This is a POC and it is not intended to be merged into master, so don't expect to find a high quality code here! 😺
This is a continuation of #2366

Please don't rebase on master. If necessary, merge the master branch but instead we will create a new POC with the latest changes from the master branch.

Start from master e8fa907 (0.37.0 with dev dependencies update only)

Purpose

• evaluate the migration effort
• detect problems early
• apply improvements to the master branch to ease the future migration and improve tests
• provide feedback to the maxGraph community and if possible fixes that we integrated in this PR as workaround
• be ready to easily reuse this effort in a new Pull Request to test new maxGraph releases

Status

This POC is completed.

• rebase previous POC on master branch e8fa907 (post 0.37.0 version)
• source compile
• dev server starts, the demo is usable
  • label position OK (wasn't working in the previous POC), navigation and theme switch OK (see video below)
  • elements-identification demo works. It uses overlays, CSS and Style update (see video below)
• ✔️ unit tests pass 💪🏿
• ✔️ integration tests 🎉
• ❌ e2e tests: they detect real issues.
  • Some BPMN rendering tests fails as in the previous POC due to issues in maxGraph 0.1.0 which are fixed in later versions.
    • message flow icon not correctly positioned
    • edge marker are not filled
  • To investigate
    • edge: the arcSize seems larger than with mxGraph
    • association and message flow dashed: the dashed positions are not exactly in the same order as with mxGraph
  • apparently work (currently failed because of existing issues described above)
    • overlays
    • fit/zoom
    • pan
    • theme
• ❌ SVG export KO as in the previous POC. No work done on this topic
• Remaining tasks associated to the migration are marked in the code as // TODO maxgraph@0.1.0. Most tasks are related to changes to do with newer versions of maxGraph

Bundle sizes comparison with commit 52f9c80

Demo: navigation, theme and label position

See #2756 (comment)

Demo: Overlays, CSS and Style Update API

Improvements ported to the master branch

• refactor: remove mx prefix in variables related to mxGraph objects #2834
• test: add more tests for StyleComputer #2835
• fix!: generate correct CSS class name for adhoc subprocess #3058

Detected maxGraph issues

• model.setCellStyle: require to pass a clone of the current style. Otherwise, the Style is not updated. See Graph.setCellStyles may not propagate style changes maxGraph/maxGraph#326
• styleUtils.setStyleFlag set the value to 0 when the original value for the key is undefined. See fix: correctly set the flag value in setStyleFlag maxGraph/maxGraph#377
• fix: correctly compute the style when setting undefined/none maxGraph/maxGraph#383

Remaining tasks

### Handle TODO in the code
- [x] manage the "TODO rebase" in the code. Created while rebasing the previous code on the master branch
- [x] review all "TODO maxgraph@0.1.0": some can be handled thanks to the fix done on the master branch and that weren't available in the previous POC
- [x] the extraCssClasses should be a property in the CellStyle and not defined with a deep nested object

### CSS classes not applied with the API
- [x] in the `elements-identifications.html` demo, the CSS are sometimes applied but seems to disappear during navigation
- [x] integration tests fail: the CSS classes are in the maxGraph model, but they are not generated in the DOM

### Update Style API: make it work
- [x] font style value is incorrect. Is is lower by one. Use workaround to fix the problem (seems to be an issue in maxGraph)
- [x] passing default value work
- [x] update and reset work

### Rework the tests
- [x] Make the tests pass
- [x] Provide a status of the e2e tests.