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Re: Object Graphics [message #39388 is a reply to message #9626]

Tue, 11 May 2004 19:42

Michael Wallace
Messages: 409
Registered: December 2003

Senior Member

> Well, you can make the argument that retaining an object
> graphics window is a gross misuse of the Earth's resources.
> Why retain? You have the whole damn graphics hierarchy
> already in memory. When you get an EXPOSE event in your
> draw widget, just re-draw the graphics.

window = obj_new('IDLgrWindow', RETAIN=0)

This command works like a charm. No error. No problem. I had a setup
file I was using which always set RETAIN to 2 since my work up until now
had been in Direct Graphics. And for the curious, here's what RSI has
to say about this buried way down in their documentation:

In some situations, IDL cannot provide this backing store.

In IDL Object Graphics, it is almost always best to disable backing
store (that is, set the RETAIN property equal to zero). This is because
drawing to an off-screen pixmap (which is what happens when backing
store is enabled) almost always bypasses any hardware graphics
acceleration that may be available, causing all rendering to be done in
software. To ensure that windows are redrawn properly, enable the
generation of expose events on the WIDGET_DRAW window and redraw the
windows explicitly when an expose event is received.

If you are using software rendering (that is, the RENDERER property is
set equal to one), IDL will refresh the window automatically regardless
of the setting of the RETAIN property.

> That's what you *had* to do when object graphics were
> first released, although they have become more user
> friendly over the years. (To much chagrin in the IEPA,
> I can tell you!) You can think of this (if you choose,
> of course) as your machine wanting to force you into
> good programming practices. Those of us with Windows
> machines will be drooling at your good luck! :-)

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[Message index]

		Object Graphics By: Reinhold Kroll on Wed, 23 July 1997 00:00
		Re: Object Graphics By: Michael Wallace on Thu, 13 May 2004 08:10
		Re: Object Graphics By: Karl Schultz on Thu, 13 May 2004 07:17
		Re: Object Graphics By: Michael Wallace on Wed, 12 May 2004 14:14
		Re: Object Graphics By: Rick Towler on Wed, 12 May 2004 13:15
		Re: Object Graphics By: David Fanning on Wed, 12 May 2004 12:39
		Re: Object Graphics By: Michael Wallace on Wed, 12 May 2004 11:36
		Re: Object Graphics By: Rick Towler on Wed, 12 May 2004 10:25
		Re: Object Graphics By: marc schellens[1] on Wed, 12 May 2004 00:52
		Re: Object Graphics By: Mark Hadfield on Tue, 11 May 2004 20:33
		Re: Object Graphics By: Michael Wallace on Tue, 11 May 2004 19:42
		Re: Object Graphics By: David Fanning on Tue, 11 May 2004 18:12
		Re: Object Graphics By: Michael Wallace on Tue, 11 May 2004 18:06
		Re: Object Graphics By: Michael Wallace on Tue, 11 May 2004 17:58
		Re: Object Graphics By: David Fanning on Tue, 11 May 2004 16:18

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