Remove Rayon dependency

With the move to storing sprites as parsed SVG trees instead of pixmaps
(to support metadata), the data structures are no longer thread-safe.
Since adding Rayon was more fun than necessity, I'm just going to remove
it (Spreet now takes 10ms longer to render the osm-bright-gl-style
spritesheet, for example).

CHANGELOG.md

@@ -6,7 +6,7 @@
 - Fix bug that meant URLs in SVG `<image>` elements were resolved relative to the current working directory, not to the SVG itself (see [#60](https://github.com/flother/spreet/issues/60))
 - Update [resvg](https://crates.io/crates/resvg) dependency to v0.35
 - Update [clap](https://crates.io/crates/clap) dependency to v4.4
-- Update [Rayon](https://crates.io/crates/rayon) dependency to v1.8
+- Remove [Rayon](https://crates.io/crates/rayon) dependency. This means the Spreet CLI no longer parses SVGs in parallel, but that was a fun-but-unnecessary optimisation in the first place that generally saved only a handful of milliseconds
 
 Because of the change to Rayon, Spreet's minimum Rust version is now 1.63.0 (released August 2022).
 

Cargo.toml

@@ -13,7 +13,7 @@ categories = ["command-line-utilities", "encoding", "filesystem", "graphics"]
 
 [features]
 default = ["cli"]
-cli = ["dep:clap", "dep:exitcode", "dep:rayon"]
+cli = ["dep:clap", "dep:exitcode"]
 
 [dependencies]
 clap = { version = "4.4", features = ["derive"], optional = true }
@@ -22,7 +22,6 @@ exitcode = { version = "1.1", optional = true }
 multimap = "0.9"
 oxipng = { version = "8.0", features = ["parallel", "zopfli", "filetime"], default-features = false }
 png = "0.17"
-rayon = { version = "1.8", optional = true }
 resvg = "0.35"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"

README.md

@@ -6,7 +6,7 @@ Compared to other tools for creating spritesheets from SVGs, Spreet:
 
 - outputs smaller spritesheets (both fewer pixels and fewer bytes)
 - is a self-contained ~2.2 MB binary
-- is faster (multi-threaded)
+- is faster
 
 _Spreet_ (also _spreit_, _spret_, _sprit_) is the [Scots](https://en.wikipedia.org/wiki/Scots_language) word for a sprite, the fairy-like creature from Western folklore.
 

src/bin/spreet/main.rs

@@ -1,7 +1,6 @@
 use std::collections::BTreeMap;
 
 use clap::Parser;
-// use rayon::prelude::*;
 
 use spreet::fs::{get_svg_input_paths, load_svg};
 use spreet::sprite;
@@ -21,7 +20,6 @@ fn main() {
     // bitmapped SVGs will be added to the spritesheet, and the keys will be used as the unique
     // sprite ids in the JSON index file.
     let sprites = get_svg_input_paths(&args.input, args.recursive)
-        // .par_iter()
         .iter()
         .map(|svg_path| {
             if let Ok(svg) = load_svg(svg_path) {