Edit Menu

The Edit menu provides per-document history control: Undo and Redo.

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Undo

• What it does: Steps the active image one edit backward.

• Scope: Affects only the active document/view (not global).

• Details:

  • Each edit pushes the previous state to an undo stack with a human-readable step name (e.g., “Edit”, or a tool-provided name).
  • You can check if undo is possible (can_undo).
  • When you Undo, the reverted state is pushed onto Redo.

Redo

• What it does: Steps forward to the next state after an Undo.

• Scope: Per document.

• Details:

  • Available only after at least one Undo (can_redo).
  • Performing a new edit after Undo clears the Redo stack (standard behavior).

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How history works (under the hood)

• Every edit uses ImageDocument.apply_edit(...) which:

  • Saves the current (image, metadata, step_name) onto Undo.
  • Clears Redo.
  • Sets the new image/metadata and emits changed.

• Helpers exist to query history:

  • can_undo(), can_redo()
  • last_undo_name(), last_redo_name()
  • get_undo_stack() returns labeled steps (oldest→newest before current).

• History is persisted in Projects:

  • Save Project… writes both undo and redo stacks.
  • Load Project… restores them, so you can keep undoing/redoing after reopening.

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Notes & tips

• New edits clear Redo: If you want to keep the ability to step forward, Redo before making new changes.
• Closing a view with edits: If a document has undo history, the app asks for confirmation when closing that view to prevent accidental loss of work.
• Per-view layers/overlays: Visual composites happen in the view; Undo/Redo tracks the document image and metadata steps.