sprite animation api mock

gistfile1.dart

import 'dart:math' as math;

void main() {
  var sc = new AnimationCmp();
  
  sc.add('idle', [1,2,3,4], 8);
  sc.add('walk', [5,6,7,8], 12, loop: false);
  
  sc.play('walk');
  
  print(sc);
  
  var sys = new AnimationSys();
  
//simulate a game loop
  for(int i = 0; i < 80; i++) {
    sys.update(sc, 1/60);
    print(sc.frame);
  }
}

class AnimationSys {
  update(AnimationCmp sc, num dt) {
    if (sc.animation == null) return;
    sc.timer = sc.timer - dt; 
    
    if (sc.timer <= 0) {
      sc.animationIndex = sc.animationIndex + 1;
      if (sc.animationIndex > sc.animation['frames'].length -1) {
        if (sc.animation['loop']) {
          sc.animationIndex = 0;
        } else {
          sc.animation = null;
          return;
        }
      }
      sc.timer = sc.timer + sc.animation['fps'];
      sc.frame = sc.animation['frames'][sc.animationIndex];
    }
  }
}

class AnimationCmp {
  Map<String, Map> animations = {};
  
  Map animation = {};
  num timer;
  int animationIndex = 0;
  int frame;
  
  add(String name, List<int> frames, num fps, {bool loop : true}) {
    animations[name] = {
      'frames' : frames, 
      'fps': fps != 0 ? 1 / fps.abs() : 1, 
      'loop': loop
    };
  }
  
  play(String name, {bool reset : true}) {
    var last = animation;
    animation = animations[name];
    
    if(reset || (animation != null && animation != last)) {
      timer = animation['fps'];
      animationIndex = 0;
      frame = animation['frames'].first;
    }
    
  }
  
  toString() => "$timer, $animationIndex, $frame, $animation, $animations";
}