Why expose event of my GTK+ widget will be freezed after a long time? Is it a GTK+ bug?
Here is my code:
#include <gtk/gtk.h>
static int counter = 0;
static PangoLayout* layout;
static GdkGC* gc1;
static GdkGC* gc2;
//**/static GMutex* mu;
static gboolean on_expose_event(GtkWidget* widget, GdkEventExpose* event)
{
gchar the_string[20];
//**/g_mutex_lock(mu);
gdk_draw_rectangle(GDK_DRAWABLE(widget->window), gc1, TRUE, 0, 0, widget->allocation.width, widget->allocation.height);
snprintf(the_string, 20, "%d", counter);
pango_layout_set_text(layout, the_string, -1);
gdk_draw_l开发者_如何学Goayout(GDK_DRAWABLE(widget->window), gc2, 180, 120, layout);
//**/g_mutex_unlock(mu);
g_print (".");
return FALSE;
}
gpointer func(gpointer data)
{
//**/g_usleep(10000);
GdkWindow* window = GDK_WINDOW(data);
while(TRUE)
{
gdk_window_invalidate_rect(window, NULL, FALSE);
//**/gdk_window_process_updates(window, FALSE);
if(counter % 100 == 0) g_print("X");
g_usleep(10);
++counter;
}
return FALSE;
}
int main(int argc, char** argv)
{
GtkWidget* window;
GtkWidget* drawer;
GdkColormap* colormap;
GdkColor color;
g_thread_init(NULL);
gdk_threads_init();
gtk_init(&argc, &argv);
//:Create widgets and
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
drawer = gtk_drawing_area_new();
gtk_widget_set_size_request(drawer, 400, 300);
gtk_container_add(GTK_CONTAINER(window), drawer);
//.
gtk_widget_show_all(window);
//:Initializing Graphic Contexts
colormap = gtk_widget_get_colormap(GTK_WIDGET(drawer));
layout = gtk_widget_create_pango_layout(GTK_WIDGET(drawer), NULL);
gc1 = gdk_gc_new(GDK_DRAWABLE(GTK_WIDGET(drawer)->window));
gc2 = gdk_gc_new(GDK_DRAWABLE(GTK_WIDGET(drawer)->window));
gdk_color_parse("#000", &color);
gdk_colormap_alloc_color(colormap, &color, FALSE, TRUE);
gdk_gc_set_background(gc1, &color);
gdk_color_parse("#fff", &color);
gdk_colormap_alloc_color(colormap, &color, FALSE, TRUE);
gdk_gc_set_foreground(gc2, &color);
//.
g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL);
g_signal_connect(G_OBJECT(drawer), "expose_event", G_CALLBACK(on_expose_event), NULL);
//**/mu = g_mutex_new();
//Run the problematic thread!
g_thread_create(func, GTK_WIDGET(drawer)->window, TRUE, NULL);
gdk_threads_enter();
gtk_main();
gdk_threads_leave();
//**/g_mutex_free(mu);
return 0;
}
It's a multithreaded program, and did nothing so especial! It just force a GtkDrawingArea to redraw itself from the main thread (GTK+ main loop).
My problem (or GTK+ problem!) is that after a long time running (maybe 0.5, 1 or 4 minutes!), the expose event will not work (does not response to my requests until I'm resizing the whole window!)! Please, compile and run the code to check this situation. I added some print commands which may help! but i can't detect the problem, because of my little experience.
I hoped this program can redraws its context for almost always, but it didn't (or couldn't). What can i do to solve this problem? Maybe i should report a bug to GTK+ developers?
I'm using Debian + GCC + GTK2.20
Most likely, you need to surround your gdk_window_invalidate_rect() call with gdk_threads_enter()/gdk_threads_leave() pair. Read the gdk threads for more information about gtk and threads. Look at the example there.
You should use g_timeout_add
with your callback and NOT use a second thread that is messing with the UI.
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