content/browser/renderer_host/text_input_manager.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 CONTENT_BROWSER_RENDERER_HOST_TEXT_INPUT_MANAGER_H__
#define CONTENT_BROWSER_RENDERER_HOST_TEXT_INPUT_MANAGER_H__

#include <unordered_map>

#include "base/observer_list.h"
#include "content/common/content_export.h"
#include "content/common/text_input_state.h"

namespace content {

class RenderWidgetHostView;
class RenderWidgetHostViewBase;
class WebContents;

// A class which receives updates of TextInputState from multiple sources and
// decides what the new TextInputState is. It also notifies the observers when
// text input state is updated.
class CONTENT_EXPORT TextInputManager {
 public:
  // The tab's top-level RWHV should be an observer of TextInputManager to get
  // notifications about changes in TextInputState or other IME related state
  // for child frames.
  class CONTENT_EXPORT Observer {
   public:
    // Called when a view has called UpdateTextInputState on TextInputManager.
    // If the call has led to a change in TextInputState, |did_update_state| is
    // true. In some plaforms, we need this update even when the state has not
    // changed (e.g., Aura for updating IME).
    virtual void OnUpdateTextInputStateCalled(
        TextInputManager* text_input_manager,
        RenderWidgetHostViewBase* updated_view,
        bool did_update_state) {}
  };

  TextInputManager();
  ~TextInputManager();

  // Returns the currently active view (i.e., the RWHV with a focused <input>
  // element), or nullptr if none exist. The |active_view_| cannot have a
  // |TextInputState.type| of ui::TEXT_INPUT_TYPE_NONE.
  RenderWidgetHostViewBase* GetActiveView() const;

  // Returns the TextInputState corresponding to |active_view_|.
  // Users of this method should not hold on to the pointer as it might become
  // dangling if the TextInputManager or |active_view_| might go away.
  const TextInputState* GetTextInputState();

  // Updates the TextInputState for |view|.
  void UpdateTextInputState(RenderWidgetHostViewBase* view,
                            const TextInputState& state);

  // Registers the given |view| for tracking its TextInputState. This is called
  // by any view which has updates in its TextInputState (whether tab's RWHV or
  // that of a child frame). The |view| must unregister itself before being
  // destroyed (i.e., call TextInputManager::Unregister).
  void Register(RenderWidgetHostViewBase* view);

  // Clears the TextInputState from the |view|. If |view == active_view_|, this
  // call will lead to a TextInputState update since the TextInputState.type
  // should be reset to none.
  void Unregister(RenderWidgetHostViewBase* view);

  // Returns true if |view| is already registered.
  bool IsRegistered(RenderWidgetHostViewBase* view) const;

  // Add and remove observers for notifications regarding updates in the
  // TextInputState. Clients must be sure to remove themselves before they go
  // away.
  // Only the tab's RWHV should observer TextInputManager. In tests, however,
  // in addition to the tab's RWHV, one or more test observers might observe
  // TextInputManager.
  void AddObserver(Observer* observer);
  void RemoveObserver(Observer* observer);

 private:
  friend bool GetTextInputTypeForView(WebContents* web_contents,
                                      RenderWidgetHostView* view,
                                      ui::TextInputType* type);

  void NotifyObserversAboutInputStateUpdate(RenderWidgetHostViewBase* view,
                                            bool did_update_state);

  // The view with active text input state.
  RenderWidgetHostViewBase* active_view_;

  std::unordered_map<RenderWidgetHostViewBase*, TextInputState>
      text_input_state_map_;

  base::ObserverList<Observer> observer_list_;

  DISALLOW_COPY_AND_ASSIGN(TextInputManager);
};
}

#endif  // CONTENT_BROWSER_RENDERER_HOST_TEXT_INPUT_MANAGER_H__