iced_graphics/geometry/path/
builder.rs

1use crate::geometry::path::{Arc, Path, arc};
2
3use crate::core::border;
4use crate::core::{Point, Radians, Size};
5
6use lyon_path::builder::{self, SvgPathBuilder};
7use lyon_path::geom;
8use lyon_path::math;
9
10/// A [`Path`] builder.
11///
12/// Once a [`Path`] is built, it can no longer be mutated.
13pub struct Builder {
14    raw: builder::WithSvg<lyon_path::path::BuilderImpl>,
15}
16
17impl Builder {
18    /// Creates a new [`Builder`].
19    pub fn new() -> Builder {
20        Builder {
21            raw: lyon_path::Path::builder().with_svg(),
22        }
23    }
24
25    /// Moves the starting point of a new sub-path to the given `Point`.
26    #[inline]
27    pub fn move_to(&mut self, point: Point) {
28        let _ = self.raw.move_to(math::Point::new(point.x, point.y));
29    }
30
31    /// Connects the last point in the [`Path`] to the given `Point` with a
32    /// straight line.
33    #[inline]
34    pub fn line_to(&mut self, point: Point) {
35        let _ = self.raw.line_to(math::Point::new(point.x, point.y));
36    }
37
38    /// Adds an [`Arc`] to the [`Path`] from `start_angle` to `end_angle` in
39    /// a clockwise direction.
40    #[inline]
41    pub fn arc(&mut self, arc: Arc) {
42        self.ellipse(arc.into());
43    }
44
45    /// Adds a circular arc to the [`Path`] with the given control points and
46    /// radius.
47    ///
48    /// This essentially draws a straight line segment from the current
49    /// position to `a`, but fits a circular arc of `radius` tangent to that
50    /// segment and tangent to the line between `a` and `b`.
51    ///
52    /// With another `.line_to(b)`, the result will be a path connecting the
53    /// starting point and `b` with straight line segments towards `a` and a
54    /// circular arc smoothing out the corner at `a`.
55    ///
56    /// See [the HTML5 specification of `arcTo`](https://html.spec.whatwg.org/multipage/canvas.html#building-paths:dom-context-2d-arcto)
57    /// for more details and examples.
58    pub fn arc_to(&mut self, a: Point, b: Point, radius: f32) {
59        let start = self.raw.current_position();
60        let mid = math::Point::new(a.x, a.y);
61        let end = math::Point::new(b.x, b.y);
62
63        if start == mid || mid == end || radius == 0.0 {
64            let _ = self.raw.line_to(mid);
65            return;
66        }
67
68        let double_area =
69            start.x * (mid.y - end.y) + mid.x * (end.y - start.y) + end.x * (start.y - mid.y);
70
71        if double_area == 0.0 {
72            let _ = self.raw.line_to(mid);
73            return;
74        }
75
76        let to_start = (start - mid).normalize();
77        let to_end = (end - mid).normalize();
78
79        let inner_angle = to_start.dot(to_end).acos();
80
81        let origin_angle = inner_angle / 2.0;
82
83        let origin_adjacent = radius / origin_angle.tan();
84
85        let arc_start = mid + to_start * origin_adjacent;
86        let arc_end = mid + to_end * origin_adjacent;
87
88        let sweep = to_start.cross(to_end) < 0.0;
89
90        let _ = self.raw.line_to(arc_start);
91
92        self.raw.arc_to(
93            math::Vector::new(radius, radius),
94            math::Angle::radians(0.0),
95            lyon_path::ArcFlags {
96                large_arc: false,
97                sweep,
98            },
99            arc_end,
100        );
101    }
102
103    /// Adds an ellipse to the [`Path`] using a clockwise direction.
104    pub fn ellipse(&mut self, arc: arc::Elliptical) {
105        let arc = geom::Arc {
106            center: math::Point::new(arc.center.x, arc.center.y),
107            radii: math::Vector::new(arc.radii.x, arc.radii.y),
108            x_rotation: math::Angle::radians(arc.rotation.0),
109            start_angle: math::Angle::radians(arc.start_angle.0),
110            sweep_angle: math::Angle::radians((arc.end_angle - arc.start_angle).0),
111        };
112
113        let _ = self.raw.move_to(arc.sample(0.0));
114
115        arc.cast::<f64>().for_each_quadratic_bezier(&mut |curve| {
116            let curve = curve.cast::<f32>();
117            let _ = self.raw.quadratic_bezier_to(curve.ctrl, curve.to);
118        });
119    }
120
121    /// Adds a cubic Bézier curve to the [`Path`] given its two control points
122    /// and its end point.
