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Route graph connection splitting does not work

There are several quite simple but still "complex"-classified route graph cases where the current RouteGraph connection splitting doesn't work properly. At least the following two cases (in Apros) didn't work properly:

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Problem 1

The first problem was that the splitting algorithm didn't really have any chance of working because the previous splitting logic loaded the whole connection invalidly so that not all route point positions were correctly determined. This was caused by the RouteGraph loading logic in https://gitlab.simantics.org/simantics/platform/-/blob/2b0fe692f116091f8d65da664174c92591a077b8/bundles/org.simantics.diagram/src/org/simantics/diagram/flag/RouteGraphConnectionSplitter.java#L423, which was not using a real diagram editor's ICanvasContext and IDiagram and the connection IElement for retrieving the RouteGraph instance from the connection. It is possible this happens due to more dynamic terminal position support added a long time ago (2b0fe692) but this was never ascertained.

Decided to continue by changing the UI code to use a copy of the actual diagram editor's RouteGraph, which is valid, to perform the splitting to avoid this issue entirely on the UI. This does leave the problem that the utility function which is can be used for SCL-scripted splitting still doesn't work properly.

Problem 2

The second problem was that RouteGraph.splitGraph was not functioning correctly with route graph like the ones shown in the screenshots above:

The SplittedRouteGraph formed for the example pictures left existing terminals and route lines completely out from the result which caused the split application logic to disconnect such terminals and remove lines, effectively corrupting the connections instead of getting an expected result.

  1. A persistent RouteLine that was being split was often left out of the result
  2. RouteTerminals were left out of the result

The changes:

  • add logic to ensure all RouteTerminals are processed and added to either side of the split connection
  • add a validation to the end to ensure that all route lines added to either side of the split connection