Re: Alpha in Pango Color

[Matthias Clasen <mclasen redhat com>]

On Sat, 2015-08-08 at 11:36 +0200, Behdad Esfahbod wrote:
> Hi William,
>
> Currently Pango doesn't support alpha in colors.  At this point, it 
> might make
> sense to add a separate PANGO_ATTR_ALPHA, instead of an RGBA type.
>
> I'd take a patch.  Matthias, is this something you can possibly 
> implement?
> Shouldn't take long to implement and test...

No, sorry. Not in the short term. But I would be interested in having
alpha support in pango, and would look at making GTK+ use it if it
appears.

If we make this a separate attribute, we would need fg-alpha, bg-alpha,
strikethrough-alpha and underline-alpha. And there would be some
complication where you could end up with (say) the underline-color and
underline-alpha attributes ending at different positions. We would fall
back to fg for the underline color where underline-color has ended. But
do we combine it with the underline-alpha? Maybe that is just a corner
-case that needs clear documentation.