Bug 1436409 - Remove gecko/APZ hit-test codepath from WebRenderCommandBuilder. r=botond

This removes the gfx.webrender.hit-test pref, assumes a value of true
everywhere it is used, and deletes all the resulting dead code.

Some gtests were setting this pref to false, and they are now updated to
set gfxVars::UseWebRender to false instead, which has the desired effect
of using the non-WR hit-testing codepath in APZ. (The data needed for
this codepath is set up by the gtests themselves).

MozReview-Commit-ID: 9ljDr8eEnv1

--HG--
extra : rebase_source : fbc321861428e7bb0bf7ab811935b682785debdc

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -2469,7 +2469,7 @@ APZCTreeManager::GetTargetAPZC(const ScreenPoint& aPoint,
   CompositorHitTestInfo hitResult = CompositorHitTestInfo::eInvisibleToHitTest;
   HitTestingTreeNode* scrollbarNode = nullptr;
   RefPtr<AsyncPanZoomController> target;
-  if (gfx::gfxVars::UseWebRender() && gfxPrefs::WebRenderHitTest()) {
+  if (gfx::gfxVars::UseWebRender()) {
     target = GetAPZCAtPointWR(aPoint, &hitResult, &scrollbarNode);
   } else {
     target = GetAPZCAtPoint(mRootNode, aPoint, &hitResult, &scrollbarNode);

gfx/layers/apz/test/gtest/APZTestCommon.h

@@ -16,6 +16,7 @@
 #include "gmock/gmock.h"
 
 #include "mozilla/Attributes.h"
+#include "mozilla/gfx/gfxVars.h"
 #include "mozilla/layers/AsyncCompositionManager.h" // for ViewTransform
 #include "mozilla/layers/GeckoContentController.h"
 #include "mozilla/layers/CompositorBridgeParent.h"
@@ -62,31 +63,37 @@ CreateSingleTouchData(int32_t aIdentifier, ScreenIntCoord aX, ScreenIntCoord aY)
   return CreateSingleTouchData(aIdentifier, ScreenIntPoint(aX, aY));
 }
 
-template<class T>
-class ScopedGfxPref {
+template<class SetArg, class Storage>
+class ScopedGfxSetting {
 public:
-  ScopedGfxPref(T (*aGetPrefFunc)(void), void (*aSetPrefFunc)(T), T aVal)
+  ScopedGfxSetting(SetArg (*aGetPrefFunc)(void), void (*aSetPrefFunc)(SetArg), SetArg aVal)
     : mSetPrefFunc(aSetPrefFunc)
   {
     mOldVal = aGetPrefFunc();
     aSetPrefFunc(aVal);
   }
 
-  ~ScopedGfxPref() {
+  ~ScopedGfxSetting() {
     mSetPrefFunc(mOldVal);
   }
 
 private:
-  void (*mSetPrefFunc)(T);
-  T mOldVal;
+  void (*mSetPrefFunc)(SetArg);
+  Storage mOldVal;
 };
 
 #define SCOPED_GFX_PREF(prefBase, prefType, prefValue) \
-  ScopedGfxPref<prefType> pref_##prefBase( \
+  ScopedGfxSetting<prefType, prefType> pref_##prefBase( \
     &(gfxPrefs::prefBase), \
     &(gfxPrefs::Set##prefBase), \
     prefValue)
 
+#define SCOPED_GFX_VAR(varBase, varType, varValue) \
+  ScopedGfxSetting<const varType&, varType> var_##varBase( \
+    &(gfxVars::varBase), \
+    &(gfxVars::Set##varBase), \
+    varValue)
+
 static TimeStamp GetStartupTime() {
   static TimeStamp sStartupTime = TimeStamp::Now();
   return sStartupTime;

gfx/layers/apz/test/gtest/TestEventRegions.cpp

@@ -161,7 +161,7 @@ protected:
 };
 
 TEST_F(APZEventRegionsTester, HitRegionImmediateResponse) {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   CreateEventRegionsLayerTree1();
 
@@ -228,7 +228,7 @@ TEST_F(APZEventRegionsTester, HitRegionAccumulatesChildren) {
 }
 
