PassOwnPtr<WebCore::GraphicsContext> LayerTreeCoordinator::beginContentUpdate(const WebCore::IntSize& size, ShareableBitmap::Flags flags, ShareableSurface::Handle& handle, WebCore::IntPoint& offset)
{
OwnPtr<WebCore::GraphicsContext> graphicsContext;
for (int i = 0; i < m_updateAtlases.size(); ++i) {
UpdateAtlas* atlas = m_updateAtlases[i].get();
if (atlas->flags() == flags) {
// This will return null if there is no available buffer space.
graphicsContext = atlas->beginPaintingOnAvailableBuffer(handle, size, offset);
if (graphicsContext)
return graphicsContext.release();
}
}
static const int ScratchBufferDimension = 1024; // Should be a power of two.
m_updateAtlases.append(adoptPtr(new UpdateAtlas(ScratchBufferDimension, flags)));
return m_updateAtlases.last()->beginPaintingOnAvailableBuffer(handle, size, offset);
}
void LayerTreeCoordinator::releaseInactiveAtlasesTimerFired(Timer<LayerTreeCoordinator>*)
{
// We always want to keep one atlas for non-composited content.
OwnPtr<UpdateAtlas> atlasToKeepAnyway;
bool foundActiveAtlasForNonCompositedContent = false;
for (int i = m_updateAtlases.size() - 1; i >= 0; --i) {
UpdateAtlas* atlas = m_updateAtlases[i].get();
if (!atlas->isInUse())
atlas->addTimeInactive(ReleaseInactiveAtlasesTimerInterval);
bool usableForNonCompositedContent = atlas->flags() == ShareableBitmap::NoFlags;
if (atlas->isInactive()) {
if (!foundActiveAtlasForNonCompositedContent && !atlasToKeepAnyway && usableForNonCompositedContent)
atlasToKeepAnyway = m_updateAtlases[i].release();
m_updateAtlases.remove(i);
} else if (usableForNonCompositedContent)
foundActiveAtlasForNonCompositedContent = true;
}
if (!foundActiveAtlasForNonCompositedContent && atlasToKeepAnyway)
m_updateAtlases.append(atlasToKeepAnyway.release());
if (m_updateAtlases.size() <= 1)
m_releaseInactiveAtlasesTimer.stop();
}