[ltk-user] Displaying mouse pointer coordinates

[christopher melen]

Thanks Felip, but I've actually solved it by writing a bit of Tcl/Tk code and putting it in init-wish. Instead of displaying coordinates on the statusbar I've decided to have them follow the mouse pointer on the canvas itself.  

Many thanks for your suggestion though.

Chris

--- On Thu, 1/1/09, Felip Alàez Nadal <uu.nix.uu at gmail.com> wrote:

> From: Felip Alàez Nadal <uu.nix.uu at gmail.com>
> Subject: Re: [ltk-user] Displaying mouse pointer coordinates
> To: chris_melen at yahoo.com, "Talk about Ltk the Lisp Toolkit" <ltk-user at common-lisp.net>
> Date: Thursday, 1 January, 2009, 11:13 AM
> Maybe It would be better if you insert a label inside your
> canvas and you
> only change the text on It. It would be really faster than
> destrolling and
> creating the canvas everytime. You can also write text on
> the canvas, and
> change It when you need.
> 
> Felip.
> 
> 2008/12/29 christopher melen <chris_melen at yahoo.com>
> 
> > Hi,
> >
> > I'm trying to display the coordinates of the mouse
> pointer. My app consists
> > of a canvas and a 'statusbar', both of which
> are contained in a toplevel.
> > The statusbar (which is just a frame containing
> another canvas) contains
> > text displaying the current position of the mouse
> pointer, and this is
> > updated as the pointer moves. What I'm doing is
> deleting and then recreating
> > the text with the new coordinates, but this results in
> an unpleasant
> > 'flashing' effect (not so bad on WinXP but
> terrible on OS X). Is there a
> > more efficient way of doing this? I know there are
> Tk-based apps which
> > achieve this effect (such as Wavesurfer), so it must
> be do-able. This is the
> > relevant event handler code -
> >
> > (bind *canvas* "<Motion>"
> >      (lambda (evt)
> >            (let* ((x (event-x evt))
> >                   (y (event-y evt)))
> >                  (setf *x-coord* x *y-coord* y)
> >                  (itemdelete *statusbar*
> *coord-display*)
> >                  (make-coord-display))))
> >
> > *canvas* is the main canvas, and *statusbar* the
> statusbar. *x-coord* and
> > *y-coord* are bound to the current pointer
> coordinates, which are used by
> > the statusbar's text item (bound to
> *coord-display*). The function
> > MAKE-COORD-DISPLAY then recreates the text on the
> statusbar immediately
> > after it has been deleted (hence the flashing).
> >
> > Many thanks in advance for any suggestions.
> >
> > Chris
> >
> > P.S: Also a strange thing happens if I use the above
> code for a canvas
> > owned by a paned-window - the sash disappears. Odd...
> >
> >
> >
> >
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> >
> 
> 
> 
> -- 
> Felip Alàez Nadal