On Mon, 16 Apr 2007 22:46:49 +0200
Marc Weustink <[EMAIL PROTECTED]> wrote:
> Mattias Gaertner wrote:
> > On Mon, 16 Apr 2007 11:20:55 +0200
> > Marc Weustink <[EMAIL PROTECTED]> wrote:
> >
> >> Continuing my TRawImageQuestion.
> >>
> >> While implementing cursors and imagelists, Paul and I start to get
> >> confused. It appears that Mask and Alpha are treated as equal while
> >> in fact they are each others inverse. (An 1 in a mask means that
> >> this part of the image is masked, not drawn, where for alpha a 1
> >> means opaque, fully drawn)
> >>
> >> A RawImageDesription describes the RGB and Alpha parts of an image.
> >> It has also a flag that the Alpha is separate. This got introduced
> >> since traditional windows has only an image and a (1bpp) mask.
> >> When reading such image, the mask gets converted into a 1bit
> >> separate alpha.
> >>
> >> With CreateBitmapFromRawImage the fun starts. It creates a bitmap
> >> and mask handle form the rawimage. The maskhandle is created from
> >> the (separate) alpha and is in fact returning an alpha handle and
> >> not a maskhandle. On win32 this is nonsense since alpha is never
> >> separated. So I think a Maskhandle should return what it means: a
> >> handle to a Mask (and only in the case when the description had
> >> the AlphaSeparate flag).
> >>
> >> Comments ?
> >
> > Maybe we need an enum, how to interpret the alpha value?
>
> I was think on that also, but somehow didn't sound right. I don't know
> exactly for all widgets, but as far as I can tell the separate alpha
> is only used for win32 1bit masks.
> If this is the case, then ignore my other mail since
> TRawImage.MaskData is indeed MaskData. But then the AlphaSeparate,
> AlphaBitsPerPixel, AlphaLineEnd, AlphaBitOrder and AlphaByteOrder are
> not really Alpha, but Mask -> MaskSeparate (or HasMask),
> MaskBitsPerPixel, MaskLineEnd, MaskBitOrder and MaskByteOrder
True.
What do we take instead of the enum?
define: if Mask is separate, then it is opacity, otherwise transparency?
Mattias
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