edsdk

EDSDK Handler for take pictures


I am trying to creat an Program for my Canon EOS Rebel T7, but when I try to send the command EDSDK.EdsSendCommand(CamConn,EDSDK.CameraCommand_TakePicture, 0) the program returns the error EDS_ERR_INVALID_HANDLE, how I can add an proper Handle for taking picktures? Thanks! Print of code here


Solution

  • First, welcome to StackOverflow.

    Tip for the future: copy/paste code into your question and don't link to a picture. It's easier for everyone to read and maybe copy it to try things themselves.


    Now to your question:

    Where does the CamConn handle come from? It's very likely that the OpenConnection call already returns an invalid handle error.

    To get a valid camera handle you have to do the following:

    public IntPtr[] GetConnectedCameraPointers()
    {
        // get a list of connected cameras
        EDSDK.EdsGetCameraList(out IntPtr cameraList);
        // get the number of entries in that list
        EDSDK.EdsGetChildCount(cameraList, out int cameraCount);
    
        // create an array for the camera pointers and iterate through the list
        var cameras = new IntPtr[cameraCount];
        for (int i = 0; i < cameraCount; i++)
        {
            // gets an item of the list at the specified index
            EDSDK.EdsGetChildAtIndex(cameraList, i, out IntPtr cameraPtr);
            // get a device info for that camera, this is optional but may interesting to have
            EDSDK.EdsGetDeviceInfo(cameraPtr, out EdsDeviceInfo cameraInfo);
            // store the camera pointer in our array
            cameras[i] = cameraPtr;
        }
    
        // release the camera list
        EDSDK.EdsRelease(cameraList);
    
        return cameras;
    }
    

    Note that I haven't checked the returned error codes for simplicity but you should definitely check them.