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From: kasso@aha.Eng.Sun.COM (Chris Kasso)
Newsgroups: comp.windows.open-look
Subject: Re: Double Clicks in XView
Message-ID: <4039@exodus.Eng.Sun.COM>
Date: 6 Dec 90 02:26:09 GMT
References: <ZOO.90Nov26201641@grumpy.spa.umn.edu>
Sender: news@exodus.Eng.Sun.COM
Distribution: comp
Organization: Sun Microsystems, Mt. View, Ca.
Lines: 131

In article <ZOO.90Nov26201641@grumpy.spa.umn.edu> zoo@aps1.spa.umn.edu writes:
>Howdy.  I'm trying to write an application that needs to be able to
>distinguish between single clicks and double clicks of a mouse button.
>I am using XView 2, and this processing will be in the event procedure
>of a canvas.
>
>Does anyone have sample code for this?  Thanks.
>
>david d [zoo] zuhn		Univ. of Minnesota Dept. of Astronomy
>zoo@aps1.spa.umn.edu		      Automated Plate Scanner Project

You probably want to use an interval timer to distinguish between double
and single clicks of the mouse.  Here's some code that should do
what you want:

#include <stdio.h>
#include <xview/xview.h>
#include <xview/canvas.h>
#include <xview/notify.h>

short	buttonState;

main(argc,argv)
    int		 argc;
    char	*argv[];
{
    void	 EventProc();	
    Xv_server	 server;
    Frame	 frame;
    Canvas	 canvas;

    server = xv_init(XV_INIT_ARGC_PTR_ARGV, &argc, argv, NULL);

    frame = xv_create(NULL, FRAME,
			 XV_LABEL,	"XView Example",
			 XV_X,		200,
			 XV_Y, 		200,
			 XV_WIDTH,	200,
			 XV_HEIGHT,	200,
			 NULL);

    canvas = xv_create(frame, CANVAS,
			 XV_WIDTH,	WIN_EXTEND_TO_EDGE,
			 XV_HEIGHT,	WIN_EXTEND_TO_EDGE,
			 NULL);

    xv_set(canvas_paint_window(canvas), 
			WIN_EVENT_PROC, EventProc,
			WIN_CONSUME_EVENTS,
					WIN_MOUSE_BUTTONS,
					WIN_RESIZE,
					WIN_REPAINT,
					NULL,
			NULL);
    
    buttonState = 0; 

    window_fit(frame);
    xv_main_loop(frame);
}

void
EventProc(window, event)
    Xv_Window	 window;
    Event	*event;
{
    switch (event_action(event)) {
      case ACTION_SELECT:
	  if (event_is_down(event)) {
	      struct itimerval	timer;
	      void 		ButtonTimer();

	      if (!buttonState) {
		  timer.it_value.tv_sec = 0;
		  timer.it_value.tv_usec = 200000;
		  timer.it_interval.tv_sec = 0;
		  timer.it_interval.tv_usec = 0;
		  notify_set_itimer_func(window, ButtonTimer, ITIMER_REAL,
					 &timer, NULL);
		  buttonState = 1;
	      } else {
    		  /*
     		   * Second button press happened before the timeout, this must
		   * be a double click.
     		   */
    		  notify_set_itimer_func(window, NOTIFY_FUNC_NULL, ITIMER_REAL,
					 NULL, NULL);
                  fprintf (stderr, "Double-Click on ACTION_SELECT\n");
		  buttonState = 0;
	      }
	  }
          break;
      case ACTION_ADJUST:
	  if (event_is_down(event))
              fprintf (stderr, "ACTION_ADJUST (down)\n");
	  else
              fprintf (stderr, "ACTION_ADJUST (up)\n");
          break;
      case ACTION_MENU:
	  if (event_is_down(event))
              fprintf (stderr, "ACTION_MENU (down)\n");
	  else
              fprintf (stderr, "ACTION_MENU (up)\n");
          break;
      case WIN_REPAINT:
          fprintf (stderr, "WIN_REPAINT\n");
          break;
      case WIN_RESIZE:
          fprintf (stderr, "WIN_RESIZE\n");
          break;
    }
}

void
ButtonTimer(client, which)
    Notify_client	client;
    int			which;
{
    /*
     * Timeout happened before the second button press.  This is a 
     * single click.
     */
    notify_set_itimer_func(client, NOTIFY_FUNC_NULL, ITIMER_REAL, NULL, NULL);
    fprintf (stderr, "Single-Click on ACTION_SELECT\n");
    buttonState = 0;
}

--
Chris Kasso					Internet: kasso@Eng.Sun.COM
Windows and Graphics Software			uucp: {...}!sun!kasso
Sun Microsystems, Inc.