refine spline parsing

src/font.rs

@@ -17,7 +17,7 @@ use log::{debug, info};
 use maximum_profile::MaximumProfile;
 use table_directory::TableDirectory;
 
-pub use glyph_data::{GlyphData, GlyphHeader, GlyphPoint, Glyph, SimpleGlyph};
+pub use glyph_data::{GlyphData, GlyphHeader, GlyphPoint, Glyph, SimpleGlyph, SplineElement};
 
 fn deserialize<R: Read, T: serde::de::DeserializeOwned>(reader: R) -> bincode::Result<T> {
 	bincode::options().with_big_endian().with_fixint_encoding().deserialize_from::<R, T>(reader)

src/font/glyph_data.rs

@@ -2,7 +2,7 @@ use std::{collections::HashMap, fs::File, io::{BufReader, Read, Seek, SeekFrom},
 
 use bincode::{ErrorKind, Result};
 use bitfield::bitfield;
-use log::{debug, info, warn};
+use log::{debug, error, info, warn};
 use serde::Deserialize;
 
 use super::{deserialize, deserialize_vec, index_to_location::IndexToLocation, table_directory::{FontTable, TableDirectoryRecord}};
@@ -252,6 +252,108 @@ pub struct Glyph {
 	pub data: GlyphData
 }
 
+#[derive(Debug)]
+pub enum SplineElement {
+	Line(GlyphPoint, GlyphPoint),
+	Bezier(GlyphPoint, GlyphPoint, GlyphPoint)
+}
+
+pub struct SplineIter<'a> {
+	points: Box<dyn Iterator<Item = GlyphPoint> + 'a>,
+
+	last_point: Option<GlyphPoint>,
+	final_control: Option<GlyphPoint>,
+	first_point: Option<GlyphPoint>
+}
+
+impl<'a> SplineIter<'a> {
+	fn handle_spline_start(&mut self) -> Result<()> {
+		let Some(point) = self.points.next() else {
+			return Err(ErrorKind::Custom("Not enough points in contous to form a spline".into()).into());
+		};
+
+		if point.on_curve {
+			self.last_point = Some(point);
+			self.first_point = Some(point);
+			return Ok(());
+		} else {
+			self.final_control = Some(point);
+		}
+
+		let Some(point) = self.points.next() else {
+			return Err(ErrorKind::Custom("Not enough points in contous to form a spline".into()).into());
+		};
+
+		if !point.on_curve {
+			return Err(ErrorKind::Custom("Iterator returned invalid point sequence".into()).into());
+		}
+
+		self.last_point = Some(point);
+		self.first_point = Some(point);
+
+		Ok(())
+	}
+
+	fn handle_spline_close(&mut self) -> Option<SplineElement> {
+		let Some(last_point) = self.last_point else {
+			return None;
+		};
+
+		if let Some(final_control) = self.final_control {
+			Some(SplineElement::Bezier(last_point, final_control, self.first_point.unwrap()))
+		} else {
+			Some(SplineElement::Line(last_point, self.first_point.unwrap()))
+		}
+	}
+}
+
+impl<'a> Iterator for SplineIter<'a> {
+	type Item = SplineElement;
+
+	fn next(&mut self) -> Option<Self::Item> {
+		let Some(last_point) = self.last_point else {
+			debug!("spline iter: last point is None");
+			return None;
+		};
+
+		if last_point.is_endpoint {
+			debug!("spline iter: point is an endpoint of contour. closing spline, starting new one (if possible)");
+			let result = self.handle_spline_close();
+			if let Err(err) = self.handle_spline_start() {
+				debug!("spline iter: no more contours");
+				self.last_point = None;
+			}
+
+			return result;
+		}
+
+		let Some(point) = self.points.next() else {
+			self.last_point = None;
+			debug!("spline iter: no more points, closing spline");
+			return self.handle_spline_close();
+		};
+
+		if point.on_curve {
+			self.last_point = Some(point);
+			debug!("spline iter: point is on curve");
+
+			return Some(SplineElement::Line(last_point, point));
+		} 
+
+		debug!("spline iter: point is control point");
+
+		let Some(next_point) = self.points.next() else {
+			debug!("spline iter: no more data after control point, closing spline");
+			self.last_point = None;
+			return self.handle_spline_close();
+		};
+
+		debug!("spline iter: returning bezier");
+		self.last_point = Some(next_point);
+		Some(SplineElement::Bezier(last_point, point, next_point))
+	}
+}
+
 impl Glyph {
 	pub fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = GlyphPoint> + 'a> {
 		Box::new(
@@ -261,6 +363,19 @@ impl Glyph {
 			}
 		)
 	}
+
+	pub fn splines<'a>(&'a self) -> Result<SplineIter<'a>> {
+		let mut splines = SplineIter {
+			points: self.iter(),
+			last_point: None,
+			final_control: None,
+			first_point: None
+		};
+
+		splines.handle_spline_start()?;
+
+		Ok(splines)
+	}
 }
 
