LBase::OverlayCallBack

#include "ltwrappr.h"

virtual L_INT LBase::OverlayCallBack(pOverlayCallbackData)

Override this function to get the overlay bitmap and other information from the user when loading a file containing an overlay.

Returns

Comments

When loading a file containing an overlay, typically PTOCA files, LEADTOOLS will call this function to let the user provide the overlay bitmap. Typically, the overlay bitmap is in a different file on the disk. The callback can be called before or after LEADTOOLS tries to load the overlay bitmap. For more information, refer to LBase::EnableOverlayCallBack.

When this function is called, you should fill the appropriate fields in the FILEOVERLAYCALLBACKDATA structure to set up the overlay bitmap and its information. For more information, refer to the FILEOVERLAYCALLBACKDATA structure

Required DLLs and Libraries

See Also

Example

class LUserBitmapExt : public LBitmap  
{
   public: 
      LUserBitmapExt();
      virtual L_INT  OverlayCallBack(pFILEOVERLAYCALLBACKDATA pOverlayCallbackData); 
      virtual ~LUserBitmapExt();
      LMemoryFile MyBitmap; 
};
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
LUserBitmapExt::LUserBitmapExt()
{
}
LUserBitmapExt::~LUserBitmapExt()
{
}
L_INT LUserBitmapExt::OverlayCallBack(pFILEOVERLAYCALLBACKDATA pOverlayCallbackData) 
{
   L_TCHAR szBuffer[800]; 
   L_TCHAR szOverlayFileName[_MAX_PATH]; 
   FILEINFO FileInfo; 
   L_INT nRet; 
   LBitmap MyBitmap; 
   // show overlay information
   wsprintf(szBuffer, TEXT("File: %s\nPageNumber: %d\nInfo: %d"),
      pOverlayCallbackData->pszFilename, 
      pOverlayCallbackData->nPageNumber, 
      pOverlayCallbackData->bInfo); 
   MessageBox(NULL, szBuffer, TEXT("Overlay Callback"), 0); 
   // construct the overlay file name (assume its c:\temp\overlay_#.tmp where # is the page number) 
   wsprintf(szOverlayFileName, TEXT("c:\\temp\\overlay_%d.tmp"), pOverlayCallbackData->nPageNumber); 
   MyBitmap.SetFileName(szOverlayFileName); 
   if(pOverlayCallbackData->bInfo) 
   {
      // info, we only need to fill in the nInfoXXX members of the structure
      ZeroMemory(&FileInfo, sizeof(FILEINFO)); 
      nRet = MyBitmap.File()->GetInfo(&FileInfo, sizeof(FILEINFO) ,0, NULL); 
      if(nRet == SUCCESS) 
      {
         pOverlayCallbackData->nInfoWidth = FileInfo.Width; 
         pOverlayCallbackData->nInfoHeight = FileInfo.Height; 
         pOverlayCallbackData->nInfoXResolution = FileInfo.XResolution; 
         pOverlayCallbackData->nInfoYResolution = FileInfo.YResolution; 
      }
   }
   else
   {
      // we need to load the overlay bitmap into the pLoadBitmap member
      nRet = MyBitmap.File()->Load(0, 
											  ORDER_BGRORGRAY, 
											  NULL, 
											  NULL); 
											  *pOverlayCallbackData->pLoadBitmap = *MyBitmap.GetHandle();
   }
   return nRet; 
}
L_INT LBase__OverlayCallBackExample() 
{
	L_INT nRet;
   L_TCHAR* pszPtokaFileName = TEXT("c:\\temp\\SUPPLEMENT ON CHECK.tmp");
   L_TCHAR* pszTiffFileName = TEXT("%UserProfile%\\My Documents\\LEADTOOLS Images\\test.tif");
   LUserBitmapExt Bitmap; 
   nRet = SUCCESS; 
   // load the PTOCA file from memory
   Bitmap.EnableOverlayCallBack(TRUE); 
   nRet = Bitmap.Load(pszPtokaFileName, 0, ORDER_BGRORGRAY, NULL, NULL); 
	if(nRet != SUCCESS)
		return nRet;
   Bitmap.EnableOverlayCallBack (FALSE); 
   
   // save the bitmap as TIFF
   nRet = Bitmap.Save(pszTiffFileName, FILE_TIF, 1, 0, NULL); 
	if(nRet != SUCCESS)
		return nRet;
   // free the bitmap
   if(Bitmap.IsAllocated())
      Bitmap.Free();
   return nRet; 
}