1use plotters::prelude::*;
2use std::ops::Range;
3
4const OUT_FILE_NAME: &'static str = "plotters-doc-data/mandelbrot.png";
5fn main() -> Result<(), Box<dyn std::error::Error>> {
6 let root = BitMapBackend::new(OUT_FILE_NAME, (800, 600)).into_drawing_area();
7
8 root.fill(&WHITE)?;
9
10 let mut chart = ChartBuilder::on(&root)
11 .margin(20)
12 .x_label_area_size(10)
13 .y_label_area_size(10)
14 .build_cartesian_2d(-2.1f64..0.6f64, -1.2f64..1.2f64)?;
15
16 chart
17 .configure_mesh()
18 .disable_x_mesh()
19 .disable_y_mesh()
20 .draw()?;
21
22 let plotting_area = chart.plotting_area();
23
24 let range = plotting_area.get_pixel_range();
25
26 let (pw, ph) = (range.0.end - range.0.start, range.1.end - range.1.start);
27 let (xr, yr) = (chart.x_range(), chart.y_range());
28
29 for (x, y, c) in mandelbrot_set(xr, yr, (pw as usize, ph as usize), 100) {
30 if c != 100 {
31 plotting_area.draw_pixel((x, y), &MandelbrotHSL::get_color(c as f64 / 100.0))?;
32 } else {
33 plotting_area.draw_pixel((x, y), &BLACK)?;
34 }
35 }
36
37 // To avoid the IO failure being ignored silently, we manually call the present function
38 root.present().expect("Unable to write result to file, please make sure 'plotters-doc-data' dir exists under current dir");
39 println!("Result has been saved to {}", OUT_FILE_NAME);
40
41 Ok(())
42}
43
44fn mandelbrot_set(
45 real: Range<f64>,
46 complex: Range<f64>,
47 samples: (usize, usize),
48 max_iter: usize,
49) -> impl Iterator<Item = (f64, f64, usize)> {
50 let step = (
51 (real.end - real.start) / samples.0 as f64,
52 (complex.end - complex.start) / samples.1 as f64,
53 );
54 return (0..(samples.0 * samples.1)).map(move |k| {
55 let c = (
56 real.start + step.0 * (k % samples.0) as f64,
57 complex.start + step.1 * (k / samples.0) as f64,
58 );
59 let mut z = (0.0, 0.0);
60 let mut cnt = 0;
61 while cnt < max_iter && z.0 * z.0 + z.1 * z.1 <= 1e10 {
62 z = (z.0 * z.0 - z.1 * z.1 + c.0, 2.0 * z.0 * z.1 + c.1);
63 cnt += 1;
64 }
65 return (c.0, c.1, cnt);
66 });
67}
68#[test]
69fn entry_point() {
70 main().unwrap()
71}
72