font-explorer/src/writer/svg.rs

use std::{fs::File, io::{BufWriter, Write}};

use crate::font::{GlyphHeader, GlyphPoint};

use super::Visitor;

pub struct SvgWriter {
	first_point: bool,
	last_on_curve: bool,
	final_point: Option<(i32, i32)>,
	final_control: Option<(i32, i32)>,
	writer: BufWriter<File>
}

impl SvgWriter {
	pub fn new(file: File) -> Self {
		SvgWriter {
			first_point: true,
			last_on_curve: false,
			final_control: None,
			final_point: None,
			writer: BufWriter::new(file)
		}
	}
}

impl Visitor for SvgWriter {
	fn write_prefix(&mut self, header: &GlyphHeader) {
		write!(
			self.writer,
			"<svg width=\"1000\" height=\"1000\" viewBox=\"{} {} {} {}\" xmlns=\"http://www.w3.org/2000/svg\"><path d=\"",
			header.xmin, -header.ymax,
			header.xmax - header.xmin,
			header.ymax - header.ymin
		);
	}

	fn write_point(&mut self, point: &GlyphPoint) {
		if self.final_point.is_none() && point.on_curve {
			self.final_point = Some((point.x, point.y));
		}

		if self.first_point && self.final_control.is_none() && !point.on_curve {
			self.final_control = Some((point.x, point.y));
		}

		if self.first_point {
			if !point.on_curve {
				return;
			}

			write!(self.writer, "M{} {} ", point.x, -point.y);
			self.first_point = false;
			self.last_on_curve = true;
			return;
		}

		let prefix = if point.on_curve { if self.last_on_curve { "L" } else { "" } } else { "Q" };
		self.last_on_curve = point.on_curve;

		write!(
			self.writer,
			"{prefix}{} {} ",
			point.x, -point.y
		);

		if point.is_endpoint {
			if let Some(final_control) = self.final_control {
				if let Some(final_point) = self.final_point {
					write!(self.writer, "Q{} {} {} {} ", final_control.0, -final_control.1, final_point.0, -final_point.1);
				} else {
					write!(self.writer, "Z ");
				}
			} else {
				write!(self.writer, "Z ");
			}

			self.final_point = None;
			self.final_control = None;
		}
		self.first_point = point.is_endpoint;
	}

	fn write_suffix(&mut self) {
		write!(
			self.writer,
			"\" style=\"fill:none; stroke:black; stroke-width:3;\" /></svg>"
		);
	}
}