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 #include "mozilla/webrender/WebRenderAPI.h"
   9 #include "nsDisplayList.h"
  10 #include "nsIFrame.h"
  11
  12 namespace mozilla {
  13
  14 static const HitTestInfo* gEmptyHitTestInfo = nullptr;
  15
  16 const HitTestInfo& HitTestInfo::Empty() {
  17   if (gEmptyHitTestInfo) {
  18     gEmptyHitTestInfo = new HitTestInfo();
  19   }
  20
  21   return *gEmptyHitTestInfo;
  22 }
  23
  24 void HitTestInfo::Shutdown() {
  25   delete gEmptyHitTestInfo;
  26   gEmptyHitTestInfo = nullptr;
  27 }
  28
  29 using ViewID = layers::ScrollableLayerGuid::ViewID;
  30
  31 ViewID HitTestInfo::GetViewId(wr::DisplayListBuilder& aBuilder,
  32                               const ActiveScrolledRoot* aASR) const {
  33   if (mScrollTarget) {
  34     return *mScrollTarget;
  35   }
  36
  37   Maybe<ViewID> fixedTarget = aBuilder.GetContainingFixedPosScrollTarget(aASR);
  38
  39   if (fixedTarget) {
  40     return *fixedTarget;
  41   }
  42
  43   if (aASR) {
  44     return aASR->GetViewId();
  45   }
  46
  47   return ScrollableLayerGuid::NULL_SCROLL_ID;
  48 }
  49
  50 void HitTestInfo::Initialize(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame) {
  51   if (!aBuilder->BuildCompositorHitTestInfo()) {
  52     return;
  53   }
  54
  55   mInfo = aFrame->GetCompositorHitTestInfo(aBuilder);
  56   if (mInfo != gfx::CompositorHitTestInvisibleToHit) {
  57     mArea = aFrame->GetCompositorHitTestArea(aBuilder);
  58     InitializeScrollTarget(aBuilder);
  59   }
  60 }
  61
  62 void HitTestInfo::InitializeScrollTarget(nsDisplayListBuilder* aBuilder) {
  63   if (aBuilder->GetCurrentScrollbarDirection().isSome()) {
  64     // In the case of scrollbar frames, we use the scrollbar's target
  65     // scrollframe instead of the scrollframe with which the scrollbar actually
  66     // moves.
  67     MOZ_ASSERT(Info().contains(CompositorHitTestFlags::eScrollbar));
  68     mScrollTarget = Some(aBuilder->GetCurrentScrollbarTarget());
  69   }
  70 }
  71
  72 }  // namespace mozilla