Anchor table¶

The anchor table is the per-camera-clip list of alignment anchors — the raw data behind Phase 2 of the two-phase approach. It lives at the bottom of Level 2 with a fixed maximum height of 200 px.

Layout¶

┌────────────────────────────────────────────────────────────────────┐
│ [Alignment Anchors] [ Add Anchor (A) ]          [Delete Selected]  │ ← header row
├───┬──────────────┬─────────────┬──────────────┬───────────────┬────┤
│ # │ MIDI File    │ MIDI Time(s)│ Camera Frame │ Derived Shift │ L  │*│
├───┼──────────────┼─────────────┼──────────────┼───────────────┼────┤
│ 1 │ trial_001.mid│ 12.456      │ 2987         │ 0.0123        │    │*│ ← active
│ 2 │ trial_001.mid│ 47.802      │ 11487        │ 0.0125        │    │ │
│ 3 │ trial_002.mid│ 4.105       │ 984          │ 0.0112        │    │ │ ← greyed out
└───┴──────────────┴─────────────┴──────────────┴───────────────┴────┘

Columns¶

#	Column	Meaning
0	`#`	1-based row number (resizes to fit)
1	`MIDI File`	`anchor.midi_filename`
2	`MIDI Time (s)`	`anchor.midi_timestamp_seconds`, 3 decimals
3	`Camera Frame`	`anchor.camera_frame`
4	`Derived Shift (s)`	`compute_anchor_shift` output, 4 decimals. `N/A` if the anchor's MIDI file isn't in the current session.
5	`Label`	`anchor.label` (free text, optional)
6	`Active`	`*` if this row's anchor is the active one; blank otherwise. Centered; dark green background + white text when active.

All columns stretch to fit the available width except # and Active, which resize to their contents. Rows are not editable.

Header buttons¶

Add Anchor (A) — injected by Level 2 into the header row (see add_header_action). Disabled until both markers are set. Clicking opens an input dialog for an optional label, then calls AlignmentService.add_anchor with the anchor built from the markers.
Delete Selected — disabled until a row is selected. Deletes the currently-selected anchor via AlignmentService.delete_anchor, which also repairs active_anchor_index if the deleted anchor was active (sets it to None) or earlier in the list than the active one (shifts it down by 1).

Filtering¶

Anchors whose midi_filename doesn't match the currently-selected MIDI combo are rendered greyed out (grey foreground text) and made non-selectable. They still show every column for reference, but:

Clicking the Active cell is ignored.
Double-clicking the MIDI Time / Camera Frame cells is ignored.
The row cannot be selected, so Delete Selected cannot be invoked on them.

This prevents confusion when the same camera clip is viewed against a different MIDI file — only anchors tied to the shown MIDI are actionable.

Interactions¶

Input	Action
Single-click on the `Active` cell (col 6)	Toggle active. If this row is already active → deactivate (`set_active_anchor(None)`, emit `anchor_deactivated`). Otherwise → activate (`set_active_anchor(row)`, emit `anchor_activated(row)`). Ignored for greyed rows.
Double-click on `MIDI Time (s)` (col 2)	Emit `midi_time_jump_requested(seconds)` → Level 2 jumps the MIDI panel to that time and makes it the active panel. Ignored for greyed rows.
Double-click on `Camera Frame` (col 3)	Emit `camera_frame_jump_requested(frame)` → Level 2 jumps the camera panel to that frame and makes it the active panel. Ignored for greyed rows.
Row selection	Enables/disables Delete Selected. Multiple selection is disabled.

Signals¶

Signal	When
`anchor_activated(int)`	A row's Active cell was clicked, setting that row active
`anchor_deactivated()`	A row's Active cell was clicked while already active
`anchor_deleted(int)`	A row was successfully deleted via Delete Selected
`midi_time_jump_requested(float)`	Double-click on col 2
`camera_frame_jump_requested(int)`	Double-click on col 3

Level 2 catches all five and re-syncs the panels, refreshes the overlap bar, and marks the session dirty as appropriate.

What the table doesn't do¶

No in-place editing — the anchor's MIDI time, camera frame, and label are immutable once created. To "edit" an anchor, delete it and add a new one.
No multi-select or bulk delete.
No import/export outside the main save/load. Anchors travel with the session JSON.