LBitmapBase::SetAlpha
#include "ltwrappr.h"
virtual L_INT LBitmapBase::SetAlpha(LBitmapAlpha)
LBitmapBase& LBitmapAlpha; |
/* an LBitmap object */ |
Replaces the class object's existing alpha channel data or creates new alpha channel data in the class object's bitmap using the specified class object's bitmap.
Parameter |
Description |
LBitmapAlpha |
A bitmap object that has an allocated bitmap to be set as the alpha channel for the calling object’s bitmap. |
Returns
SUCCESS |
The function was successful. |
< 1 |
An error occurred. Refer to Return Codes. |
Comments
Typically, an alpha channel contains a mask that is used for transparency. This function, together with the LEADTOOLS region processing functions, lets you use the alpha channel to implement transparency.
Only 16- and 32-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 LBitmapBase::ColorRes, if necessary, before calling this function.)
The pAlpha bitmap does not have to be grayscale. This function converts the data from the pAlpha bitmap to the necessary grayscale or 1-bit format as it replaces the alpha channel in pBitmap. (The pAlpha bitmap, itself, remains unchanged.)
Note: |
The LBitmapAlpha parameter is passed by reference, and is a required parameter. |
This function does not support signed data images, unless they are DICOM images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image that is not a DICOM image is passed to this function.
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. |
See Also
Elements: |
LFile::LoadCMYKArray, LFile::SaveCMYKArray, LPaint::PaintDCCMYKArray, LBitmapBase::CreateAlphaBitmap, Class Members |
Topics: |
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Example
LBitmapBase MyBitmap,
Bitmap2;
MyBitmap.SetFileName(TEXT("image1.cmp"));
MyBitmap.Load(32); //load
at 32 bit per pixel
Bitmap2.CreateAlphaBitmap(MyBitmap);
MyBitmap.Load(TEXT("image2.cmp"),32);
//load at 32 bit per pixel
MyBitmap.SetAlpha(Bitmap2);