Add Edge Reverse
Elk really wants to make edges go left to right. Really. So much so that if you ever create a feedback edge (one going in the reverse direction from the regular data flow) it shifts heaven and earth (all the nodes!) so that it can do this. This results in some pretty awful diagrams.
The solution implemented here is to add a flag that conveys to Elk that this link, in fact, wants to run in reverse.
Before
{
label:"Simple",
color:"#EEE",
children:[
{ id:"P1", port:1 }
{ id:"C1", highlight:2, inPorts:[ "In", "Loop" ], outPorts:[ "Out", ] },
{ id:"C2", highlight:3, inPorts:[ "In" ], outPorts:["Out", "Loop" ] }
{ id:"P2", port:1 }
],
edges:[
["P1","C1.In"],
["C1.Out","C2.In"],
["C2.Out","P2"]
["C2.Loop","C1.Loop"]
]
}
This problem is solved by adding a “-1” after the link spec to hint to the layout engine that the link should be rendered backwards.
After
{
label:"Simple",
color:"#EEE",
children:[
{ id:"P1", port:1 }
{ id:"C1", highlight:2, inPorts:[ "In", "Loop" ], outPorts:[ "Out", ] },
{ id:"C2", highlight:3, inPorts:[ "In" ], outPorts:["Out", "Loop" ] }
{ id:"P2", port:1 }
],
edges:[
["P1","C1.In"],
["C1.Out","C2.In"],
["C2.Out","P2"]
["C2.Loop","C1.Loop", -1]
]
}
So much nicer.