1 files changed, 91 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/IAPZHitTester.h b/gfx/layers/apz/src/IAPZHitTester.h
new file mode 100644
index 0000000000..8822b40ea8
--- /dev/null
+++ b/gfx/layers/apz/src/IAPZHitTester.h
@@ -0,0 +1,91 @@
+/* -*- 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/. */
+
+#ifndef mozilla_layers_IAPZHitTester_h
+#define mozilla_layers_IAPZHitTester_h
+
+#include "HitTestingTreeNode.h"  // for HitTestingTreeNodeAutoLock
+#include "mozilla/RefPtr.h"
+#include "mozilla/gfx/CompositorHitTestInfo.h"
+#include "mozilla/layers/LayersTypes.h"
+
+namespace mozilla {
+namespace layers {
+
+class AsyncPanZoomController;
+class APZCTreeManager;
+
+class IAPZHitTester {
+ public:
+  virtual ~IAPZHitTester() = default;
+
+  // Not a constructor because we want external code to be able to pass a hit
+  // tester to the APZCTreeManager constructor, which will then initialize it.
+  void Initialize(APZCTreeManager* aTreeManager) {
+    mTreeManager = aTreeManager;
+  }
+
+  // Represents the results of an APZ hit test.
+  struct HitTestResult {
+    // The APZC targeted by the hit test.
+    RefPtr<AsyncPanZoomController> mTargetApzc;
+    // The applicable hit test flags.
+    gfx::CompositorHitTestInfo mHitResult;
+    // The layers id of the content that was hit.
+    // This effectively identifiers the process that was hit for
+    // Fission purposes.
+    LayersId mLayersId;
+    // If a scrollbar was hit, this will be populated with the
+    // scrollbar node. The AutoLock allows accessing the scrollbar
+    // node without having to hold the tree lock.
+    HitTestingTreeNodeAutoLock mScrollbarNode;
+    // If content that is fixed to the root-content APZC was hit,
+    // the sides of the viewport to which the content is fixed.
+    SideBits mFixedPosSides = SideBits::eNone;
+    // If a fixed/sticky position element was hit, this will be populated with
+    // the hit-testing tree node. The AutoLock allows accessing the node
+    // without having to hold the tree lock.
+    HitTestingTreeNodeAutoLock mNode;
+    // This is set to true If mTargetApzc is overscrolled and the
+    // event targeted the gap space ("gutter") created by the overscroll.
+    bool mHitOverscrollGutter = false;
+
+    HitTestResult() = default;
+    // Make it move-only.
+    HitTestResult(HitTestResult&&) = default;
+    HitTestResult& operator=(HitTestResult&&) = default;
+  };
+
+  virtual HitTestResult GetAPZCAtPoint(
+      const ScreenPoint& aHitTestPoint,
+      const RecursiveMutexAutoLock& aProofOfTreeLock) = 0;
+
+  HitTestResult CloneHitTestResult(RecursiveMutexAutoLock& aProofOfTreeLock,
+                                   const HitTestResult& aHitTestResult) const;
+
+ protected:
+  APZCTreeManager* mTreeManager = nullptr;
+
+  // We are a friend of APZCTreeManager but our derived classes
+  // are not. Wrap a few private members of APZCTreeManager for
+  // use by derived classes.
+  LayersId GetRootLayersId() const;
+  HitTestingTreeNode* GetRootNode() const;
+  HitTestingTreeNode* FindRootNodeForLayersId(LayersId aLayersId) const;
+  AsyncPanZoomController* FindRootApzcForLayersId(LayersId aLayersId) const;
+  already_AddRefed<HitTestingTreeNode> GetTargetNode(
+      const ScrollableLayerGuid& aGuid,
+      ScrollableLayerGuid::Comparator aComparator);
+  void InitializeHitTestingTreeNodeAutoLock(
+      HitTestingTreeNodeAutoLock& aAutoLock,
+      const RecursiveMutexAutoLock& aProofOfTreeLock,
+      RefPtr<HitTestingTreeNode>& aNode) const;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_IAPZHitTester_h