make image preloading parallel

Cargo.lock

@@ -279,6 +279,7 @@ dependencies = [
  "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "image 0.22.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.11.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rayon 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 

Cargo.toml

@@ -9,6 +9,7 @@ clap = "2.31"
 image = "0.22"
 num_cpus = "1.8"
 regex = "1.3"
+rayon = "1.3.0"
 
 [profile.release]
 lto = true

src/image_manager.rs

@@ -1,6 +1,7 @@
 use std::path::Path;
 use std::thread::sleep;
 use std::time::Duration;
+use rayon::prelude::*;
 
 use image;
 use image::{DynamicImage, FilterType};
@@ -32,7 +33,7 @@ impl ImageManager {
 
         // Load the images from the paths
         let image_manager =
-            ImageManager::from(paths.iter().map(|path| load_image(path, size)).collect());
+            ImageManager::from(paths.par_iter().map(|path| load_image(path, size)).collect());
 
         // TODO: process the image slices
 

src/main.rs

@@ -1,5 +1,6 @@
 extern crate clap;
 extern crate image;
+extern crate rayon;
 
 mod app;
 mod arg_handler;