app/gtk_signal.h

// Copyright (c) 2010 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 APP_GTK_SIGNAL_H_
#define APP_GTK_SIGNAL_H_

#include <gtk/gtk.h>
#include <map>
#include <vector>

#include "base/basictypes.h"

// At the time of writing this, there were two common ways of binding our C++
// code to the gobject C system. We either defined a whole bunch of "static
// MethodThunk()" which just called nonstatic Method()s on a class (which hurt
// readability of the headers and signal connection code) OR we declared
// "static Method()" and passed in the current object as the gpointer (and hurt
// readability in the implementation by having "context->" before every
// variable).

// The hopeful result of using these macros is that the code will be more
// readable and regular. There shouldn't be a bunch of static Thunks visible in
// the headers and the implementations shouldn't be filled with "context->"
// de-references.

#define CHROMEG_CALLBACK_0(CLASS, RETURN, METHOD, SENDER)           \
  static RETURN METHOD ## Thunk(SENDER sender, gpointer userdata) { \
    return reinterpret_cast<CLASS*>(userdata)->METHOD(sender);      \
  }                                                                 \
                                                                    \
  virtual RETURN METHOD(SENDER);

#define CHROMEG_CALLBACK_1(CLASS, RETURN, METHOD, SENDER, ARG1)     \
  static RETURN METHOD ## Thunk(SENDER sender, ARG1 one,            \
                                gpointer userdata) {                \
    return reinterpret_cast<CLASS*>(userdata)->METHOD(sender, one); \
  }                                                                 \
                                                                    \
  virtual RETURN METHOD(SENDER, ARG1);

#define CHROMEG_CALLBACK_2(CLASS, RETURN, METHOD, SENDER, ARG1, ARG2)    \
  static RETURN METHOD ## Thunk(SENDER sender, ARG1 one, ARG2 two,       \
                                gpointer userdata) {                     \
    return reinterpret_cast<CLASS*>(userdata)->METHOD(sender, one, two); \
  }                                                                      \
                                                                         \
  virtual RETURN METHOD(SENDER, ARG1, ARG2);

#define CHROMEG_CALLBACK_3(CLASS, RETURN, METHOD, SENDER, ARG1, ARG2, ARG3) \
  static RETURN METHOD ## Thunk(SENDER sender, ARG1 one, ARG2 two,          \
                                ARG3 three, gpointer userdata) {            \
    return reinterpret_cast<CLASS*>(userdata)->                             \
        METHOD(sender, one, two, three);                                    \
  }                                                                         \
                                                                            \
  virtual RETURN METHOD(SENDER, ARG1, ARG2, ARG3);

#define CHROMEG_CALLBACK_4(CLASS, RETURN, METHOD, SENDER, ARG1, ARG2, ARG3, \
                           ARG4)                                            \
  static RETURN METHOD ## Thunk(SENDER sender, ARG1 one, ARG2 two,          \
                                ARG3 three, ARG4 four,                      \
                                gpointer userdata) {                        \
    return reinterpret_cast<CLASS*>(userdata)->                             \
        METHOD(sender, one, two, three, four);                              \
  }                                                                         \
                                                                            \
  virtual RETURN METHOD(SENDER, ARG1, ARG2, ARG3, ARG4);

#define CHROMEG_CALLBACK_5(CLASS, RETURN, METHOD, SENDER, ARG1, ARG2, ARG3, \
                           ARG4, ARG5)                                      \
  static RETURN METHOD ## Thunk(SENDER sender, ARG1 one, ARG2 two,          \
                                ARG3 three, ARG4 four, ARG5 five,           \
                                gpointer userdata) {                        \
    return reinterpret_cast<CLASS*>(userdata)->                             \
        METHOD(sender, one, two, three, four, five);                        \
  }                                                                         \
                                                                            \
  virtual RETURN METHOD(SENDER, ARG1, ARG2, ARG3, ARG4, ARG5);

