Trait kurbo::Shape [−][src]
pub trait Shape: Sized {
type PathElementsIter: Iterator<Item = PathEl>;
Show 14 methods
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>ⓘ { ... }
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]> { ... }
}
Expand description
A generic trait for open and closed shapes.
This trait provides conversion from shapes to BezPath
s, as well as
general geometry functionality like computing area
, bounding_box
es,
and winding
number.
Associated Types
type PathElementsIter: Iterator<Item = PathEl>
type PathElementsIter: Iterator<Item = PathEl>
The iterator returned by the path_elements
method.
Required methods
fn path_elements(&self, tolerance: f64) -> Self::PathElementsIter
fn path_elements(&self, tolerance: f64) -> Self::PathElementsIter
Returns an iterator over this shape expressed as PathEl
s;
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 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.
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).
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
fn bounding_box(&self) -> Rect
The smallest rectangle that encloses the shape.
Provided methods
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
.
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()
.
Returns an iterator over this shape expressed as Bézier path
segments (PathSeg
s).
The allocation behaviour and tolerance
parameter are the
same as for path_elements()
Returns true
if the Point
is inside this shape.
This is only meaningful for closed shapes.
fn as_rounded_rect(&self) -> Option<RoundedRect>
fn as_rounded_rect(&self) -> Option<RoundedRect>
If the shape is a rounded rectangle, make it available.
Implementations on Foreign Types
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>>
Blanket implementation so impl Shape
will accept owned or reference.