gtk为窗口设置背景图片

void
update_widget_bg(GtkWidget *widget, gchar *img_file)
{       
GtkStyle *style;     
GdkPixbuf *pixbuf;       
GdkPixmap *pixmap;     
gint width, height;    

pixbuf = gdk_pixbuf_new_from_file(img_file, NULL);    
width = gdk_pixbuf_get_width(pixbuf);   
height = gdk_pixbuf_get_height(pixbuf);    
pixmap = gdk_pixmap_new(NULL, width, height, 24);   
gdk_pixbuf_render_pixmap_and_mask(pixbuf, &pixmap, NULL, 0);
style = gtk_style_copy(GTK_WIDGET (widget)->style);    

if (style->bg_pixmap[GTK_STATE_NORMAL])        
g_object_unref(style->bg_pixmap[GTK_STATE_NORMAL]);    

style->bg_pixmap[GTK_STATE_NORMAL] = g_object_ref(pixmap);    
style->bg_pixmap[GTK_STATE_ACTIVE] = g_object_ref(pixmap);
style->bg_pixmap[GTK_STATE_PRELIGHT] = g_object_ref(pixmap);
style->bg_pixmap[GTK_STATE_SELECTED] = g_object_ref(pixmap);
style->bg_pixmap[GTK_STATE_INSENSITIVE] = g_object_ref(pixmap);
gtk_widget_set_style(GTK_WIDGET (widget), style);
g_object_unref(style);
}

gcc test.c `pkg-config --cflags --libs gtk+-2.0`