QT example of a method that USES canon sdk to take a photo and save it to the machine

1. An overview of the

Connect canon SLR through usb, take photos through QT, and save the captured images to the machine.

2. Operation steps

1. Initialize SDK

EdsInitializeSDK();

2. Get the camera list object

  EdsCameraListRef cameraList = NULL;
  error = EdsGetCameraList(&cameraList);

3. Get the number of camera list objects

  //  Iterate through the camera list objects to get the number of camera list objects 
  EdsUInt32 cameraCount = 0;
  error = EdsGetChildCount(cameraList, &cameraCount);
  if (error != EDS_ERR_OK)
  {
    qDebug() << "ERROR - failed to get camera count";
    EdsRelease(cameraList);
    return;
  }

4. Get a single camera object instance

  for (uint32_t idx = 0; idx < cameraCount; idx++)
  {
    //  Gets a single camera object 
    EdsCameraRef cam = NULL;
    error = EdsGetChildAtIndex(cameraList, idx, &cam);
    m_camera = cam;
  }

And then what we do with the camera is mainly through this.

5. Set up camera sessions

EdsOpenSession(m_camera);

6. Save the picture to the machine

  EdsUInt32 saveTo = kEdsSaveTo_Both;    //  Save to camera and native 
  //EdsUInt32 saveTo = kEdsSaveTo_Host;  //  Save to local 
  error = EdsSetPropertyData(m_camera, kEdsPropID_SaveTo, 0, sizeof(saveTo), &saveTo);

7. Set a large enough capacity to store pictures on the machine

  EdsCapacity capacity = {0x7FFFFFFF, 0x1000, 1};
  error = EdsSetCapacity(m_camera, capacity);

8. Register a handle to an object event

error = EdsSetObjectEventHandler(m_camera, kEdsObjectEvent_All, objectEventHandler, this);

But a change in the camera object triggers the objectEventHandler callback

9. objectEventHandler callback function

EdsError EDSCALLBACK MainWindow::objectEventHandler(EdsUInt32 inEvent, EdsBaseRef inRef, EdsVoid* inContext)
{
  EdsStreamRef stream = NULL;
  EdsDirectoryItemInfo dirItemInfo;
  QString m("C:/Users/Administrator/Desktop/");
  switch (inEvent)
  {
   //  Notify the object ( Such as a new folder or file ) The creation of 
   case kEdsObjectEvent_DirItemCreated:
      qDebug() << "Directory Item Created";
      break;
   //  Notifies the camera that an object is to be transferred to the computer. 
   case kEdsObjectEvent_DirItemRequestTransfer:
      qDebug() << "Directory Item Requested Transfer";
      err = EdsGetDirectoryItemInfo(inRef, &dirItemInfo);
      m = m + dirItemInfo.szFileName;  //  Splice local image to save location 
      //  Download the picture to the machine 
      err = EdsCreateFileStream(m.toStdString().data(), kEdsFileCreateDisposition_CreateAlways, kEdsAccess_ReadWrite, &stream);
      if (err != EDS_ERR_OK)
      {
       qDebug("failed to create file stream");
      }
      err = EdsDownload(inRef, dirItemInfo.size, stream);
      if (err != EDS_ERR_OK)
      {
       qDebug("failed to download");
      }
      err = EdsDownloadComplete(inRef);
      if (err != EDS_ERR_OK)
      {
        qDebug("failed to mark download as complete");
      }
      EdsRelease(stream);
      stream = NULL;
      break;
    default:
        qDebug() << " unknowns ";
        break;
    }
   return EDS_ERR_OK;
}

10. Send the command to take photos

error = EdsSendCommand(m_camera, kEdsCameraCommand_TakePicture, 0);

11. Close the camera session

  EdsCameraListRef cameraList = NULL;
  error = EdsGetCameraList(&cameraList);

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12. End SDK

  EdsCameraListRef cameraList = NULL;
  error = EdsGetCameraList(&cameraList);

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3. References

Canon EDSDK Tutorial in C#
EDSDK-cpp
Cinder-EDSDK