| Re: IDL and C- [message #39413] |
Thu, 20 May 2004 13:50  |
rsmith1
Messages: 3
Registered: May 2004
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Junior Member |
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M. Katz-
Thanks a bunch for your response. I tried the code and ran into more
issues. Upon using the call_external it simply converts the image
variable back to a long since IDL does its variable type declarations
on the fly. I then tried the following code:
image = ptr_new(bytarr(call_external("C:\Users\11ryan\CIDLFinal\testDLL\Debug\testDLL.dll ","testDLL")))
window, xsize=640, ysize=480 ;--- open a window for display
help, image
tvscl, *image
And the help, image says that it is a pointer, but when trying to
display it i get an error saying TVSCL: Width and Height must be less
than 32000. It looks as if it is trying to take the value and use it
as a dimension instead. Any more advice on what I could try? thanks
again for all the help-
-Ryan
MKatz843@onebox.com (M. Katz) wrote in message news:<4a097d6a.0405192255.693cd62b@posting.google.com>...
> This is just a guess, but you might try the following.
>
> ;--- declare image as a pointer to an array of byte type
> image = ptr_new(bytarr(640,480))
> image = call_external("C:\11ryan\temp\Debug\testDLL.dll","testDLL ")
> window, xsize=640, ysize=480 ;--- open a window for display
> tvscl, *image ;--- scale and display the contents of the image pointer
>
> after the call_external, you might also issue
> print, image
> If it returns something like this <PtrHeapVar1> then it's certainly a pointer.
> M. Katz
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| Re: IDL and C- [message #39475 is a reply to message #39413] |
Mon, 24 May 2004 11:51  |
MKatz843
Messages: 98
Registered: March 2002
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Member |
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> .... I then tried the following code:
> image = ptr_new(bytarr(call_external("C:\Users\11ryan\CIDLFinal\testDLL\Debug\testDLL.dll ","testDLL")))
> window, xsize=640, ysize=480 ;--- open a window for display
> help, image
> tvscl, *image
>
> And the help, image says that it is a pointer, but when trying to
> display it i get an error saying TVSCL: Width and Height must be less
> than 32000. It looks as if it is trying to take the value and use it
> as a dimension instead. Any more advice on what I could try? ...
When you say
BYTARR(something) you're creating a new array of zeros with a size
given by "something." That's not what you wanted. You might want the
BYTE() function, but even that should be unnecessary. I have found
that in some cases, it's important to use a RETURN_TYPE keyword with
call_externals. You're talling the call_external what type of data is
being returned. Double check the list below with the IDL manual, but I
think it goes like this:
1 = Byte
2 = Integer
3 = Longword Integer
4 = Floating-point
5 = Double-precision floating
6 = Complex floating
7 = String
8 = Structure
9 = Double-precision complex
10 = Pointer
11 = Object reference
12 = Unsigned Integer
13 = Unsigned Longword Integer
14 = 64-bit Integer
15 = Unsigned 64-bit Integer
Your camera software will probably return Byte or Unsigned Integer
types (or a pointer to them). So in the Call_External, you'd add
RETURN_TYPE = 1, if appropriate.
image = ptr_new( call_external("...testDLL.dll","testDLL",
RETURN_TYPE=1 ) )
If that doesn't work, figure out exactly what types these data are
coming back as.
IDL> print, size( call_external("...testDLL.dll","testDLL") , /type)
See the SIZE() function for more information on this.
If it's returning a pointer, then don't do the RETURN_TYPE=1 above.
M. Katz
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| Re: IDL and C- [message #39510 is a reply to message #39413] |
Thu, 20 May 2004 14:49 |
JD Smith
Messages: 850
Registered: December 1999
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Senior Member |
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On Thu, 20 May 2004 13:50:43 -0700, Ryan Smith wrote:
> M. Katz-
>
> Thanks a bunch for your response. I tried the code and ran into more
> issues. Upon using the call_external it simply converts the image
> variable back to a long since IDL does its variable type declarations
> on the fly. I then tried the following code:
> image = ptr_new(bytarr(call_external("C:\Users\11ryan\CIDLFinal\testDLL\Debug\testDLL.dll ","testDLL")))
> window, xsize=640, ysize=480 ;--- open a window for display
> help, image
> tvscl, *image
>
> And the help, image says that it is a pointer, but when trying to
> display it i get an error saying TVSCL: Width and Height must be less
> than 32000. It looks as if it is trying to take the value and use it
> as a dimension instead. Any more advice on what I could try? thanks
> again for all the help-
>
> -Ryan
>
> MKatz843@onebox.com (M. Katz) wrote in message news:<4a097d6a.0405192255.693cd62b@posting.google.com>...
>> This is just a guess, but you might try the following.
>>
>> ;--- declare image as a pointer to an array of byte type
>> image = ptr_new(bytarr(640,480))
>> image = call_external("C:\11ryan\temp\Debug\testDLL.dll","testDLL ")
>> window, xsize=640, ysize=480 ;--- open a window for display
>> tvscl, *image ;--- scale and display the contents of the image pointer
>>
>> after the call_external, you might also issue
>> print, image
>> If it returns something like this <PtrHeapVar1> then it's certainly a pointer.
>> M. Katz
You can't just return a raw character pointer from C and expect IDL to
convert it into an IDL array variable. The traditional way to do this
is first make an array in IDL, pass it by reference to the function
via call_external, and copy the camera data over to it before
returning. Something like:
image=bytarr(1024,1024)
ret = call_external("C:\11ryan\temp\Debug\testDLL.dll","testDLL ",image)
and in the C code:
int _blah _blah newtestDLL(int argc, void *argv[]) {
char *buffer,*out;
int i;
/* Grab buffer from the camera */
...
/* Copy to output array */
out=(char *)argv[0]; /* This points to the IDL image variable's data */
for(i=0;i<1024*1024;i++) out[i]=buffer[i];
return 1;
}
Note that IDL pointers and C pointers are completely different beasts
which share almost nothing in common (IDL's could more properly have
been called "references").
JD
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