Mirror

Edit tab → Mirror. Keep one half of the drawing and reflect it onto the other, for logos that should be symmetrical but weren’t drawn (or scanned) that way.

Use it

1. Choose the Axis: Vertical (left/right) or Horizontal (top/bottom).
2. Choose which side to Keep. The other side is washed out on the canvas.
3. Set the Position: drag the dashed line, type a value, or Centre.
4. Press Mirror left onto right (or the matching label). The tool switches back to Select so you can see the result. It’s one undo step.

How it works

For each shape, in paint order:

1. Intersect it with the kept half.
2. Reflect that across the axis.
3. Unite the two.

A shape that crossed the axis comes out as one seamless shape, not two halves meeting at a hairline. Shapes entirely on the discarded side are dropped; fills and paint order are kept.

The booleans are paper.js (MIT), loaded only the first time you open the Mirror tool: 71 KB gzipped, against a 110 KB app. The unit tests run the same build, and the browser tests render the exported SVG and compare each half pixel by pixel: 0.0% of pixels differ on a symmetrical logo.

Mirroring is a shape edit, so afterwards changing a trace setting asks first.