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by rajandatta 1610 days ago
My single biggest issue with Graphic is that the quality of Arrow end-points is very poor. They don't terminate cleanly at the destination. This is visible in the 2nd link you've posted.

I'm amazed that this hasn't been addressed. It's been there for years.

Makes the end products impracticable for distribution in a professional setting. It's Ok if you're the only consumer ... not great for other cases.
2 comments
feanaro 1610 days ago
I remember this issue being raised, I think on the graphviz Discourse, and the graphviz developers responding to it as if it was a hard to solve limitation of graphviz for some reason. But I can't for the life of me remember the details.
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graphviz 1610 days ago
"Very poor" seems harsh, but, yes, it hurts us, too. (That, and text with slightly-off baselines.)

The relevant code starts around https://gitlab.com/graphviz/graphviz/-/blob/main/lib/common/... If this isn't right, maybe somebody can figure out why. Perhaps the loop stops sometimes on the wrong side of the boundary? Anyway, it's equally possible that when the endpoint coord is handed off to a lower level driver, the arrowhead mitering is wrong. There is no question there was once upon time explicit code to try to cope with this problem, at least in the native PSgen, but I can't find it now. Maybe it wore away as waves of open source development washed over it, along with static tables for a bunch of "standard" PS fonts.

For more background, see for example https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/s...

In the worst case, this has to be debugged for all the drivers in https://gitlab.com/graphviz/graphviz/-/tree/main/plugin

No doubt there are more details if anyone can remember them.

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s5806533 1609 days ago
I think I found at some point that the arrows could be made correct -- at least for the SVG rendering in Firefox -- by removing the stroke (stroke-width="0").
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pphysch 1610 days ago
Ostensibly each arrow style graphic would need an explicitly-defined "attach point" at whatever is deemed the "tip", so that the tip can be oriented perfectly in relation to the vertex and edge of the GraphViz graph.

If nothing like that exists, I can see how it would be a very troublesome refactor.

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graphviz 1610 days ago
Oh, that too. Feature interaction is a killer, isn't it.
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pvaldes 1609 days ago
I never had this problem. Arrow style is configurable if I remember correctly. You can configure (extend) also overlapping in boxes so the arrows never enter into the box area.

I'm talking by heart and I could be wrong in any case.

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