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L_ConvertToDDB

#include "l_bitmap.h"

L_LTDIS_API L_HBITMAP L_ConvertToDDB(hDC, pBitmap)

Converts a LEAD Technologies bitmap into a Windows device dependent bitmap (DDB). When this function is completed, there are two copies of the image in memory: the DDB and the original LEAD bitmap. Freeing one will not affect the other.

Parameters

L_HDC hDC

Handle to the device responsible for the conversion. The mapping mode of the device context must be MM_TEXT.

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to copy.

Returns

This function returns a handle to the DDB, or it returns a NULL if there is an error.

Comments

This function allocates a DDB bitmap and copies the LEAD bitmap to the DDB.

If this function fails, the return value is a NULL HBITMAP. This can happen if the image is too large for the Windows C API functions that LEADTOOLS uses internally. To get more information about why the Windows C API functions may have failed, you can use the Windows C API GetLastError.

/* Change the initial bitmap to a DDB */ 
hDDB = L_ChangeToDDB( hDC, &Bitmap ); 
if(!hDDB) 
{ 
   DWORD dwRet = GetLastError(); 
   /* process the error code here */ 
}

Required DLLs and Libraries

LTDIS
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64.

Functions

Topics

Example

For complete sample code, refer to the DIBDDB
example.
This example loads a bitmap, converts it to a DDB, then converts
the DDB back to a bitmap.

L_INT ConvertToDDBExample(L_HWND          hWnd,pBITMAPHANDLE pLeadBitmap) 
{ 
   L_INT nRet; 
   BITMAPHANDLE   TmpBitmap;        /* Bitmap handle for the initial image */ 
   HBITMAP        hDDB;             /* Handle for the DDB */ 
   HPALETTE       hPalette;         /* Palette handle */ 
   HPALETTE       hpalSave = NULL;  /* Saved palette handle */ 
   HDC            hDC;              /* Handle to the device context for the current window */ 
 
   /* Get the device context for the current window */ 
   hDC = GetDC( hWnd ); 
   /* Load a bitmap, keeping its own bits per pixel */ 
   nRet = L_LoadBitmap (MAKE_IMAGE_PATH(TEXT("ImageProcessingDemo\\Image3.cmp")), &TmpBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
   hPalette = L_CreatePaintPalette(hDC, &TmpBitmap); 
   if (hPalette) 
   { 
      hpalSave = SelectPalette(hDC, hPalette, FALSE); 
      RealizePalette(hDC); 
   } 
   /* Convert the initial bitmap to a DDB */ 
   hDDB = L_ConvertToDDB( hDC, &TmpBitmap ); 
   if (hPalette) 
      SelectPalette(hDC, hpalSave, FALSE); 
   /* Free the initial bitmap */ 
   L_FreeBitmap(&TmpBitmap); 
   /* Convert the DDB to create a new LEAD bitmap */ 
   nRet = L_ConvertFromDDB(hDC, pLeadBitmap, sizeof(BITMAPHANDLE), hDDB, hPalette); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Clean up */ 
   ReleaseDC( hWnd, hDC ); 
   DeleteObject(hDDB); 
   DeleteObject(hPalette); 
   return SUCCESS; 
}

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