#include "l_bitmap.h"
L_LTKRN_API L_INT L_SetBitmapAlphaValues(pBitmap, uAlpha)
pBITMAPHANDLE pBitmap; |
points to the destination bitmap handle |
L_UINT16 uAlpha; |
value to set |
Replaces existing alpha channel data or creates new alpha channel data in the destination bitmap.
Parameter |
Description |
pBitmap |
Points to the destination bitmap handle, which references the bitmap where the alpha channel data will be updated or added. |
uAlpha |
Value which will be used to create or replace the alpha channel data. The entire alpha channel will be filled with this value. |
SUCCESS |
The function was successful. |
< 1 |
An error occurred. Refer to Return Codes. |
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.
Typically, an alpha channel contains a mask that is used for transparency. This function, together with L_GetBitmapAlpha and the LEADTOOLS region processing functions, lets you use the alpha channel to implement transparency.
Only 16-, 32- and 64-bit images can have an alpha channel. If pBitmap references a bitmap of any other color resolution, this function converts the pBitmap bitmap to 32-bit before it replaces the alpha channel. (If you want 16-bit, you should change it using L_ColorResBitmap, if necessary, before calling this function.)
If pBitmap is 48-bit, it will be converted to 64-bit and then have the alpha information added to it.
Required DLLs and Libraries
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application. |
Win32, x64, Linux.
Functions: |
L_GetBitmapAlpha, L_SetBitmapAlpha, L_CreateMaskFromBitmapRgn, L_SetBitmapRgnFromMask, L_BitmapHasMeaningfulAlpha |
Topics: |
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This example fills the Alpha Channel with a specified value.
#define MAKE_IMAGE_PATH(pFileName) TEXT("C:\\Users\\Public\\Documents\\LEADTOOLS Images\\")pFileName
L_INT SetBitmapAlphaValuesExample()
{
L_INT nRet;
BITMAPHANDLE MainBitmap; /* Main bitmap */
L_UINT16 uAlpha=0xFFFF; /* Alpha channel value */
/* Load a bitmap at 32 bits per pixel */
nRet = L_LoadBitmap(MAKE_IMAGE_PATH(TEXT("Image1.cmp")), &MainBitmap, sizeof(BITMAPHANDLE), 32, ORDER_BGR, NULL, NULL);
if(nRet != SUCCESS)
return nRet;
/* Update the alpha channel in the bitmap */
nRet = L_SetBitmapAlphaValues(&MainBitmap, uAlpha);
if(nRet != SUCCESS)
return nRet;
/* Save the bitmap at 32 bits per pixel to keep the alpha channel */
nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.PNG")), &MainBitmap, FILE_PNG, 24, 0, NULL);
if(nRet != SUCCESS)
return nRet;
/* Free the bitmap */
L_FreeBitmap(&MainBitmap);
return SUCCESS;
}
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