#include <Xm/Xm.h>
#include <Xm/DrawingA.h>
#include <Xm/RowColumn.h>
#include <Xm/PushB.h>
#include <Xm/Form.h>

void eraseCallback ();
void quitCallback ();
void plusCallback ();
void minusCallback ();
void HandleBoardEvents ( Widget w, XtPointer clientData, XEvent *event, Boolean *flag );



Widget quit;
Widget draw;
Widget erase;
Widget plus;
Widget minus;
Widget canvas;
Display *display;
int screen;
long fgcolor, bgcolor;
XGCValues gcval;
GC drawgc;
Colormap cmap;
XColor color, ignore;
char *colorname = "red";
int L = 300;
int pointx, pointy;
int FirstPt = TRUE;
int DrawLength = 20; 



void main ( int argc, char **argv )
{
	Widget shell,  panel, commands;
	XtAppContext app;
	
	shell = XtAppInitialize ( &app, "Q2", NULL, 0, &argc, argv, NULL, NULL, 0 );
	
	
	panel = XtCreateManagedWidget ( "panel", xmFormWidgetClass,
	shell, NULL, 0 );
	
	display= XtDisplay(shell);
      	screen = DefaultScreen(display);
	
   canvas =
       XtVaCreateManagedWidget ( "canvas", xmDrawingAreaWidgetClass,
       panel,
       XmNtopAttachment, XmATTACH_FORM,
       XmNrightAttachment, XmATTACH_FORM,
       XmNleftAttachment, XmATTACH_FORM,
       XmNbottomAttachment,XmATTACH_NONE,
       XmNwidth,L,
       XmNheight,L,
       XmNbackground,WhitePixel(display,screen),
       NULL );

   commands =
       XtVaCreateManagedWidget ( "commands", xmRowColumnWidgetClass,
       panel,
       XmNnumColumns, 3,
       XmNorientation, XmHORIZONTAL,
       XmNtopAttachment, XmATTACH_WIDGET,
       XmNtopWidget, canvas,
       XmNrightAttachment, XmATTACH_FORM,
       XmNleftAttachment, XmATTACH_FORM,
       XmNbottomAttachment, XmATTACH_FORM,
       NULL );

	erase = XtCreateManagedWidget ( "Erase", xmPushButtonWidgetClass, commands, NULL, 0 );
	quit = XtCreateManagedWidget ( "Quit", xmPushButtonWidgetClass, commands, NULL, 0 );
	plus = XtCreateManagedWidget ( "+", xmPushButtonWidgetClass, commands, NULL, 0 );
	minus = XtCreateManagedWidget ( "-", xmPushButtonWidgetClass, commands, NULL, 0 );

 XtAddCallback ( quit, XmNactivateCallback, quitCallback, NULL );
 XtAddCallback ( erase, XmNactivateCallback, eraseCallback, NULL );
 XtAddCallback ( plus, XmNactivateCallback, plusCallback, NULL );
 XtAddCallback ( minus, XmNactivateCallback, minusCallback, NULL );
	
	
cmap = DefaultColormap (display, screen);
XAllocNamedColor(display, cmap, colorname, &color, &ignore);

      gcval.foreground =  color.pixel;
      drawgc = XtGetGC ( canvas, GCForeground | GCBackground , &gcval );
      gcval.foreground = BlackPixel(display,screen);
XtAddEventHandler(canvas,ButtonPressMask,
FALSE,HandleBoardEvents, NULL);

	
	XtRealizeWidget ( shell );
	XtAppMainLoop ( app );
}


void HandleBoardEvents ( Widget w, XtPointer clientData, XEvent *event, Boolean *flag )
{

if (FirstPt) {
FirstPt=FALSE;
pointx = event->xbutton.x;
pointy = event->xbutton.y;
XDrawLine(XtDisplay(w),XtWindow(w),drawgc,pointx-DrawLength,pointy, pointx+DrawLength, pointy);
XDrawLine(XtDisplay(w),XtWindow(w),drawgc,pointx,pointy-DrawLength, pointx, pointy+DrawLength);

}
else {
FirstPt=TRUE;

XDrawArc (XtDisplay(w),XtWindow(w),drawgc, event->xbutton.x-DrawLength, event->xbutton.y-DrawLength, 2*DrawLength, 2*DrawLength,0,360*64);
}
}

void eraseCallback ()
{
	XClearArea( XtDisplay(canvas),XtWindow(canvas),  0,0, L, L, 0);
}

void quitCallback ( )
{
	exit (0);
}
void plusCallback ( )
{
	DrawLength=DrawLength*2;
}
void minusCallback ( )
{
	DrawLength=DrawLength/2;
}