Albrecht Schlosser wrote:
> Greg Ercolano wrote:
>
>> But 1.1.9 doesn't support full 8 bit alpha; you can either
>> see the image 100%, or you see through to the background 100%..
>> no blending.
>>
>> In 1.3.x you have full alpha for images like pngs,
>> so you can have images with nice anti-aliased edges
>> that fall off into the background.
>
> I don't remember that anything with alpha has changed between 1.1.9 and
> 1.3.0, except that Matt added alpha support in fl_draw_image() for Mac
> OS X only - but Fl_RGB_Image and derived classes can use alpha channels
> in 1.1.9, IIRC. Am I wrong here ?
Hey you're right -- I thought alpha support appeared only recently
(in the last year or two) with PNG's, but I guess it goes back
a lot earlier than that.
Sorry about that wrong info regarding 1.1.9.
I think there were some older versions where alpha blending
wasn't working yet that have since been fixed.
According to my tests just now, fltk 1.1.8, 1.1.9 and 1.3.x
all support blending in the alpha channel on Linux and OSX
(didn't try windows).
But when I roll back to 1.1.6, it appears to be doing a
"screendoor dithering" instead of blending:
http://seriss.com/people/erco/fltk/tmp/alpha-blend-screenshot-1-1-6.png
Anyway, I posted the test code for PNG alpha blending
on the cheat page:
http://seriss.com/people/erco/fltk/#AlphaBlend
> P.S. All this doesn't mean that you can use alpha blending for xpm's
> other than what Greg wrote already.
Right; xpms only have one transparency color.
For sure PNGs should support full alpha. Probably
other image formats that FLTK supports handle alphas as well.
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