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List:       koffice-devel
Subject:    Re: 32-bit bimaps and QImage
From:       David Faure <dfaure () klaralvdalens-datakonsult ! se>
Date:       2003-02-20 14:41:19
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On Thursday 20 February 2003 13:39, Nicolas Goutte wrote:
> The difference of the depth is just due to padding.
> 
> In true color, pixels are normally 3 bytes for red, gren and blue (RGB). This 
> makes 24 bits. But processors (be it a CPU or a graphic ship) can only handle 
> 8, 16 or 32 bits (and more). So 24 bits must be handled as 3 times 8 bits. So 
> for handling (especially moving) a pixel you need three 8 bit operations.
> 
> With 32 bits, you have 8 bits that are used as padding.

Alpha channel, not padding.

(see docu for QImage::setAlphaBuffer)

- -- 
David Faure -- faure@kde.org, dfaure@klaralvdalens-datakonsult.se
Qt/KDE/KOffice developer
Klarälvdalens Datakonsult AB, Platform-independent software solutions
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