ggplot_rs/geom/
polygon.rs

1use crate::aes::Aesthetic;
2use crate::coord::Coord;
3use crate::data::DataFrame;
4use crate::position::identity::PositionIdentity;
5use crate::position::Position;
6use crate::render::backend::{DrawBackend, RectStyle};
7use crate::render::RenderError;
8use crate::scale::ScaleSet;
9use crate::stat::identity::StatIdentity;
10use crate::stat::Stat;
11use crate::theme::Theme;
12
13use super::{Geom, GeomParams};
14
15/// Polygon geometry — arbitrary filled polygon from (x, y) grouped by group column.
16pub struct GeomPolygon {
17    pub fill: (u8, u8, u8),
18    pub color: (u8, u8, u8),
19    pub alpha: f64,
20    pub line_width: f64,
21}
22
23impl Default for GeomPolygon {
24    fn default() -> Self {
25        GeomPolygon {
26            fill: (97, 156, 255),
27            color: (50, 50, 50),
28            alpha: 0.5,
29            line_width: 0.5,
30        }
31    }
32}
33
34impl Geom for GeomPolygon {
35    fn draw(
36        &self,
37        data: &DataFrame,
38        coord: &dyn Coord,
39        scales: &ScaleSet,
40        _theme: &Theme,
41        backend: &mut dyn DrawBackend,
42    ) -> Result<(), RenderError> {
43        let x_col = data
44            .column("x")
45            .ok_or(RenderError::MissingAesthetic("x".into()))?;
46        let y_col = data
47            .column("y")
48            .ok_or(RenderError::MissingAesthetic("y".into()))?;
49        let group_col = data.column("group");
50        let fill_col = data.column("fill");
51
52        let plot_area = backend.plot_area();
53        let x_scale = scales.get(&Aesthetic::X);
54        let y_scale = scales.get(&Aesthetic::Y);
55
56        // Group indices
57        let groups: Vec<(String, Vec<usize>)> = if let Some(gc) = group_col {
58            let mut groups: Vec<(String, Vec<usize>)> = Vec::new();
59            for (i, v) in gc.iter().enumerate() {
60                let key = v.to_group_key();
61                if let Some(entry) = groups.iter_mut().find(|(k, _)| k == &key) {
62                    entry.1.push(i);
63                } else {
64                    groups.push((key, vec![i]));
65                }
66            }
67            groups
68        } else {
69            vec![("".to_string(), (0..data.nrows()).collect())]
70        };
71
72        for (_, indices) in &groups {
73            if indices.len() < 3 {
74                continue;
75            }
76            let first_idx = indices[0];
77
78            let fill_color = fill_col
79                .and_then(|fc| scales.map_color(&Aesthetic::Fill, &fc[first_idx]))
80                .unwrap_or(self.fill);
81
82            let points: Vec<(f64, f64)> = indices
83                .iter()
84                .map(|&i| {
85                    let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
86                    let ny = y_scale.map(|s| s.map(&y_col[i])).unwrap_or(0.0);
87                    coord.transform((nx, ny), &plot_area)
88                })
89                .collect();
90
91            backend.draw_polygon(
92                &points,
93                &RectStyle {
94                    fill: Some(fill_color),
95                    // No outline when line_width <= 0 (e.g. filled contour bands,
96                    // where per-triangle strokes would show the triangulation).
97                    stroke: (self.line_width > 0.0).then_some(self.color),
98                    stroke_width: self.line_width,
99                    alpha: self.alpha,
100                    clip: true,
101                },
102            )?;
103        }
104
105        Ok(())
106    }
107
108    fn required_aes(&self) -> Vec<Aesthetic> {
109        vec![Aesthetic::X, Aesthetic::Y, Aesthetic::Group]
110    }
111
112    fn default_stat(&self) -> Box<dyn Stat> {
113        Box::new(StatIdentity)
114    }
115
116    fn default_position(&self) -> Box<dyn Position> {
117        Box::new(PositionIdentity)
118    }
119
120    fn default_params(&self) -> GeomParams {
121        GeomParams::default()
122    }
123
124    fn name(&self) -> &str {
125        "polygon"
126    }
127
128    fn set_series_color(&mut self, color: (u8, u8, u8)) {
129        self.fill = color;
130    }
131}
ggplot_rs/geom/polygon.rs

ggplot_rs/geom/
polygon.rs
