#include "l_bitmap.h"

L_LTSCR_API L_INT L_CaptureActiveWindow(pBitmap, uBitmapStructSize, pCaptureInfo, uInfoStructSize, pfnCaptureCallback, pUserData)

Captures an image of the currently active window.



Pointer to a bitmap handle that references the captured data.

L_UINT uBitmapStructSize

Size in bytes, of the structure pointed to by pBitmap, for versioning. Use sizeof(BITMAPHANDLE).


Address of the LEADCAPTUREINFO structure to be filled with information regarding the captured image's source. Pass NULL if you are not interested in extra information about the capture.

L_UINT uInfoStructSize

Size in bytes, of the structure pointed to by pCaptureInfo, for versioning. Use sizeof(LEADCAPTURE).

CAPTURECALLBACK pfnCaptureCallback

Optional callback function for additional processing.

If you do not provide a callback function, use NULL as the value of this parameter. If you do provide a callback function, use the function pointer as the value of this parameter. The callback function must adhere to the function prototype described in CAPTURECALLBACK Function.

L_VOID * pUserData

Void pointer that you can use to pass one or more additional parameters that the callback function needs.

To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID ;*. The callback function, which receives the address in its own pUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure. If the additional parameters are not needed, you can pass NULL in this parameter.


Value Meaning
SUCCESS The function was successful.
< 1 An error occurred. Refer to Return Codes.


This function performs a screen capture of the currently active window. The callback can be used to do multiple captures, depending on the options set using L_SetCaptureOption.

Required DLLs and Libraries

See Also




static L_INT EXT_CALLBACK pfnCaptureCallback(pBITMAPHANDLE    pBitmap, 
                                             pLEADCAPTUREINFO pCaptureInfo, 
                                             L_VOID         * pUserData) 
   /* save the captured image */ 
   return(L_SaveBitmap (MAKE_IMAGE_PATH(TEXT("ActiveWindow.bmp")), pBitmap, FILE_BMP, 0, 0, NULL)); 
L_INT CaptureActiveWindowExample(L_VOID) 
   BITMAPHANDLE    Bitmap; 
   memset(&CaptureInfo, 0, sizeof(LEADCAPTUREINFO)); 
   /*To call the L_CaptureActiveWindow*/ 
   L_INT nRet = L_CaptureActiveWindow (&Bitmap, sizeof(BITMAPHANDLE), 
      &CaptureInfo, sizeof(LEADCAPTUREINFO), 
   if (Bitmap.Flags.Allocated) 
      L_FreeBitmap (&Bitmap); 
   return nRet; 
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LEADTOOLS Screen Capture C API Help