Re: undocumented IDL built-in TVRDC [message #2264] |
Mon, 13 June 1994 12:51  |
velt
Messages: 19 Registered: June 1994
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Junior Member |
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In article 21061@noao.edu, eharold@corona.sunspot.noao.edu (Elliotte Harold) writes:
> I recently ran across what appears to be an undocumented built-in
> procedure in IDL 3.5 called TVRDC. I can't find a reference to it anywhere,
> but it seems to return the point in the IDL window which the user
> clicked. It's syntax is
>
> tvrdc,x,y,/dev
>
>
> After calling this x and y now contain the x and y coordinates where the
> mouse was clicked. Here at NSO we found it useful for a program that
> tracks Jupiter's moons between frames. In the picture of Jupiter taken
> with the Vacuum Tower Telescope the moons are fairly small, pretty much
> single pixel objects so to locate them we just move the mouse and click
> on the moon. Has anyone else used this? More to the point is there some
> reason it's undocumented? Or is it documented somewhere that I just haven't
> been able to find? If you're wondering how I found out about it, I saw it
> used in the TVRD userlib procedure.
>
> --
>
> Elliotte Rusty Harold National Solar Observatory
> eharold@sunspot.noao.edu Sunspot NM 88349
It appears that tvrdc has similar functionality as cursor. When I first read
your message it appeared that you could retrieve the *last* cursor position
where the mouse was clicked, which would have great advantages over the
current routines, that read the cursor postion *after* the routine is called.
Tvrdc is a fossil from IDL version 1. The IDL users guide VS 2.1 (1991) describes
the differences between cursor and tvrdc.
Robert Velthuizen
velt@rad.usf.edu
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