[fpc-pascal] Questions regarding FPImage's TFPMemoryImage.FData variable
nc-gaertnma at netcologne.de
Wed Jun 1 12:26:19 CEST 2016
On Thu, 26 May 2016 11:24:44 +0100
Graeme Geldenhuys <mailinglists at geldenhuys.co.uk> wrote:
> 3) The FData image buffer (assuming (1) is correct) uses Integer instead
> of Byte as it's element size. So I'm assuming a singe Integer hold
> all the colour information for a single pixel?
No, TFPMemoryImage uses one TFPColor per pixel (48bit).
TFPCompactImgGray8Bit uses 8bit.
TFPCompactImgGray16Bit uses 16bit.
TFPCompactImgRGB8Bit uses 24bit.
TFPCompactImgRGBA8Bit uses 32bit.
and so forth...
> But then again, I have noticed that TFPColor uses Word size data
> elements, thus the whole RGBA information per pixel will be 8 bytes
> of data, and Integer is only 4 bytes large.
The integer is only the palette index.
> 4) What is the order in which the colour channel information is stored
> in memory? RGB, BGR, RGBA, BGRA, ARGB, ABGR etc?
Each memory image uses a packed record. For example TFPMemoryImage uses
TFPColor, TFPCompactImgRGBA8Bit uses TFPCompactImgRGBA8BitValue.
It is typically RGBA.
> 5) Is the Alpha channel actually stored? I assume it is, because the
> Integer type is large enough to hold that information.
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