Added support to different diagrams per XML file

[snakebyte85]

Different diagrams (processes or collaborations) can be saved inside a single XML file, following BPMN 2.0 standard, but bpmn-js renders only the first diagram.

This commit allows a developer to select a specific diagram to be rendered, using the ID of the process or collaboration in this simply way:

bpmnViewer.importXML(bpmnXML, done, processId);

The first diagram (like before) will be rendered if processId is null

bpmn-js internally already supported the selection of a specific diagram to render, but the interfaces did not allow this

This is useful for #87

[philippfromme]

Thanks for filing this pull request. Being able to specify which diagram you want to import would definitely be an improvement. We'll look into this. In the meantime, a few thoughts:

• the specified ID should always reference a bpmndi:BPMNDiagram
• importXML could support specifying a model instance when opening a diagram so you can switch between different diagrams in an XML file without reimporting the XML every single time - alternatively we could use importDefinitions

[snakebyte85]

• select diagram only for diagramId
• Created method to switch diagram for an already imported XML in this way
  switchDiagram("<diagramId>")

Let me know if something else is needed

[nikku]

Thanks for your follow up @snakebyte85. Could you add some test cases that bring the code coverage to a decent amount?

[snakebyte85]

I added the needed test cases. I added two bpmns to be tested:

• One simple BPMN (with two diagrams) created by me
• Ones that comes from https://github.com/bpmn-miwg/bpmn-miwg-test-suite/blob/master/Reference/C.4.0.bpmn as official test case

Sorry if I didn't that before but I am not practical of the used test enviroment and used patterns.

Let me know if tests needed to be modified

[barmac]

Thank you for your further commits. I left a few comments that will need to be resolved before we merge the PR.

Can you please make sure your commits adhere to our contributing rules?

Can we also have a test case for a situation when the selected diagram is not present?

[barmac]

Please read the comments in the code and in the issue for feedback.

[snakebyte85]

All done

Let me know for something else

[barmac]

I slightly changed the API so that instead of #switchDiagram we have #open. Also, callback will be invoked with real errors instead of objects with message property. Furthermore, I added documentation.

@nikku Can you please have a look at this?

[nikku]

@snakebyte85 Thanks again for your contribution.

@barmac I discovered an issue with re-opens if elements are shown in multiple BPMNDiagram instances. Cf. 95c1895 for a test case that fails. We'd need to sort out this issue before merging this feature. Could you have a look into it?

[barmac]

Current state is on https://github.com/bpmn-io/bpmn-js/tree/select-diagram

I pushed a bugfix for BpmnTreeWalker when context wasn't passed. This revealed that the current implementation renders more elements than enough, as a result of this.

There is also a problem of unnecessary warnings when an element is included in more than one DI.

[barmac]

I rebased the branch on top of master. There are still two failing test cases.

1. We never deregister elements DI once it's registered, which for some diagrams results in unnecessary rendering here during diagram switch. See this test case for details.

2. At the moment, we send a warning if an element's DI prop has already been registered. This is noticeable during a render of second diagram which uses the same elements, as in this test case. I think if we fix the first issue, the second one might be resolved, too.

Please feel free to update your branch with bpmn-js/select-diagram and add solution for the abovementioned issues :).

[nikku]

Merged via #983.

Thanks for your contribution 🎉