Question

我确切知道这个函数在做什么，但是我不知道如何更改它，以便3个符号只添加一次，只有位图发生变化。谢谢您的帮助！它可能很简单，但我似乎无法弄明白，我是一名中级程序员，但我的知识仍然有一些漏洞。

var randCount:int = 3
        function loadImage():void
        {
            for(var i:int = 0; i<randCount; i++)
            {
                var imgLoader:Loader = new Loader();
                var imgRequest:URLRequest = new URLRequest();
                imgRequest.url = "../img/planet" + int(2*Math.random()) +".png";
                trace(imgRequest.url);
                imgLoader.load(imgRequest);
                imgLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, onLoadedImg);
            }
        }

        function onLoadedImg(e:Event):void
        {
            e.currentTarget.removeEventListener(Event.COMPLETE, onLoadedImg);
            var bmp:Bitmap = e.currentTarget.content;
            bmp.x = 600;
            bmp.y = Math.random() * 520;
            bmp.width = 80;
            bmp.height = 80;
            addChild(bmp);

        }
button.addEventListener(MouseEvent.CLICK, changeBitmap);
        function changeBitmap(event:MouseEvent):void {
            loadImage();
        }

Answer 1

猜测你问这个问题是因为你只是在前面的位置上添加了更多的位图，而通过“更改位图”你的意思是添加新的位图。

您需要删除之前添加的内容，然后才能添加新内容。例如，一个简单的改变：

    var randCount:int = 3
    var bitmaps:Array = [];
    function loadImage():void
    {
        for(var i:int = 0; i<randCount; i++)
        {
            var imgLoader:Loader = new Loader();
            var imgRequest:URLRequest = new URLRequest();
            imgRequest.url = "../img/planet" + int(2*Math.random()) +".png";
            trace(imgRequest.url);
            imgLoader.load(imgRequest);
            imgLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, onLoadedImg);                
        }
    }

    function onLoadedImg(e:Event):void
    {
        e.currentTarget.removeEventListener(Event.COMPLETE, onLoadedImg);
        var bmp:Bitmap = e.currentTarget.content;
        bitmaps.push(bmp);
        bmp.x = 600;
        bmp.y = Math.random() * 520;
        bmp.width = 80;
        bmp.height = 80;
        addChild(bmp);
        while(bitmaps.length > randCount)
        {
            var oldbitmap:DisplayObject = bitmaps.shift() as DisplayObject;
            removeChild(oldbitmap);
        }
    }

Answer 2

Just create a new BitmapData and assign it to the Bitmap#bitmapData. That is the most economic way to deal with the problem. (One BitmapData for many Bitmaps works as well.)

Answer 3

要执行您要查找的内容，您还可以使用Sprite作为图像的容器，并且每次都可以删除它们以添加新图像。看看这个例子：

var nb_images:int = 3,
    bmp:Bitmap,
    // set 5px as vertical margin between images
    img_margin:int = 5, 
    img_request:URLRequest,
    img_loader:Loader;

var images_container:Sprite = new Sprite();
addChild(images_container);

function remove_all_images(): void 
{
    // remove all images
    for(var i:int = images_container.numChildren - 1; i >= 0; i--)
    {
        images_container.removeChildAt(i);
    }
}

function load_images(): void 
{
    remove_all_images();
    for(var i:int = 0; i < nb_images; i++)
    {
        // to generate randomly values between 0 and n (excluded) we use : int(n * Math.random())
        img_request = new URLRequest('images/' + (int(nb_images * Math.random())) + '.png')
        img_loader = new Loader();            
        img_loader.load(img_request);
        img_loader.contentLoaderInfo.addEventListener(Event.COMPLETE, on_img_loaded);                
    }
}

function on_img_loaded(e:Event): void 
{
    e.currentTarget.removeEventListener(Event.COMPLETE, on_img_loaded);
    bmp = e.currentTarget.content;      
    bmp.smoothing = true;
    bmp.x = 0, bmp.width = bmp.height = 80;
    // set image.y
    // 1st image : y = 0, 2nd image : y = 80 + 5 = 85, 3rd image : y = 2 x 85 = 170
    bmp.y = images_container.numChildren * (bmp.height + img_margin);
    // add the image to images_container
    images_container.addChild(bmp);
}

希望可以提供帮助。

如何更改位图而不向舞台添加另一个子节点

3 个答案: