通过 Actionscript3 加载图像两次？

Question

我正在尝试使用我在 这个问题。我正在使用 FlashCS5 IDE 进行开发。

我需要做的绝对最后一件事是在电影的其余部分加载后从外部加载大背景图像（“header_bg_vert.jpg”），而不是要求预先加载整个动画（或预加载标题动画） 。

我的AS3如下。 “无限循环”的工作原理是首尾相连放置同一无缝图像的两个副本，然后在滚动到屏幕外后将第二个图像移动到前面 - 目前，此代码仅显示图像的一个副本。有什么问题吗？另外，这是实现这一目标的最佳方法吗？

非常感谢。

stop();

//load the bg image
var request:URLRequest = new URLRequest("header_bg_vert.jpg");
var s1:Loader = new Loader();
var s2:Loader = new Loader();

s1.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, loadProgress);
s1.contentLoaderInfo.addEventListener(Event.COMPLETE, loadComplete);

s2.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, loadProgress);
s2.contentLoaderInfo.addEventListener(Event.COMPLETE, loadComplete);


function loadProgress(event:ProgressEvent):void {
var percentLoaded:Number = event.bytesLoaded/event.bytesTotal;
percentLoaded = Math.round(percentLoaded * 100);
trace("Loading: "+percentLoaded+"%");
}
function loadComplete(event:Event):void {
trace("Complete");
}

s1.load(request);
s2.load(request);

//The speed of the scroll movement.
var scrollSpeed:uint = 1;

//Originally, this added two instances of the movie clip onto the stage.
//var s1:ScrollBg = new ScrollBg();
//var s2:ScrollBg = new ScrollBg();

addChild(s1); 
addChild(s2);
setChildIndex(s1, 0);
setChildIndex(s2, 0);
//This positions the second movieclip next to the first one.
s1.y = 0;
s2.y = s1.height;

//Adds an event listener to the stage.
stage.addEventListener(Event.ENTER_FRAME, moveScroll); 

//This function moves both the images to left. If the first and second 
//images goes pass the left stage boundary then it gets moved to 
//the other side of the stage. 
function moveScroll(e:Event):void{
s1.y -= scrollSpeed;  
s2.y -= scrollSpeed;  

if(s1.y <= -s1.height){
s1.y = s1.height - scrollSpeed;
}else if(s2.y <= -s2.height){
s2.y = s2.height - scrollSpeed;
}
}

Answer 1

显然它显示了两个副本，但彼此重叠。
发生这种情况是因为 Flash Player 在加载之前不知道 s1 有多高。您应该将图像放置在 loadComplete() 中

Answer 2

您可以加载无缝图像一次，然后使用 copyPixels() 制作该图像的 2 个副本：

import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.Loader;
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.events.ProgressEvent;
import flash.geom.Point;
import flash.geom.Rectangle;
import flash.net.URLRequest;

var bitmap1:Bitmap;
var bitmap2:Bitmap;

var loader:Loader = new Loader();
loader.load(new URLRequest("images/seemless.png"));
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onLoaderComplete);
loader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, onLoaderProgress);

function onLoaderProgress(e:ProgressEvent):void
{
    var percent:Number = Math.floor((e.bytesLoaded/e.bytesTotal)*100); 

}// end function

function onLoaderComplete(e:Event):void
{
    var bitmap:Bitmap = Bitmap(e.target.content);

    var bitmapData1:BitmapData = new BitmapData(bitmap.width, bitmap.height);
    var bitmapData2:BitmapData = new BitmapData(bitmap.width, bitmap.height);

    bitmapData1.copyPixels(bitmap.bitmapData,
                           bitmap.bitmapData.rect,
                           new Point(0,0));

    bitmapData2.copyPixels(bitmap.bitmapData,
                           bitmap.bitmapData.rect,
                           new Point(0,0));

    bitmap1 = new Bitmap(bitmapData1);
    var bitmapSprite1:Sprite = new Sprite();

    bitmapSprite1.addChild(bitmap1);

    bitmap2 = new Bitmap(bitmapData2);
    var bitmapSprite2:Sprite = new Sprite();
    bitmapSprite2.addChild(bitmap2);
    bitmap2.x = bitmap2.width;

    addChild(bitmapSprite1);
    addChild(bitmapSprite2);

    stage.addEventListener(MouseEvent.MOUSE_OVER, onStageMouseOver);
    stage.addEventListener(MouseEvent.MOUSE_OUT, onStageMouseOut);

}// end function

function onStageEnterFrame(e:Event):void
{
    var speed:Number = 10;

    if(stage.mouseX < stage.stageWidth/2)
    {
        bitmap1.x -= speed;
        bitmap2.x -= speed;

    }// end if

    if(stage.mouseX > stage.stageWidth/2)
    {
        bitmap1.x += speed;
        bitmap2.x += speed;

    }// end if

    if(bitmap1.x <= -(bitmap1.width))
    {
        bitmap1.x = bitmap1.width;

    }// end if

    if(bitmap2.x <= -(bitmap2.width))
    {
        bitmap2.x = bitmap2.width;

    }// end if

    if(bitmap1.x >= bitmap1.width)
    {
        bitmap1.x = -(bitmap1.width);

    }// end if

    if(bitmap2.x >= bitmap2.width)
    {
        bitmap2.x = -(bitmap2.width);

    }// end if

}// end function

function onStageMouseOver(e:MouseEvent):void
{
    stage.addEventListener(Event.ENTER_FRAME, onStageEnterFrame);

}// end function

function onStageMouseOut(e:MouseEvent):void
{
    if(stage.hasEventListener(Event.ENTER_FRAME))
    stage.removeEventListener(Event.ENTER_FRAME, onStageEnterFrame);

}// end function

我使用鼠标事件来滚动图像，因为我不确定您使用的是哪种滚动条，但应该很容易修改它以适应您的场景。