Cannot prevent UndoRedo from storing state on Translate event with no actual movement

[aleupons]

Hello, I have encountered the following issue using the Transform and UndoRedo classes from the library:

OpenLayers triggers the interaction Translate events when a feature is selected even if we just click on the feature itself and it does not move. To prevent this, since in the captured "translateend" event we do not have, as we do in native OL, the "e.startCoordinate" or "e.coordinate" properties, I had to store all "e.features" coordinates during "translatestart" and compare them at "translateend". This workaround works, but I am not sure if it is the best solution.

The real problem comes when trying to prevent this "phantom change" from also adding a new state to UndoRedo, but it seems impossible. Somehow, an internal change event is triggered automatically and this new false state is added to the stack, and it is impossible to prevent or undo it: using "setActive(false)" the state is still added (as if something is called before "translatestart"), if we programmatically force an "undo()" a later state will be pushed to the redo stack, and if we use "shift()" only the first undo state is ever removed. This means that if this "phantom change" occurs at any other point in the flow than the first change, the solution will be incorrect.

I think it would be useful to be able to manually disable the creation of new states in UndoRedo, or at least to be able to call a function similar to "shift()" but that deletes the last state and not the first.

You can see this behavior in all examples of the UndoRedo class: https://viglino.github.io/ol-ext/examples/interaction/map.interaction.undoredo.html

Thank you very much

[Viglino]

I've added a abort() method to abort the last action.
UndoRedo now check the translateend envent to prevent null translation and reverse (abort) the action.
There is still a "phantm change" at start but it will be removed on end.
Check : https://viglino.github.io/ol-ext/examples/interaction/map.interaction.undoredo.html

[Viglino]

I also mad it avaliable for scale and rotate actions

[aleupons]

Thanks @Viglino, but the behavior is still not entirely correct. When the abort method is called, the states in the redo stack are also cleared, so if we are undoing and encounter a "ghost action," the subsequent states are lost.

[aleupons]

Another bug I found related to this "phantom change" is:

• It also gets pushed onto the redo stack when we are in the native OL mode and modify a selected point-type feature (clicking on it without movement). This can be seen in the example: https://viglino.github.io/ol-ext/examples/interaction/map.interaction.undoredo.html (this is critical because we need the Modify interaction for functionalities that Transform does not have, such as editing polygon vertices, and because we move points with Modify).

• The abort is applied incorrectly to features selected and moved with OL's native translate, even when their coordinates are changing (this might be less critical if we assume we will never activate OL's Translate since we already have that functionality via Transform).

[Viglino]

I've updated the method to register the operation only after (no more ghost).
Now it should now work with the Modify and Translate interaction too.

[aleupons]

Thank you!
Now it works well with all Transform interactions (Rotate, Scale, Translate) and with native OL Modify and Translate (and without ghost)