Bug 1539673 - Make sure we build layers for empty items, since they might contain hit test information. r=miko

Depends on D25169

Differential Revision: https://phabricator.services.mozilla.com/D25331

--HG--
extra : moz-landing-system : lando

gfx/layers/apz/test/mochitest/helper_touch_action_zero_opacity_bug1500864.html

@@ -33,7 +33,11 @@ waitUntilApzStable()
   <div id="spacer" style="height: 2000px">
     Inside the black border is a zero-opacity touch-action none.
     <div id="border" style="border: solid 1px black">
-        <div id="target" style="opacity: 0; height: 300px; touch-action: none">this text shouldn't be visible</div>
+        <div style="opacity: 0; height: 300px;">
+            <div style="transform:translate(0px)">
+                <div id="target" style="height: 300px; touch-action: none">this text shouldn't be visible</div>
+            </div>
+        </div>
     </div>
   </div>
 </body>

layout/painting/FrameLayerBuilder.cpp

@@ -4618,15 +4618,6 @@ void ContainerState::ProcessDisplayItems(nsDisplayList* aList) {
           item->Frame(), item->GetPerFrameKey());
       InvalidateForLayerChange(item, nullptr, oldData);
 
-      // If the item would have its own layer but is invisible, just hide it.
-      // Note that items without their own layers can't be skipped this
-      // way, since their PaintedLayer may decide it wants to draw them
-      // into its buffer even if they're currently covered.
-      if (itemVisibleRect.IsEmpty() &&
-          !item->ShouldBuildLayerEvenIfInvisible(mBuilder)) {
-        continue;
-      }
-
       // 3D-transformed layers don't necessarily draw in the order in which
       // they're added to their parent container layer.
       bool mayDrawOutOfOrder = itemType == DisplayItemType::TYPE_TRANSFORM &&

layout/painting/nsDisplayList.cpp

@@ -6473,13 +6473,6 @@ bool nsDisplayOwnLayer::IsZoomingLayer() const {
   return GetType() == DisplayItemType::TYPE_ASYNC_ZOOM;
 }
 
-bool nsDisplayOwnLayer::ShouldBuildLayerEvenIfInvisible(
-    nsDisplayListBuilder* aBuilder) const {
-  // Render scroll thumb layers even if they are invisible, because async
-  // scrolling might bring them into view.
-  return IsScrollThumbLayer();
-}
-
 // nsDisplayOpacity uses layers for rendering
 already_AddRefed<Layer> nsDisplayOwnLayer::BuildLayer(
     nsDisplayListBuilder* aBuilder, LayerManager* aManager,
@@ -6834,18 +6827,6 @@ bool nsDisplaySubDocument::ComputeVisibility(nsDisplayListBuilder* aBuilder,
   return visible;
 }
 
-bool nsDisplaySubDocument::ShouldBuildLayerEvenIfInvisible(
-    nsDisplayListBuilder* aBuilder) const {
-  bool usingDisplayPort = UseDisplayPortForViewport(aBuilder, mFrame);
-
-  if ((mFlags & nsDisplayOwnLayerFlags::eGenerateScrollableLayer) &&
-      usingDisplayPort) {
-    return true;
-  }
-
-  return nsDisplayOwnLayer::ShouldBuildLayerEvenIfInvisible(aBuilder);
-}
-
 nsRegion nsDisplaySubDocument::GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
                                                bool* aSnap) const {
   bool usingDisplayPort = UseDisplayPortForViewport(aBuilder, mFrame);
@@ -8150,14 +8131,6 @@ const Matrix4x4& nsDisplayTransform::GetAccumulatedPreserved3DTransform(
   return *mTransformPreserves3D;
 }
 
