GTK implementation of MessageBox - c

Question

I have been trying to implement Win32's MessageBox using GTK. The app uses SDL/OpenGL, so this isn't a GTK app.
I handle the initialization (gtk_init) sort of stuff inside the MessageBox function as follows:
int MessageBox(HWND hwnd, const char* text, const char* caption, UINT type)
{
GtkWidget *window = NULL;
GtkWidget *dialog = NULL;
gtk_init(&gtkArgc, &gtkArgv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
g_signal_connect(G_OBJECT(window), "delete_event", G_CALLBACK(delete_event), NULL);
g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(destroy), NULL);
// gcallback calls gtk_main_quit()
gtk_init_add((GtkFunction)gcallback, NULL);
if (type & MB_YESNO) {
dialog = gtk_message_dialog_new(GTK_WINDOW(window), GTK_DIALOG_DESTROY_WITH_PARENT, GTK_MESSAGE_QUESTION, GTK_BUTTONS_YES_NO, text);
} else {
dialog = gtk_message_dialog_new(GTK_WINDOW(window), GTK_DIALOG_DESTROY_WITH_PARENT, GTK_MESSAGE_INFO, GTK_BUTTONS_OK, text);
}
gtk_window_set_title(GTK_WINDOW(dialog), caption);
gint result = gtk_dialog_run(GTK_DIALOG(dialog));
gtk_main();
gtk_widget_destroy(dialog);
if (type & MB_YESNO) {
switch (result) {
default:
case GTK_RESPONSE_DELETE_EVENT:
case GTK_RESPONSE_NO:
return IDNO;
break;
case GTK_RESPONSE_YES:
return IDYES;
break;
}
}
return IDOK;
}
Now, I am by no means an experienced GTK programmer, and I realize that I'm probably doing something horribly wrong.
However, my problem is that the last dialog popped up with this function staying around until the process exits. Any ideas?

Answer 1

Hmm, ok. I'd suggest code like this, then:
typedef struct {
int type;
int result;
} DialogData;
static gboolean
display_dialog(gpointer user_data)
{
DialogData *dialog_data = user_data;
GtkWidget *dialog;
if (dialog_data->type & MB_YESNO)
dialog = gtk_message_dialog_new(...);
else
dialog = gtk_message_dialog_new(...);
// Set title, etc.
dialog_data->result = gtk_dialog_run(...);
gtk_main_quit(); // Quits the main loop run in MessageBox()
return FALSE;
}
int MessageBox(...)
{
DialogData dialog_data;
dialog_data.type = type;
gtk_idle_add(display_dialog, &dialog_data);
gtk_main();
// Do stuff based on dialog_data.result
}
The struct is required because you need to pass around a couple pieces of data. The gtk_idle_add() call adds a method to be run when the main loop is running and idle, and the FALSE return value from the display_dialog() call means that it's only run once. After we get the result from the dialog, we quit the main loop. That'll cause the gtk_main() in your main MessageBox() method to return, and you'll be able to access the result from there.

Answer 2

To manage a dialog box with GTK+, use a GtkDialog and gtk_dialog_run() instead of managing a window and a main loop by yourself.
EDIT / ADDENDUM :
What I mean is "just use" : I don't understand why you create a windows you never use and a main loop which seems useless (at least from the piece of code you posted). You can write something as short as :
int MessageBox(HWND hwnd, const char* text, const char* caption, UINT type)
{
GtkWidget *dialog ;
/* Instead of 0, use GTK_DIALOG_MODAL to get a modal dialog box */
if (type & MB_YESNO)
dialog = gtk_message_dialog_new(NULL, 0, GTK_MESSAGE_QUESTION, GTK_BUTTONS_YES_NO, text );
else
dialog = gtk_message_dialog_new(NULL, 0, GTK_MESSAGE_INFO, GTK_BUTTONS_OK, text );
gtk_window_set_title(GTK_WINDOW(dialog), caption);
gint result = gtk_dialog_run(GTK_DIALOG(dialog));
gtk_widget_destroy( GTK_WIDGET(dialog) );
if (type & MB_YESNO)
{
switch (result)
{
default:
case GTK_RESPONSE_DELETE_EVENT:
case GTK_RESPONSE_NO:
return IDNO;
case GTK_RESPONSE_YES:
return IDYES;
}
return IDOK;
}
}

Answer 3

A few things:
You are creating (and not using) an unnecessary toplevel window, named window. You can just delete these lines:
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
g_signal_connect(G_OBJECT(window), "delete_event", G_CALLBACK(delete_event), NULL);
g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(destroy), NULL);
Also, the flow doesn't seem quite right. gtk_main() starts the GTK main loop, which blocks until something exits it. gtk_dialog_run() also starts a main loop, but it exits as soon as one of the buttons is clicked.
I think it might be enough for you to remove the gtk_init_add() and gtk_main() calls, and simply deal with the return value. Also the gtk_widget_destroy() call is unnecessary, as the dialog window is automatically destroyed when gtk_dialog_run() returns.