L_FeatherAlphaBlendBitmap

Summary

Combines image data from two bitmaps with feathering. The two bitmaps can be combined with a variable opacity applied by specifying the region of a fade mask.

Syntax

#include "l_bitmap.h"

L_LTIMGEFX_API L_INT L_FeatherAlphaBlendBitmap(pBitmapDst, nXDst, nYDst, nWidth, nHeight, pBitmapSrc, nXSrc, nYSrc, pBitmapMask, nXMaskShift, nYMaskShift, uFlags)

Parameters

pBITMAPHANDLE pBitmapDst

Pointer to the bitmap handle that references the destination bitmap. The function will update this bitmap.

L_INT nXDst

The X coordinate of the origin of the destination rectangle.

L_INT nYDst

The Y coordinate of the origin of the destination rectangle.

L_INT nWidth

Width of the area to be combined, in pixels. This width applies to both the source and the destination areas.

L_INT nHeight

Height of the area to be combined, in pixels. This height applies to both the source and the destination areas.

pBITMAPHANDLE pBitmapSrc

Pointer to the bitmap handle that references the source bitmap.

L_INT nXSrc

The X coordinate of the origin of the source rectangle.

L_INT nYSrc

The Y coordinate of the origin of the source rectangle.

pBITMAPHANDLE pBitmapMask

Pointer to the bitmap handle that references the fade mask.

L_INT nXMaskShift

The X coordinate of the origin of the mask rectangle.

L_INT nYMaskShift

The Y coordinate of the origin of the mask rectangle.

Returns

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

Comments

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

To combine two bitmaps with a fixed opacity, use the L_AlphaBlendBitmap function.

The L_FeatherAlphaBlendBitmap function achieves feathering between two bitmaps by using variable opacity values, obtained from the fade mask referenced by pBitmapMask. The origin coordinates of the region of the fade mask bitmap are specified by the values of nXMaskShift and nYMaskShift parameters.

To create a bitmap that contains a fade mask, use L_CreateFadedMask function.

To update a status bar or detect a user interrupt during execution of this function, refer to L_SetStatusCallback.

This function supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available in the Document and Medical Imaging toolkits.

This function does not support 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

Feather Alpha Blend Function - Before

Feather Alpha Blend Function - After

View additional platform support for this Feather Alpha Blend function.

Required DLLs and Libraries

LTIMGEFX
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, Linux.

Example

L_INT FeatherAlphaBlendBitmapExample(L_VOID) 
{ 
   L_INT nRet; 
   BITMAPHANDLE   BitmapDst;  /* Bitmap handle to hold the loaded image */ 
   BITMAPHANDLE   BitmapSrc;  /* source bitmap */ 
   BITMAPHANDLE   BitmapMask; /* Bitmap handle to the fade mask bitmap */ 
   RECT           rRgnRect;   /* Rectangle that defines the region */ 
   L_INT          XDst;       /* Column offset of the destination */ 
   L_INT          XSize;      /* Pixel width of the rectangle to combine */ 
   L_INT          YDst;       /* Row offset of the destination */ 
   L_INT          YSize;      /* Pixel height of the rectangle to combine */ 
   L_INT          XSrc;       /* Column offset of the source */ 
   L_INT          YSrc;       /* Column offset of the source */ 
 
   /* Load both bitmaps, at 24 bits per pixel */ 
   nRet = L_LoadBitmap (MAKE_IMAGE_PATH(TEXT("IMAGE1.CMP")), &BitmapDst, sizeof(BITMAPHANDLE), 24, ORDER_BGR, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
   nRet = L_LoadBitmap (MAKE_IMAGE_PATH(TEXT("IMAGE2.CMP")), &BitmapSrc, sizeof(BITMAPHANDLE), 24, ORDER_BGR, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   /* Specify a position in the top left part of the displayed image */ 
   XDst = BITMAPWIDTH(&BitmapDst) / 8; 
   YDst = BITMAPHEIGHT(&BitmapDst) / 8; 
   /* Use the half size of the source bitmap */ 
   YSize = BITMAPHEIGHT(&BitmapSrc) / 2; 
   XSize = BITMAPWIDTH(&BitmapSrc) / 2; 
   XSrc = 0; 
   YSrc = 0; 
   // specify a rectangle  
   SetRect(&rRgnRect, XSrc, YSrc, XSrc + XSize , YSrc + YSize); 
   /* Create a rectangular region */ 
   nRet = L_SetBitmapRgnRect (&BitmapSrc, NULL, &rRgnRect, L_RGN_SET); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   /* create the fade mask */ 
   nRet = L_CreateFadedMask(&BitmapSrc, &BitmapMask, sizeof(BITMAPHANDLE), 60, 20, 3, 0, FADE_DUMPFILL | FADE_NOTRANSPARENCY, 255,RGB(0, 0, 255)); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Combine BitmapSrc with BitmapDst, with fade mask bitmap  */ 
   nRet = L_FeatherAlphaBlendBitmap (&BitmapDst, XDst, YDst, XSize, YSize, 
       & BitmapSrc, XSrc, YSrc, &BitmapMask, 0,0, 0); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &BitmapDst, FILE_BMP, 24, 0, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   /* Free the temporary bitmap */ 
   L_FreeBitmap(&BitmapSrc); 
   L_FreeBitmap(&BitmapMask); 
   L_FreeBitmap(&BitmapDst); 
   return SUCCESS; 
}