Ketan,
The Symbol API is nice, but I would be wary of it's use as it makes you hardware dependent - e.g. Unless you modify the code and remove the control from the projects, you won't be able to use the CE program on another device (Jornada, iPaq, Intermec, etc.) Secondly, Symbol makes more then one decive for scanning in CE. In fact, they have two other devices that act as add-ons to other CE devices. One is the SPS3000, and the other is sold by a company called Socket Devices (the "In-Hand" scanner). All three use the EXACT same bascis API engine to scan information. The only difference is implementation. The PPT devices already have a button that initiates the scanner, the others require a software trigger to run.
Now, if you're not adverse to writing a small C/C++ program, you can implement a "one size fits all" solution for your scanning needs by writing a DLL or separate EXE file to access the API directly.
If you'll notice in the \Windows directory on your handheld, there is an API called SCNAPI32.DLL. This is the scan engine that the Symbol API interfaces with to access the scanner. It exports a buch of functions that you can use to access the scanner. These are as follows:
LPSCAN_BUFFER_W (CALLBACK *SCAN_AllocateBuffer_W)(BOOL bText,DWORD dwSize);
DWORD (CALLBACK *SCAN_DeallocateBuffer_W)(LPSCAN_BUFFER_W lpScanBuffer);
DWORD (CALLBACK *SCAN_FindFirst_W)(LPSCAN_FINDINFO_W lpScanFindInfo,LPHANDLE lphFindHandle);
DWORD (CALLBACK *SCAN_FindNext_W)(LPSCAN_FINDINFO_W lpScanFindInfo,HANDLE hFindHandle);
DWORD (CALLBACK *SCAN_FindClose)(HANDLE hFindHandle);
DWORD (CALLBACK *SCAN_Open)(LPCTSTR lpszDeviceName,LPHANDLE lphScanner);
DWORD (CALLBACK *SCAN_GetVersionInfo)(HANDLE hScanner,LPSCAN_VERSION_INFO lpScanVersionInfo);
DWORD (CALLBACK *SCAN_Close)(HANDLE hScanner);
DWORD (CALLBACK *SCAN_Enable)(HANDLE hScanner);
DWORD (CALLBACK *SCAN_Disable)(HANDLE hScanner);
DWORD (CALLBACK *SCAN_ReadLabelEvent_W)(HANDLE hScanner,LPSCAN_BUFFER_W lpScanBuffer,HANDLE hEvent,DWORD dwTimeout,LPDWORD lpdwRequestID);
DWORD (CALLBACK *SCAN_ReadLabelMsg_W)(HANDLE hScanner,LPSCAN_BUFFER_W lpScanBuffer,HWND hWnd,UINT uiMsgNo,DWORD dwTimeout,LPDWORD lpdwRequestID);
DWORD (CALLBACK *SCAN_ReadLabelWait_W)(HANDLE hScanner,LPSCAN_BUFFER_W lpScanBuffer,DWORD dwTimeout);
DWORD (CALLBACK *SCAN_CancelRead)(HANDLE hScanner,DWORD dwRequestID);
DWORD (CALLBACK *SCAN_Flush)(HANDLE hScanner);
DWORD (CALLBACK *SCAN_GetSoftTrigger)(HANDLE hScanner,LPBOOL lpSoftTrigger);
DWORD (CALLBACK *SCAN_SetSoftTrigger)(HANDLE hScanner,LPBOOL lpSoftTrigger);
DWORD (CALLBACK *SCAN_GetDeviceInfo)(HANDLE hScanner,LPDEVICE_INFO lpDeviceInfo);
DWORD (CALLBACK *SCAN_GetSupportedDecoders)(HANDLE hScanner,LPDECODER_LIST lpDecoderList);
DWORD (CALLBACK *SCAN_GetEnabledDecoders)(HANDLE hScanner,LPDECODER_LIST lpDecoderList);
DWORD (CALLBACK *SCAN_SetEnabledDecoders)(HANDLE hScanner,LPDECODER_LIST lpDecoderList);
DWORD (CALLBACK *SCAN_GetDecoderParams)(HANDLE hScanner,LPDECODER lpDecoder,LPDECODER_PARAMS lpDecoderParams);
