On Tue, 17 Apr 2007 10:24:36 +0200
Marc Weustink <[EMAIL PROTECTED]> wrote:
> Mattias Gaertner wrote:
> > 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?
>
> Something like that. But IMO there is no such thing as MaskIsSeparate
> since there won't be an included mask. HasMask is a better name I
> think.
ok. Will you change it?
> And if we add MaskPrec and MaskShift: cardinal; then the Alpha
> definition is complete independent of a Mask definition
Ehm, but they are not independent, are they? You can not have both!?
> BTW, why are the xxxPrec and xxxShift defined as Cardinal and not
> byte ?
Why should they?
Mattias
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