i-am-legend/src/app.rs

use crate::dmc;
use anyhow::{anyhow, bail, Result};

/// The data necessary to represent a stich legend icon.
pub struct Data {
    /// The character we want to draw.
    pub symbol: char,
    /// The DMC thread color we want to use. This will be `None` if
    /// the user has not entered in a valid DMC thread, and we'll draw
    /// a bland gray background in that case
    pub dmc: Option<dmc::DMC>,
}

impl Data {
    pub fn draw_to_file<P: AsRef<std::path::Path>>(&self, path: P) -> Result<()> {
        let f = std::fs::File::create(path)?;
        let surf = cairo::SvgSurface::for_stream(100.0, 100.0, f)?;
        self.render(&cairo::Context::new(&surf), 100.0, 100.0)?;
        if let Err(err) = surf.finish_output_stream() {
            bail!(err.error);
        };
        Ok(())
    }

    pub fn render(&self, ctx: &cairo::Context, w: f64, h: f64) -> Result<()> {
        let off_x = (w - 100.) / 2.0;
        let off_y = (h - 100.) / 2.0;

        let color = self.color();
        ctx.set_source_rgb(color.0, color.1, color.2);
        ctx.paint();

        ctx.set_source_rgb(0., 0., 0.);
        ctx.rectangle(off_x, off_y, 100., 100.);
        ctx.stroke();

        ctx.move_to(off_x, off_y - 23.0);

        let layout = pangocairo::functions::create_layout(&ctx)
            .ok_or_else(|| anyhow!("Could not create layout"))?;
        layout.set_width(100 * 1024);
        layout.set_alignment(pango::Alignment::Center);
        let font = pango::FontDescription::from_string("Fira Sans 92");
        layout.set_font_description(Some(&font));

        layout.set_text(&self.symbol.to_string());
        pangocairo::functions::show_layout(&ctx, &layout);
        Ok(())
    }

    fn color(&self) -> (f64, f64, f64) {
        self.dmc
            .map(|dmc| dmc.color)
            .unwrap_or_else(|| (0.5, 0.5, 0.5))
    }
}