PInvoke void * parameter

[jmcpeak]

Here is the unmanged definition:

 
//============================================================================
// DcamCapture()
// Start to acquire one image from the camera.
// ---------------------------------------------------------------------------
// [Argument]
// pImageBuff : /O: Specify the start address in the buffer where image
// data is to be stored.
// nBuffSize :I/ : Specify the buffer size (number of bytes).
// [Return values]
// If the function succeeds the return value is TRUE (1).
// If the function fails the return value is FALSE (0).
// To obtain detailed error information, use the DcamGetLastError function.
// [Note]
// 1. This function issues an instruction to start image acquisition.
// Since image acquisition is not complete even when this function ends,
// use the DcamWait function to check whether image acquisition is complete.
// 2. The necessary buffer size can be obtained with the DcamGetFrameBytes function.
//============================================================================
_DCAMLIBEXPORT BOOL _DCAMLIBSTDCALL DcamCapture( LPVOID pImageBuff, INT nBuffSize );
 

Here is my C# code which does not work:

class DCamLIB
{
private IntPtr ImageBuffer;
 
public DCamLIB()
{
ImageBuffer = new IntPtr( 0 );
}
 
[DllImport( "DCamLIB.dll" )]
private static extern bool DcamCapture( out IntPtr imageBuffer, Int32 bufferSize );
 
public void Capture( Int32 bufferSize )
{
if ( !DcamCapture( out ImageBuffer, bufferSize ) )
{
throw new DCamLIBException( this );
}
}
}
 

No matter what ImageBuffer = 0.

Ideas?

[tlhintoq]

// 2. The necessary buffer size can be obtained with the DcamGetFrameBytes function.

Question 1: What kind of camera is this?
Question 2: Are you receiving a buffersize from the above function that makes sense for the size of the image you are expecting?

[jmcpeak]

> What kind of camera is this?
X-Ray

> Are you receiving a buffersize from the above function that makes sense for the size of the image you are expecting?
Yes, it is is returning the correct width and height variables - 1000 x 1500

[tlhintoq]

The function doesn't look like it would be turning H & W values, judging by its name: GetFrameBytes. It looks like it would be returning a single number that is the size of the buffer to hold the image data. You would then use your knowledge of the expected data to translate all those bytes to an image (height, width, color depth, header size)

[tlhintoq]

// 1. This function issues an instruction to start image acquisition.
// Since image acquisition is not complete even when this function ends,
// use the DcamWait function to check whether image acquisition is complete.

I don't see where you are checking the DcamWait function.

[jmcpeak]

The real issue I can't solve is how to pass a void * as a parameter to the dll.

[DllImport( "DCamLIB.dll" )]
private unsafe static extern bool DcamCapture( int* imageBuffer, Int32 bufferSize );
 
public unsafe void CaptureReverseX( Int32 bufferSize )
{
    fixed ( int* buf = new int[ bufferSize ] )
    {
        if ( !DcamCapture( ImageBuffer, bufferSize ) )
        {
            throw new DCamLIBException( this );
        }
        // Here the pointer buf is defined, but the value is still 0
        // It's like the DcamCapture() method does not populate buf
    }
}
 

[tlhintoq]

The real issue I can't solve is how to pass a void * as a parameter to the dll.

A void pointer ???

I don't see where you are checking the DcamWait function.

Are you checking the DcamWait function before you try to get the data out of the buffer?

[jmcpeak]

I got it working, needed to change a setting - set the trigger mode to internal. Using fixed worked great.

[cooldj]

HDCAM is a typedef struct tag_dcam* HDCAM


In DCAM-API , HDCAM is one of the input arguments.

which is declare as...
// declaration of DCAM helper function
HDCAM dcamcon_init_open();

In main function it can Initialize as...
HDCAM hdcam;

& call as...
// initialize DCAM-API and get HDCAM camera handle.
hdcam = dcamcon_init_open();


How I can write code in c# if I want to access HDCAM?