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Re: IDL Shapefile Object [message #28298 is a reply to message #28297]

Thu, 29 November 2001 13:26

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Kelly Dean (krdean@lamar.colostate.edu) writes:

> I created a little procedure to plot Shapefiles with IDLffShape.
> However, it has a memory leak. Can someone point out a plug to stop my
> memory leak?
>
> The routine works great, but when I have to add graphics to 800 images,
> I run out of memory at around 500 images.
>
> A sample routine is available at ...
>
> ftp://ftp.cira.colostate.edu/Dean/teststate.pro

The problem here is that the shapefile object returns
a structure that itself has pointers in it. (This is really
the only way it can be done, because the object doesn't
really know anything about the actual shapefile you will
load.)

When this happens, you are responsible for cleaning
those pointers up yourself. Your particular test program
can clean itself up by changing these lines in the DrawSHPMap
module:

pEnts = PTR_NEW(/ALLOCATE_HEAP)
*pEnts = oShapefile->GetEntity(/ALL, /ATTRIBUTES)
;
FOR I = N_ELEMENTS(*pEnts)-1, 0, -1 DO BEGIN
PlotEnt, (*pEnts)[I], color=color
ENDFOR

To this:

pEnts = PTR_NEW(/ALLOCATE_HEAP)
*pEnts = oShapefile->GetEntity(/ALL, /ATTRIBUTES)
;
FOR I = N_ELEMENTS(*pEnts)-1, 0, -1 DO BEGIN
PlotEnt, (*pEnts)[I], color=color
Ptr_Free, ((*pEnts)[I]).vertices
Ptr_Free, ((*pEnts)[I]).measure
Ptr_Free, ((*pEnts)[I]).parts
Ptr_Free, ((*pEnts)[I]).part_types
Ptr_Free, ((*pEnts)[I]).attributes
ENDFOR
Ptr_Free, pEnts

That should do it. :-)

Cheers,

David

--
David W. Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155

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[Message index]

		Re: IDL Shapefile Object By: Kelly Dean on Fri, 30 November 2001 11:52
		Re: IDL Shapefile Object By: alt on Thu, 29 November 2001 19:29
		Re: IDL Shapefile Object By: Mark Hadfield on Thu, 29 November 2001 17:26
		Re: IDL Shapefile Object By: David Fanning on Thu, 29 November 2001 16:40
		Re: IDL Shapefile Object By: Mark Hadfield on Thu, 29 November 2001 15:47
		Re: IDL Shapefile Object By: David Fanning on Thu, 29 November 2001 14:31
		Re: IDL Shapefile Object By: David Fanning on Thu, 29 November 2001 13:26
		Re: IDL Shapefile Object By: mvukovic on Mon, 03 December 2001 07:15

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