c - GTK implementation of MessageBox


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I have been trying to implement Win32's MessageBox using GTK. The app using SDL/OpenGL, so this isn't a GTK app.

I handle the initialisation (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 realise that I'm probably doing something horribly wrong.

However, my problem is that the last dialog popped up with this function stays around until the process exits. Any ideas?


所有的回答
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    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 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.

    Hope this helps!


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    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;
        } 
    }
    

  • Translate

    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.