Add a program to generate diagram of the uncompressed bitmap

Cargo.toml

@@ -6,4 +6,4 @@ edition = "2021"
 publish = false
 
 [workspace]
-members = ["generate"]
+members = ["diagram", "generate"]

diagram/.gitignore

@@ -0,0 +1 @@
+*.png

diagram/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "unicode-ident-diagram"
+version = "0.0.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+image = "0.24"
+unicode-ident = { path = ".." }

diagram/src/main.rs

@@ -0,0 +1,25 @@
+use image::{ImageBuffer, Rgb};
+use std::process;
+
+fn main() {
+    let width = 512;
+    let height = 400;
+    let diagrams: [(&str, fn(char) -> bool); 2] = [
+        ("xid_start.png", unicode_ident::is_xid_start),
+        ("xid_continue.png", unicode_ident::is_xid_continue),
+    ];
+    for (name, f) in diagrams {
+        let mut imgbuf = ImageBuffer::new(width, height);
+        for (col, row, pixel) in imgbuf.enumerate_pixels_mut() {
+            *pixel = if char::from_u32(row * width + col).map_or(false, f) {
+                Rgb([0u8, 0, 0])
+            } else {
+                Rgb([255, 255, 255])
+            };
+        }
+        if let Err(err) = imgbuf.save(name) {
+            eprintln!("Error: {}", err);
+            process::exit(1);
+        }
+    }
+}