feat: add command-line interface (CLI)

Cargo.toml

@@ -4,5 +4,6 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+clap = { version = "4.5.8", features = ["derive"] }
 image = "0.25.1"
 indicatif = "0.17.8"

src/cli.rs

@@ -0,0 +1,47 @@
+use clap::Parser;
+use std::fmt::{self, Display};
+use std::str::FromStr;
+
+#[derive(Parser)]
+#[command(version)]
+pub struct Cli {
+    /// The image size of the output
+    #[arg(short, long, default_value_t = Size::new(1024, 768))]
+    pub size: Size,
+
+    /// The path to the output
+    #[arg(short, long, default_value_t = String::from("output.png"))]
+    pub output: String,
+}
+
+#[derive(Clone)]
+pub struct Size {
+    pub width: u32,
+    pub height: u32,
+}
+
+impl Size {
+    pub fn new(width: u32, height: u32) -> Self {
+        Self { width, height }
+    }
+}
+
+impl FromStr for Size {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let size: Vec<_> = s.split('x').collect();
+        if size.len() != 2 {
+            return Err(String::from("invalid number of dimensions found in string"));
+        }
+        let width = size[0].parse().map_err(|e| format!("{e}"))?;
+        let height = size[1].parse().map_err(|e| format!("{e}"))?;
+        Ok(Self::new(width, height))
+    }
+}
+
+impl Display for Size {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}x{}", self.width, self.height)
+    }
+}

src/main.rs

@@ -1,17 +1,21 @@
+mod cli;
+
+use clap::Parser;
+use cli::{Cli, Size};
 use image::{Rgb, RgbImage};
 use indicatif::ProgressBar;
 
 fn main() {
-    let image_width = 256;
-    let image_height = 256;
+    let cli = Cli::parse();
+    let Size { width, height } = cli.size;
 
-    let mut image = RgbImage::new(image_width, image_height);
-    let progress_bar = ProgressBar::new(image_height as u64);
+    let mut image = RgbImage::new(width, height);
+    let progress_bar = ProgressBar::new(height as u64);
 
-    for y in 0..image_height {
-        for x in 0..image_width {
-            let r = x as f64 / (image_width - 1) as f64;
-            let g = y as f64 / (image_height - 1) as f64;
+    for y in 0..height {
+        for x in 0..width {
+            let r = x as f64 / (width - 1) as f64;
+            let g = y as f64 / (height - 1) as f64;
             let b = 0.0;
 
             let r = (255.999 * r) as u8;
@@ -23,6 +27,6 @@ fn main() {
         progress_bar.inc(1);
     }
 
-    image.save("output.png").unwrap();
+    image.save(cli.output).unwrap();
     progress_bar.finish();
 }