bool RenderViewMLGPU::UpdateVisibleRegion(ItemInfo& aItem) {
// If the item has some kind of complex transform, we perform a very
// simple occlusion test and move on. We using a depth buffer we skip
// CPU-based occlusion culling as well, since the GPU will do most of our
// culling work for us.
if (mUseDepthBuffer || !aItem.translation ||
!gfxPrefs::AdvancedLayersEnableCPUOcclusion()) {
// Update the render region even if we won't compute visibility, since some
// layer types (like Canvas and Image) need to have the visible region
// clamped.
LayerIntRegion region = aItem.layer->GetShadowVisibleRegion();
aItem.layer->SetRenderRegion(std::move(region));
AL_LOG("RenderView %p simple occlusion test, bounds=%s, translation?=%d\n",
this, Stringify(aItem.bounds).c_str(), aItem.translation ? 1 : 0);
return mInvalidBounds.Intersects(aItem.bounds);
}
MOZ_ASSERT(aItem.rectilinear);
AL_LOG("RenderView %p starting visibility tests:\n", this);
AL_LOG(" occluded=%s\n", Stringify(mOccludedRegion).c_str());
// Compute the translation into render target space.
LayerIntPoint translation = LayerIntPoint::FromUnknownPoint(
aItem.translation.value() - mTargetOffset);
AL_LOG(" translation=%s\n", Stringify(translation).c_str());
IntRect clip = aItem.layer->GetComputedClipRect().ToUnknownRect();
AL_LOG(" clip=%s\n", Stringify(translation).c_str());
LayerIntRegion region = aItem.layer->GetShadowVisibleRegion();
region.MoveBy(translation);
AL_LOG(" effective-visible=%s\n", Stringify(region).c_str());
region.SubOut(mOccludedRegion);
region.AndWith(LayerIntRect::FromUnknownRect(mInvalidBounds));
region.AndWith(LayerIntRect::FromUnknownRect(clip));
if (region.IsEmpty()) {
return false;
}
// Move the visible region back into layer space.
region.MoveBy(-translation);
AL_LOG(" new-local-visible=%s\n", Stringify(region).c_str());
aItem.layer->SetRenderRegion(std::move(region));
// Apply the new occluded area. We do another dance with the translation to
// avoid copying the region. We do this after the SetRegionToRender call to
// accomodate the possiblity of a layer changing its visible region.
if (aItem.opaque) {
mOccludedRegion.MoveBy(-translation);
mOccludedRegion.OrWith(aItem.layer->GetRenderRegion());
mOccludedRegion.MoveBy(translation);
AL_LOG(" new-occluded=%s\n", Stringify(mOccludedRegion).c_str());
// If the occluded region gets too complicated, we reset it.
if (mOccludedRegion.GetNumRects() >= 32) {
mOccludedRegion.SetEmpty();
AL_LOG(" clear-occluded, too many rects\n");
}
}
return true;
}
