Adding a run animation to our dinosaur.

dino.dart

class Dino extends GameObject {
  int frame = 1;
 
  @override
  Widget render() {
    return Image.asset(
      "assets/images/dino/dino_$frame.png",
      gaplessPlayback: true,
    );
  }
 
  @override
  Rect getRect(Size screenSize, double runDistance) {
    return Rect.fromLTWH(
        screenSize.width / 10,
        4 / 7 * screenSize.height - dino.imageHeight,
        dino.imageWidth.toDouble(),
        dino.imageHeight.toDouble());
  }
 
  @override
  void update(Duration lastTime, Duration elapsedTime) {
    frame = (elapsedTime.inMilliseconds / 100).floor() % 2 + 3 
  }
}