Allign node's stroke with end of the arrow's path width

#1

Hi all,

When you have graphs with a significant edgewidth.

for instance:

digraph {
    A -> B [penwidth=10]
}

Capture

It seems like the fill of the arrow-head aligns with the fill of the nodes shape, i.e. the stroke or border of the arrow overlaps significantly with the node…

Is there a way to counteract this behavior, e.g. using a do-not-overlap setting or manually adding an offset between the arrowhead and the node.

#2

Yep, looks like a bug to me. You get the same result with png and svg. I’m surprised this hasn’t been reported before.
The only work-around I found was this:

  1. dot -T dot yourfile.gv >yourfile.dot
  2. edit all the pos values for edges with penwidth>1 (see https://www.graphviz.org/doc/info/attrs.html#k:splineType and example below)
  3. neato -n2 -Tpng youreditedfile.dot >yourfile.png

(See also the FAQ - https://www.graphviz.org/faq/#FaqDotWithCoords)

Like so:

digraph {
	graph [bb="0,0,54,108"];
	node [label="\N"];
	A	[height=0.5,
		pos="27,90",
		width=0.75];
	B	[height=0.5,
		pos="27,18",
		width=0.75];
	A -> B	[penwidth=10,
		 //pos="e,27,36.104 27,71.697 27,63.983 27,54.712 27,46.112"];
	pos="e,27,44.104 27,71.697 27,63.983 27,54.712 27,46.112"];
}

Giving:
fatEdge0

#3

Well I’ve known about the bug for almost two years. But I just put up with it since I saw no alternatives… I only recently was pointed to the forums

#4

Note that this happens to me even with the most simple of graphs, with the default settings. E.g. see this graph and its PDF output.

digraph {
    a -> b;
}

I personally find it a real eye sore. Another eye sore is that the label of a vertically straight edge touches the edge. Both problems visible in the image below.

image
image1074×971 16 KB