[MU4 Task] Automation UI implementation

[avvvvve]

Task description
This is the first implementation task to introduce Automation in MuseScore 4. Users should be able to:

• Toggle showing automation on the score via an 'Automation' button in the top bar
• Add, move, and delete points on the automation line
• Draw custom automation by clicking and dragging
• Bend line segments
• Select from Dynamics (or Velocity for VSTs/Soundfonts), Pan, Volume, plugin-specific parameters, and MIDI CCs to automate
• Choose which voice to automate
• ...and more, as detailed in Figma!

A later task will handle drawing the default Dynamics (for MuseSounds) and Velocity (VSTs, Soundfounts) curves based on the dynamics in the score.

[avvvvve]

cc @bkunda @Tantacrul

[KJinx101]

Wow this is a great concept. Perhaps eventually, things that can capitalize on this UI design and grant full control over playback:

• Offset note position/ Duration (as note properties like velocity): One of the strengths of the Legacy Piano Roll Editor from MS 3 was that you didn't actually have to use the 'piano roll' to edit note position. Similarly to how velocity was edited in automation below, note position (when the sound starts to play) and duration could be changed there as well, like velocity. (but offset position started in the middle) Being able to do this without the need for Piano Roll editing would allow for VST features like legato (controlled by overlapping notes) and allow for more human-like rubato without affecting tempo; or simply change the interpretation without affecting notation.

While a piano roll wouldn't be ready for implementation now, these would grant similar capabilities before that is ready without having to worry about the UI and editor complications. This could really eliminate the need for a piano roll while it may still be handy later on as a bonus.

Edit: I've been alerted that one of the main reasons the PRE is not currently in development is because of the desire to avoid having to use these which are deemed not sufficiently flexible enough to implement and subsequently not worth adding to the codebase / maintaining. Understood. If any similar temporary measures can be instated sooner to affect finer note position/ where the attack starts and note duration separate from the notation conveniently that would be amazing. Otherwise looking forward to the playback engine improvements in MU5 or later.

• Something similar to Studio One sound variations where things like midi channel, keyswitches, and other automatic midi CC changes can be triggered by something similar to automation... [and perhaps can automatically be linked to/ applied by staff text]. Mainly for working with VST plugins

Seeing that this is now marked ready for development I just wanted to bring these to attention before development was fully underway, in case these could be taken into account before possible road-blocks may come up in implementation once it's partially built.
Haven't looked at the figma (not sure how to see that or if users are allowed) so I'm not sure if these are already mentioned there or already deemed not possible there. Thank you

[TobyTwo32]

When can we expect this to be released. In 4.6? I'd like to be able to used other VSTs I bought outside of the paid muse sounds I got.