PathPoint

Added in version 4.14.

class PathPoint(*args, **kwargs)

GskPathPoint is an opaque type representing a point on a path.

It can be queried for properties of the path at that point, such as its tangent or its curvature.

To obtain a GskPathPoint, use get_closest_point, get_start_point, get_end_point or get_point.

Note that GskPathPoint structs are meant to be stack-allocated, and don’t hold a reference to the path object they are obtained from. It is the callers responsibility to keep a reference to the path as long as the GskPathPoint is used.

Methods

class PathPoint

compare(point2: PathPoint) → int

Returns whether point1 is before or after point2.

Added in version 4.14.

Parameters:

point2 – another GskPathPoint

equal(point2: PathPoint) → bool

Returns whether the two path points refer to the same location on all paths.

Note that the start- and endpoint of a closed contour will compare nonequal according to this definition. Use is_closed to find out if the start- and endpoint of a concrete path refer to the same location.

Added in version 4.14.

Parameters:

point2 – another GskPathPoint

free() → None

get_curvature(path: Path, direction: PathDirection) → tuple[float, Point]

Calculates the curvature of the path at the point.

Optionally, returns the center of the osculating circle as well. The curvature is the inverse of the radius of the osculating circle.

Lines have a curvature of zero (indicating an osculating circle of infinite radius. In this case, the center is not modified.

Circles with a radius of zero have INFINITY as curvature

Note that certain points on a path may not have a single curvature, such as sharp turns. At such points, there are two curvatures – the (limit of) the curvature of the path going into the point, and the (limit of) the curvature of the path coming out of it. The direction argument lets you choose which one to get.

Added in version 4.14.

Parameters:

• path – the path that point is on

• direction – the direction for which to return the curvature

get_distance(measure: PathMeasure) → float

Returns the distance from the beginning of the path to point.

Added in version 4.14.

Parameters:

measure – a GskPathMeasure for the path

get_position(path: Path) → Point

Gets the position of the point.

Added in version 4.14.

Parameters:

path – the path that point is on

get_rotation(path: Path, direction: PathDirection) → float

Gets the direction of the tangent at a given point.

This is a convenience variant of get_tangent that returns the angle between the tangent and the X axis. The angle can e.g. be used in gtk_snapshot_rotate().

Added in version 4.14.

Parameters:

• path – the path that point is on

• direction – the direction for which to return the rotation

get_tangent(path: Path, direction: PathDirection) → Vec2

Gets the tangent of the path at the point.

Note that certain points on a path may not have a single tangent, such as sharp turns. At such points, there are two tangents – the direction of the path going into the point, and the direction coming out of it. The direction argument lets you choose which one to get.

If the path is just a single point (e.g. a circle with radius zero), then tangent is set to 0, 0.

If you want to orient something in the direction of the path, get_rotation may be more convenient to use.

Added in version 4.14.

Parameters:

• path – the path that point is on

• direction – the direction for which to return the tangent