/****************************************************************

                      Uebungen zur Vorlesung
		  "Graphische Datenverarbeitung"
                       Sommersemester  1997

       Programm: stoppuhr2.c
       Autor:    Christian Boehm

****************************************************************/

# include <Xm/XmAll.h>
# include <time.h>
# include <stdlib.h>

struct timeval time1, time2 ;

XtAppContext kontext;        /* Applikations-Umgebung */
Widget textWdgt ;
XtIntervalId timerId ;

float Startzeit ;

/*  tdiff
 *  Hilfsfunktion zur Ermittlung der Zeitdifferenz in Millisekunden
 */

int tdiff (struct timeval t1, struct timeval t2)
{
    return (t2.tv_sec*1000+t2.tv_usec/1000-t1.tv_sec*1000-t1.tv_usec/1000) ;
}

/* Callback-Funktionen */

void timerCB (XtPointer p, XtIntervalId *i)
{
    char s [80] ;
    gettimeofday(&time2, NULL);
    sprintf (s, "%.3f", (float)tdiff (time1, time2) * 0.001 + Startzeit) ;
    XmTextFieldSetString (textWdgt, s) ;
    timerId = XtAppAddTimeOut (kontext, 10, timerCB, (XtPointer) NULL) ;
}

void StartCB (Widget w , XtPointer p1, XtPointer p2) 
{
    char * s ;
    gettimeofday(&time1, NULL);
    s = XmTextFieldGetString (textWdgt) ;
    Startzeit = atof (s) ;
    XtFree (s) ;
    timerId = XtAppAddTimeOut (kontext, 10, timerCB, (XtPointer) NULL) ;
}

void StopCB (Widget w , XtPointer p1, XtPointer p2) 
{
    char s [80] ;
    gettimeofday(&time2, NULL);
    sprintf (s, "%.3f", (float)tdiff (time1, time2) * 0.001 + Startzeit) ;
    XmTextFieldSetString (textWdgt, s) ;
    XtRemoveTimeOut (timerId) ;
}

void LoeschenCB (Widget w , XtPointer p1, XtPointer p2) 
{
    XmTextFieldSetString (textWdgt, "0.000") ;
}

void ExitCB (Widget w , XtPointer p1, XtPointer p2) 
{
    exit (0) ;
}

main (int argc, char ** argv)
{
    Widget applShell, box, startBt, stopBt, loeschenBt, exitBt;

    applShell =  XtAppInitialize (& kontext, "Stoppuhr", (XrmOptionDescRec *) NULL, 0,
                                  & argc, argv, (String *) NULL, (Arg *) NULL, 0);

    box =        XtCreateManagedWidget ("box",      xmRowColumnWidgetClass,  applShell, (Arg *) NULL, 0);
    textWdgt =   XtCreateManagedWidget ("zeit",     xmTextFieldWidgetClass,  box,       (Arg *) NULL, 0);
    startBt =    XtCreateManagedWidget ("START",    xmPushButtonWidgetClass, box,       (Arg *) NULL, 0);
    stopBt =     XtCreateManagedWidget ("STOP",     xmPushButtonWidgetClass, box,       (Arg *) NULL, 0);
    loeschenBt = XtCreateManagedWidget ("LOESCHEN", xmPushButtonWidgetClass, box,       (Arg *) NULL, 0);
    exitBt =     XtCreateManagedWidget ("EXIT",     xmPushButtonWidgetClass, box,       (Arg *) NULL, 0);

    /* Callbacks registrieren */

    XtAddCallback (startBt,    XmNactivateCallback, StartCB,    (XtPointer) NULL) ;
    XtAddCallback (stopBt,     XmNactivateCallback, StopCB,     (XtPointer) NULL) ;
    XtAddCallback (loeschenBt, XmNactivateCallback, LoeschenCB, (XtPointer) NULL) ;
    XtAddCallback (exitBt,     XmNactivateCallback, ExitCB,     (XtPointer) NULL) ;

    XmTextFieldSetString (textWdgt, "0.000") ;

    XtRealizeWidget (applShell);
    XtAppMainLoop (kontext);
}