Shape Recognition

Shape recognition is an opt-in mode for the Pencil tool. With it on, a rough sketch is matched against real shapes when you release, so a wobbly square becomes a proper square and a quick loop becomes a circle, no need to draw precisely.

Turning it on

A magic-wand toggle sits in the Pencil's mode banner, to the left of Cancel, with a tooltip describing whether recognition is on or off. Toggle it on, then draw as normal. The setting is remembered as a per-tool preference, so it sticks across pencil sessions (and across devices when you are signed in). It deliberately lives on the tool itself rather than in the Settings dialog, so it is right where you draw.

What it recognises

When the mode is on, your simplified stroke is scored against a handful of shapes, and if it is a confident enough match, a real shape is created instead of a freehand sketch:

• A rough four-corner outline becomes a square.
• A closed loop becomes a circle.
• A four-corner shape with corners at the edge midpoints becomes a diamond.
• A three-corner outline becomes a triangle.
• A five-pointed sketch becomes a star.
• A straight stroke becomes an arrow (a line with no arrowheads).

A few shapes are intentionally not recognised, such as trapezoids, speech bubbles, frames, and the device frames: they are either ambiguous to draw freehand or are not freehand-drawable, so they stay palette-only. If a stroke is not confidently matched, it simply commits as a normal freehand sketch.

How it decides

Recognition uses heuristics rather than template matching, measuring how closely your sample points hug each idealised shape, so it tolerates strokes drawn at any rotation or size. The confidence threshold leans toward converting: once you have turned the mode on you have stated you want strokes classified, and a false positive is a single undo away. The frustrating case is a wobbly square that stays a sketch when you wanted a real one, so the detector errs toward conversion.