123    #[inline]
124    pub fn bezier_curve_to(&mut self, control_a: Point, control_b: Point, to: Point) {
125        let _ = self.raw.cubic_bezier_to(
126            math::Point::new(control_a.x, control_a.y),
127            math::Point::new(control_b.x, control_b.y),
128            math::Point::new(to.x, to.y),
129        );
130    }
131
132    /// Adds a quadratic Bézier curve to the [`Path`] given its control point
133    /// and its end point.
134    #[inline]
135    pub fn quadratic_curve_to(&mut self, control: Point, to: Point) {
136        let _ = self.raw.quadratic_bezier_to(
137            math::Point::new(control.x, control.y),
138            math::Point::new(to.x, to.y),
139        );
140    }
141
142    /// Adds a rectangle to the [`Path`] given its top-left corner coordinate
143    /// and its `Size`.
144    #[inline]
145    pub fn rectangle(&mut self, top_left: Point, size: Size) {
146        self.move_to(top_left);
147        self.line_to(Point::new(top_left.x + size.width, top_left.y));
148        self.line_to(Point::new(
149            top_left.x + size.width,
150            top_left.y + size.height,
151        ));
152        self.line_to(Point::new(top_left.x, top_left.y + size.height));
153        self.close();
154    }
155
156    /// Adds a rounded rectangle to the [`Path`] given its top-left
157    /// corner coordinate its [`Size`] and [`border::Radius`].
158    #[inline]
159    pub fn rounded_rectangle(&mut self, top_left: Point, size: Size, radius: border::Radius) {
160        let min_size = (size.height / 2.0).min(size.width / 2.0);
161        let [
162            top_left_corner,
163            top_right_corner,
164            bottom_right_corner,
165            bottom_left_corner,
166        ] = radius.into();
167
168        self.move_to(Point::new(
169            top_left.x + min_size.min(top_left_corner),
170            top_left.y,
171        ));
172        self.line_to(Point::new(
173            top_left.x + size.width - min_size.min(top_right_corner),
174            top_left.y,
175        ));
176        self.arc_to(
177            Point::new(top_left.x + size.width, top_left.y),
178            Point::new(
179                top_left.x + size.width,
180                top_left.y + min_size.min(top_right_corner),
181            ),
182            min_size.min(top_right_corner),
183        );
184        self.line_to(Point::new(
185            top_left.x + size.width,
186            top_left.y + size.height - min_size.min(bottom_right_corner),
187        ));
188        self.arc_to(
189            Point::new(top_left.x + size.width, top_left.y + size.height),
190            Point::new(
191                top_left.x + size.width - min_size.min(bottom_right_corner),
192                top_left.y + size.height,
193            ),
194            min_size.min(bottom_right_corner),
195        );
196        self.line_to(Point::new(
197            top_left.x + min_size.min(bottom_left_corner),
198            top_left.y + size.height,
199        ));
200        self.arc_to(
201            Point::new(top_left.x, top_left.y + size.height),
202            Point::new(
203                top_left.x,
204                top_left.y + size.height - min_size.min(bottom_left_corner),
205            ),
206            min_size.min(bottom_left_corner),
207        );
208        self.line_to(Point::new(
209            top_left.x,
210            top_left.y + min_size.min(top_left_corner),
211        ));
212        self.arc_to(
213            Point::new(top_left.x, top_left.y),
214            Point::new(top_left.x + min_size.min(top_left_corner), top_left.y),
215            min_size.min(top_left_corner),
216        );
217        self.close();
218    }
219
220    /// Adds a circle to the [`Path`] given its center coordinate and its
221    /// radius.
222    #[inline]
223    pub fn circle(&mut self, center: Point, radius: f32) {
224        self.arc(Arc {
225            center,
226            radius,
227            start_angle: Radians(0.0),
228            end_angle: Radians(2.0 * std::f32::consts::PI),
229        });
230    }
231
232    /// Closes the current sub-path in the [`Path`] with a straight line to
233    /// the starting point.
234    #[inline]
235    pub fn close(&mut self) {
236        self.raw.close();
237    }
238
239    /// Builds the [`Path`] of this [`Builder`].
240    #[inline]
241    pub fn build(self) -> Path {
242        Path {
243            raw: self.raw.build(),
244        }
245    }
246}
247
248impl Default for Builder {
249    fn default() -> Self {
250        Self::new()
251    }
252}
iced_graphics/geometry/path/builder.rs

iced_graphics/geometry/path/
builder.rs
