Fully handle inner/outer determination and nesting in contour tracing

examples/contours.rs

@@ -15,22 +15,29 @@ const INNER: image::SRGBA = image::SRGBA {
     a: 1.0,
 };
 
+fn draw(contour: &contour::Contour, img: &mut image::Image<image::SRGBA>) {
+    let n = contour.vertices.len();
+    for i in 0..n {
+        let (x0, y0) = contour.vertices[i];
+        let (x1, y1) = contour.vertices[(i + 1) % n];
+        let colour = match contour.kind {
+            contour::Kind::Outer => OUTER,
+            contour::Kind::Inner => INNER,
+        };
+        draw::line(x0, y0, x1, y1, img, colour);
+    }
+}
+
 fn main() -> std::process::ExitCode {
     common::process_image(|mut img| {
         let greyscale = img.map(|p| image::Luminance::from(p));
-		let thresholded = filter::threshold_auto(greyscale);
+        let thresholded = filter::threshold_auto(greyscale);
+
         let contours = contour::find(thresholded);
         for contour in contours {
-			let n = contour.vertices.len();
-			for i in 0..n {
-				let (x0, y0) = contour.vertices[i];
-				let (x1, y1) = contour.vertices[(i + 1) % n];
-				draw::line(x0, y0, x1, y1, &mut img, match contour.kind {
-					contour::Kind::Outer => OUTER,
-					contour::Kind::Inner => INNER,
-				});
-			}
+            draw(&contour, &mut img);
         }
+
         img
     })
 }