Mozart: Add helpers for building view associates.

mojo/ui/associates/view_tree_hit_tester_client.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_UI_ASSOCIATES_VIEW_TREE_HIT_TESTER_CLIENT_H_
+#define MOJO_UI_ASSOCIATES_VIEW_TREE_HIT_TESTER_CLIENT_H_
+
+#include <queue>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "mojo/services/gfx/composition/interfaces/hit_tests.mojom.h"
+#include "mojo/services/ui/views/interfaces/view_trees.mojom.h"
+#include "mojo/ui/associates/view_inspector_client.h"
+
+namespace mojo {
+namespace ui {
+
+// Holds a hit tester for a view tree and keeps it up to date as the
+// hit tester is invalidated.
+class ViewTreeHitTesterClient
+    : public base::RefCounted<ViewTreeHitTesterClient> {
+ public:
+  ViewTreeHitTesterClient(
+      const scoped_refptr<ViewInspectorClient>& view_inspector_client,
+      mojo::ui::ViewTreeTokenPtr view_tree_token);
+
+  // Performs a hit test for the specified point then invokes the callback.
+  // Note: May invoke the callback immediately if no remote calls were required.
+  void HitTest(mojo::PointPtr point, const ResolvedHitsCallback& callback);
+
+  // Sets a callback to invoke when the hit tester changes.
+  void set_hit_tester_changed_callback(const base::Closure& callback) {
+    hit_tester_changed_callback_ = callback;
+  }
+
+ private:
+  friend class base::RefCounted<ViewTreeHitTesterClient>;
+  ~ViewTreeHitTesterClient();
+
+  void OnHitTestResult(mojo::gfx::composition::HitTestResultPtr result);
+
+  void UpdateHitTester();
+  void ReleaseHitTester();
+  void OnHitTesterInvalidated(bool renderer_changed);
+  void OnHitTesterDied();
+
+  scoped_refptr<ViewInspectorClient> view_inspector_client_;
+  mojo::ui::ViewTreeTokenPtr view_tree_token_;
+  mojo::gfx::composition::HitTesterPtr hit_tester_;
+
+  std::queue<ResolvedHitsCallback> pending_callbacks_;
+  base::Closure hit_tester_changed_callback_;
+
+  base::WeakPtrFactory<ViewTreeHitTesterClient> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ViewTreeHitTesterClient);
+};
+
+}  // namespace ui
+}  // namespace mojo
+
+#endif  // MOJO_UI_ASSOCIATES_VIEW_TREE_HIT_TESTER_CLIENT_H_