Re: emitting the "delete_event" in a "key_press_event" --> crash

[Olexiy Avramchenko <ath beast stu cn ua>]

Olivier Sessink wrote:

> On Wed, 06 Nov 2002 16:15:33 -0500 (EST) "Owen Taylor"
> <otaylor redhat com> wrote:
>
> > Small test case? Escape is automatically hooked up for GTK+ dialogs and
> > doesn't usually crash GTK+, so there must be something else going on
> > here.
> >
> > (Bug report filed in bugzilla would be appreciated)
I looked more at your source... Sorry its completely broken... "destroy" 
signal and
"destroy_event" are not the same. "destroy" signal (GtkObject) doesnt 
have a parameters
but "destroy_event" (GtkWidget) has. By the way, you are connecting the 
same function (where
you're doing gfree) to two different signals.

> I don't know if the code is valid, so here is my testcase, if the code is
> valid please let me know and I'll enter it as a bug.
> /*
> escape_testcase.c
> compile with
> gcc escape_testcase.c -o escape_testcase `pkg-config --cflags gtk+-2.0`
> `pkg-config --libs gtk+-2.0` */
>
> #include <gtk/gtk.h>
> #include <gdk/gdkkeysyms.h>
> static void create_testwin();
>
> static gboolean create_window_key_press_event_lcb(GtkWidget
> *widget,GdkEventKey *event,GtkWidget *win) {    if (event->keyval ==
> GDK_Escape) {           g_signal_emit_by_name(G_OBJECT(win), "delete_event");
> /*              gtk_widget_destroy(win);*/
>                 return TRUE;
>         }
>         return FALSE;
> }
>
> GtkWidget *create_window(GCallback close_func,gpointer close_data) {
>         GtkWidget *returnwidget = gtk_window_new(GTK_WINDOW_TOPLEVEL);
>         g_signal_connect(G_OBJECT(returnwidget), "delete_event", close_func,
> close_data);    g_signal_connect(G_OBJECT(returnwidget), "destroy",
Here's the bug: you connecting to "destroy" and expecting that your 
handler will get
close_data parameter.

> close_func, close_data);        g_signal_connect(G_OBJECT(returnwidget),
> "key_press_event", G_CALLBACK(create_window_key_press_event_lcb),
> returnwidget);  return returnwidget;
> }
>
> typedef struct {
>         GtkWidget *win;
>         int various_other_data;
> } TestWinStruct;
>
> void testwin_destroy_cb(GtkWidget * widget, GdkEvent *event, 
> TestWinStruct *testwin) {
> g_signal_handlers_destroy(G_OBJECT(testwin->win));
> gtk_widget_destroy(testwin->win);    g_free(testwin);
Here's one more bug - you may call gfree two times.

> }
>
> static void testwin_button_clicked_cb(GtkWidget *widget, gpointer data) {
>         create_testwin();
> }
>
> static void create_testwin() {
>         GtkWidget *button;
>         TestWinStruct *testwin;
>         testwin = g_new(TestWinStruct,1);
>         testwin->win = create_window(G_CALLBACK(testwin_destroy_cb), testwin);
>         button = gtk_button_new_with_label("create another testwin\n");
>         g_signal_connect(G_OBJECT(button), "clicked",
> G_CALLBACK(testwin_button_clicked_cb), NULL);
> gtk_container_add(GTK_CONTAINER(testwin->win), button);
> gtk_widget_show_all(testwin->win);}
>
> int main(int argc, char *argv[]) {
>
>         gtk_init(&argc, &argv);
>         create_testwin();
>         gtk_main();
> }
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Olexiy