Fixed behavior of insert track queue in AnimationTrackEditor is unstable

[TokageItLab]

Fixed #51415.

The queue for insert track in AnimationTrackEditor gets the drawing frame of the Engine and determines if the operation was done on the same frame. Why do we implement it this way? This implementation seems to be special compared to other queues.

There does not seem to be any code anywhere that uses the insert track queue, but when we actually try to use it, it does not work well in 4.0 (at least it was working well in 3.3) where the renderer has changed significantly.

I made it so that the queue creation and commit is done manually.

[TokageItLab]

I found a problem with undo in BezierTrack and am working on fixing it.

[TokageItLab]

The undo problem has been fixed. I assume that this queue was only for BezierTrack, and if we try to use it from outside of AnimationTrackEditor, it works fine in 3.3 and earlier, but not in 4.0. Anyway, I think this is not a good way to implement queue, and it is actually causing problems in the implementation of #45699, so I fixed it.

[TokageItLab]

I fixed the part that was reviewed.

[TokageItLab]

@JFonS As I mentioned in #45699, if this implementation is not done, inserting bone animation will not work properly and the implementation of SkeletonGizmo is halted, so if you can, it would be helpful that you review and approve this PR.
Alternatively, it's one way to merge this PR into SkeletonGizmo without separating as this.

CC @fire

[JFonS]

I don't know much about the animation track system, so I can't properly review this PR, sorry.

[TokageItLab]

@fire Here is video demo.

This is the behavior in the current master.

2021-08-23.1.32.41-1.mov

If I do track_insert_key() from within SkeletonEditorPlugin with the number of bones, only one track is inserted. Also, you can see that the timing of the popup warning is wrong.

Thus, for example, I provided one frame of grace for the judging.

void AnimationTrackEditor::_query_insert(const InsertData &p_id) {
	if (insert_frame != Engine::get_singleton()->get_frames_drawn()) {
		//clear insert list for the frame if frame changed
		if (insert_confirm->is_visible()) {
			return; //do nothing
		}
		insert_data.clear();
		insert_query = false;
	}
	insert_frame = Engine::get_singleton()->get_frames_drawn() + 1; // <- one frame of grace

2021-08-23.1.35.53-1.mov

The result is that two tracks are now inserted at the same time. But, the timing of the popup warning is still wrong.

After this PR makes elimination of judging by drawing frame and setting the queue manually, all tracks will be inserted correctly at the same time with the same code except for setting the queue manually.

2021-08-23.1.43.22-1.mov

[TokageItLab]

#45699 has been merged, so I updated it. Currently multiple animation tracks insertion by SkeletonEditor is broken, but it will be fixed when this PR is merged.

[akien-mga]

Thanks!