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use std::f64::consts::PI;
use crate::prelude::*;
/// A closed polygon.
///
/// The polygon is defined by its corner points and is closed automatically.
///
/// # Example
/// ```example
/// #polygon(
/// fill: blue.lighten(80%),
/// stroke: blue,
/// (20%, 0pt),
/// (60%, 0pt),
/// (80%, 2cm),
/// (0%, 2cm),
/// )
/// ```
#[elem(scope, Layout)]
pub struct PolygonElem {
/// How to fill the polygon.
///
/// When setting a fill, the default stroke disappears. To create a
/// rectangle with both fill and stroke, you have to configure both.
///
/// Currently all polygons are filled according to the
/// [non-zero winding rule](https://en.wikipedia.org/wiki/Nonzero-rule).
pub fill: Option<Paint>,
/// How to [stroke]($stroke) the polygon. This can be:
///
/// Can be set to `{none}` to disable the stroke or to `{auto}` for a
/// stroke of `{1pt}` black if and if only if no fill is given.
#[resolve]
#[fold]
pub stroke: Smart<Option<Stroke>>,
/// The vertices of the polygon. Each point is specified as an array of two
/// [relative lengths]($relative).
#[variadic]
pub vertices: Vec<Axes<Rel<Length>>>,
}
#[scope]
impl PolygonElem {
/// A regular polygon, defined by its size and number of vertices.
///
/// ```example
/// #polygon.regular(
/// fill: blue.lighten(80%),
/// stroke: blue,
/// size: 30pt,
/// vertices: 3,
/// )
/// ```
#[func(title = "Regular Polygon")]
pub fn regular(
/// How to fill the polygon. See the general
/// [polygon's documentation]($polygon.fill) for more details.
#[named]
fill: Option<Option<Paint>>,
/// How to stroke the polygon. See the general
/// [polygon's documentation]($polygon.stroke) for more details.
#[named]
stroke: Option<Smart<Option<Stroke>>>,
/// The diameter of the [circumcircle](https://en.wikipedia.org/wiki/Circumcircle)
/// of the regular polygon.
#[named]
#[default(Em::one().into())]
size: Length,
/// The number of vertices in the polygon.
#[named]
#[default(3)]
vertices: u64,
) -> Content {
let radius = size / 2.0;
let angle = |i: f64| {
2.0 * PI * i / (vertices as f64) + PI * (1.0 / 2.0 - 1.0 / vertices as f64)
};
let (horizontal_offset, vertical_offset) = (0..=vertices)
.map(|v| {
(
(radius * angle(v as f64).cos()) + radius,
(radius * angle(v as f64).sin()) + radius,
)
})
.fold((radius, radius), |(min_x, min_y), (v_x, v_y)| {
(
if min_x < v_x { min_x } else { v_x },
if min_y < v_y { min_y } else { v_y },
)
});
let vertices = (0..=vertices)
.map(|v| {
let x = (radius * angle(v as f64).cos()) + radius - horizontal_offset;
let y = (radius * angle(v as f64).sin()) + radius - vertical_offset;
Axes::new(x, y).map(Rel::from)
})
.collect();
let mut elem = PolygonElem::new(vertices);
if let Some(fill) = fill {
elem.push_fill(fill);
}
if let Some(stroke) = stroke {
elem.push_stroke(stroke);
}
elem.pack()
}
}
impl Layout for PolygonElem {
#[tracing::instrument(name = "PolygonElem::layout", skip_all)]
fn layout(
&self,
_: &mut Vt,
styles: StyleChain,
regions: Regions,
) -> SourceResult<Fragment> {
let points: Vec<Point> = self
.vertices()
.iter()
.map(|c| {
c.resolve(styles).zip_map(regions.base(), Rel::relative_to).to_point()
})
.collect();
let size = points.iter().fold(Point::zero(), |max, c| c.max(max)).to_size();
let mut frame = Frame::new(size);
// Only create a path if there are more than zero points.
if points.is_empty() {
return Ok(Fragment::frame(frame));
}
// Prepare fill and stroke.
let fill = self.fill(styles);
let stroke = match self.stroke(styles) {
Smart::Auto if fill.is_none() => Some(FixedStroke::default()),
Smart::Auto => None,
Smart::Custom(stroke) => stroke.map(Stroke::unwrap_or_default),
};
// Construct a closed path given all points.
let mut path = Path::new();
path.move_to(points[0]);
for &point in &points[1..] {
path.line_to(point);
}
path.close_path();
let shape = Shape { geometry: Geometry::Path(path), stroke, fill };
frame.push(Point::zero(), FrameItem::Shape(shape, self.span()));
Ok(Fragment::frame(frame))
}
}
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