Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-vax!josh
From: josh@mit-vax.LCS.MIT.EDU (Joshua Marantz)
Newsgroups: comp.windows.x
Subject: Motion hints and pointer grabbing
Message-ID: <5389@mit-vax.LCS.MIT.EDU>
Date: 29 Dec 88 21:00:27 GMT
Organization: MIT LCS, Cambridge, MA
Lines: 129

I sent this to xbugs and got no reply, and I'm curious to see if anyone else
has had a problem with this.  The bug report follows.

-Joshua Marantz
Viewlogic Systems, Inc.
----------------
			  X Window System Bug Report
			    xbugs@expo.lcs.mit.edu

VERSION:
    R3

CLIENT MACHINE and OPERATING SYSTEM:
    Sun 3/60 running SunOS 3.4.

DISPLAY:
    Sun 3/60, SunOS 3.4, Sun CG4.

WINDOW MANAGER:
    uwm

AREA:
    server

SYNOPSIS:
    MotionNotifyHints do not work when the cursor is grabbed in a ConfineTo
    window.

DESCRIPTION:
 
    R2 servers (running on Sun 3/60/SunOS 3.4/CG4 and uVAXII/VMS/GPX) do
    this correctly.  The code creates an InputOnly limiting window, and
    does an XGrabPointer with the ConfineTo window set to the limiting
    window.  The event mask (MotionNotify | PointerMotionMask) is
    selected.  The server responds to the first mouse movement with a
    MotionNotify event.  XQueryPointer routine is then called to reset
    the hint mechanism.  In R3, the server will not send another
    MotionNotify event until a button is pressed or the mouse leaves
    the window.  In R2, the server will send a new MotionNotify event
    each time the mouse is moved after an intervening XQueryPointer,
    as expected.

REPEAT BY:
    I have modified xev.c to demonstrate the problem.  The context diffs
    follow, but all I did was to call XQueryEvent each time a MotionNotify
    event was received, and to toggle grabbing (confining) the pointer each
    time the mouse button is pressed.

*** /usr/local/X11/clients/xev/xev.c	Sun Oct  9 15:43:32 1988
--- xev.c	Mon Dec 12 19:44:41 1988
***************
*** 95,108 ****
  {
      char *displayname = NULL;
      char *geom = NULL;
!     int i;
      XSizeHints hints;
      int borderwidth = 2;
!     Window w, subw;
!     XSetWindowAttributes attr;
!     unsigned long mask = 0L;
!     int done;
! 
      ProgramName = argv[0];
      for (i = 1; i < argc; i++) {
  	char *arg = argv[i];
--- 95,108 ----
  {
      char *displayname = NULL;
      char *geom = NULL;
!     int i, root_x, root_y, query_x, query_y;
      XSizeHints hints;
      int borderwidth = 2;
!     Window w, subw, query_root, query_child, limit_window;
!     XSetWindowAttributes attr, limit_attr;
!     unsigned long mask = 0L, query_mask;
!     int done, limited = 0;
!     
      ProgramName = argv[0];
      for (i = 1; i < argc; i++) {
  	char *arg = argv[i];
***************
*** 205,210 ****
--- 205,238 ----
  	    do_KeyRelease (&event);
  	    break;
  	  case ButtonPress:
+ 
+             /* If the cursor is confined to the window, let it rome free! */
+             if (limited) {
+                 XUngrabPointer (dpy, CurrentTime);
+                 XDestroyWindow (dpy, limit_window);
+                 limited = 0;
+             }
+ 
+             /* If the cursor was free, confine it to the window */
+             else {
+                 limited = 1;
+                 limit_window = XCreateWindow (dpy, w,
+                                               0, 0, hints.width, hints.height,
+                                               0, 0,
+                                               InputOnly,
+                                               (Visual *) CopyFromParent,
+                                               0, &limit_attr);
+ 
+                 XMapWindow (dpy, limit_window);
+                 XGrabPointer (dpy, w,
+                               True,
+                               ButtonPressMask | PointerMotionMask,
+                               GrabModeAsync,	    /* pointer mode */
+                               GrabModeAsync,	    /* kbd mode */
+                               limit_window,         /* confine-to window */
+                               None,
+                               CurrentTime);
+             }
  	    prologue (&event, "ButtonPress");
  	    do_ButtonPress (&event);
  	    break;
***************
*** 214,219 ****
--- 242,249 ----
  	    break;
  	  case MotionNotify:
  	    prologue (&event, "MotionNotify");
+             XQueryPointer (dpy, w, &query_root, &query_child,
+                            &root_x, &root_y, &query_x, &query_y, &query_mask);
  	    do_MotionNotify (&event);
  	    break;
  	  case EnterNotify: