layout/painting/HitTestInfo.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "HitTestInfo.h"
   8
   9 #include "mozilla/StaticPtr.h"
  10 #include "mozilla/webrender/WebRenderAPI.h"
  11 #include "nsDisplayList.h"
  12 #include "nsIFrame.h"
  13 #include "mozilla/layers/ScrollableLayerGuid.h"
  14
  15 using namespace mozilla::gfx;
  16
  17 namespace mozilla {
  18
  19 static StaticAutoPtr<const HitTestInfo> gEmptyHitTestInfo;
  20
  21 const HitTestInfo& HitTestInfo::Empty() {
  22   if (!gEmptyHitTestInfo) {
  23     gEmptyHitTestInfo = new HitTestInfo();
  24   }
  25
  26   return *gEmptyHitTestInfo;
  27 }
  28
  29 void HitTestInfo::Shutdown() { gEmptyHitTestInfo = nullptr; }
  30
  31 using ViewID = layers::ScrollableLayerGuid::ViewID;
  32
  33 ViewID HitTestInfo::GetViewId(wr::DisplayListBuilder& aBuilder,
  34                               const ActiveScrolledRoot* aASR) const {
  35   if (mScrollTarget) {
  36     return *mScrollTarget;
  37   }
  38
  39   Maybe<ViewID> fixedTarget = aBuilder.GetContainingFixedPosScrollTarget(aASR);
  40
  41   if (fixedTarget) {
  42     return *fixedTarget;
  43   }
  44
  45   if (aASR) {
  46     return aASR->GetViewId();
  47   }
  48
  49   return layers::ScrollableLayerGuid::NULL_SCROLL_ID;
  50 }
  51
  52 void HitTestInfo::Initialize(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame) {
  53   if (!aBuilder->BuildCompositorHitTestInfo()) {
  54     return;
  55   }
  56
  57   mInfo = aFrame->GetCompositorHitTestInfo(aBuilder);
  58   if (mInfo != gfx::CompositorHitTestInvisibleToHit) {
  59     mArea = aFrame->GetCompositorHitTestArea(aBuilder);
  60     InitializeScrollTarget(aBuilder);
  61   }
  62 }
  63
  64 void HitTestInfo::InitializeScrollTarget(nsDisplayListBuilder* aBuilder) {
  65   if (aBuilder->GetCurrentScrollbarDirection().isSome()) {
  66     // In the case of scrollbar frames, we use the scrollbar's target
  67     // scrollframe instead of the scrollframe with which the scrollbar actually
  68     // moves.
  69     MOZ_ASSERT(Info().contains(CompositorHitTestFlags::eScrollbar));
  70     mScrollTarget = Some(aBuilder->GetCurrentScrollbarTarget());
  71   }
  72 }
  73
  74 }  // namespace mozilla