flame/lib/animation.dart

import 'dart:math' as math;
import 'sprite.dart';

class Animation {
  List<Sprite> sprites;
  double stepTime = 0.1;
  double lifeTime = 0.0;
  bool loop = true;

  Animation() {
    this.sprites = [];
  }

  Animation.spriteList(this.sprites, {this.stepTime, this.lifeTime});

  Animation.sequenced(
    String imagePath,
    int amount, {
    double textureX = 0.0,
    double textureY = 0.0,
    double textureWidth = null,
    double textureHeight = null,
  }) {
    this.sprites = new List<Sprite>(amount);
    for (var i = 0; i < amount; i++) {
      this.sprites[i] = new Sprite(
        imagePath,
        x: textureX + i * textureWidth,
        y: textureY,
        width: textureWidth,
        height: textureHeight,
      );
    }
  }

  int get currentStep => (lifeTime / stepTime).round();

  Sprite getSprite() {
    int i = currentStep;
    return sprites[loop ? i % sprites.length : math.min(i, sprites.length - 1)];
  }

  bool done() {
    return loop ? false : currentStep >= sprites.length;
  }

  void update(double t) {
    this.lifeTime += t;
  }

  bool loaded() {
    return !sprites.any((sprite) => !sprite.loaded());
  }
}