_DESIGNING A PORTABLE GUI TOOLKIT_
by Robert T. Nicholson

[LISTING ONE]

/* make_my_window -- Application code to create a window demonstrates use of 
     attributes for overspecification. The programmer can specify values for 
     window properties applying to any underlying GUI, or can accept 
     platform-specific defaults. Routines and constants prefaced with the
     letters "ui" are toolkit routines.  
*/

uiWindow make_my_window(private_data)

ptr_t	private_data;

{
struct 
uiWindowAttr	window_attr;	/* window attributes */
  
uiWindow		the_window;	/* The window created */

/* Set the attibute "mask" for the attributes we're concerned with */
window_attr.mask =	uiWINDOW_A_EVENT |
	uiWINDOW_A_TYPE |
	uiWINDOW_A_MODALITY |
	uiWINDOW_A_POSITION |
	uiWINDOW_A_SIZE |
	uiWINDOW_A_TITLE |
	uiWINDOW_A_CANRESIZE |
	uiWINDOW_A_CANCLOSE |
	uiWINDOW_A_CANMINIMIZE |
	uiWINDOW_A_CANMAXIMIZE |
	uiWINDOW_A_CANTITLE |
	uiWINDOW_A_VSATYPE |
	uiWINDOW_A_HSATYPE;

/* Set the desired attribute values */
/* EVENT - register the event handler, and a pointer to an application data 
   structure that will be passed to the event routine when it is called.  */
window_attr.eventproc = my_event_routine; 
window_attr.eventarg = private_data; 

/* TYPE & MODALITY - a non-modal document window */
window_attr.type = uiWINDOW_DOCUMENT;  
window_attr.modality = uiWINDOW_MODALITY_NONE;

/* POSITION, SIZE, and TITLE */
window_attr.x = 200;   
window_attr.y = 100;
window_attr.width = 500;
window_attr.height = 300;
window_attr.title = "Untitled"; 

/* CANRESIZE, CANCLOSE, CANMINIMIZE, CANMAXIMIZE, CANTITLE - these permissions
     determine how the user can manipulate this window. We could simply accept
     platform-specific defaults for these, to maintain local look and feel.  */
window_attr.canresize = TRUE; 
window_attr.canclose = TRUE;	
window_attr.canminimize = TRUE; 
window_attr.canmaximize = TRUE; 
window_attr.cantitle = TRUE;

/* VSATYPE & HSATYPE - window will have vertical and horizontal scrollbars */
window_attr.vsatype = uiWINDOW_SATYPE_BAR; 
window_attr.hsatype = uiWINDOW_SATYPE_BAR; 

the_window = uiWindowCreate(&window_attr);

return the_window;
}


[LISTING TWO]

/*  button_routine -- A sample of an event handler routine that processes 
     events for three buttons in a dialog box. Data structures prefaced with 
     the letters "ui" are toolkit structures.
*/

void button_routine(the_event, private_data)

uiEvent *the_event;		/* Event record pointer */
ptr_t	private_data;		/* Dialog's data pointer */
{

switch (the_event->type)
	{
	/* Handle button-push events for all three of the
		dialog's buttons. */
	case uiEVENT_PUSHB:
	if (the_event->recipient == 
		((dialog_data_struct *) private_data)->yes_button)
		do_yes_action(private_data);
	if (the_event->recipient == 
		((dialog_data_struct *) private_data)->no_button)
		do_no_action(private_data);
	if (the_event->recipient == 
		((dialog_data_struct *) private_data)->cancel_button)
		do_cancel_action(private_data);
	break;

	/* Handle key events - if the user pressed the Return
		key, treat it the same as the "Yes" button, which
		is the default button for this dialog.	*/
	case uiEVENT_KEY:
	if (((uiEventKey *) the_event)->key) == '\n')
		do_yes_action(private_data);
	else
		uiWSBeep();
	/* (Not interested in any other events that the buttons
		may receive.)  */
	}
return;
}