 TEST_F(APZEventRegionsTester, Obscuration) {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   CreateObscuringLayerTree();
   ScopedLayerTreeRegistration registration(manager, LayersId{0}, root, mcc);

gfx/layers/apz/test/gtest/TestHitTesting.cpp

@@ -104,7 +104,7 @@ protected:
 
 // A simple hit testing test that doesn't involve any transforms on layers.
 TEST_F(APZHitTestingTester, HitTesting1) {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   CreateHitTesting1LayerTree();
   ScopedLayerTreeRegistration registration(manager, LayersId{0}, root, mcc);
@@ -171,7 +171,7 @@ TEST_F(APZHitTestingTester, HitTesting1) {
 
 // A more involved hit testing test that involves css and async transforms.
 TEST_F(APZHitTestingTester, HitTesting2) {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
   SCOPED_GFX_PREF(APZVelocityBias, float, 0.0); // Velocity bias can cause extra repaint requests
 
   CreateHitTesting2LayerTree();
@@ -282,7 +282,7 @@ TEST_F(APZHitTestingTester, HitTesting2) {
 }
 
 TEST_F(APZHitTestingTester, HitTesting3) {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   const char* layerTreeSyntax = "c(t)";
   // LayerID                     0 1
@@ -308,7 +308,7 @@ TEST_F(APZHitTestingTester, HitTesting3) {
 }
 
 TEST_F(APZHitTestingTester, ComplexMultiLayerTree) {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   CreateComplexMultiLayerTree();
   ScopedLayerTreeRegistration registration(manager, LayersId{0}, root, mcc);

gfx/layers/apz/test/gtest/TestScrollHandoff.cpp

@@ -240,7 +240,7 @@ TEST_F(APZScrollHandoffTester, StuckInOverscroll_Bug1073250) {
   // Enable overscrolling.
   SCOPED_GFX_PREF(APZOverscrollEnabled, bool, true);
   SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   CreateScrollHandoffLayerTree1();
 
@@ -279,7 +279,7 @@ TEST_F(APZScrollHandoffTester, StuckInOverscroll_Bug1231228) {
   // Enable overscrolling.
   SCOPED_GFX_PREF(APZOverscrollEnabled, bool, true);
   SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   CreateScrollHandoffLayerTree1();
 
@@ -347,7 +347,7 @@ TEST_F(APZScrollHandoffTester, StuckInOverscroll_Bug1240202a) {
 TEST_F(APZScrollHandoffTester, StuckInOverscroll_Bug1240202b) {
   // Enable overscrolling.
   SCOPED_GFX_PREF(APZOverscrollEnabled, bool, true);
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   CreateScrollHandoffLayerTree1();
 
@@ -411,7 +411,7 @@ TEST_F(APZScrollHandoffTester, OpposingConstrainedAxes_Bug1201098) {
 // handed off to the parent, while the original APZC continues flinging in the
 // other direction.
 TEST_F(APZScrollHandoffTester, PartialFlingHandoff) {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   CreateScrollHandoffLayerTree1();
 
@@ -499,14 +499,14 @@ TEST_F(APZScrollHandoffTester, ScrollgrabFling) {
 
 TEST_F(APZScrollHandoffTester, ScrollgrabFlingAcceleration1) {
   SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
   CreateScrollgrabLayerTree(true /* make parent scrollable */);
   TestFlingAcceleration();
 }
 
 TEST_F(APZScrollHandoffTester, ScrollgrabFlingAcceleration2) {
   SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
   CreateScrollgrabLayerTree(false /* do not make parent scrollable */);
   TestFlingAcceleration();
 }

gfx/layers/apz/test/gtest/TestSnapping.cpp

@@ -15,7 +15,7 @@ class APZCSnappingTester : public APZCTreeManagerTester
 
 TEST_F(APZCSnappingTester, Bug1265510)
 {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   const char* layerTreeSyntax = "c(t)";
   nsIntRegion layerVisibleRegion[] = {
@@ -68,7 +68,7 @@ TEST_F(APZCSnappingTester, Bug1265510)
 
