chrome/browser/chooser_controller/chooser_controller.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 CHROME_BROWSER_CHOOSER_CONTROLLER_CHOOSER_CONTROLLER_H_
#define CHROME_BROWSER_CHOOSER_CONTROLLER_CHOOSER_CONTROLLER_H_

#include <vector>

#include "base/macros.h"
#include "base/strings/string16.h"

namespace content {
class RenderFrameHost;
}

// Subclass ChooserController to implement a chooser, which has some
// introductory text and a list of options that users can pick one of.
// Your subclass must define the set of options users can pick from;
// the actions taken after users select an item or press the 'Cancel'
// button or the chooser is closed.
// After Select/Cancel/Close is called, this object is destroyed and
// calls back into it are not allowed.
class ChooserController {
 public:
  ChooserController(content::RenderFrameHost* owner,
                    int title_string_id_origin,
                    int title_string_id_extension);
  virtual ~ChooserController();

  // Since the set of options can change while the UI is visible an
  // implementation should register a view to observe changes.
  class View {
   public:
    // Called after the options list is initialized for the first time.
    // OnOptionsInitialized should only be called once.
    virtual void OnOptionsInitialized() = 0;

    // Called after GetOption(index) has been added to the options and the
    // newly added option is the last element in the options list. Calling
    // GetOption(index) from inside a call to OnOptionAdded will see the
    // added string since the options have already been updated.
    virtual void OnOptionAdded(size_t index) = 0;

    // Called when GetOption(index) is no longer present, and all later
    // options have been moved earlier by 1 slot. Calling GetOption(index)
    // from inside a call to OnOptionRemoved will NOT see the removed string
    // since the options have already been updated.
    virtual void OnOptionRemoved(size_t index) = 0;

    // Called when the option at |index| has been updated.
    virtual void OnOptionUpdated(size_t index) = 0;

    // Called when the device adapter is turned on or off.
    virtual void OnAdapterEnabledChanged(bool enabled) = 0;

    // Called when refreshing options is in progress or complete.
    virtual void OnRefreshStateChanged(bool refreshing) = 0;

   protected:
    virtual ~View() {}
  };

  // Returns the text to be displayed in the chooser title.
  base::string16 GetTitle() const;

  // Returns whether the chooser needs to show an icon before the text.
  // For WebBluetooth, it is a signal strength icon.
  virtual bool ShouldShowIconBeforeText() const;

  // Returns whether the chooser needs to show a help button.
  virtual bool ShouldShowHelpButton() const;

  // Returns whether the chooser needs to show a button to re-scan for devices.
  virtual bool ShouldShowReScanButton() const;

  // Returns whether the chooser allows multiple items to be selected.
  virtual bool AllowMultipleSelection() const;

  // Returns the text to be displayed in the chooser when there are no options.
  virtual base::string16 GetNoOptionsText() const = 0;

  // Returns the label for OK button.
  virtual base::string16 GetOkButtonLabel() const = 0;

  // The number of options users can pick from. For example, it can be
  // the number of USB/Bluetooth device names which are listed in the
  // chooser so that users can grant permission.
  virtual size_t NumOptions() const = 0;

  // The signal strength level (0-4 inclusive) of the device at |index|, which
  // is used to retrieve the corresponding icon to be displayed before the
  // text. Returns -1 if no icon should be shown.
  virtual int GetSignalStrengthLevel(size_t index) const;

  // The |index|th option string which is listed in the chooser.
  virtual base::string16 GetOption(size_t index) const = 0;