IWICPalette::HasAlpha method (wincodec.h)
Indicates whether the palette contains an entry that is non-opaque (that is, an entry with an alpha that is less than 1).
HRESULT HasAlpha( [out] BOOL *pfHasAlpha );
Pointer that receives
TRUE if the palette contains a transparent color; otherwise,
If this method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.
Various image formats support alpha in different ways. PNG has full alpha support by supporting partially transparent palette entries. GIF stores colors as 24bpp, without alpha, but allows one palette entry to be specified as fully transparent. If a palette has multiple fully transparent entries (0x00RRGGBB), GIF will use the last one as its transparent index.
|Minimum supported client||Windows XP with SP2, Windows Vista [desktop apps | UWP apps]|
|Minimum supported server||Windows Server 2008 [desktop apps | UWP apps]|