Draw from Rust

The charts pcmp draws come from the pito_compare library, and a Rust program can call it directly: build the data in code, or read the same JSON and TOML files, and get PNGs back.

Add it

[dependencies]
pito-compare = { git = "https://github.com/gmrdad82/pito-compare", tag = "vX.Y.Z", default-features = false }

Replace vX.Y.Z with a tag. default-features = false leaves out the command line and its clap; the library then needs png, serde, serde_json and toml.

Build a chart in code

use pito_compare::{Better, Chart, Group, Kind, Row};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut chart = Chart::new(
        "DECODE SPEED",
        "FRAMES PER SECOND",
        Better::Higher,
        &["OURS", "THEIRS"],
    );
    chart.suffix = " FPS".into();
    chart.groups.push(Group {
        name: "CPU".into(),
        rows: vec![
            Row::new("H.264 1080P", &[412.0, 298.0]),
            Row::new("H.265 1080P", &[251.0, 187.0]),
        ],
    });
    for (kind, canvas) in pito_compare::render(&chart, Kind::All)? {
        canvas.save(format!("decode-{kind}.png").as_ref())?;
    }
    Ok(())
}

This writes decode-paired.png and decode-ratio.png. render checks the chart first, with the same one-line errors pcmp prints, and returns each chart’s kind with its canvas: paired, ratio, bars, or bars-<party> for each party.

Read a data file

Chart::load reads a .json or .toml file in the data format; Chart::parse reads text you already hold:

use pito_compare::{Chart, Format};

let chart = Chart::load("speed.toml".as_ref())?;
pito_compare::paired(&chart)?.save("speed-paired.png".as_ref())?;

let text = r#"{"title": "PARSE SPEED", "better": "higher",
    "parties": [{"name": "V2"}, {"name": "V1"}],
    "rows": [{"label": "CONFIG FILES", "values": [612, 240]}]}"#;
let chart = Chart::parse(text, Format::Json)?;
let png: Vec<u8> = pito_compare::ratios(&chart)?.png()?;

One chart at a time

Function	Draws
paired(&chart)	the paired bars
ratios(&chart)	the balanced ratio chart
bars(&chart, party)	one party’s single bars
render(&chart, kind)	what pcmp --kind draws, named

Each returns a Canvas. png() encodes it to bytes, write_png writes it to any Write, and save writes a file. Errors are pito_compare::Error, whose message is the line pcmp would print.

Every public type and function is in the API reference.