static gfx::Matrix4x4
GetTransformToAncestorsParentLayer(Layer* aStart, const LayerMetricsWrapper& aAncestor)
{
gfx::Matrix4x4 transform;
const LayerMetricsWrapper& ancestorParent = aAncestor.GetParent();
for (LayerMetricsWrapper iter(aStart, LayerMetricsWrapper::StartAt::BOTTOM);
ancestorParent ? iter != ancestorParent : iter.IsValid();
iter = iter.GetParent()) {
transform = transform * iter.GetTransform();
if (gfxPrefs::LayoutUseContainersForRootFrames()) {
// When scrolling containers, layout adds a post-scale into the transform
// of the displayport-ancestor (which we pick up in GetTransform() above)
// to cancel out the pres shell resolution (for historical reasons). The
// compositor in turn cancels out this post-scale (i.e., scales by the
// pres shell resolution), and to get correct calculations, we need to do
// so here, too.
//
// With containerless scrolling, the offending post-scale is on the
// parent layer of the displayport-ancestor, which we don't reach in this
// loop, so we don't need to worry about it.
const FrameMetrics& metrics = iter.Metrics();
transform.PostScale(metrics.GetPresShellResolution(), metrics.GetPresShellResolution(), 1.f);
}
}
return transform;
}
static gfx::Matrix4x4
GetTransformToAncestorsParentLayer(Layer* aStart, const LayerMetricsWrapper& aAncestor)
{
gfx::Matrix4x4 transform;
const LayerMetricsWrapper& ancestorParent = aAncestor.GetParent();
for (LayerMetricsWrapper iter(aStart, LayerMetricsWrapper::StartAt::BOTTOM);
ancestorParent ? iter != ancestorParent : iter.IsValid();
iter = iter.GetParent()) {
transform = transform * iter.GetTransform();
// If the layer has a non-transient async transform then we need to apply it here
// because it will get applied by the APZ in the compositor as well
const FrameMetrics& metrics = iter.Metrics();
transform.PostScale(metrics.mPresShellResolution, metrics.mPresShellResolution, 1.f);
}
return transform;
}
