controller script: support parameter-space access to controls

[Be]

To handle incoming and outgoing signals for controllers, script writers have to look up the range of each control object on http://mixxx.org/wiki/doku.php/mixxxcontrols and write the logic to scale the controller's signals to Mixxx's values. This is inconvenient and results in a lot of code duplication. With XML mappings, this is handled automatically by Mixxx.

See also: https://bugs.launchpad.net/mixxx/+bug/398350

[Sean M. Pappalardo (pegasus-renegadetech)]

This and the linked bug will be addressed with a control system rewrite. (What we've been calling "Control 2.0")

[Ferran Pujol (ferranpujol)]

So essentially you're proposing to work at parameter level instead of at value level in scripts, isn't it? This is great idea, but IMHO scriptwriters should still be able to access CO at value-level if they need to.

[Be (be.ing)]

Yes. The most simple syntax should automatically scale values but there should be an alternate syntax that would still allow finer control.

[Sean M. Pappalardo (pegasus-renegadetech)]

Careful, the XML mappings assume 0..127 MIDI ranges. Any physical controls that have ranges that differ from this would not work correctly. There's no way for Mixxx to know such ranges without at least extending the XML schema, a bit like what's on the proposed HID XML schema wiki page.

[Be (be.ing)]

Do you mean there is no way for Mixxx to tell whether a script is for MIDI or HID? Mixxx should have a default range for each protocol and there should be a way for scripts to easily specify a different range for each control.

[Be (be.ing)]

This could be done with a JS library, but it would have to be updated with each new CO that is added.

[RJ Skerry-Ryan (rryan)]

We added engine.getParameter and engine.setParameter a while back so this should be fixed.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/8261