capstyle

CapStyle refers to the style used to terminate the ends of stroked lines in vector graphics and drawing APIs. It defines how the end of a line is rendered when the stroke ends at a point or at a bend, affecting visual length and form.

The most common options are butt, round, and square. A butt cap ends exactly at the line's end point, with no extension beyond. A round cap adds a semicircular end whose diameter equals the line width. A square cap extends beyond the end by half the line width, producing a rectangular projection that can slightly lengthen the line visually.

Different graphics frameworks expose this setting under different names but with similar behavior. In SVG and CSS, the property stroke-linecap accepts butt, round, or square. In HTML5 Canvas, the lineCap property takes 'butt', 'round', or 'square'. Other toolkits may call it by terms such as FlatCap, RoundCap, or SquareCap, but the effect is equivalent.

Practical use: capStyle influences how lines look at open paths and when joining segments. Choice of cap affects perceived alignment with adjacent shapes, the apparent length of hairline strokes, or the smoothness of rounded ends in rounded line motifs.