Build UI for DrumKit music generation mode

[alexfjw]

Requirements

Control Panel
Tempo control | Playback control | Clear
(up, down) | (play, pause, record)

Rows of instruments
Row: Instrument name | 16 grey boxes
Clear should clear the currently selected row
....

Tempo varies from 60-120
Line moves at 1 grey box per second for tempo = 60

TODO:

• control panel
• timing line
• instrument row
• combining rows & timing line into 1 view object
• move seekbar when recording/playing
• add row selection ui & clear logic
• snap seekbar to start of nearest beat if record/play is clicked

[alexfjw]

Looks like this for now, left with checking the length of the boxes & moving the timing line.

[senyuuri]

Looks amazing!