docima 0.9.1

//! an example showing how to generate images for embedding in Rust docs.

use docima_builddep::{DocimaResult, ImageFile, StdResult};
use plotters::prelude::*;
use rand::{Rng, SeedableRng};
use rand_xoshiro::Xoshiro256PlusPlus;

fn main() -> DocimaResult<()> {
    if option_env!("DOCS_RS").is_some() {
        println!("cargo:warning=Wont run the build script on 'docs.rs'.");
        return Ok(());
    }

    // an example using the `plotters` crate
    ImageFile::new()
        .path("images/plotters-histogram.html")
        .width(400)
        .height(300)
        .attr("title", "an example histogram")
        .attr("style", "display: block; margin: auto;")
        .wrapper("div")
        .wrapper_attr(
            "style",
            "padding: 10px;
            max-width: 430px;
            margin: auto;
            background-color: rgba(225,225,225,0.5);
            border: 4px solid rgba(200,200,200,0.3);
            border-radius: 4px;
        ",
        )
        .generate(plot_histogram)?;

    // an example using a custom closure
    ImageFile::new()
        .path("images/square-random-pixels.html")
        .width(32)
        .height(32)
        .attr("title", "random pixels linking to 'rust-lang.org'")
        .attr("alt", "A 32x32 square filled with random color pixels.")
        .attr(
            "style",
            "vertical-align: middle;
            margin: 8px 0;
            padding: 2px;
            background: #22f4cd;
        ",
        )
        .wrapper("a")
        .wrapper_attr("href", "https://www.rust-lang.org/")
        .wrapper_attr("target", "_blank")
        .generate(|buffer, _x, _y| {
            // using a seed so that the rendered image doesn't change
            let mut rng = Xoshiro256PlusPlus::seed_from_u64(1234);
            for chunk in buffer.chunks_mut(3) {
                chunk[0] = rng.gen();
                chunk[1] = rng.gen();
                chunk[2] = rng.gen();
            }
            Ok(())
        })?;

    Ok(())
}

/// source: <https://github.com/38/plotters/blob/master/examples/histogram.rs>
pub fn plot_histogram(buffer: &mut Vec<u8>, max_x: u32, max_y: u32) -> StdResult<()> {
    let root = BitMapBackend::with_buffer(buffer, (max_x, max_y)).into_drawing_area();

    root.fill(&WHITE)?;

    let mut chart = ChartBuilder::on(&root)
        .x_label_area_size(35)
        .y_label_area_size(40)
        .margin(5)
        .caption("Histogram Test", ("sans-serif", 50.0))
        .build_cartesian_2d((0u32..10u32).into_segmented(), 0u32..10u32)?;

    chart
        .configure_mesh()
        .disable_x_mesh()
        .bold_line_style(&WHITE.mix(0.3))
        .y_desc("Count")
        .x_desc("Bucket")
        .axis_desc_style(("sans-serif", 15))
        .draw()?;

    let data = [
        0u32, 1, 1, 1, 4, 2, 5, 7, 8, 6, 4, 2, 1, 8, 3, 3, 3, 4, 4, 3, 3, 3,
    ];

    chart.draw_series(
        Histogram::vertical(&chart)
            .style(RED.mix(0.5).filled())
            .data(data.iter().map(|x: &u32| (*x, 1))),
    )?;
    Ok(())
}