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Re: Turn Object Automatic Clean-up Off? [message #81466 is a reply to message #81465]

Thu, 20 September 2012 14:11

DavidF[1]
Messages: 94
Registered: April 2012

Member

Marc writes:

> Out of curiosity:
>
> Could you please post an example code where this problem is exposed?
> How can an object which has no references any more be of relevance in
> an IDL program?
>
> I have a lack of imagination here.

Alright, here is *another* irritating example. I have a widget program,
cgZImage, that allows me to zoom into an image. As I move my cursor over
the zoomed image, it prints out the image location and the value of
the image at that location.

I'm working with GeoTiff files a lot, so it would be useful to
have the image location in lat/lon values rather than pixel values.
I want to pass the program a cgMap object, which is what I use to set up
a map projection and coordinate system. I can use this object to covert
a pixel location to a lat/lon value.

I create the map object outside the program:

mapObj = cgGeoMap(geoTiffFile, Image=image)

Then, I pass both the image and the map object into
my widget program:

cgZImage, image, Map=mapObj

Inside the program, I store the map object in the info
structure of the program, and try to use it in an event
handler. It is always invalid!!

Indeed:

IDL> mapObj = cgGeoMap(geoTiffFile, Image=image)
IDL> Print, Obj_Valid(mapObj)
1
IDL> cgZImage, image, MAP=mapObj
IDL> Print, Obj_Valid(mapObj)
0

Not at all what I wanted!

Cheers,

David

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[Message index]

		Re: Turn Object Automatic Clean-up Off? By: DavidF[1] on Thu, 20 September 2012 14:32
		Re: Turn Object Automatic Clean-up Off? By: DavidF[1] on Thu, 20 September 2012 14:11
		Re: Turn Object Automatic Clean-up Off? By: Lajos Foldy on Thu, 20 September 2012 08:07
		Re: Turn Object Automatic Clean-up Off? By: David Fanning on Thu, 20 September 2012 07:09
		Re: Turn Object Automatic Clean-up Off? By: m_schellens on Thu, 20 September 2012 06:49
		Re: Turn Object Automatic Clean-up Off? By: Lajos Foldy on Tue, 18 September 2012 14:03
		Re: Turn Object Automatic Clean-up Off? By: DavidF[1] on Tue, 18 September 2012 13:57
		Re: Turn Object Automatic Clean-up Off? By: Lajos Foldy on Tue, 18 September 2012 13:43

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