 TEST_F(APZCSnappingTester, Snap_After_Pinch)
 {
-  SCOPED_GFX_PREF(WebRenderHitTest, bool, false);
+  SCOPED_GFX_VAR(UseWebRender, bool, false);
 
   const char* layerTreeSyntax = "c";
   nsIntRegion layerVisibleRegion[] = {

gfx/layers/wr/WebRenderCommandBuilder.cpp

@@ -1231,22 +1231,15 @@ WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(nsDisplayList* a
   mClipManager.BeginList(aSc);
 
   bool apzEnabled = mManager->AsyncPanZoomEnabled();
-  EventRegions eventRegions;
 
   FlattenedDisplayItemIterator iter(aDisplayListBuilder, aDisplayList);
   while (nsDisplayItem* i = iter.GetNext()) {
     nsDisplayItem* item = i;
     DisplayItemType itemType = item->GetType();
 
-    // If the item is a event regions item, but is empty (has no regions in it)
-    // then we should just throw it out
-    if (itemType == DisplayItemType::TYPE_LAYER_EVENT_REGIONS) {
-      nsDisplayLayerEventRegions* eventRegions =
-        static_cast<nsDisplayLayerEventRegions*>(item);
-      if (eventRegions->IsEmpty()) {
-        continue;
-      }
-    }
+    // We should never get event regions items in WR now that we always have
+    // WR hit-testing enabled.
+    MOZ_ASSERT(itemType != DisplayItemType::TYPE_LAYER_EVENT_REGIONS);
 
     // Peek ahead to the next item and try merging with it or swapping with it
     // if necessary.
@@ -1286,45 +1279,6 @@ WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(nsDisplayList* a
         forceNewLayerData = true;
       }
 
-      // If we're creating a new layer data then flush whatever event regions
-      // we've collected onto the old layer.
-      if (forceNewLayerData && !eventRegions.IsEmpty()) {
-        // If eventRegions is non-empty then we must have a layer data already,
-        // because we (below) force one if we encounter an event regions item
-        // with an empty layer data list. Additionally, the most recently
-        // created layer data must have been created from an item whose ASR
-        // is the same as the ASR on the event region items that were collapsed
-        // into |eventRegions|. This is because any ASR change causes us to force
-        // a new layer data which flushes the eventRegions.
-        MOZ_ASSERT(!mLayerScrollData.empty());
-        mLayerScrollData.back().AddEventRegions(eventRegions);
-        eventRegions.SetEmpty();
-      }
-
-      // Collapse event region data into |eventRegions|, which will either be
-      // empty, or filled with stuff from previous display items with the same
-      // ASR.
-      if (itemType == DisplayItemType::TYPE_LAYER_EVENT_REGIONS) {
-        nsDisplayLayerEventRegions* regionsItem =
-            static_cast<nsDisplayLayerEventRegions*>(item);
-        int32_t auPerDevPixel = item->Frame()->PresContext()->AppUnitsPerDevPixel();
-        EventRegions regions(
-            regionsItem->HitRegion().ScaleToOutsidePixels(1.0f, 1.0f, auPerDevPixel),
-            regionsItem->MaybeHitRegion().ScaleToOutsidePixels(1.0f, 1.0f, auPerDevPixel),
-            regionsItem->DispatchToContentHitRegion().ScaleToOutsidePixels(1.0f, 1.0f, auPerDevPixel),
-            regionsItem->NoActionRegion().ScaleToOutsidePixels(1.0f, 1.0f, auPerDevPixel),
-            regionsItem->HorizontalPanRegion().ScaleToOutsidePixels(1.0f, 1.0f, auPerDevPixel),
-            regionsItem->VerticalPanRegion().ScaleToOutsidePixels(1.0f, 1.0f, auPerDevPixel),
-            /* mDTCRequiresTargetConfirmation = */ false);
-
-        eventRegions.OrWith(regions);
-        if (mLayerScrollData.empty()) {
-          // If we don't have a layer data yet then create one because we will
-          // need it to store this event region information.
-          forceNewLayerData = true;
-        }
-      }
-
       // If we're going to create a new layer data for this item, stash the
       // ASR so that if we recurse into a sublist they will know where to stop
       // walking up their ASR chain when building scroll metadata.
@@ -1335,7 +1289,7 @@ WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(nsDisplayList* a
 
     mClipManager.BeginItem(item, aSc);
 
