expand strokes

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Modeling - Editing

Expand Strokes (command)

Build the shape a stroke draws, at its own width, as geometry you can work on.

Command palette: Expand Strokes | In depth: Style palettes & Re-ink

It lives in the command palette

No menu row and no icon, the same as Flatten.

Why it exists

A stroke's width, placement, joins and caps are drawn and never stored. The band you see on the screen existed nowhere as geometry, so it could not be combined with a boolean, offset, measured as an area, or written into an export. Expand Strokes builds it: both sides of the stroke at its own width, turned the way its joins turn and ended the way its caps end.

What comes out

• A closed stroke gives a ring. An outer boundary and an inner one, and the inner reads as a hole because it nests inside the outer.
• An open stroke gives one shape. Up one side, across the end cap, back down the other side, across the start cap.
• The result wears the stroke's color as its fill, and carries no stroke of its own. A stroke on the outline of a stroke would draw a second, wider shape nobody asked for.
• Pieces that touch are treated as one stroke. Four segments meeting end to end outline as one band, not as four bands with a cap at every corner.
• Crossing bands merge. A letterform comes out solid rather than gapped at each crossing, and a stroke that crosses its own path resolves too.
• The original is hidden, not deleted, the same as Convert to Spline.

What it turns down

• A dashed stroke is refused by name: "a dashed stroke cannot be expanded yet". Nothing turns a dash pattern into geometry, and a solid outline is not what a dashed stroke draws, so it says so rather than quietly handing back the wrong shape.
• An object with no stroke is told to give it a stroke color and a width first.
• A stroke too wide for its own curve is refused. Past a certain width a side breaks into several pieces, and there is no honest way to pair the halves back into one boundary.

It is not Illustrator's Expand

Two differences, and both catch people arriving from there.

• There is no Fill option and no options panel. Illustrator's Fill earns its keep on gradients, pattern fills, live shapes and blends, none of which exist here; on a plain filled path it hands back the same path. What it would be useful for here, turning a circle, an arc or a region into an editable path, is what Convert to Spline already does. The name says Strokes for the same reason: Illustrator's Expand covers far more than this one does.
• Merging is not optional. Illustrator does not offer that choice either.

Note

One known limit. With the corner style set to Miter or Bevel the outline comes out as short straight runs rather than curves. Round is the default, so the common case is right. It is filed.

Related

• Style palettes & Re-ink: where a stroke's width, color, joins and caps are set.
• Flatten: the other command that turns what is drawn into geometry.
• Convert to Spline: a circle, an arc or a region made editable.
• Regions & booleans: what an expanded outline can then be combined with.
• Unhide All: how the original comes back.

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