ui/views/mus/ax_remote_host.h

// Copyright 2018 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 UI_VIEWS_MUS_AX_REMOTE_HOST_H_
#define UI_VIEWS_MUS_AX_REMOTE_HOST_H_

#include <memory>
#include <vector>

#include "base/macros.h"
#include "mojo/public/cpp/bindings/binding.h"
#include "ui/accessibility/ax_tree_id.h"
#include "ui/accessibility/ax_tree_serializer.h"
#include "ui/accessibility/mojom/ax_host.mojom.h"
#include "ui/display/display_observer.h"
#include "ui/views/accessibility/ax_aura_obj_cache.h"
#include "ui/views/accessibility/ax_event_observer.h"
#include "ui/views/mus/mus_export.h"
#include "ui/views/widget/widget_observer.h"

namespace service_manager {
class Connector;
}

namespace ui {
struct AXActionData;
struct AXNodeData;
struct AXTreeData;
}  // namespace ui

namespace views {

class AXAuraObjWrapper;
class AXTreeSourceMus;
class View;
class Widget;

// Manages a tree of automation nodes for a mojo app outside the browser process
// (e.g. the keyboard shortcut viewer app).
class VIEWS_MUS_EXPORT AXRemoteHost : public ax::mojom::AXRemoteHost,
                                      public WidgetObserver,
                                      public display::DisplayObserver,
                                      public AXAuraObjCache::Delegate,
                                      public AXEventObserver {
 public:
  AXRemoteHost();
  ~AXRemoteHost() override;

  // Initializes and adds ourself as a client of the host service.
  void Init(service_manager::Connector* connector);

  // Initializes with a fake host.
  void InitForTesting(ax::mojom::AXHostPtr host_ptr);

  // Sends the initial AX node tree to the host then starts monitoring for AX
  // events and tree changes.
  void StartMonitoringWidget(Widget* widget);
  void StopMonitoringWidget();

  // ax::mojom::AXRemoteHost:
  void OnAutomationEnabled(bool enabled) override;
  void PerformAction(const ui::AXActionData& action) override;

  // WidgetObserver:
  void OnWidgetClosing(Widget* widget) override;
  void OnWidgetDestroying(Widget* widget) override;

  // display::DisplayObserver:
  void OnDisplayMetricsChanged(const display::Display& display,
                               uint32_t changed_metrics) override;

  // AXAuraObjCache::Delegate:
  void OnChildWindowRemoved(AXAuraObjWrapper* parent) override;
  void OnEvent(AXAuraObjWrapper* aura_obj,
               ax::mojom::Event event_type) override;

  // AXEventObserver:
  void OnViewEvent(View* view, ax::mojom::Event event_type) override;

  void FlushForTesting();
  Widget* widget_for_testing() { return widget_; }

 private:
  // Registers this object as a remote host for the parent AXHost.
  void BindAndRegisterRemote();

  // Callback for initial state from AXHost.
  void RegisterRemoteHostCallback(const ui::AXTreeID& tree_id, bool enabled);

  void Enable();
  void Disable();

  // Sends an event to the host.
  void SendEvent(AXAuraObjWrapper* aura_obj, ax::mojom::Event event_type);

  void PerformHitTest(const ui::AXActionData& action);

  // Updates the display device scale factor used when serializing nodes.
  void UpdateDeviceScaleFactor();

  // Accessibility host service in the browser.
  ax::mojom::AXHostPtr ax_host_ptr_;

  mojo::Binding<ax::mojom::AXRemoteHost> binding_{this};

  // ID to use for the AX tree.
  ui::AXTreeID tree_id_;

  // Whether accessibility automation support is enabled.
  bool enabled_ = false;

  // Top-level widget being tracked.
  Widget* widget_ = nullptr;

  // Holds the active views-based accessibility tree. A tree consists of all
  // views descendant to a Widget's content area.
  std::unique_ptr<AXTreeSourceMus> tree_source_;

  // Serializes incremental updates on the currently active |tree_source_|.
  using AuraAXTreeSerializer =
      ui::AXTreeSerializer<AXAuraObjWrapper*, ui::AXNodeData, ui::AXTreeData>;
  std::unique_ptr<AuraAXTreeSerializer> tree_serializer_;

  DISALLOW_COPY_AND_ASSIGN(AXRemoteHost);
};

}  // namespace views

#endif  // UI_VIEWS_MUS_AX_REMOTE_HOST_H_