ggplot_rs/geom/
col.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/// Tessellate a bar — angle span `[t0, t1]`, radius span `[r0, r1]` in
16/// normalized coords — into a radial-sector polygon of pixel points under a
17/// polar `coord`. Both arcs are sampled so the fill follows the circle.
18pub(crate) fn polar_sector(
19    coord: &dyn Coord,
20    area: &crate::render::Rect,
21    t0: f64,
22    t1: f64,
23    r0: f64,
24    r1: f64,
25) -> Vec<(f64, f64)> {
26    const N: usize = 24;
27    let mut pts = Vec::with_capacity(2 * (N + 1));
28    for k in 0..=N {
29        let t = t0 + (t1 - t0) * k as f64 / N as f64;
30        pts.push(coord.transform((t, r1), area));
31    }
32    for k in 0..=N {
33        let t = t1 + (t0 - t1) * k as f64 / N as f64;
34        pts.push(coord.transform((t, r0), area));
35    }
36    pts
37}
38
39/// Column geometry — like GeomBar but with pre-computed heights (uses StatIdentity).
40pub struct GeomCol {
41    pub fill: (u8, u8, u8),
42    pub color: (u8, u8, u8),
43    pub alpha: f64,
44    pub width: f64,
45}
46
47impl Default for GeomCol {
48    fn default() -> Self {
49        GeomCol {
50            fill: (97, 156, 255),
51            color: (50, 50, 50),
52            alpha: 1.0,
53            width: 0.9,
54        }
55    }
56}
57
58impl Geom for GeomCol {
59    fn draw(
60        &self,
61        data: &DataFrame,
62        coord: &dyn Coord,
63        scales: &ScaleSet,
64        _theme: &Theme,
65        backend: &mut dyn DrawBackend,
66    ) -> Result<(), RenderError> {
67        let x_col = data
68            .column("x")
69            .ok_or(RenderError::MissingAesthetic("x".into()))?;
70        let y_col = data
71            .column("y")
72            .ok_or(RenderError::MissingAesthetic("y".into()))?;
73        let fill_col = data.column("fill");
74
75        let plot_area = backend.plot_area();
76        let x_scale = scales.get(&Aesthetic::X);
77        let y_scale = scales.get(&Aesthetic::Y);
78        let x_is_discrete = x_scale.map(|s| s.is_discrete()).unwrap_or(false);
79
80        let ymin_col = data.column("ymin");
81
82        for i in 0..data.nrows() {
83            let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
84            let ny = y_scale.map(|s| s.map(&y_col[i])).unwrap_or(0.0);
85            // Honor a stacked/filled base (ymin) so stacked columns draw as
86            // distinct segments rather than all from zero.
87            let ny_base = ymin_col
88                .and_then(|c| c[i].as_f64())
89                .and_then(|v| y_scale.map(|s| s.map(&crate::data::Value::Float(v))))
90                .unwrap_or_else(|| {
91                    y_scale
92                        .map(|s| s.map(&crate::data::Value::Float(0.0)))
93                        .unwrap_or(0.0)
94                });
95
96            let half_width = if x_is_discrete {
97                let n_breaks = x_scale.map(|s| s.breaks().len()).unwrap_or(1);
98                let bar_frac = self.width / (n_breaks.max(1) as f64 * 1.1);
99                bar_frac / 2.0
100            } else {
101                0.02
102            };
103
104            let (fr, fg, fb) = if let Some(fc) = fill_col {
105                scales
106                    .map_color(&Aesthetic::Fill, &fc[i])
107                    .unwrap_or(self.fill)
108            } else {
109                self.fill
110            };
111            let style = RectStyle {
112                fill: Some((fr, fg, fb)),
113                stroke: Some(self.color),
114                stroke_width: 0.5,
115                alpha: self.alpha,
116                clip: !coord.is_polar(),
117            };
118
119            if coord.is_polar() {
120                // A bar becomes a radial sector: tessellate the outer arc
121                // (radius = value) and the inner arc (radius = base) so the
122                // filled polygon follows the circle instead of a warped quad.
123                let points = polar_sector(
124                    coord,
125                    &plot_area,
126                    nx - half_width,
127                    nx + half_width,
128                    ny_base,
129                    ny,
130                );
131                backend.draw_polygon(&points, &style)?;
132            } else {
133                let (left_px, top_px) = coord.transform((nx - half_width, ny), &plot_area);
134                let (right_px, bottom_px) = coord.transform((nx + half_width, ny_base), &plot_area);
135                backend.draw_rect(
136                    (left_px, top_px.min(bottom_px)),
137                    (right_px, top_px.max(bottom_px)),
138                    &style,
139                )?;
140            }
141        }
142
143        Ok(())
144    }
145
146    fn required_aes(&self) -> Vec<Aesthetic> {
147        vec![Aesthetic::X, Aesthetic::Y]
148    }
149
150    fn default_stat(&self) -> Box<dyn Stat> {
151        Box::new(StatIdentity)
152    }
153
154    fn default_position(&self) -> Box<dyn Position> {
155        Box::new(PositionIdentity)
156    }
157
158    fn default_params(&self) -> GeomParams {
159        GeomParams::default()
160    }
161
162    fn name(&self) -> &str {
163        "col"
164    }
165
166    fn set_series_color(&mut self, color: (u8, u8, u8)) {
167        self.fill = color;
168    }
169}
ggplot_rs/geom/col.rs

ggplot_rs/geom/
col.rs
