void RenderScrollbar::updateScrollbarPart(ScrollbarPart partType, bool destroy)
{
if (partType == NoPart)
return;
RefPtr<RenderStyle> partStyle = !destroy ? getScrollbarPseudoStyle(partType, pseudoForScrollbarPart(partType)) : PassRefPtr<RenderStyle>(0);
bool needRenderer = !destroy && partStyle && partStyle->display() != NONE && partStyle->visibility() == VISIBLE;
if (needRenderer && partStyle->display() != BLOCK) {
// See if we are a button that should not be visible according to OS settings.
ScrollbarButtonsPlacement buttonsPlacement = theme()->buttonsPlacement();
switch (partType) {
case BackButtonStartPart:
needRenderer = (buttonsPlacement == ScrollbarButtonsSingle || buttonsPlacement == ScrollbarButtonsDoubleStart ||
buttonsPlacement == ScrollbarButtonsDoubleBoth);
break;
case ForwardButtonStartPart:
needRenderer = (buttonsPlacement == ScrollbarButtonsDoubleStart || buttonsPlacement == ScrollbarButtonsDoubleBoth);
break;
case BackButtonEndPart:
needRenderer = (buttonsPlacement == ScrollbarButtonsDoubleEnd || buttonsPlacement == ScrollbarButtonsDoubleBoth);
break;
case ForwardButtonEndPart:
needRenderer = (buttonsPlacement == ScrollbarButtonsSingle || buttonsPlacement == ScrollbarButtonsDoubleEnd ||
buttonsPlacement == ScrollbarButtonsDoubleBoth);
break;
default:
break;
}
}
RenderScrollbarPart* partRenderer = m_parts.get(partType);
if (!partRenderer && needRenderer) {
partRenderer = new (owningRenderer()->renderArena()) RenderScrollbarPart(owningRenderer()->document(), this, partType);
m_parts.set(partType, partRenderer);
} else if (partRenderer && !needRenderer) {
m_parts.remove(partType);
partRenderer->destroy();
partRenderer = 0;
}
if (partRenderer)
partRenderer->setStyle(partStyle.release());
}