-    if (itemType != DisplayItemType::TYPE_LAYER_EVENT_REGIONS) {
+    { // scope restoreDoGrouping
       AutoRestore<bool> restoreDoGrouping(mDoGrouping);
       if (itemType == DisplayItemType::TYPE_SVG_WRAPPER) {
         // Inside an <svg>, all display items that are not LAYER_ACTIVE wrapper
@@ -1417,31 +1371,10 @@ WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(nsDisplayList* a
           mLayerScrollData.back().Initialize(mManager->GetScrollData(), item,
               descendants, stopAtAsr, deferred ? Some((*deferred)->GetTransform().GetMatrix()) : Nothing());
         }
-      } else if (mLayerScrollData.size() != layerCountBeforeRecursing &&
-                 !eventRegions.IsEmpty()) {
-        // We are not forcing a new layer for |item|, but we did create some
-        // layers while recursing. In this case, we need to make sure any
-        // event regions that we were carrying end up on the right layer. So we
-        // do an event region "flush" but retroactively; i.e. the event regions
-        // end up on the layer that was mLayerScrollData.back() prior to the
-        // recursion.
-        MOZ_ASSERT(layerCountBeforeRecursing > 0);
-        mLayerScrollData[layerCountBeforeRecursing - 1].AddEventRegions(eventRegions);
-        eventRegions.SetEmpty();
       }
     }
   }
 
-  // If we have any event region info left over we need to flush it before we
-  // return. Again, at this point the layer data list must be non-empty, and
-  // the most recently created layer data will have been created by an item
-  // with matching ASRs.
-  if (!eventRegions.IsEmpty()) {
-    MOZ_ASSERT(apzEnabled);
-    MOZ_ASSERT(!mLayerScrollData.empty());
-    mLayerScrollData.back().AddEventRegions(eventRegions);
-  }
-
   mClipManager.EndList(aSc);
 }
 

gfx/thebes/gfxPrefs.h

@@ -517,7 +517,6 @@ private:
   DECL_GFX_PREF(Live, "gfx.webrender.blob-images",             WebRenderBlobImages, bool, true);
   DECL_GFX_PREF(Live, "gfx.webrender.blob.invalidation",       WebRenderBlobInvalidation, bool, false);
   DECL_GFX_PREF(Live, "gfx.webrender.highlight-painted-layers",WebRenderHighlightPaintedLayers, bool, false);
-  DECL_GFX_PREF(Live, "gfx.webrender.hit-test",                WebRenderHitTest, bool, true);
 
   // Use vsync events generated by hardware
   DECL_GFX_PREF(Once, "gfx.work-around-driver-bugs",           WorkAroundDriverBugs, bool, true);

layout/painting/nsDisplayList.cpp

@@ -1035,11 +1035,8 @@ nsDisplayListBuilder::nsDisplayListBuilder(nsIFrame* aReferenceFrame,
 {
   MOZ_COUNT_CTOR(nsDisplayListBuilder);
 
-  const bool useWRHitTest =
-    gfxPrefs::WebRenderHitTest() && gfxVars::UseWebRender();
-
   mBuildCompositorHitTestInfo = mAsyncPanZoomEnabled && IsForPainting() &&
-    (useWRHitTest || gfxPrefs::SimpleEventRegionItems());
+    (gfxVars::UseWebRender() || gfxPrefs::SimpleEventRegionItems());
 
   mLessEventRegionItems = gfxPrefs::LessEventRegionItems();
 

modules/libpref/init/all.js

@@ -873,7 +873,6 @@ pref("gfx.webrender.highlight-painted-layers", false);
 pref("gfx.webrender.async-scene-build", true);
 pref("gfx.webrender.blob-images", true);
 pref("gfx.webrender.blob.invalidation", true);
-pref("gfx.webrender.hit-test", true);
 
 // WebRender debugging utilities.
 pref("gfx.webrender.debug.texture-cache", false);