Giving up for now

[Roderick Colenbrander]

On Sun, May 3, 2009 at 6:28 PM, Roderick Colenbrander
<thunderbird2k at gmail.com> wrote:
> On Sat, May 2, 2009 at 11:18 PM, Joel Holdsworth
> <joel at airwebreathe.org.uk> wrote:
>> On Sat, 2009-05-02 at 22:56 +0200, Roderick Colenbrander wrote:
>>> On Sat, May 2, 2009 at 8:57 PM, Joel Holdsworth
>>> <joel at airwebreathe.org.uk> wrote:
>>> > On Sat, 2009-05-02 at 20:38 +0200, Roderick Colenbrander wrote:
>>> >> On Sat, May 2, 2009 at 6:55 PM, Joel Holdsworth
>>> >> <joel at airwebreathe.org.uk> wrote:
>>> >> > Hi All,
>>> >> >
>>> >> > I've hit a bit of a wall with alpha blended icons. CreateIcon is working
>>> >> > fine for icon creation, but ExtractIcon and LoadIconFromResource etc.
>>> >> > are all proving more of a problem. All of these use various GDI DIB
>>> >> > functions to coerce the icon bitmap to the correct colour depth and
>>> >> > size. The problem is that preserving the alpha channel through these DIB
>>> >> > functions seems to be impossible because they go via X11, so until the
>>> >> > dib engine is merged (after hell freezes over) I'm not sure I can go
>>> >> > much further.
>>> >> >
>>> >> > Joel
>>> >> >
>>> >> >
>>> >> >
>>> >> >
>>> >> >
>>> >>
>>> >> If you say X11 might be problematic note that more and more display
>>> >> drivers are offering visuals with alpha, so 32-bit ones instead of
>>> >> 24-bit. You could force the selection of such a visual in winex11.drv
>>> >> for testing.
>>> >>
>>> >> Roderick
>>> >
>>> > Is that right? I simply assumed it would screw it up. If the problem can
>>> > be solved with fixes to user32 or gdi32, then I can probably find the
>>> > solution. If it involves work on winex11, then I'm not really the right
>>> > guy for the job.
>>> >
>>> >
>>> >
>>>
>>> Why again did you need this specific alphablend method? The icon can't
>>> be converted to use some basic color keying for transparency or so?
>>
>> The reason is that the outlines will look aliased, and there will be no
>> drop-shadows - without alpha the Tango icons won't look better than the
>> current set. Also, I figured that icon rendering should be fixed for the
>> sake of wine as a whole - which I think it should. It seems like a good
>> little task for a wine beginner, and indeed I've made a lot of progress
>> - I'm just a bit stuck.
>>
>> The culprit is a transfer through StretchDIBits in user32 which strips
>> the alpha channel. I can't see a way round it - using StretchBlt doesn't
>> help, and neither does GdiTransparentBlt.
>>
>> Another insentive: I suspect fixing this would also fix bug #201 which
>> is now over 8 years old!
>>
>>
>>
>
> I just looked a little more into it. As you mentioned StretchDIBits in
> user32 removes the alpha channel. According to this post at MSDN
> (http://msdn.microsoft.com/en-us/library/dd145023(VS.85).aspx) the
> function got extended in Vista to include PNG support because PNG is
> used for most icons in Vista. It might be useful to check that out.
> The page mentions it was meant for printers but most likely they also
> use this for icon rendering. I think it can be used in cooperation
> with XRender (there are various xrender examples for dealing with
> alpha).
>
> Roderick
>

Have you also tried to use the GDI AlphaBlend function? This is the
one which should be used I think and we back it by XRender ..

Roderick