font-explorer/src/writer/svg.rs

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

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

use super::Visitor;

pub struct SvgWriter {
	first_point: bool,

	writer: BufWriter<File>,
	points: Vec<(i32, i32)>,
	control_points: Vec<(i32, i32)>,
	virtual_points: Vec<(i32, i32)>
}

impl SvgWriter {
	pub fn new(file: File) -> Self {
		SvgWriter {
			first_point: true,

			writer: BufWriter::new(file),
			points: vec![],
			control_points: vec![],
			virtual_points: vec![]
		}
	}
}

impl SvgWriter {
	fn handle_start_point(&mut self, point: &GlyphPoint) {
		if self.first_point {
			write!(self.writer, "M{} {} ", point.x, -point.y);
			self.first_point = false;
		}
	}

	fn handle_end_point(&mut self, point: &GlyphPoint) {
		if point.is_endpoint {
			self.first_point = true;
		}
	}

	fn write_points(writer: &mut BufWriter<File>, points: &Vec<(i32, i32)>, color: &'static str) {
		for (x, y) in points {
			write!(writer, "<circle cx=\"{x}\" cy=\"{y}\" r=\"10\" fill=\"{color}\" />");
		}
	}
}

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: &SplineElement) {
		match point {
			SplineElement::Line(start, end) => {
				self.handle_start_point(start);
				write!(self.writer, "L{} {} ", end.x, -end.y);

				self.points.push((start.x, -start.y));
				self.handle_end_point(start);
			},

			SplineElement::Bezier(start, control, end) => {
				self.handle_start_point(start);
				write!(self.writer, "Q{} {} {} {} ", control.x, -control.y, end.x, -end.y);

				if start.is_virtual {
					self.virtual_points.push((start.x, -start.y));
				} else {
					self.points.push((start.x, -start.y));
				}

				self.control_points.push((control.x, -control.y));
				self.handle_end_point(start);
			}
		}
	}

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

		SvgWriter::write_points(&mut self.writer, &self.points, "red");
		SvgWriter::write_points(&mut self.writer, &self.control_points, "blue");
		SvgWriter::write_points(&mut self.writer, &self.virtual_points, "green");

		write!(self.writer, "</svg>");
	}
}