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QccAlphaOpaque, QccAlphaTransparent, QccAlphaTranslucent - transparency
values
#include "libQccPack.h"
QccAlphaOpaque(alpha)
QccAlphaTransparent(alpha)
QccAlphaTranslucent(alpha)
QccAlphaOpaque(), QccAlphaTransparent(),
and QccAlphaTranslucent() are macros for evaluting the transparency of
the alpha argument. Values less than or equal to QCCALPHA_TRANSPARENT are
considered transparent, and QccAlphaTransparent() will evaluate to 1 for
such alpha values, and 0 otherwise. Values greater than or equal to QCCALPHA_OPAQUE
are considered to be opaque, and QccAphaOpaque() will evaluate to 1 for
such alpha values, and 0 otherwise. Values greater than QCCALPHA_TRANSPARENT
and less than QCCALPHA_OPAQUE are considered to be partially transparent,
or translucent, and QccAlphaTranslucent() will evaluate to 1 for such
alpha values, and 0 otherwise.
Often alpha is considered to represent a
pixel from a grayscale image; in that case, QCCALPHA_TRANSPARENT would
be full black, QCCALPHA_OPAQUE would be full white, and values between
the two would be some shade of gray.
QccPack(3)
Copyright
(C) 1997-2021 James E. Fowler
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