Re: new transparent colors

[Ethan A M. <sf...@us...>]

On Thursday, April 19, 2012 06:09:27 am Mojca Miklavec wrote:
> Dear developers,
> 
> are other terminals (apart from svg, wxwidgets, qt) supposed to
> implement new transparent colors now, 

Sure. Feel free to contribute a patch for aquaterm or whatever.
I had a look at lua.trm, but frankly I don't understand how it 
works so I left it alone.

> What should terminal do if it gets instructions:
>     set_color(r,g,b,a=0.5)
> and then
>    fill(...)
> with FS_TRANSPARENT_SOLID and fillpar 30 for example?

From the user's perspective, the two commands below should produce
the same result:
   set style fill solid fillcolor "#7FRRGGBB"
   set style fill transparent solid 0.5 fillcolor "RRGGBB"

The latter command cannot be deprecated yet because as you point out
some terminals do not yet recognize the alpha component of a RGB color.

Consider FS_TRANSPARENT_SOLID as a backwards-compatibility feature.
Since no existing script that uses it could be relying on the high
bits of the RGB color to hold alpha, the backwards compatible way
of handling them is to ignore them.

> See also pdfcairo's result of the new demo, attachmed. To me it seems
> at least a tiny bit problematic that each line of the arrow is drawn
> separately.

See also Bug #3514186.
It may be worth revisiting how arrows are drawn.
In particular it may be desirable to offer an arrow style that treats
the entire arrow as a single filled polygon, with or without a separate
bounding stroke.

	Ethan