SoundAsset  - AS3 Flex

套件	mx.core
類別	public class SoundAsset
繼承	SoundAsset Sound EventDispatcher Object
實作	IFlexAsset

語言版本:

ActionScript 3.0

產品版本:

Flex 3

執行階段版本:

Flash Player 9, AIR 1.1

SoundAsset is a subclass of the flash.media.Sound class which represents sounds that you embed in a Flex application.

The sound that you're embedding can be in an MP3 file. You can also embed a sound symbol that is in a SWF file produced by Flash. In both cases, the MXML compiler autogenerates a class that extends SoundAsset to represent the embedded sound data.

You don't generally have to use the SoundAsset class directly when you write a Flex application. For example, you can embed an MP3 file and use it in a SoundEffect simply by writing the following:

  <mx:SoundEffect id="beep" source="@Embed(source='Beep.mp3')"/>

without having to understand that the MXML compiler has created a subclass of SoundAsset for you.

However, it may be useful to understand what is happening at the ActionScript level. To embed a bitmap in ActionScript, you declare a variable of type Class, and put [Embed] metadata on it. For example, you embed an MP3 file like this:

  [Bindable]
  [Embed(source="Beep.mp3")]
  private var beepClass:Class;

The MXML compiler sees the .mp3 extension, transcodes the MP3 data into the sound format that the player uses, autogenerates a subclass of the SoundAsset class, and sets your variable to be a reference to this autogenerated class. You can then use this class reference to create instances of the SoundAsset using the new operator, and you can use APIs of the Sound class on them:

    var beepSound:SoundAsset = SoundAsset(new beepClass());
    beepSound.play();

However, you rarely need to create SoundAsset instances yourself because sound-related properties and styles can simply be set to a sound-producing class, and components will create sound instances as necessary. For example, to play this sound with a SoundEffect, you can set the SoundEffect's source property to beepClass. In MXML you could do this as follows:

  <mx:SoundEffect id="beepEffect" source="{beepClass}"/>

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