| Re: object oriented dilemma [message #21925] |
Mon, 09 October 2000 00:00 |
Jason Li
Messages: 7
Registered: April 1999
|
Junior Member |
|
|
Hi David,
>
> I presume you mean you are taking a line of your image
> like this:
>
> line = (*self.imagePointer)[5,*]
That is what I was looking for. I had searched the manual all over, just
could not find an example on how to dereference an element of a pointer that
is pointing to an array. Basically I messed up the syntax. In hindsight,
(*pointer)[i,j] makes a lot of sense.
Thanks very much! Now I can chuck along in my OOP adventure.
PS. Thanks for your recommendation on Arthur Riel's book.
|
|
|
|
| Re: object oriented dilemma [message #21926 is a reply to message #21925] |
Mon, 09 October 2000 00:00  |
davidf
Messages: 2866
Registered: September 1996
|
Senior Member |
|
|
Jason Li (jylimd@yahoo.com) writes:
> If I want to write an image processing software using OOP method, I would
> normally define a structure in __define module:
>
> PRO myProgram__define
> struct = {imagePointer:Ptr_New()}
> END
>
> Traditionally, a pointer is used to take care of variable image size. Then
> load an image to self.imagePointer in the myProgram__init module.
>
> hugeImage = bytarr(huge, huge)
> self.imagePointer = Ptr_New(hugeImage, /no_copy)
>
>
> Now in my METHOD modules, I have to perform an operation on line by line
> basis. I don't know how to get a line data out of this self.imagePointer
> without making a copy (dereferencing) of it first. My image size is rather
> large. I don't how to be more memory efficient.
>
> Question: What is the solution to this?
I presume you mean you are taking a line of your image
like this:
line = (*self.imagePointer)[5,*]
I find it hard to believe (given what I know about how
pointers work in IDL) that this takes any more memory
than this does:
line = self.image[5,*]
What evidence do you have that a huge amount of memory
is being used?
Everything I know about pointer variables convinces me
that they are really treated like any other IDL variable
inside of IDL. Evidence to the contrary would be depressing. :-(
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