#define CHROMEG_CALLBACK_6(CLASS, RETURN, METHOD, SENDER, ARG1, ARG2, ARG3, \
                           ARG4, ARG5, ARG6)                                \
  static RETURN METHOD ## Thunk(SENDER sender, ARG1 one, ARG2 two,          \
                                ARG3 three, ARG4 four, ARG5 five,           \
                                ARG6 six, gpointer userdata) {              \
    return reinterpret_cast<CLASS*>(userdata)->                             \
        METHOD(sender, one, two, three, four, five, six);                   \
  }                                                                         \
                                                                            \
  virtual RETURN METHOD(SENDER, ARG1, ARG2, ARG3, ARG4, ARG5, ARG6);

// These macros handle the common case where the sender object will be a
// GtkWidget*.
#define CHROMEGTK_CALLBACK_0(CLASS, RETURN, METHOD) \
  CHROMEG_CALLBACK_0(CLASS, RETURN, METHOD, GtkWidget*);

#define CHROMEGTK_CALLBACK_1(CLASS, RETURN, METHOD, ARG1) \
  CHROMEG_CALLBACK_1(CLASS, RETURN, METHOD, GtkWidget*, ARG1);

#define CHROMEGTK_CALLBACK_2(CLASS, RETURN, METHOD, ARG1, ARG2) \
  CHROMEG_CALLBACK_2(CLASS, RETURN, METHOD, GtkWidget*, ARG1, ARG2);

#define CHROMEGTK_CALLBACK_3(CLASS, RETURN, METHOD, ARG1, ARG2, ARG3) \
  CHROMEG_CALLBACK_3(CLASS, RETURN, METHOD, GtkWidget*, ARG1, ARG2, ARG3);

#define CHROMEGTK_CALLBACK_4(CLASS, RETURN, METHOD, ARG1, ARG2, ARG3, ARG4) \
  CHROMEG_CALLBACK_4(CLASS, RETURN, METHOD, GtkWidget*, ARG1, ARG2, ARG3, ARG4);

#define CHROMEGTK_CALLBACK_5(CLASS, RETURN, METHOD, ARG1, ARG2, ARG3, ARG4, \
                             ARG5)                                          \
  CHROMEG_CALLBACK_5(CLASS, RETURN, METHOD, GtkWidget*, ARG1, ARG2, ARG3,   \
                     ARG4, ARG5);

#define CHROMEGTK_CALLBACK_6(CLASS, RETURN, METHOD, ARG1, ARG2, ARG3, ARG4, \
                             ARG5, ARG6)                                    \
  CHROMEG_CALLBACK_6(CLASS, RETURN, METHOD, GtkWidget*, ARG1, ARG2, ARG3,   \
                     ARG4, ARG5, ARG6);

// A class that ensures that callbacks don't run on stale owner objects. Similar
// in spirit to NotificationRegistrar. Use as follows:
//
//   class ChromeObject {
//    public:
//     ChromeObject() {
//       ...
//
//       signals_.Connect(widget, "event", CallbackThunk, this);
//     }
//
//     ...
//
//    private:
//     GtkSignalRegistrar signals_;
//   };
//
// When |signals_| goes down, it will disconnect the handlers connected via
// Connect.
class GtkSignalRegistrar {
 public:
  GtkSignalRegistrar();
  ~GtkSignalRegistrar();

  // Connect before the default handler. Returns the handler id.
  glong Connect(gpointer instance, const gchar* detailed_signal,
                GCallback signal_handler, gpointer data);
  // Connect after the default handler. Returns the handler id.
  glong ConnectAfter(gpointer instance, const gchar* detailed_signal,
                     GCallback signal_handler, gpointer data);

 private:
  static void WeakNotifyThunk(gpointer data, GObject* where_the_object_was) {
    reinterpret_cast<GtkSignalRegistrar*>(data)->WeakNotify(
        where_the_object_was);
  }
  void WeakNotify(GObject* where_the_object_was);

  glong ConnectInternal(gpointer instance, const gchar* detailed_signal,
                        GCallback signal_handler, gpointer data, bool after);

  typedef std::vector<glong> HandlerList;
  typedef std::map<GObject*, HandlerList> HandlerMap;
  HandlerMap handler_lists_;

  DISALLOW_COPY_AND_ASSIGN(GtkSignalRegistrar);
};

#endif  // APP_GTK_SIGNAL_H_