Re: why i can't draw the graphic??

[=?gb2312?b?6Zkg6IM=?= <bdragon2001 hotmail com>]

hi,james

  There are two programmes which represent my confusion.My last 
description is 

too simple.
 
  1)
gint
expose(GtkWidget *widget, GdkEventExpose *event, gpointer data)
{
	gdk_draw_line (widget->window,
                      widget->style->black_gc,
                      100, 50, 50, 100);
	return TRUE;
}

gint
configure(GtkWidget *widget,GdkEventConfigure *event,gpointer data)
{
	
	gdk_draw_line (widget->window,
                      widget->style->black_gc,
                      100, 50, 50, 100);
	return TRUE;
}

void quit(){
	gtk_exit(0);
}

int
main(int argc, char *argv[])
{
 GtkWidget *window;
 GtkWidget *drawing_area;
 GtkWidget *vbox;

 gtk_init(&argc,&argv);

 window=gtk_window_new(GTK_WINDOW_TOPLEVEL);

 vbox=gtk_vbox_new(FALSE,0);

 gtk_container_add(GTK_CONTAINER(window),vbox);

 gtk_widget_show(vbox);

 gtk_signal_connect(GTK_OBJECT(window),"destroy",
		     GTK_SIGNAL_FUNC(quit),NULL);
 
 drawing_area=gtk_drawing_area_new();
 gtk_drawing_area_size(GTK_DRAWING_AREA(drawing_area),200,200);

 gtk_box_pack_start(GTK_BOX(vbox),drawing_area,TRUE,TRUE,0);

 gtk_widget_show(drawing_area);
 
 gtk_signal_connect (GTK_OBJECT (window), "expose_event",
                     GTK_SIGNAL_FUNC(expose), NULL);
  
 gtk_signal_connect (GTK_OBJECT (window), "configure_event",
                     GTK_SIGNAL_FUNC(configure), NULL);
 
 gtk_widget_show (window);
 
 gtk_main ();

 return 0;
}

In this code,the configure event only happen when i hit the window,but it 
should 

happen when "the gtk_widget_show(window)" is executed.whether my idea is 
right?

2)
gint repaint(gpointer data)
{
       GtkWidget * drawing_area=(GtkWidget *)data;

       gdk_draw_rectangle(drawing_area->window,
		           drawing_area->style->white_gc,
		           TRUE,
		           0,0,
		           drawing_area->allocation.width,
		           drawing_area->allocation.height);
	
	gdk_draw_line (drawing_area->window,
                      drawing_area->style->black_gc,
                      100, 50, 50, 100);

	gdk_draw_arc(drawing_area->window,
	             drawing_area->style->black_gc,
		     FALSE,
		     0,0,
		     30,30,0,(360*64));
	
	return TRUE;

}

void quit(){
	gtk_exit(0);
}

int
main(int argc, char *argv[])
{
 GtkWidget *window;
 GtkWidget *drawing_area;
 GtkWidget *vbox;

 gtk_init(&argc,&argv);

 window=gtk_window_new(GTK_WINDOW_TOPLEVEL);

 vbox=gtk_vbox_new(FALSE,0);

 gtk_container_add(GTK_CONTAINER(window),vbox);

 gtk_widget_show(vbox);

 gtk_signal_connect(GTK_OBJECT(window),"destroy",
		     GTK_SIGNAL_FUNC(quit),NULL);
 
 drawing_area=gtk_drawing_area_new();
 gtk_drawing_area_size(GTK_DRAWING_AREA(drawing_area),200,200);

 gtk_box_pack_start(GTK_BOX(vbox),drawing_area,TRUE,TRUE,0);

 gtk_widget_show(drawing_area);
 
 gtk_widget_show (window);

 gtk_timeout_add(100,repaint,(gpointer)drawing_area);
 
 gtk_main ();
 return 0;
}

Use the timer to draw the graphic,from it i think why the result is 
different 

between the way of using "gdk_draw_XXX" function in "main",and the way of 
using

timer to draw it.Now the timer drawing is ok,but the directly drawing in 
main is 

failed.I don't understand why,can hardly tell the reason?


Best regards
 
thanks for your help

ps the directly drawing:

int
main(int argc, char *argv[])
{
 GtkWidget *window;
 GtkWidget *drawing_area;
 GtkWidget *vbox;

 gtk_init(&argc,&argv);

 window=gtk_window_new(GTK_WINDOW_TOPLEVEL);

 vbox=gtk_vbox_new(FALSE,0);

 gtk_container_add(GTK_CONTAINER(window),vbox);

 gtk_widget_show(vbox);

 gtk_signal_connect(GTK_OBJECT(window),"destroy",
		     GTK_SIGNAL_FUNC(quit),NULL);
 
 drawing_area=gtk_drawing_area_new();
 gtk_drawing_area_size(GTK_DRAWING_AREA(drawing_area),200,200);

 gtk_box_pack_start(GTK_BOX(vbox),drawing_area,TRUE,TRUE,0);

 gtk_widget_show(drawing_area);
 
 gtk_widget_show (window);

 /*directly drawing*/
 gdk_draw_line (drawing_area->window,
                drawing_area->style->black_gc,
                100, 50, 50, 100);


 gtk_main ();
 return 0;
}

in this code,i can't view the line in the drawing_area,






_________________________________________________________________
享用世界上最大的电子邮件系统— MSN Hotmail。http://www.hotmail.com/cn