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Re: Problems with draw widget scrolling in IDL 5.0 [message #9770 is a reply to message #9692]

Tue, 12 August 1997 00:00

davidf
Messages: 2866
Registered: September 1996

Senior Member

Roberto Racca writes:

> I have encountered a few puzzling quirks in the Draw widget under IDL
> 5.0 (first full release) running on a Windows 95 platform. They have
> to do with the scrolling of the viewport over a larger drawing area.
>
> 1) I need to resize the underlying drawing area at run time. I use
> the widget_control procedure with the parameters draw_xsize and
> draw_ysize. Everything works properly if the viewport is located at
> the top left corner of the image. Otherwise, IDL appears to 'lose
> track' of the location of the viewport and starts displaying bands of
> grey background at the edges of the image, or in worst cases no image
> at all. The effect is cumulative over repeated resizings, and there
> is no way of restoring the proper positioning.
>
> I would sincerely appreciate having someone's opinion on this. I very
> much need the resizing feature for a critical application, and I cannot
> find a work-around. Does anyone know whether the problem been
> addressed in 5.0.2?

The problem is still apparent in IDL 5.0.2 on my Windows NT machine.
Toggling the size in your example program after I move the scroll
bars results in a draw widget that is about 1 pixel by 1 pixel.
I'll add this to my IDL 5 Information page, which is currently under
construction.

As a work-around, what about making the draw widget as large
as you will possibly need and then restricting the viewport
scrolling in such a way as to keep the viewport over the
current image.

Cheers,

David

------------------------------------------------------------ ----
David Fanning, Ph.D.
Fanning Software Consulting
Customizable IDL Programming Courses
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com

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[Message index]

		Problems with draw widget scrolling in IDL 5.0 By: Roberto Racca on Mon, 11 August 1997 00:00
		Re: Problems with draw widget scrolling in IDL 5.0 By: Roberto Racca on Tue, 12 August 1997 00:00
		Re: Problems with draw widget scrolling in IDL 5.0 By: davidf on Tue, 12 August 1997 00:00
		Re: Problems with draw widget scrolling in IDL 5.0 By: Roberto Racca on Tue, 12 August 1997 00:00
		Re: Problems with draw widget scrolling in IDL 5.0 By: davidf on Tue, 12 August 1997 00:00

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