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Re: repeated use of TVRD() gives different results [message #93825 is a reply to message #93750]

Fri, 28 October 2016 12:03

penteado
Messages: 866
Registered: February 2018

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On Wednesday, October 12, 2016 at 6:42:06 AM UTC-7, ri...@crd.ge.com wrote:
> There's a note in the documentation under TVRD about "unexpected results" unless IDL is providing the backing store (which I hadn't seen before). Ages ago, I found that TVRD() didn't work properly when the graphics window extended off the edge of the screen. (I solved it by copying the window's contents to a pixmap and calling TVRD on the pixmap.) The note explains why.
>

A long time ago, I used to have problems with tvrd() when the backing store was set to 1, for some versions of the X server under Linux. It would copy whatever was shown in that area of the screen, meaning if there was another window over the window I was reading from, that window's contents would show up in the result of tvrd(). I have not seen the problem in many years, but I rarely use direct graphics, and I generally stopped using tvrd() from a real window (as opposed to a pixmap), except when doing it interactively (so I would then see the result right away and notice any problems).

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[Message index]

		repeated use of TVRD() gives different results By: wlandsman on Tue, 11 October 2016 11:44
		Re: repeated use of TVRD() gives different results By: Burch on Tue, 11 October 2016 12:55
		Re: repeated use of TVRD() gives different results By: wlandsman on Tue, 11 October 2016 20:29
		Re: repeated use of TVRD() gives different results By: Bill Nel on Wed, 12 October 2016 06:41
		Re: repeated use of TVRD() gives different results By: wlandsman on Wed, 12 October 2016 20:11
		Re: repeated use of TVRD() gives different results By: penteado on Fri, 28 October 2016 12:03
		Re: repeated use of TVRD() gives different results By: rawahranger on Sat, 15 October 2016 11:36

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