gfxRect
ThebesLayerComposite::GetDisplayPort()
{
// We use GetTransform instead of GetEffectiveTransform in this function
// as we want the transform of the shadowable layers and not that of the
// shadow layers, which may have been modified due to async scrolling/
// zooming.
gfx3DMatrix transform = GetTransform();
// Find out the area of the nearest display-port to invalidate retained
// tiles.
gfxRect displayPort;
gfxSize parentResolution = GetEffectiveResolution();
for (ContainerLayer* parent = GetParent(); parent; parent = parent->GetParent()) {
const FrameMetrics& metrics = parent->GetFrameMetrics();
if (displayPort.IsEmpty()) {
if (!metrics.mDisplayPort.IsEmpty()) {
// We use the bounds to cut down on complication/computation time.
// This will be incorrect when the transform involves rotation, but
// it'd be quite hard to retain invalid tiles correctly in this
// situation anyway.
displayPort = gfxRect(metrics.mDisplayPort.x,
metrics.mDisplayPort.y,
metrics.mDisplayPort.width,
metrics.mDisplayPort.height);
displayPort.ScaleRoundOut(parentResolution.width, parentResolution.height);
}
parentResolution.width /= metrics.mResolution.scale;
parentResolution.height /= metrics.mResolution.scale;
}
if (parent->UseIntermediateSurface()) {
transform.PreMultiply(parent->GetTransform());
}
}
// If no display port was found, use the widget size from the layer manager.
if (displayPort.IsEmpty()) {
LayerManagerComposite* manager = static_cast<LayerManagerComposite*>(Manager());
const nsIntSize& widgetSize = manager->GetWidgetSize();
displayPort.width = widgetSize.width;
displayPort.height = widgetSize.height;
}
// Transform the display port into layer space.
displayPort = transform.Inverse().TransformBounds(displayPort);
return displayPort;
}
