GTK 新手 画图疑问

ntuguy

I wrote a very simple program,  which should draw a rectangle on the left part of the main window ( main window contains a hbox with 2 columns)

1. 
   
2. //----------------------------------------
   
3. #include<gtk/gtk.h>
   
4. gint main(gint argc,gchar * argv[])
   
5. {
   
6.         GtkWidget * main;
   
7.         GtkWidget * hbox;
   
8.         GtkWidget * button;
   
9.         GtkWidget * draw;
   
10.         GdkDrawable * drawable;
    
11.        
    
12.         gtk_init(&argc,&argv);
    
13.        
    
14.         main = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    
15.         gtk_window_set_default_size(GTK_WINDOW(main),500,400);
    
16.         gtk_window_set_title(GTK_WINDOW(main),"New Window");
    
17.         gtk_signal_connect(GTK_OBJECT(main),"destroy",GTK_SIGNAL_FUNC(gtk_main_quit),NULL);
    
18.        
    
19.         gtk_widget_show(main);  
    
20.        
    
21.         hbox = gtk_hbox_new(FALSE,10);
    
22.         gtk_container_add(GTK_CONTAINER(main),hbox);
    
23.         gtk_widget_show(hbox);
    
24.        
    
25.         draw = gtk_drawing_area_new();
    
26.         gtk_widget_set_usize(draw,300,300);
    
27.         gtk_box_pack_start(GTK_BOX(hbox),draw,TRUE,TRUE,5);
    
28.         gtk_widget_show(draw);
    
29.         drawable = draw->window;
    
30.         g_assert(drawable != NULL);
    
31.         gdk_draw_rectangle(drawable,draw->style->black_gc,TRUE,100,100,(draw->allocation.width)/2,(draw->allocation.height)/2);
    
32. 
    
33.        
    
34.         button = gtk_button_new_with_label("Click Me");
    
35.         gtk_box_pack_end(GTK_BOX(hbox),button,FALSE,FALSE,0);
    
36.        
    
37.         gtk_widget_show_all(main);
    
38.        
    
39.         gtk_main();
    
40.         return 0;
    
41. }
    
42. //-----------------------------------------------------
    

复制代码

It runs ok but no content on the left cell. Then I comment the line
gtk_widget_show(main);
drawable will be NULL and an assert will given in runtime.

I am a newbee to GTK programming, anyone can help me to figure out the error?

Thanks!

wide288

画矩形要在某个控件上，控件名忘了。
看API 有函数的。

Linux_Lyb

例程在在附件里,画图需要一个GdkPixmap和GtkDrawingArea的expose_event和
configure_event连接,然后在pixmap上画.
具体请看gtk带的gtk-demo.