list_16_20.c

This source code has been tested under OpenWindows 2.0, Sun s X11/NeWS server. For Xlib programs th

/***********************************************************************
**                                                                    **
**  listing_16_20.c                                                   **
**                                                                    **
**  Example of explicit converter calls. This program presents a      **
**  pushbutton. Each time the button is pushed, its background        **
**  color changes.                                                    **
**                                                                    **
***********************************************************************/


#include <string.h>
#include <Xm/PushB.h>


void    ButtonCB();			/* FORWARD Definitions	      */
void	SetBackground();


Widget	appshell,
	the_btn;


void main( argc, argv )
    int     argc;
    char    *argv[];
{
    appshell = XtInitialize( argv[0], "Listing_16_20", NULL, 0, &argc, argv );

    the_btn = XmCreatePushButton( appshell, "TheBtn", NULL, 0 );
    XtManageChild( the_btn );

    XtAddCallback( the_btn, XmNactivateCallback, ButtonCB, NULL );

    XtRealizeWidget( appshell );
    XtMainLoop();
}



void ButtonCB( w, client_data, call_data )
    Widget	w;
    caddr_t	client_data;
    caddr_t	call_data;
{
    static int	cnum = 0;

    switch (cnum++)
        {
	case 0 :
		SetBackground( w, "Red" );
		break;
	case 1 :
		SetBackground( w, "Green" );
		break;
	case 2 :
		SetBackground( w, "Blue" );
		break;
	case 3 :
		SetBackground( w, "Black" );
		cnum = 0;
		break;
	}
}



/**
*** SetBackground( w, cname )
***
*** Sets the "background" resource of widget "w" to the color
*** named by "cname".
**/

void SetBackground( w, cname )
    Widget	w;
    String	cname;
{
    XrmValue    from, to;
    Arg		arg;

    from.addr = cname;
    from.size = strlen(cname);
    to.addr   = NULL;
    to.size   = 0;

    XtConvert( w, XmRString, &from, XmRPixel, &to );
    if (to.addr != NULL)
	{
	XtSetArg( arg, XmNbackground, *(Pixel*)to.addr );
	XtSetValues( w, &arg, 1 );
	}
}