为加载 MP3 文件创建进度条

1. 创建一个名为 loadSound.fla 的新 Flash 文档。
2. 在时间轴中选择第 1 帧，然后在“动作”面板中键入下面的代码：
var pb_height:Number = 10;
var pb_width:Number = 100;
var pb:MovieClip = this.createEmptyMovieClip("progressBar_mc",
this.getNextHighestDepth());
pb.createEmptyMovieClip("bar_mc", pb.getNextHighestDepth());
pb.createEmptyMovieClip("vBar_mc", pb.getNextHighestDepth());
pb.createEmptyMovieClip("stroke_mc", pb.getNextHighestDepth());
pb.createTextField("pos_txt", pb.getNextHighestDepth(), 0, pb_height,
pb_width, 22);
pb._x = 100;
pb._y = 100;
with (pb.bar_mc) {
   beginFill(0x00FF00);
   moveTo(0, 0);
   lineTo(pb_width, 0);
   lineTo(pb_width, pb_height);
   lineTo(0, pb_height);
   lineTo(0, 0);
   endFill();
   _xscale = 0;
}
with (pb.vBar_mc) {
   lineStyle(1, 0x000000);
   moveTo(0, 0);
   lineTo(0, pb_height);
}
with (pb.stroke_mc) {
   lineStyle(3, 0x000000);
   moveTo(0, 0);
   lineTo(pb_width, 0);
   lineTo(pb_width, pb_height);
   lineTo(0, pb_height);
   lineTo(0, 0);
}
var my_interval:Number;
var my_sound:Sound = new Sound();
my_sound.onLoad = function(success:Boolean) {
   if (success) {
      trace("sound loaded");
   }
};
my_sound.onSoundComplete = function() {
   clearInterval(my_interval);
   trace("Cleared interval");
}
my_sound.loadSound("http://www.helpexamples.com/flash/sound/song2.mp3", true);
my_interval = setInterval(updateProgressBar, 100, my_sound);
function updateProgressBar(the_sound:Sound):Void {
   var pos:Number = Math.round(the_sound.position / the_sound.duration * 100);
   pb.bar_mc._xscale = pos;
   pb.vBar_mc._x = pb.bar_mc._width;
   pb.pos_txt.text = pos + "%";
}
3. 选择“控制” >“测试影片”来加载 MP3 文件并观察进度条。

注：与预加载MP3一节的内容很相似。