欲按钮的图形动态地加载到所述按钮（上和以上）的每个帧中一个MC。 在每个帧我有一个影片剪辑（帆布canvas_over）

I want to dynamically load the graphic of the button into an mc inside each frame of the button (up and over). Inside each frame I have a movie clip (canvas and canvas_over)

绿框是按钮对象（header_btn）：

The green box is the button object (header_btn):

这是我的code：

var hLoader:Loader = new Loader();
hLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, hLoaded);
hLoader.load(new URLRequest("https://m.xsw88.com/allimgs/daicuo/20230909/106.png"));

function hLoaded(event:Event):void {
    var image:Bitmap = new Bitmap(event.target.content.bitmapData);
    header_btn.canvas.addChild(image);
}

var hoLoader:Loader = new Loader();
hoLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, hoLoaded);
hoLoader.load(new URLRequest("https://m.xsw88.com/allimgs/daicuo/20230909/107.png"));

function hoLoaded(event:Event):void {
    var image:Bitmap = new Bitmap(event.target.content.bitmapData);
    header_btn.over_canvas.addChild(image);
}

我得到的错误是：

The error I get is:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
    at MethodInfo-78()
TypeError: Error #1009: Cannot access a property or method of a null object reference.
    at MethodInfo-77()

编辑 - 解决：

header_canvas 和 header_canvas_over 被放置在舞台上。 header_canvas_over 放置在 header_canvas 。

Edit - Solved:

header_canvas and header_canvas_over are placed on stage. header_canvas_over is placed over header_canvas.

code：

var context:LoaderContext = new LoaderContext();
context.checkPolicyFile = true;

var hLoader:Loader = new Loader();
hLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, hLoaded);
hLoader.load(new URLRequest("https://m.xsw88.com/allimgs/daicuo/20230909/106.png"), context);

function hLoaded(event:Event):void {
    var image:Bitmap = new Bitmap(event.target.content.bitmapData);
    header_canvas_up.addChild(image);
}

var hoLoader:Loader = new Loader();
hoLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, hoLoaded);
hoLoader.load(new URLRequest("https://m.xsw88.com/allimgs/daicuo/20230909/107.png"), context);

function hoLoaded(event:Event):void {
    var image:Bitmap = new Bitmap(event.target.content.bitmapData);
    header_canvas_over.addChild(image);
    header_canvas_over.visible = false;

    header_btn.addEventListener(MouseEvent.MOUSE_OVER, onHover);
    function onHover(event:Event):void {
        header_canvas_over.visible = true;
    }

    header_btn.addEventListener(MouseEvent.MOUSE_OUT, onOut);
    function onOut(event:Event):void {
        header_canvas_over.visible = false;
    }
}

这将是很好但如果AS3允许按钮，包含对象。 ：/

It would be nice though if as3 allowed for buttons to contain objects. :/

推荐答案

使用SimpleButton类是从的DisplayObject，不是的DisplayObjectContainer延长。这意味着，你不能访问某个按钮的时间轴那样的对象，也不能添加或删除的孩子。

The SimpleButton class is extended from DisplayObject, not DisplayObjectContainer. That means that you can't access objects on a button's timeline in that way, nor can you add or remove children.

有关你在想什么做它可能是值得创建扩展影片剪辑的自定义按钮类。你不得不增加code自己的用户交互的状态之间移动，但你会得到更多的控制状态之间的视觉过渡，以及他们的内容。

For what you're wanting do do it might be worth creating a custom button class that extends MovieClip. You'd have to add code yourself for moving between the states on user interaction, but you would get a lot more control over the visual transition between states as well as the content of them.