-bool nsDisplayTransform::ShouldBuildLayerEvenIfInvisible(
-    nsDisplayListBuilder* aBuilder) const {
-  // The visible rect of a Preserves-3D frame is just an intermediate
-  // result.  It should always build a layer to make sure it is
-  // rendering correctly.
-  return MayBeAnimated(aBuilder) || Combines3DTransformWithAncestors();
-}
-
 bool nsDisplayTransform::CreateWebRenderCommands(
     mozilla::wr::DisplayListBuilder& aBuilder,
     mozilla::wr::IpcResourceUpdateQueue& aResources,

layout/painting/nsDisplayList.h

@@ -2546,15 +2546,6 @@ class nsDisplayItem : public nsDisplayItemLink {
     return mozilla::LAYER_NONE;
   }
 
-  /**
-   * Return true to indicate the layer should be constructed even if it's
-   * completely invisible.
-   */
-  virtual bool ShouldBuildLayerEvenIfInvisible(
-      nsDisplayListBuilder* aBuilder) const {
-    return false;
-  }
-
   /**
    * Returns true if this item supports PaintWithClip, where the clipping
    * is used directly as the primitive geometry instead of needing an explicit
@@ -5876,8 +5867,6 @@ class nsDisplayOwnLayer : public nsDisplayWrapList {
 
   NS_DISPLAY_DECL_NAME("OwnLayer", TYPE_OWN_LAYER)
 
-  bool ShouldBuildLayerEvenIfInvisible(
-      nsDisplayListBuilder* aBuilder) const override;
   already_AddRefed<Layer> BuildLayer(
       nsDisplayListBuilder* aBuilder, LayerManager* aManager,
       const ContainerLayerParameters& aContainerParameters) override;
@@ -5981,9 +5970,6 @@ class nsDisplaySubDocument : public nsDisplayOwnLayer {
 
   bool ComputeVisibility(nsDisplayListBuilder* aBuilder,
                          nsRegion* aVisibleRegion) override;
-  bool ShouldBuildLayerEvenIfInvisible(
-      nsDisplayListBuilder* aBuilder) const override;
-
   bool ShouldFlattenAway(nsDisplayListBuilder* aBuilder) override {
     return mShouldFlatten;
   }
@@ -6256,11 +6242,6 @@ class nsDisplayScrollInfoLayer : public nsDisplayWrapList {
       nsDisplayListBuilder* aBuilder, LayerManager* aManager,
       const ContainerLayerParameters& aContainerParameters) override;
 
-  bool ShouldBuildLayerEvenIfInvisible(
-      nsDisplayListBuilder* aBuilder) const override {
-    return true;
-  }
-
   nsRegion GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
                            bool* aSnap) const override {
     *aSnap = false;
@@ -6726,8 +6707,6 @@ class nsDisplayTransform : public nsDisplayHitTestInfoItem {
   bool UpdateScrollData(
       mozilla::layers::WebRenderScrollData* aData,
       mozilla::layers::WebRenderLayerScrollData* aLayerData) override;
-  bool ShouldBuildLayerEvenIfInvisible(
-      nsDisplayListBuilder* aBuilder) const override;
   bool ComputeVisibility(nsDisplayListBuilder* aBuilder,
                          nsRegion* aVisibleRegion) override;
 
@@ -7053,15 +7032,6 @@ class nsDisplayPerspective : public nsDisplayHitTestInfoItem {
       mozilla::layers::RenderRootStateManager* aManager,
       nsDisplayListBuilder* aDisplayListBuilder) override;
 
-  bool ShouldBuildLayerEvenIfInvisible(
-      nsDisplayListBuilder* aBuilder) const override {
-    if (!mList.GetChildren()->GetTop()) {
-      return false;
-    }
-    return mList.GetChildren()->GetTop()->ShouldBuildLayerEvenIfInvisible(
-        aBuilder);
-  }
-
   already_AddRefed<Layer> BuildLayer(
       nsDisplayListBuilder* aBuilder, LayerManager* aManager,
       const ContainerLayerParameters& aContainerParameters) override;