ggplot_rs/geom/
step.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, LineStyle, Linetype};
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/// Step direction: horizontal-then-vertical or vertical-then-horizontal.
16pub enum StepDirection {
17    /// Draw horizontal first, then vertical (default).
18    Hv,
19    /// Draw vertical first, then horizontal.
20    Vh,
21}
22
23/// Step function line geometry.
24pub struct GeomStep {
25    pub color: (u8, u8, u8),
26    pub width: f64,
27    pub alpha: f64,
28    pub direction: StepDirection,
29}
30
31impl Default for GeomStep {
32    fn default() -> Self {
33        GeomStep {
34            color: (0, 0, 0),
35            width: 1.5,
36            alpha: 1.0,
37            direction: StepDirection::Hv,
38        }
39    }
40}
41
42impl Geom for GeomStep {
43    fn draw(
44        &self,
45        data: &DataFrame,
46        coord: &dyn Coord,
47        scales: &ScaleSet,
48        _theme: &Theme,
49        backend: &mut dyn DrawBackend,
50    ) -> Result<(), RenderError> {
51        let x_col = data
52            .column("x")
53            .ok_or(RenderError::MissingAesthetic("x".into()))?;
54        let y_col = data
55            .column("y")
56            .ok_or(RenderError::MissingAesthetic("y".into()))?;
57        let color_col = data.column("color");
58
59        let plot_area = backend.plot_area();
60        let x_scale = scales.get(&Aesthetic::X);
61        let y_scale = scales.get(&Aesthetic::Y);
62
63        // Sort by x
64        let mut sorted: Vec<usize> = (0..data.nrows()).collect();
65        sorted.sort_by(|&a, &b| {
66            let xa = x_col[a].as_f64().unwrap_or(0.0);
67            let xb = x_col[b].as_f64().unwrap_or(0.0);
68            xa.partial_cmp(&xb).unwrap_or(std::cmp::Ordering::Equal)
69        });
70
71        // Build raw normalized points
72        let raw: Vec<(f64, f64)> = sorted
73            .iter()
74            .map(|&i| {
75                let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
76                let ny = y_scale.map(|s| s.map(&y_col[i])).unwrap_or(0.0);
77                (nx, ny)
78            })
79            .collect();
80
81        // Insert step points
82        let mut step_points: Vec<(f64, f64)> = Vec::new();
83        for (j, &(nx, ny)) in raw.iter().enumerate() {
84            if j > 0 {
85                let (prev_nx, prev_ny) = raw[j - 1];
86                match self.direction {
87                    StepDirection::Hv => step_points.push((nx, prev_ny)),
88                    StepDirection::Vh => step_points.push((prev_nx, ny)),
89                }
90            }
91            step_points.push((nx, ny));
92        }
93
94        let points: Vec<(f64, f64)> = step_points
95            .iter()
96            .map(|&(nx, ny)| coord.transform((nx, ny), &plot_area))
97            .collect();
98
99        let line_color = color_col
100            .and_then(|cc| {
101                if cc.is_empty() {
102                    None
103                } else {
104                    scales.map_color(&Aesthetic::Color, &cc[0])
105                }
106            })
107            .unwrap_or(self.color);
108
109        if points.len() >= 2 {
110            backend.draw_line(
111                &points,
112                &LineStyle {
113                    color: line_color,
114                    alpha: self.alpha,
115                    width: self.width,
116                    linetype: Linetype::Solid,
117                },
118            )?;
119        }
120
121        Ok(())
122    }
123
124    fn required_aes(&self) -> Vec<Aesthetic> {
125        vec![Aesthetic::X, Aesthetic::Y]
126    }
127
128    fn default_stat(&self) -> Box<dyn Stat> {
129        Box::new(StatIdentity)
130    }
131
132    fn default_position(&self) -> Box<dyn Position> {
133        Box::new(PositionIdentity)
134    }
135
136    fn default_params(&self) -> GeomParams {
137        GeomParams::default()
138    }
139
140    fn name(&self) -> &str {
141        "step"
142    }
143
144    fn set_series_color(&mut self, color: (u8, u8, u8)) {
145        self.color = color;
146    }
147}
ggplot_rs/geom/step.rs

ggplot_rs/geom/
step.rs
