L_GetBitmapAlpha

Summary

Creates a grayscale bitmap from the source bitmap's alpha channel data.

Syntax

#include "l_bitmap.h"

L_LTKRN_API L_INT L_GetBitmapAlpha(pBitmap, pAlpha, uStructSize)

Parameters

pBITMAPHANDLE pBitmap

Points to the source bitmap handle.

pBITMAPHANDLE pAlpha

Points to the destination bitmap handle to hold the alpha channel data.

L_UINT uStructSize

Size in bytes, of the structure pointed to by pAlpha, for versioning. Use sizeof(BITMAPHANDLE).

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.

Only 16-, 32-, and 64-bit images can have an alpha channel. If the source bitmap has another color resolution, the result is an image filled with zeros.

Typically, the alpha channel contains a mask that is used for transparency, as shown in the example for L_SetBitmapAlpha.

Required DLLs and Libraries

Platforms

Win32, x64, Linux.

See Also

Functions

Topics

Example

For an example, refer to L_SetBitmapAlpha.

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LEADTOOLS Raster Imaging C API Help

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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.