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Re: vertical line that moves with cursor in draw widget [message #60723 is a reply to message #60713]

Sat, 07 June 2008 00:49

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

cgoethel@igpp.ucla.edu writes:

> Hello, I have a draw_widget with motion events set up. I draw a
> vertical line (using plots) which follows the cursor as it moves
> through the draw area. I can get the vertical line to follow the
> cursor easily enough - but I can't seem to figure out how to erase the
> previous lines. All the lines remain drawn. Any suggestions?
> Thanks! Cindy

Hello--

My personal favorite would be to use the DEVICE, SET_GRAPHICS_FUNCTION=
function to change to XOR drawing mode. In this mode you should be able
to draw the line once to make it appear and then repeat the operation
to make it disappear.

Something like,

DEVICE, GET_GRAPHICS_FUNCTION=oldg, SET_GRAPHICS_FUNCTION=6
;; Erase previous symbol
if n_elements(old_posx) then plots, old_posx, old_posy
;; Plot new symbol
plots, new_posx, new_posy
DEVICE, SET_GRAPHICS_FUNCTION=oldg

;; Save the new position for the next call
old_posx = new_posx
old_posy = new_posy

Good luck!
Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@REMOVEcow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: vertical line that moves with cursor in draw widget By: Michael Galloy on Sun, 08 June 2008 15:56
		Re: vertical line that moves with cursor in draw widget By: Craig Markwardt on Sat, 07 June 2008 00:49
		Re: vertical line that moves with cursor in draw widget By: ben.bighair on Fri, 06 June 2008 19:51
		Re: vertical line that moves with cursor in draw widget By: Rick Towler on Fri, 06 June 2008 14:55
		Re: vertical line that moves with cursor in draw widget By: Jean H. on Fri, 06 June 2008 14:28

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