New attributes: fill-opacity, stroke-opacity

[tkvogt]

SVG differentiates between fill-opacity and stroke-opacity. It would be handy to have this for the svg parser in diagrams-input. Of course this could be implemented by overlaying two diagrams: One where fill is mempty and one where the outline linewidth is set to 0. But this depends on solving issue issue 247.

[cchalmers]

The fill and stroke opacities can be different by chaining the opacity of the AlphaColour Double in their Texture.

[tkvogt]

Can you give me an example how to set the fill and stroke opacity separately?

[cchalmers]

Hmm, if you want to set just the fill opacity for everything in a diagram after you're already set the fill colour, that would be more difficult. If you know the fill opacity when you're setting the fill colour it's just fcA (c withOpacity o).

[byorgey]

@tkvogt Is this still an issue, or did you figure out a workaround?

[tkvogt]

Am 11.09.2015 um 22:59 schrieb Brent Yorgey:

@tkvogt https://github.com/tkvogt Is this still an issue, or did you
figure out a workaround?

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#248 (comment).

There is no workaround. These attributes are necessary for a perfect
loading of SVG images. But this only makes every 10th image look bad.
Could someone of you implement this? I am not so fluent in diagrams
internals.
It reminds me that I have to finish diagrams-input, mention it in
diagrams-manual an upload it to hackage.

[byorgey]

I don't think this should be too hard to implement. The hardest part will just be changing backends to support it. But that can be done incrementally. I will see if I can get around to this sometime soon.