).get();
+
     // If no scrollbars are present, it does not indicate content is not be scrollable.
-    if (!m_horizontalScrollbar && !m_verticalScrollbar && !prohibitsScrolling()) {
+    if (!scrollbar) {
         IntSize scrollSize = m_contentsSize - visibleContentRect().size();
         scrollSize.clampNegativeToZero();
         return orientation == HorizontalScrollbar ? scrollSize.width() : scrollSize.height();
     }
 
-    Scrollbar* scrollbar = ((orientation == HorizontalScrollbar) ? m_horizontalScrollbar : m_verticalScrollbar).get();
-    return scrollbar ? (scrollbar->totalSize() - scrollbar->visibleSize()) : 0;
+    return scrollbar->totalSize() - scrollbar->visibleSize();
 }
 
 void ScrollView::notifyPageThatContentAreaWillPaint() const
 {
 }
 
 void ScrollView::setScrollOffset(const IntPoint& offset)
 {
     scrollTo(toIntSize(adjustScrollPositionWithinRange(offset)));
 }
@@ skipping 17 matching lines @@
 {
     if (scrollbar->orientation() == HorizontalScrollbar)
         return scrollPosition().x() + scrollOrigin().x();
     if (scrollbar->orientation() == VerticalScrollbar)
         return scrollPosition().y() + scrollOrigin().y();
     return 0;
 }
 
 void ScrollView::setScrollPosition(const IntPoint& scrollPoint)
 {
-    if (prohibitsScrolling())
-        return;
-
     IntPoint newScrollPosition = adjustScrollPositionWithinRange(scrollPoint);
 
     if (newScrollPosition == scrollPosition())
         return;
 
     updateScrollbars(IntSize(newScrollPosition.x(), newScrollPosition.y()));
 }
 
 bool ScrollView::logicalScroll(ScrollLogicalDirection direction, ScrollGranularity granularity)
 {
@@ skipping 21 matching lines @@
 
 void ScrollView::windowResizerRectChanged()
 {
     updateScrollbars(scrollOffset());
 }
 
 static const unsigned cMaxUpdateScrollbarsPass = 2;
 
 void ScrollView::updateScrollbars(const IntSize& desiredOffset)
 {
-    if (m_inUpdateScrollbars || prohibitsScrolling())
+    if (m_inUpdateScrollbars)
         return;
 
     // 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) {
         m_inUpdateScrollbars = true;
         visibleContentsResized();
         m_inUpdateScrollbars = false;
     }
@@ skipping 427 matching lines @@
     graphicsLayer->setSize(cornerRect.size());
 }
 
 void ScrollView::positionScrollbarLayers()
 {
     positionScrollbarLayer(layerForHorizontalScrollbar(), horizontalScrollbar());
     positionScrollbarLayer(layerForVerticalScrollbar(), verticalScrollbar());
     positionScrollCornerLayer(layerForScrollCorner(), scrollCornerRect());
 }
 
+bool ScrollView::isHorizontallyScrollable() const
+{
+    return m_horizontalScrollbarMode == ScrollbarAuto || m_horizontalScrollbarMode == ScrollbarAlwaysOn;
+}
+
+bool ScrollView::isVerticallyScrollable() const
+{
+    return m_verticalScrollbarMode == ScrollbarAuto || m_verticalScrollbarMode == ScrollbarAlwaysOn;
+}
+
 void ScrollView::repaintContentRectangle(const IntRect& rect)
 {
     IntRect paintRect = rect;
     if (clipsRepaints() && !paintsEntireContents())
         paintRect.intersect(visibleContentRect());
     if (paintRect.isEmpty())
         return;
 
     if (hostWindow())
         hostWindow()->invalidateContentsAndRootView(contentsToWindow(paintRect));
@@ skipping 419 matching lines @@
 {
 }
 
 bool ScrollView::platformIsOffscreen() const
 {
     return false;
 }
 
 
 }