1 files changed, 74 insertions, 0 deletions
diff --git a/layout/painting/HitTestInfo.cpp b/layout/painting/HitTestInfo.cpp
new file mode 100644
index 0000000000..872773c32f
--- /dev/null
+++ b/layout/painting/HitTestInfo.cpp
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "HitTestInfo.h"
+
+#include "mozilla/StaticPtr.h"
+#include "mozilla/webrender/WebRenderAPI.h"
+#include "nsDisplayList.h"
+#include "nsIFrame.h"
+#include "mozilla/layers/ScrollableLayerGuid.h"
+
+using namespace mozilla::gfx;
+
+namespace mozilla {
+
+static StaticAutoPtr<const HitTestInfo> gEmptyHitTestInfo;
+
+const HitTestInfo& HitTestInfo::Empty() {
+  if (!gEmptyHitTestInfo) {
+    gEmptyHitTestInfo = new HitTestInfo();
+  }
+
+  return *gEmptyHitTestInfo;
+}
+
+void HitTestInfo::Shutdown() { gEmptyHitTestInfo = nullptr; }
+
+using ViewID = layers::ScrollableLayerGuid::ViewID;
+
+ViewID HitTestInfo::GetViewId(wr::DisplayListBuilder& aBuilder,
+                              const ActiveScrolledRoot* aASR) const {
+  if (mScrollTarget) {
+    return *mScrollTarget;
+  }
+
+  Maybe<ViewID> fixedTarget = aBuilder.GetContainingFixedPosScrollTarget(aASR);
+
+  if (fixedTarget) {
+    return *fixedTarget;
+  }
+
+  if (aASR) {
+    return aASR->GetViewId();
+  }
+
+  return layers::ScrollableLayerGuid::NULL_SCROLL_ID;
+}
+
+void HitTestInfo::Initialize(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame) {
+  if (!aBuilder->BuildCompositorHitTestInfo()) {
+    return;
+  }
+
+  mInfo = aFrame->GetCompositorHitTestInfo(aBuilder);
+  if (mInfo != gfx::CompositorHitTestInvisibleToHit) {
+    mArea = aFrame->GetCompositorHitTestArea(aBuilder);
+    InitializeScrollTarget(aBuilder);
+  }
+}
+
+void HitTestInfo::InitializeScrollTarget(nsDisplayListBuilder* aBuilder) {
+  if (aBuilder->GetCurrentScrollbarDirection().isSome()) {
+    // In the case of scrollbar frames, we use the scrollbar's target
+    // scrollframe instead of the scrollframe with which the scrollbar actually
+    // moves.
+    MOZ_ASSERT(Info().contains(CompositorHitTestFlags::eScrollbar));
+    mScrollTarget = Some(aBuilder->GetCurrentScrollbarTarget());
+  }
+}
+
+}  // namespace mozilla