 #[derive(Debug)]

src/writer.rs

@@ -1,18 +1,22 @@
 mod svg;
 
-use crate::font::{GlyphHeader, GlyphPoint, Glyph};
+use crate::font::{Glyph, GlyphHeader, GlyphPoint, SplineElement};
 
+use log::debug;
 pub use svg::SvgWriter;
 
 pub trait Visitor {
 	fn write_prefix(&mut self, header: &GlyphHeader);
-	fn write_point(&mut self, point: &GlyphPoint);
+	fn write_point(&mut self, point: &SplineElement);
 	fn write_suffix(&mut self);
 
 	fn write(&mut self, glyph: &Glyph) {
 		self.write_prefix(&glyph.header);
 
-		glyph.iter().for_each(|point| self.write_point(&point));
+		glyph.splines().unwrap().for_each(|spline_element| {
+			debug!("{spline_element:#?}");
+			self.write_point(&spline_element)
+		});
 
 		self.write_suffix();
 	}

src/writer/svg.rs

@@ -1,25 +1,48 @@
 use std::{fs::File, io::{BufWriter, Write}};
 
-use crate::font::{GlyphHeader, GlyphPoint};
+use crate::font::{GlyphHeader, GlyphPoint, SplineElement};
 
 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>
+
+	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,
-			last_on_curve: false,
-			final_control: None,
-			final_point: None,
-			writer: BufWriter::new(file)
+
+			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}\" />");
 		}
 	}
 }
@@ -35,56 +58,42 @@ impl Visitor for SvgWriter {
 		);
 	}
 
-	fn write_point(&mut self, point: &GlyphPoint) {
-		if self.final_point.is_none() && point.on_curve {
-			self.final_point = Some((point.x, point.y));
-		}
+	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);
 
-		if self.first_point && self.final_control.is_none() && !point.on_curve {
-			self.final_control = Some((point.x, point.y));
-		}
+				self.points.push((start.x, -start.y));
+				self.handle_end_point(start);
+			},
 
-		if self.first_point {
-			if !point.on_curve {
-				return;
-			}
+			SplineElement::Bezier(start, control, end) => {
+				self.handle_start_point(start);
+				write!(self.writer, "Q{} {} {} {} ", control.x, -control.y, end.x, -end.y);
 
-			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);
+				if start.is_virtual {
+					self.virtual_points.push((start.x, -start.y));
 				} else {
-					write!(self.writer, "Z ");
-				}
-			} else {
-				write!(self.writer, "Z ");
+					self.points.push((start.x, -start.y));
 				}
 
-			self.final_point = None;
-			self.final_control = None;
+				self.control_points.push((control.x, -control.y));
+				self.handle_end_point(start);
+			}
 		}
-		self.first_point = point.is_endpoint;
 	}
 
 	fn write_suffix(&mut self) {
 		write!(
 			self.writer,
-			"\" style=\"fill:none; stroke:black; stroke-width:3;\" /></svg>"
+			"\" 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>");
 	}
 }