Improve rendering efficiency and add caching (#95)

Fixes #84

*Reduce heap allocations
* Add caching for rendering svgs
* Deduplicate UpdateCanvas Responses

core/document/src/layers/circle.rs

@@ -1,6 +1,8 @@
 use super::style;
 use super::LayerData;
 
+use std::fmt::Write;
+
 #[derive(Debug, Clone, Copy, PartialEq, Default)]
 pub struct Circle {
 	shape: kurbo::Circle,
@@ -17,13 +19,14 @@ impl Circle {
 }
 
 impl LayerData for Circle {
-	fn render(&self) -> String {
-		format!(
+	fn render(&mut self, svg: &mut String) {
+		let _ = write!(
+			svg,
 			r#"<circle cx="{}" cy="{}" r="{}" {} />"#,
 			self.shape.center.x,
 			self.shape.center.y,
 			self.shape.radius,
 			self.style.render(),
-		)
+		);
 	}
 }

core/document/src/layers/folder.rs

@@ -2,6 +2,8 @@ use crate::{DocumentError, LayerId};
 
 use super::{Layer, LayerData, LayerDataTypes};
 
+use std::fmt::Write;
+
 #[derive(Debug, Clone, PartialEq)]
 pub struct Folder {
 	next_assignment_id: LayerId,
@@ -10,12 +12,10 @@ pub struct Folder {
 }
 
 impl LayerData for Folder {
-	fn render(&self) -> String {
-		self.layers
-			.iter()
-			.filter(|layer| layer.visible)
-			.map(|layer| layer.data.render())
-			.fold(String::with_capacity(self.layers.len() * 30), |s, n| s + "\n" + &n)
+	fn render(&mut self, svg: &mut String) {
+		self.layers.iter_mut().for_each(|layer| {
+			let _ = writeln!(svg, "{}", layer.render());
+		});
 	}
 }
 impl Folder {

core/document/src/layers/line.rs

@@ -1,6 +1,8 @@
 use super::style;
 use super::LayerData;
 
+use std::fmt::Write;
+
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Line {
 	shape: kurbo::Line,
@@ -17,14 +19,15 @@ impl Line {
 }
 
 impl LayerData for Line {
-	fn render(&self) -> String {
-		format!(
+	fn render(&mut self, svg: &mut String) {
+		let _ = write!(
+			svg,
 			r#"<line x1="{}" y1="{}" x2="{}" y2="{}" {} />"#,
 			self.shape.p0.x,
 			self.shape.p0.y,
 			self.shape.p1.x,
 			self.shape.p1.y,
 			self.style.render(),
-		)
+		);
 	}
 }

core/document/src/layers/mod.rs

@@ -19,7 +19,7 @@ pub mod folder;
 pub use folder::Folder;
 
 pub trait LayerData {
-	fn render(&self) -> String;
+	fn render(&mut self, svg: &mut String);
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -33,14 +33,14 @@ pub enum LayerDataTypes {
 }
 
 impl LayerDataTypes {
-	pub fn render(&self) -> String {
+	pub fn render(&mut self, svg: &mut String) {
 		match self {
-			Self::Folder(f) => f.render(),
-			Self::Circle(c) => c.render(),
-			Self::Rect(r) => r.render(),
-			Self::Line(l) => l.render(),
-			Self::PolyLine(pl) => pl.render(),
-			Self::Shape(s) => s.render(),
+			Self::Folder(f) => f.render(svg),
+			Self::Circle(c) => c.render(svg),
+			Self::Rect(r) => r.render(svg),
+			Self::Line(l) => l.render(svg),
+			Self::PolyLine(pl) => pl.render(svg),
+			Self::Shape(s) => s.render(svg),
 		}
 	}
 }
@@ -50,10 +50,30 @@ pub struct Layer {
 	pub visible: bool,
 	pub name: Option<String>,
 	pub data: LayerDataTypes,
+	pub cache: String,
+	pub cache_dirty: bool,
 }
 
 impl Layer {
 	pub fn new(data: LayerDataTypes) -> Self {
-		Self { visible: true, name: None, data }
+		Self {
+			visible: true,
+			name: None,
+			data,
+			cache: String::new(),
+			cache_dirty: true,
+		}
+	}
+
+	pub fn render(&mut self) -> &str {
+		if !self.visible {
+			return "";
+		}
+		if self.cache_dirty {
+			self.cache.clear();
+			self.data.render(&mut self.cache);
+			self.cache_dirty = false;
+		}
+		self.cache.as_str()
 	}
 }

core/document/src/layers/polyline.rs

@@ -19,24 +19,26 @@ impl PolyLine {
 }
 
 impl LayerData for PolyLine {
-	fn render(&self) -> String {
+	fn render(&mut self, svg: &mut String) {
 		if self.points.is_empty() {
-			return String::new();
+			return;
 		}
-		let points = self.points.iter().fold(String::new(), |mut acc, p| {
-			let _ = write!(&mut acc, " {:.3} {:.3}", p.x, p.y);
-			acc
+		let _ = write!(svg, r#"<polyline points=""#);
+		self.points.iter().for_each(|p| {
+			let _ = write!(svg, " {:.3} {:.3}", p.x, p.y);
 		});
-		format!(r#"<polyline points="{}" {}/>"#, &points[1..], self.style.render())
+		let _ = write!(svg, r#"" {}/>"#, self.style.render());
 	}
 }
 
 #[test]
 fn polyline_should_render() {
-	let polyline = PolyLine {
+	let mut polyline = PolyLine {
 		points: vec![kurbo::Point::new(3.0, 4.12354), kurbo::Point::new(1.0, 5.54)],
 		style: style::PathStyle::new(Some(style::Stroke::new(crate::color::Color::GREEN, 0.4)), None),
 	};
 
-	assert_eq!(r#"<polyline points="3.000 4.124 1.000 5.540" style="stroke: #00FF00FF;stroke-width:0.4;"/>"#, polyline.render());
+	let mut svg = String::new();
+	polyline.render(&mut svg);
+	assert_eq!(r#"<polyline points=" 3.000 4.124 1.000 5.540" style="stroke: #00FF00FF;stroke-width:0.4;"/>"#, svg);
 }

core/document/src/layers/rect.rs

@@ -1,6 +1,8 @@
 use super::style;
 use super::LayerData;
 
+use std::fmt::Write;
+
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Rect {
 	shape: kurbo::Rect,
@@ -17,14 +19,15 @@ impl Rect {
 }
 
 impl LayerData for Rect {
-	fn render(&self) -> String {
-		format!(
+	fn render(&mut self, svg: &mut String) {
+		let _ = write!(
+			svg,
 			r#"<rect x="{}" y="{}" width="{}" height="{}" {} />"#,
 			self.shape.min_x(),
 			self.shape.min_y(),
 			self.shape.width(),
 			self.shape.height(),
 			self.style.render(),
-		)
+		);
 	}
 }

core/document/src/layers/shape.rs

@@ -3,6 +3,8 @@ use crate::shape_points;
 use super::style;
 use super::LayerData;
 
+use std::fmt::Write;
+
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Shape {
 	shape: shape_points::ShapePoints,
@@ -19,7 +21,7 @@ impl Shape {
 }
 
 impl LayerData for Shape {
-	fn render(&self) -> String {
-		format!(r#"<polygon points="{}" {} />"#, self.shape, self.style.render(),)
+	fn render(&mut self, svg: &mut String) {
+		let _ = write!(svg, r#"<polygon points="{}" {} />"#, self.shape, self.style.render(),);
 	}
 }