ui/gtk/gtk_key_bindings_handler.h

// Copyright (c) 2012 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_GTK_GTK_KEY_BINDINGS_HANDLER_H_
#define UI_GTK_GTK_KEY_BINDINGS_HANDLER_H_

#include <gtk/gtk.h>

#include <string>
#include <vector>

#include "ui/base/ime/linux/text_edit_command_auralinux.h"
#include "ui/events/platform_event.h"

namespace ui {
class Event;
}

namespace gtk {

// This class is a convenience class for handling editor key bindings defined
// in gtk keyboard theme.
// In gtk, only GtkEntry and GtkTextView support customizing editor key bindings
// through keyboard theme. And in gtk keyboard theme definition file, each key
// binding must be bound to a specific class or object. So existing keyboard
// themes only define editor key bindings exactly for GtkEntry and GtkTextView.
// Then, the only way for us to intercept editor key bindings defined in
// keyboard theme, is to create a GtkEntry or GtkTextView object and call
// gtk_bindings_activate_event() against it for the key events. If a key event
// matches a predefined key binding, corresponding signal will be emitted.
// GtkTextView is used here because it supports more key bindings than GtkEntry,
// but in order to minimize the side effect of using a GtkTextView object, a new
// class derived from GtkTextView is used, which overrides all signals related
// to key bindings, to make sure GtkTextView won't receive them.
//
// See third_party/blink/renderer/core/editing/commands/editor_command.cc for
// detailed definition of Blink edit commands.
class GtkKeyBindingsHandler {
 public:
  GtkKeyBindingsHandler();
  virtual ~GtkKeyBindingsHandler();

  // Matches a key event against predefined gtk key bindings, false will be
  // returned if the key event doesn't correspond to a predefined key binding.
  // Edit commands matched with |event| will be stored in |edit_commands|, if
  // non-nullptr.
  bool MatchEvent(const ui::Event& event,
                  std::vector<ui::TextEditCommandAuraLinux>* commands);

 private:
  // Object structure of Handler class, which is derived from GtkTextView.
  struct Handler {
    GtkTextView parent_object;
    GtkKeyBindingsHandler* owner;
  };

  // Class structure of Handler class.
  struct HandlerClass {
    GtkTextViewClass parent_class;
  };

  // Creates a new instance of Handler class.
  GtkWidget* CreateNewHandler();

  // Adds an edit command to the key event.
  void EditCommandMatched(ui::TextEditCommand command,
                          const std::string& value);

  // Initializes Handler structure.
  static void HandlerInit(Handler* self);

  // Initializes HandlerClass structure.
  static void HandlerClassInit(HandlerClass* klass);

  // Registeres Handler class to GObject type system and return its type id.
  static GType HandlerGetType();

  // Gets the GtkKeyBindingsHandler object which owns the Handler object.
  static GtkKeyBindingsHandler* GetHandlerOwner(GtkTextView* text_view);

  // Handler of "backspace" signal.
  static void BackSpace(GtkTextView* text_view);

  // Handler of "copy-clipboard" signal.
  static void CopyClipboard(GtkTextView* text_view);

  // Handler of "cut-clipboard" signal.
  static void CutClipboard(GtkTextView* text_view);

  // Handler of "delete-from-cursor" signal.
  static void DeleteFromCursor(GtkTextView* text_view,
                               GtkDeleteType type,
                               gint count);

  // Handler of "insert-at-cursor" signal.
  static void InsertAtCursor(GtkTextView* text_view, const gchar* str);

  // Handler of "move-cursor" signal.
  static void MoveCursor(GtkTextView* text_view,
                         GtkMovementStep step,
                         gint count,
                         gboolean extend_selection);

  // Handler of "move-viewport" signal.
  static void MoveViewport(GtkTextView* text_view,
                           GtkScrollStep step,
                           gint count);

  // Handler of "paste-clipboard" signal.
  static void PasteClipboard(GtkTextView* text_view);

  // Handler of "select-all" signal.
  static void SelectAll(GtkTextView* text_view, gboolean select);

  // Handler of "set-anchor" signal.
  static void SetAnchor(GtkTextView* text_view);

  // Handler of "toggle-cursor-visible" signal.
  static void ToggleCursorVisible(GtkTextView* text_view);

  // Handler of "toggle-overwrite" signal.
  static void ToggleOverwrite(GtkTextView* text_view);

#if !GTK_CHECK_VERSION(3, 90, 0)
  // Handler of "show-help" signal.
  static gboolean ShowHelp(GtkWidget* widget, GtkWidgetHelpType arg1);
#endif

  // Handler of "move-focus" signal.
  static void MoveFocus(GtkWidget* widget, GtkDirectionType arg1);

  GtkWidget* fake_window_;
  GtkWidget* handler_;

  // Buffer to store the match results.
  std::vector<ui::TextEditCommandAuraLinux> edit_commands_;
};

}  // namespace gtk

#endif  // UI_GTK_GTK_KEY_BINDINGS_HANDLER_H_