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Re: Quickly Erasing lines on direct graphics images [message #46265 is a reply to message #46264]

Sat, 12 November 2005 14:22

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Folks,

> Richard G. French writes:
>
>> I have a Direct Graphics question. How can I quickly erase lines that I have
>> drawn in displayed images?
>
> The standard way to do this kind of "quick erasing" is
> to use a pixmap and the "Device Copy" technique.

Participants in my class this week wrote a pixmap object
that proved extremely useful. I've made it available here:

ftp://ftp.dfanning.com/pub/dfanning/outgoing/misc/pixmap__de fine.pro

To create a pixmap with an X size of 300 and a Y size
of 400 pixels, you do this:

pixmap = Obj_New('pixmap', XSize=300, YSize=400)

Given that you have something in IDL graphics window
2 that you want to copy to a pixmap, you would do this:

pixmap -> CopyToPixmap, 2

Or, you can simply draw graphics in the pixmap:

pixmap -> SetWindow
Plot, findgen(11) ; etc.

To copy to a window, say window index number 3:

pixmap -> CopyToWindow, 3

If you wish to make the pixmap a different size (for
example, in a resizeable graphics window application):

pixmap -> Resize, newXsize, newYsize

But, best of all, if you want to see what you actually
have in the pixmap (i.e., so you can debug your program):

pixmap -> Map, 1

To hide it again:

pixmap -> Map, 0

Be sure to destroy it when you are done. If it is
mapped, you can destroy it with your mouse. If not,
you must do it like this:

Obj_Destroy, pixmap

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/

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[Message index]

		Re: Quickly Erasing lines on direct graphics images By: Richard French on Mon, 14 November 2005 05:11
		Re: Quickly Erasing lines on direct graphics images By: David Fanning on Sun, 13 November 2005 21:19
		Re: Quickly Erasing lines on direct graphics images By: Richard French on Sun, 13 November 2005 17:48
		Re: Quickly Erasing lines on direct graphics images By: Richard French on Sun, 13 November 2005 17:37
		Re: Quickly Erasing lines on direct graphics images By: David Fanning on Sat, 12 November 2005 14:22
		Re: Quickly Erasing lines on direct graphics images By: David Fanning on Sat, 12 November 2005 08:31

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