Trait kurbo::Shape[−][src]

pub trait Shape: Sized {
    type PathElementsIter: Iterator<Item = PathEl>;
    fn path_elements(&self, tolerance: f64) -> Self::PathElementsIter;

    fn area(&self) -> f64;

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

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

    fn bounding_box(&self) -> Rect;

    fn to_path(&self, tolerance: f64) -> BezPath { ... }

    fn into_path(self, tolerance: f64) -> BezPath { ... }

    fn path_segments(&self, tolerance: f64) -> Segments<Self::PathElementsIter>ⓘ
Notable traits for Segments<I>
impl<I: Iterator<Item = PathEl>> Iterator for Segments<I>    type Item = PathSeg;
 { ... }

    fn contains(&self, pt: Point) -> bool { ... }

    fn as_line(&self) -> Option<Line> { ... }

    fn as_rect(&self) -> Option<Rect> { ... }

    fn as_rounded_rect(&self) -> Option<RoundedRect> { ... }

    fn as_circle(&self) -> Option<Circle> { ... }

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

A generic trait for open and closed shapes.

This trait provides conversion from shapes to BezPaths, as well as general geometry functionality like computing area, bounding_boxes, and winding number.

Associated Types

type PathElementsIter: Iterator<Item = PathEl>[src]

The iterator returned by the path_elements method.

Loading content...

Required methods

fn path_elements(&self, tolerance: f64) -> Self::PathElementsIter[src]

Returns an iterator over this shape expressed as PathEls; that is, as Bézier path elements.

All shapes can be represented as Béziers, but in many situations (such as when interfacing with a platform drawing API) there are more efficient native types for specific concrete shapes. In this case, the user should exhaust the as_ methods (as_rect, as_line, etc) before converting to a BezPath, as those are likely to be more efficient.

In many cases, shapes are able to iterate their elements without allocating; however creating a a BezPath object always allocates. If you need an owned BezPath you can use to_path instead.

Tolerance

The tolerance parameter controls the accuracy of conversion of geometric primitives to Bézier curves, as curves such as circles cannot be represented exactly but only approximated. For drawing as in UI elements, a value of 0.1 is appropriate, as it is unlikely to be visible to the eye. For scientific applications, a smaller value might be appropriate. Note that in general the number of cubic Bézier segments scales as tolerance ^ (-1/6).

TODO: When GAT's land, the type of this can be changed to contain a &'a self reference, which would let us take iterators from complex shapes without cloning.

fn area(&self) -> f64[src]

Signed area.

This method only produces meaningful results with closed shapes.

The convention for positive area is that y increases when x is positive. Thus, it is clockwise when down is increasing y (the usual convention for graphics), and anticlockwise when up is increasing y (the usual convention for math).

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

Total length of perimeter.

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

The winding number of a point.

This method only produces meaningful results with closed shapes.

The sign of the winding number is consistent with that of area, meaning it is +1 when the point is inside a positive area shape and -1 when it is inside a negative area shape. Of course, greater magnitude values are also possible when the shape is more complex.

fn bounding_box(&self) -> Rect[src]

The smallest rectangle that encloses the shape.

Loading content...

Provided methods

fn to_path(&self, tolerance: f64) -> BezPath[src]

Convert to a Bézier path.

This always allocates. It is appropriate when both the source shape and the resulting path are to be retained.

If you only need to iterate the elements (such as to convert them to drawing commands for a given 2D graphics API) you should prefer path_elements, which can avoid allocating where possible.

The tolerance parameter is the same as for path_elements.

fn into_path(self, tolerance: f64) -> BezPath[src]

Convert into a Bézier path.

This allocates in the general case, but is zero-cost if the shape is already a BezPath.

The tolerance parameter is the same as for path_elements().

fn path_segments(&self, tolerance: f64) -> Segments<Self::PathElementsIter>ⓘ

Notable traits for Segments<I>

impl<I: Iterator<Item = PathEl>> Iterator for Segments<I> type Item = PathSeg;
[src]

Returns an iterator over this shape expressed as Bézier path segments (PathSegs).

The allocation behaviour and tolerance parameter are the same as for path_elements()

fn contains(&self, pt: Point) -> bool[src]

Returns true if the Point is inside this shape.

This is only meaningful for closed shapes.

fn as_line(&self) -> Option<Line>[src]

If the shape is a line, make it available.

fn as_rect(&self) -> Option<Rect>[src]

If the shape is a rectangle, make it available.

fn as_rounded_rect(&self) -> Option<RoundedRect>[src]

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

fn as_circle(&self) -> Option<Circle>[src]

If the shape is a circle, make it available.

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

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

Note: when GAT's land, a method like path_elements would be able to iterate through the slice with no extra allocation, without making any assumption that storage is contiguous.

Loading content...

Implementations on Foreign Types

impl<'a> Shape for &'a [PathEl][src]

Implements Shape for a slice of PathEl, provided that the first element of the slice is not a PathEl::ClosePath. If it is, several of these functions will panic.

If the slice starts with LineTo, QuadTo, or CurveTo, it will be treated as a MoveTo.

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

fn area(&self) -> f64[src]

Signed area.

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

Winding number of point.

impl<'a, T: Shape> Shape for &'a T[src]

Blanket implementation so impl Shape will accept owned or reference.

type PathElementsIter = T::PathElementsIter

Loading content...

Implementors

impl Shape for PathSeg[src]

type PathElementsIter = PathSegIter

fn area(&self) -> f64[src]

The area under the curve.

We could just return 0, but this seems more useful.

impl Shape for Arc[src]

type PathElementsIter = Chain<Once<PathEl>, ArcAppendIter>

fn area(&self) -> f64[src]

Note: shape isn't closed so area is not well defined.

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

Note: Finding the perimiter of an ellipse is fairly involved, so for now just approximate by using the bezier curve representation. (See https://en.wikipedia.org/wiki/Ellipse#Circumference)

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

Note: shape isn't closed so a point's winding number is not well defined.

impl Shape for BezPath[src]

type PathElementsIter = IntoIter<PathEl>

fn area(&self) -> f64[src]

Signed area.

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

Winding number of point.

impl Shape for Circle[src]

type PathElementsIter = CirclePathIter

impl Shape for CircleSegment[src]

type PathElementsIter = Chain<Chain<Chain<Chain<Once<PathEl>, Once<PathEl>>, ArcAppendIter>, Once<PathEl>>, ArcAppendIter>

impl Shape for CubicBez[src]

type PathElementsIter = CubicBezIter

impl Shape for Ellipse[src]

type PathElementsIter = Chain<Once<PathEl>, ArcAppendIter>

impl Shape for Line[src]

type PathElementsIter = LinePathIter

fn area(&self) -> f64[src]

Returning zero here is consistent with the contract (area is only meaningful for closed shapes), but an argument can be made that the contract should be tightened to include the Green's theorem contribution.

fn winding(&self, _pt: Point) -> i32[src]

Same consideration as area.

impl Shape for QuadBez[src]

type PathElementsIter = QuadBezIter

impl Shape for Rect[src]

type PathElementsIter = RectPathIter

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

Note: this function is carefully designed so that if the plane is tiled with rectangles, the winding number will be nonzero for exactly one of them.

impl Shape for RoundedRect[src]

type PathElementsIter = RoundedRectPathIter

Loading content...