can make a ppm

canvas/src/lib.rs

@@ -14,6 +14,14 @@ impl Canvas {
             pixels : vec![vec![Color::new(0.0, 0.0, 0.0); width]; height],
         }
     }
+
+    pub fn width(&self) -> usize {
+        self.width
+    }
+
+    pub fn height(&self) -> usize {
+        self.height
+    }
 }
 
 impl Canvas {