Design References and Comparing
Keep a reference when an edit needs a meaningful comparison. A mask holds artwork beside the working drawing; History lets you revisit editing states, and Rewind can explore an intermediate result between a recording and the current drawing.
Masks
A mask is reference content associated with a glyph's design layer, a case of the service-layer model developed in Layers and Masters. It can contain contours or an image used for tracing. It is excluded from ordinary rendered font output and interpolation, while native working data can retain it for further editing.
A glyph with several design layers can have a corresponding mask for each. Check which drawing is current before copying or exchanging reference content.
Compare an edit with its starting shape
Copy to Mask can add content to an existing mask. If you need one clean before-state, inspect the mask first. Preserve any reference you still need, then use Tools > Mask > Clear Mask (Cmd+K on macOS, Ctrl+K on Windows) before making the new copy. Repeated copying without checking the existing content can leave several references superimposed.
- Open the glyph and make the intended design layer current.
- Select the contours you want to preserve, or clear the selection deliberately to copy the broader drawing.
- Choose Tools > Mask > Copy to Mask (Cmd+M on macOS, Ctrl+M on Windows).
- Keep the mask visible through View > Layers & Glyphs > Mask.
- Edit the main drawing and compare it with the reference.
The mask remains reference material while you edit the design. Its appearance can be adjusted so it is visible without obscuring the working contours. A difference from the mask is not an error by itself; it shows what your edit changed.
Edit or reuse the reference
Choose Tools > Mask > Edit Mask (Ctrl+H on macOS) to make the mask itself editable. FontLab changes the editing context and background indication. Use the same command again to return to the design, and check the active state before moving points.
Paste Mask copies mask content into the design. It does not mean “restore the old design”: it can add the reference alongside the current drawing. Inspect for duplicate contours after pasting.
Swap with Mask exchanges the design and mask contents. Use it when you want the reference to become the working version and the current drawing to become the comparison. The exchanged contents are real drawing changes, not just a change of display order.
Align against a mask
Enable View > Snap > Mask to use the visible mask as a reference while dragging. This can help retain a point or edge while changing the surrounding curve.
For a direct alignment, select the intended points and choose Contour > Align Points > To Mask. This searches for nearby mask points of the appropriate type; it is not a universal match by point index or semantic feature. If the reference differs substantially, a point may not move or may find a different nearby point than you intended. Use a small selection and inspect the result.
A placed scan can also live in the mask. Move to Mask in the Autotrace dialog retains the source there while leaving traced contours in the design. Use the image to assess the trace, remembering that a blurred or noisy source does not define an exact ideal edge.
Use a Global Mask
Tools > Mask > Copy to Global Mask (Shift+Cmd+M on macOS, Ctrl+Shift+M on Windows) supplies reference artwork that can be shown across glyphs in the font. It is useful for comparing a shared motif or construction reference without making an individual copy in every glyph.
Show it with View > Layers & Glyphs > Global Mask and enable View > Snap > Global Mask when you want it as a snap target. The Global Mask is not edited directly like an ordinary glyph mask. To revise it, edit the source drawing and copy the intended reference again. Treat copying as replacing the shared reference and preserve the old source if you need both.
Paste Global Mask brings available shared content into the current design; inspect the result before editing it. Clear Global Mask (Shift+Cmd+K on macOS, Ctrl+Shift+K on Windows) removes the shared reference. These are separate from the local mask operations, so check the command name before clearing or replacing a reference.
History and Rewind
The History panel records editing states you can compare while developing a glyph. Rewind offers another kind of comparison: a local geometric blend between a recorded form and an edited form. This is interpolation applied to one glyph, an introduction to the model taught in The Variation Model, rather than a sequence of ordinary Undo steps.
The result is most predictable when the states have corresponding contours and points. Moving existing points provides a clearer comparison than rebuilding the path between states. A blend can suggest a useful intermediate shape, but it does not decide whether that shape is structurally sound or well spaced.
A mask preserves a reference for visual comparison; Rewind explores a shape between states. Keep a saved source before a major structural change. The detailed Record, Rewind, Fast-Forward, and undo-browser controls belong to the History panel reference in Volume Two.