Struct kurbo::BezPath

pub struct BezPath(_);

A path that can Bézier segments up to cubic, possibly with multiple subpaths.

Implementations

impl BezPath

pub fn new() -> BezPath

Create a new path.

pub fn from_vec(v: Vec<PathEl>) -> BezPath

Create a path from a vector of path elements.

BezPath also implements FromIterator<PathEl>, so it works with collect:

// a very contrived example:
use kurbo::{BezPath, PathEl};

let path = BezPath::new();
let as_vec: Vec<PathEl> = path.into_iter().collect();
let back_to_path: BezPath = as_vec.into_iter().collect();

pub fn push(&mut self, el: PathEl)

Push a generic path element onto the path.

pub fn move_to<P: Into<Point>>(&mut self, p: P)

Push a "move to" element onto the path.

pub fn line_to<P: Into<Point>>(&mut self, p: P)

Push a "line to" element onto the path.

pub fn quad_to<P: Into<Point>>(&mut self, p1: P, p2: P)

Push a "quad to" element onto the path.

pub fn curve_to<P: Into<Point>>(&mut self, p1: P, p2: P, p3: P)

Push a "curve to" element onto the path.

pub fn close_path(&mut self)

Push a "close path" element onto the path.

pub fn elements(&self) -> &[PathEl]

Get the path elements.

pub fn iter(&self) -> impl Iterator<Item = PathEl> + '_

Returns an iterator over the path's elements.

pub fn segments(&self) -> impl Iterator<Item = PathSeg> + '_

Iterate over the path segments.

pub fn flatten(&self, tolerance: f64, callback: impl FnMut(PathEl))

Flatten the path, invoking the callback repeatedly.

Flattening is the action of approximating a curve with a succession of line segments.

The tolerance value controls the maximum distance between the curved input segments and their polyline approximations. (In technical terms, this is the Hausdorff distance). The algorithm attempts to bound this distance between by tolerance but this is not absolutely guaranteed. The appropriate value depends on the use, but for antialiasted rendering, a value of 0.25 has been determined to give good results. The number of segments tends to scale as the inverse square root of tolerance.

The callback will be called in order with each element of the generated path. Because the result is made of polylines, these will be straight-line path elements only, no curves.

This algorithm is based on the blog post Flattening quadratic Béziers but with some refinements. For one, there is a more careful approximation at cusps. For two, the algorithm is extended to work with cubic Béziers as well, by first subdividing into quadratics and then computing the subdivision of each quadratic. However, as a clever trick, these quadratics are subdivided fractionally, and their endpoints are not included.

TODO: write a paper explaining this in more detail.

Note: the flatten function provides the same functionality but works with slices and other PathEl iterators.

pub fn get_seg(&self, ix: usize) -> Option<PathSeg>

Get the segment at the given element index.

The element index counts PathEl elements, so for example includes an initial Moveto.

pub fn is_empty(&self) -> bool

Returns true if the path contains no segments.

pub fn apply_affine(&mut self, affine: Affine)

Apply an affine transform to the path.

pub fn nearest(&self, p: Point, accuracy: f64) -> (usize, f64, f64)

Find the nearest point.

Panics if path is empty or invalid.

Note that the returned index counts segments, not elements. Thus, the initial Moveto is not counted. For a simple path consisting of a Moveto followed by Lineto/Quadto/Cubicto elements, the element index is the segment index + 1.

Returns the index of the segment, the parameter within that segment, and the square of the distance to the point.

impl BezPath

pub fn from_path_segments(segments: impl Iterator<Item = PathSeg>) -> BezPath

Create a BezPath with segments corresponding to the sequence of PathSegs

pub fn to_svg(&self) -> String

Convert the path to an SVG path string representation.

The current implementation doesn't take any special care to produce a short string (reducing precision, using relative movement).

pub fn write_to<W: Write>(&self, writer: W) -> Result<()>

Write the SVG representation of this path to the provided buffer.

pub fn from_svg(data: &str) -> Result<BezPath, SvgParseError>

Try to parse a bezier path from an SVG path element.

This is implemented on a best-effort basis, intended for cases where the user controls the source of paths, and is not intended as a replacement for a general, robust SVG parser.

Trait Implementations

impl Clone for BezPath

fn clone(&self) -> BezPath

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BezPath

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Default for BezPath

fn default() -> BezPath

Returns the "default value" for a type.

impl<'de> Deserialize<'de> for BezPath

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
    __D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.

impl Extend<PathEl> for BezPath

fn extend<I: IntoIterator<Item = PathEl>>(&mut self, iter: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬 This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬 This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl FromIterator<PathEl> for BezPath

fn from_iter<T: IntoIterator<Item = PathEl>>(iter: T) -> Self

Creates a value from an iterator.

impl<'a> IntoIterator for &'a BezPath

Allow iteration over references to BezPath.

Note: the semantics are slightly different than simply iterating over the slice, as it returns PathEl items, rather than references.

type Item = PathEl

The type of the elements being iterated over.

type IntoIter = Cloned<Iter<'a, PathEl>>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl IntoIterator for BezPath

type Item = PathEl

The type of the elements being iterated over.

type IntoIter = IntoIter<PathEl>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'a> Mul<&'a BezPath> for Affine

type Output = BezPath

The resulting type after applying the * operator.

fn mul(self, other: &BezPath) -> BezPath

Performs the * operation.

impl<'a> Mul<&'a BezPath> for TranslateScale

type Output = BezPath

The resulting type after applying the * operator.

fn mul(self, other: &BezPath) -> BezPath

Performs the * operation.

impl Mul<BezPath> for Affine

type Output = BezPath

The resulting type after applying the * operator.

fn mul(self, other: BezPath) -> BezPath

Performs the * operation.

impl Mul<BezPath> for TranslateScale

type Output = BezPath

The resulting type after applying the * operator.

fn mul(self, other: BezPath) -> BezPath

Performs the * operation.

impl Serialize for BezPath

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error> where
    __S: Serializer, 

Serialize this value into the given Serde serializer.

impl Shape for BezPath

type BezPathIter = IntoIter<PathEl>

The iterator resulting from to_bez_path.

fn to_bez_path(&self, _tolerance: f64) -> Self::BezPathIter

Convert to a Bézier path, as an iterator over path elements.

fn area(&self) -> f64

Signed area.

fn perimeter(&self, accuracy: f64) -> f64

Total length of perimeter.

fn winding(&self, pt: Point) -> i32

Winding number of point.

fn bounding_box(&self) -> Rect

The smallest rectangle that encloses the shape.

fn as_path_slice(&self) -> Option<&[PathEl]>

If the shape is stored as a slice of path elements, make that available.

fn into_bez_path(self, tolerance: f64) -> BezPath

Convert into a Bézier path.

fn as_line(&self) -> Option<Line>

If the shape is a line, make it available.

fn as_rect(&self) -> Option<Rect>

If the shape is a rectangle, make it available.

fn as_rounded_rect(&self) -> Option<RoundedRect>

If the shape is a rounded rectangle, make it available.

fn as_circle(&self) -> Option<Circle>

If the shape is a circle, make it available.