Thank you for fast answer.
Unfortunately the "fosdk" library is from vendor and I can't change
that. The values of parameters are non-issue, I was lost with the
declaration of callback function and passing the function to
FOSDKSetCallback.
I defined my own delegate (or copied from example I found from documentation):
Imports System
Imports System.Runtime.InteropServices
public class MyDeleg
Public Delegate Function MyCallback(ByVal pCBContext As Integer, ByVal
SampleTime As Double, _
ByVal pBuf As IntPtr, ByVal
lBufferSize As Integer) As Integer
End Class
Compiled it and all seemed go OK until the conversion to Int64, so I
got to this:
from System.Runtime.InteropServices import Marshal
FOSDKSetCallback(0,
Marshal.GetFunctionPointerForDelegate(MyDelegate(myCallback)).ToInt64(),
0)
Seems pretty ok for now, next I've to figure out how to get the whole
system working and start receiving callbacks, but that's different
problem..
Some more VB.NET samples:
'Delgate for callback function
Public Delegate Function MyCallback(ByVal pCBContext As Integer, ByVal
SampleTime As Double, _
ByVal pBuf As IntPtr, ByVal
lBufferSize As Integer) As Integer
<snip>
Private cb As MyCallback 'If the callback is called
asynchronously, you have to ensure that the
'callback delegate is alive as long as the function poitner is needed.
<snip>
cb = AddressOf MyCallbackFunc
<snip>
FosdkApi.FOSDKSetCallback(g_iCrntCam, cb, 12)
<snip>
Public Function MyCallbackFunc(ByVal pCBContext As Integer, ByVal
SampleTime As Double, _
ByVal pBuf As IntPtr, ByVal
lBufferSize As Integer) As Integer
sTime = SampleTime
bSize = lBufferSize
ThreadPool.QueueUserWorkItem(AddressOf ShowCallbackMsg) '
show messages in a seperate thread
Return 1
End Function
On Tue, Mar 4, 2008 at 9:24 PM, Dino Viehland
<[EMAIL PROTECTED]> wrote:
> Calling it isn't really the interesting part, the interesting part is what
> arguments do you pass to it.
>
> To call it you just need to import the class that the function is defined
> in. You can do that using:
>
> import clr
> clr.AddReference('VBAssemblyName')
> from VBNamespaceName import *
>
> where VBAssemblyName is the name of the VB assembly and VBNamespaceName is
> the name of the namespace this type lives in. From there you should be able
> to do:
>
> VBTypeName.FOSDKSetCallback(...)
>
> Then the question becomes what do you pass for nCamIndex, pCallbackFunc, and
> pCBContext.
>
> But before we go there there's a few interesting things about the
> signatures. First is that they're declared as taking Int64's instead of
> IntPtr's. If this is your own DLL then you probably want to change these to
> IntPtrs so they're passing the right size data on both 32-bit and 64-bit
> platforms. Then your callback function would look something like:
>
> Public Declare Function FOSDKSetCallback Lib "FOSDK" (ByVal nCamIndex As
> IntPtr, ByVal pCallbackFunc As Long, ByVal pCBContext As IntPtr) As Long
>
> The 2nd oddity is that pCallbackFunc is not taking a delegate. That means
> you'll need to manually call Marshal.GetFunctionPointerForDelegate on a
> delegate object. Which also means you're going to need to manually construct
> the delegate object. Again if you can change the signature you probably want
> to have this taking a delegate typed something like (using the C# syntax
> here):
>
> delegate int MyDelegate(IntPtr pContext, double sampleTime, IntPtr pBuf, int
> lBufferSize);
>
> Then your VB function would end up looking something like:
>
> Public Declare Function FOSDKSetCallback Lib "FOSDK" (ByVal nCamIndex As
> Long, ByVal pCallbackFunc As MyDelegate, ByVal pCBContext As IntPtr) As Long
>
> >From there you should be able to do:
>
> def myCallback(context, sampleTime, buffer, bufferSize):
> print context, sampleTime, buffer, bufferSize
>
> from System import IntPtr
> FOSDKSetCallback(0, myCallback, IntPtr.Zero)
>
> The only interesting thing then is what you need to pass in for nCamIndex,
> hopefully the library documentation will explain that :)
>
> If you can't change the signature you'll still need to define the delegate
> type somewhere (which you can't do from IronPython). Then your call will
> probably end up looking like:
>
> from System import Marshal, Int64
> FOSDKSetCallback(0,
> Int64(Marshal.GetFunctionPointerForDelegate(MyDelegate(myCallback))), 0)
>
>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Harri
> Vartiainen
> Sent: Tuesday, March 04, 2008 9:24 AM
> To: [email protected]
> Subject: [IronPython] Using callback function
>
> Hi,
>
> I'm trying to use callback function of dll. The API has VB.NET
> definition for callback:
>
> Public Class FosdkApi
> ...
> ' set callback function
> 'FOSDKLIB_API BOOL WINAPI FOSDKSetCallback(IN INT nCamIndex,
> ' IN INT (CALLBACK
> *pCallbackFunc)(VOID *pContext, DOUBLE SampleTime, BYTE *pBuf, LONG
> lBufferSize)
> '
> IN VOID *pCBContext);
>
> Public Declare Function FOSDKSetCallback Lib "FOSDK" (ByVal
> nCamIndex As Long, ByVal pCallbackFunc As Long, ByVal pCBContext As
> Long) As Long
>
> Help(FosdkApi.FOSDKSetCallback) prints:
>
> Help on built-in function FOSDKSetCallback
>
> | FOSDKSetCallback(...)
> | Int64 FOSDKSetCallback(Int64 nCamIndex, Int64
> pCallbackFunc, Int64 pCBContext)
>
> So how I can use that?
> _______________________________________________
> Users mailing list
> [email protected]
> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
> _______________________________________________
> Users mailing list
> [email protected]
> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
>
_______________________________________________
Users mailing list
[email protected]
http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
