JSON Format

DemoSpline stores drawings as a top-level subpaths array. Each subpath contains a closed flag and a pts array.

Shape

{
  "subpaths": [
    {
      "closed": false,
      "pts": [
        { "x": 0.0, "y": 0.0, "c": 0 },
        { "x": 50.0, "y": 20.0, "c": 1, "t": 0.35 },
        { "x": 100.0, "y": 0.0, "c": 0, "l": 2.8, "r": 0.1 }
      ]
    }
  ]
}

Point fields

x, y: point coordinates
c: point kind, where 1 means smooth and 0 means corner
t: shared tangent for smooth points
l, r: explicit left and right tangents for corner points

Notes

Coordinates are rounded to two decimal places during save.
Tangent values are rounded to three decimal places.
Smooth points deserialize t into both LTh and RTh.
Corner points may omit l or r independently.

This format is specific to the sample application rather than the reusable library package.