doc: add install guide and an example

examples/thumbnail-cat.rs

@@ -0,0 +1,32 @@
+//
+// Copyright (c) 2024 Nathan Fiedler
+//
+extern crate magick_rust;
+use magick_rust::{magick_wand_genesis, MagickError, MagickWand};
+use std::fs;
+use std::sync::Once;
+
+// Used to make sure MagickWand is initialized exactly once. Note that we do not
+// bother shutting down, we simply exit when we're done.
+static START: Once = Once::new();
+
+// Read the named file and create a thumbnail bound by a rectangle that is 240
+// by 240 pixels (for snow-covered-cat.jpg it will be 240x191 pixels).
+fn resize(filepath: &str) -> Result<Vec<u8>, MagickError> {
+    START.call_once(|| {
+        magick_wand_genesis();
+    });
+    let wand = MagickWand::new();
+    wand.read_image(filepath)?;
+    wand.fit(240, 240);
+    wand.write_image_blob("jpeg")
+}
+
+fn main() {
+    match resize("tests/data/snow-covered-cat.jpg") {
+        Ok(bytes) => {
+            fs::write("thumbnail-cat.jpg", bytes).expect("write failed");
+        }
+        Err(err) => println!("error: {}", err),
+    }
+}