nicer bound check and renamed render to flush

joystick/src/main.rs

@@ -28,7 +28,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             start = Instant::now();
             g13.clear(BinaryColor::Off)?;
             app.draw(&mut g13);
-            g13.render()?;
+            g13.flush()?;
         }
     }
 }