DWORD (CALLBACK *SCAN_SetDecoderParams)(HANDLE hScanner,LPDECODER lpDecoder,LPDECODER_PARAMS lpDecoderParams);
DWORD (CALLBACK *SCAN_GetUPCEANParams)(HANDLE hScanner,LPUPC_EAN_PARAMS lpUPCEANParams);
DWORD (CALLBACK *SCAN_SetUPCEANParams)(HANDLE hScanner,LPUPC_EAN_PARAMS lpUPCEANParams);
DWORD (CALLBACK *SCAN_GetReaderParams)(HANDLE hScanner,LPREADER_PARAMS lpReaderParams);
DWORD (CALLBACK *SCAN_SetReaderParams)(HANDLE hScanner,LPREADER_PARAMS lpReaderParams);
DWORD (CALLBACK *SCAN_GetInterfaceParams)(HANDLE hScanner,LPINTERFACE_PARAMS lpInterfaceParams);
DWORD (CALLBACK *SCAN_SetInterfaceParams)(HANDLE hScanner,LPINTERFACE_PARAMS lpInterfaceParams);
DWORD (CALLBACK *SCAN_GetScanParameters_W)(HANDLE hScanner,LPSCAN_PARAMS_W lpScanParams);
DWORD (CALLBACK *SCAN_SetScanParameters_W)(HANDLE hScanner,LPSCAN_PARAMS_W lpScanParams);
DWORD (CALLBACK *SCAN_GetScanStatus)(HANDLE hScanner,LPSCAN_STATUS lpScanStatus);
DWORD (CALLBACK *SCAN_RegisterScanMessage)(HANDLE hScanner,HWND hWnd,UINT uiMessage);
DWORD (CALLBACK *SCAN_DeregisterScanMessage)(HANDLE hScanner);
DWORD (CALLBACK *SCAN_DoRemoteFeedback)(HANDLE hScanner,LPFEEDBACK_PARAMS lpFeedbackParams);
DWORD (CALLBACK *SCAN_Ioctl)(HANDLE hScanner,DWORD dwIoctlCode,LPVOID lpvInBuf,DWORD dwInBufSize,LPVOID lpvOutBuf,DWORD dwOutBufSize,LPDWORD lpdwActualOut);
Note that I load the DLL explicitly (I don't let the system do it for me, or create the thunks during the link phase of building my C/C++ program), and import all of the functions into my routine via the LoadLibrary() API routine. So they look a little strange.
The basic process is this:
1) Call the SCAN_Open() function to access the scanner. You can used "SCN:" as the port name (this is the default scanner known by the CE device). This function returns back a scanner handle.
2) call the SCAN_Enable() to tell the scanner that it will be used for scanning.
3) call SCAN_AllocateBuffer() to allocate memory to store the scan results.
4) Call SCAN_ReadLabelMsg() to start the scan beam. This function requires the scanner handle, the allocated buffer gotten from SCAN_AllocateBuffer(), a windows message to return to the window when the scan is complete, and a timeout value (to turn off the beam).
5) When the scan is complete, the Windows Message passed in the SCANReadLabelMsg() function will be triggered, and the lParam of the message will contain the results of the scan (the text data).
6) The buffer must be analysed to get the status code, but at this time, you can pass this information back to your program.
7) Use SCAN_Disable() to disconnect from the scanner.
8) Use SCAN_Close to close the scanner, and then you're done.
Note, that some sample code can be found with the SPS3000 developer's API, which gives a better illustration then I have done here. ALl in all, it took me a week to research, develop, and test. Low and behold, it workd for all three.
Hope this helps.
