Indicate bus width about netlistsvg

[nobodywasishere]

I got double line thickness to indicate a bus working with this commit.

Before:

After (along with some other changes I made):

I've also started looking into indicating the bus width with an edge label but so far it's proved unsuccessful. ElkJS seems to make space for the labels but doesn't actually place them for some reason.

[mithro]

I would love to see this integrated into netlistsvg and demos in https://github.com/SymbiFlow/sphinxcontrib-hdl-diagrams

[nturley]

ELK supports edge labels, but it's going to really clutter up the schematic if we have every single edge labeled. So I think the only tricky part about this is deciding which edges to add labels to.

Yosys also provides net names, so in theory we could also consider putting the netnames as an edge label.

[kasbah]

I could have sworn there was some universal convention in digital logic schematics to indicate bus widths with some slanted edges. Something like this:

But maybe dotted or squiggly somehow? I can't find any examples. Do you know what I am thinking of? This would have to be done with a graph node.

[kasbah]

I guess the convention is just a single slanted line and a number next to it.

from: https://tex.stackexchange.com/questions/125460/drawing-bus-width-like-markers-with-number-on-arrows

[nturley]

finding the coordinates of the slanty line also makes this a little tricky.

[rjordans]

Would it be an option to draw buses in another color / thickness to distinguish them from individual lines? I agree that adding labels or width may clutter the figure indeed

[rjordans]

Another option may be to add the slanted line with number as one of the nodes on the line for ELK to place for you? That should help in keeping things clean

[nturley]

I like that solution. It would add more columns but I think that is fine.

[stevenbell]

This would be really helpful to me. Even just using a bold line to indicate a bus versus a single wire would be a big help.

I'm happy to submit a PR if you can point me in the right direction to get started.

[nturley]

Looks great. Well done.

[rjordans]

that's looking nice already!

[nobodywasishere]

Alright I've worked on this a bit more and figured out why labels weren't showing up - they weren't being drawn. I've added that but it seems like some labels are inline and others aren't (i think the ones with junction points are inline). Maybe there's a function that's centering all the elements of an edge when there's a junction (?). Setting 'org.eclipse.elk.edgeLabels.inline' false in each label layoutOptions doesn't seem to do anything.

Ideally the labels would be closer to the source, but setting 'org.eclipse.elk.core.options.EdgeLabelPlacement': 'HEAD' doesn't seem to do anything either. Ideally the design would also be less expanded (closer to how it was before).

Either way I've been able to manually offset it so it looks okay (but may have a line going over the label). Also, adding the labels does change layout, just an FYI.

Without manual offset (same json as above):

With manual offset:

All code is on this edgeLabels branch if anyone else wants to take a look at it. Any feedback welcome.

[nobodywasishere]

I'm also on the netlistsvg Gitter if anyone wants to talk about this there.

[mithro]

This is super cool!