Allow objects without scrollbars to be scrollable

Source/core/rendering/RenderListBox.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  *               2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * 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. 
@@ skipping 158 matching lines @@
 }
 
 void RenderListBox::layout()
 {
     StackStats::LayoutCheckPoint layoutCheckPoint;
     RenderBlock::layout();
 
     if (m_vBar) {
         bool enabled = numVisibleItems() < numItems();
         m_vBar->setEnabled(enabled);
-        m_vBar->setSteps(1, max(1, numVisibleItems() - 1), itemHeight());
         m_vBar->setProportion(numVisibleItems(), numItems());
         if (!enabled) {
             scrollToOffsetWithoutAnimation(VerticalScrollbar, 0);
             m_indexOffset = 0;
         }
     }
 
     if (m_scrollToRevealSelectionAfterLayout) {
         LayoutStateDisabler layoutStateDisabler(view());
         scrollToRevealSelection();
@@ skipping 427 matching lines @@
 
 void RenderListBox::valueChanged(unsigned listIndex)
 {
     HTMLSelectElement* element = selectElement();
     element->setSelectedIndex(element->listToOptionIndex(listIndex));
     element->dispatchFormControlChangeEvent();
 }
 
 int RenderListBox::scrollSize(ScrollbarOrientation orientation) const
 {
-    return ((orientation == VerticalScrollbar) && m_vBar) ? (m_vBar->totalSize() - m_vBar->visibleSize()) : 0;
+    return orientation == VerticalScrollbar ? (numItems() - numVisibleItems()) : 0;
 }
 
 int RenderListBox::scrollPosition(Scrollbar*) const
 {
     return m_indexOffset;
 }
 
+IntPoint RenderListBox::scrollPosition() const
+{
+    int x = 0;
+    int y = m_indexOffset;
+    return IntPoint(x, y);

[aelias_OOO_until_Jul13, 2013/06/19 22:25:12]

nit: return IntPoint(0, m_indexOffset);

[bokan, 2013/06/19 23:50:58]

Done.

+}
+
 void RenderListBox::setScrollOffset(const IntPoint& offset)
 {
     scrollTo(offset.y());
 }
 
 void RenderListBox::scrollTo(int newOffset)
 {
     if (newOffset == m_indexOffset)
         return;
 
@@ skipping 187 matching lines @@
     if (!view)
         return false;
     return view->frameView()->scrollbarsCanBeActive();
 }
 
 IntPoint RenderListBox::maximumScrollPosition() const
 {
     return IntPoint(0, numItems() - numVisibleItems());
 }
 
+bool RenderListBox::userInputScrollable(ScrollbarOrientation orientation) const
+{
+    return orientation == VerticalScrollbar;
+}
+
+int RenderListBox::lineStep(ScrollbarOrientation) const
+{
+    return 1;
+}
+
+int RenderListBox::pageStep(ScrollbarOrientation orientation) const
+{
+    return max(1, numVisibleItems() - 1);
+}
+
+float RenderListBox::pixelStep(ScrollbarOrientation) const
+{
+    return 1.0f / itemHeight();
+}
+
 ScrollableArea* RenderListBox::enclosingScrollableArea() const
 {
     // FIXME: Return a RenderLayer that's scrollable.
     return 0;
 }
 
 IntRect RenderListBox::scrollableAreaBoundingBox() const
 {
     return absoluteBoundingBoxRect();
 }
@@ skipping 36 matching lines @@
 
     if (m_vBar)
         m_vBar->styleChanged();
 
     // Force an update since we know the scrollbars have changed things.
     if (document()->hasAnnotatedRegions())
         document()->setAnnotatedRegionsDirty(true);
 }
 
 } // namespace WebCore