Keyboard shortcuts
| Action | Windows / Linux | macOS |
|---|---|---|
| Undo | CTRL+Z | CMD+Z |
| Redo | CTRL+Y | CMD+⇧+Z |
These are the only ways to undo/redo right now — the toolbar buttons exist in the codebase but are hidden in this build.
What's in scope
Undo and redo cover marker mutations on the active drawing:
- Creating a marker (any type).
- Deleting a marker.
- Moving a marker.
- Changing a marker's metadata (length, area, label).
- Group-level changes — recolouring, opacity, stroke width.
- Adding or removing markers from a group via Auto Count Symbol.
What's not in scope:
- File-level operations — uploads, rotations, deletes, services.
- Project-level operations — duplicating, archiving, renaming.
- AOI / zone / ignore-colour changes (these have their own state and don't go through the undo stack).
- Reset Drawing — it deliberately wipes the undo stack.
If you change drawing, the undo stack for the previous drawing is cleared. You can't undo across drawings.
Stack depth
The undo stack holds up to 10 actions. After 10, the oldest action falls off the bottom — undo can't go further back than that.
The redo stack is also capped at 10 and is cleared whenever you do something new after an undo.
What gets snapshotted
ZeroCount uses a snapshot-based undo system. Before every mutation, it captures the relevant state and stores it on the stack. Thumbnails are cached separately so snapshots stay small.
This keeps undo fast even on drawings with hundreds of markers — you don't pay for the size of the data, only for the actual changes.
When undo doesn't go far enough
For project-level rollback, undo is the wrong tool. Use one of these instead:
- Reset Drawing — see Resetting a drawing. Wipes the drawing back to its initial state.
- Duplicate Project before risky changes — see Duplicating a project. The duplicate is your snapshot.
- Restore from a backup — if you don't have a duplicate and undo can't help, contact your administrator.
Reset Drawing deliberately can't be undone — once you confirm the dialog, the undo stack is wiped along with the markers.
Practical patterns
A few habits that play well with the 10-deep stack:
- Check after each significant change. If something looks wrong, undo immediately rather than continuing — once you're 10 actions past the mistake, you can't get back.
- Duplicate the project before bulk operations. Auto Count Symbol on a complex drawing can spit out 50+ markers in one go — if the result is wrong, undoing it is one action, but if you continue editing first, you may not be able to recover.
- Use group merges carefully. Merges are technically not on the undo stack — they're a deliberate consolidation. The dialog warning applies.