是否有更簡單的方法來管理多個位圖（尺寸）的位圖？

Question

我有我使用的存儲圖庫應用單獨的圖像信息定製Image類：

package mtm.test 
{ 
public class Image extends Object 
{ 
    public var id:int; 
    public var filename:String; 
    public var title:String; 
    public var description:String; 

    public var thumbExists:int; 
    public var mediumExists:int; 
    public var fullExists:int; 
} 
} 

要管理的位圖的三種不同尺寸，我已經創建了下面的基類（BitmapType）和三個子 - 班（BitmapThumbnail，BitmapMediumSize，BitmapFullSize）：

package mtm.test 
{ 
    import flash.display.Bitmap; 
    import flash.display.BitmapData; 
    public class BitmapType extends Bitmap 
    { 
    public function BitmapType(bitmapData:BitmapData = null, pixelSnapping:String = 'auto', smoothing:Boolean = false) 
    { 
    super(bitmapData, pixelSnapping, smoothing); 
    } 
    } 
} 

package mtm.test 
{ 
    import flash.display.BitmapData; 
    public class BitmapFullSize extends BitmapType 
    { 
    public function BitmapFullSize(bitmapData:BitmapData = null, pixelSnapping:String = 'auto', smoothing:Boolean = false) 
    { 
    super(bitmapData, pixelSnapping, smoothing); 
    } 
    } 
} 

package mtm.test 
{ 
    import flash.display.BitmapData; 
    public class BitmapMediumSize extends BitmapType 
    { 
    public function BitmapMediumSize(bitmapData:BitmapData = null, pixelSnapping:String = 'auto', smoothing:Boolean = false) 
    { 
    super(bitmapData, pixelSnapping, smoothing); 
    } 
    } 
} 

package mtm.test 
{ 
    import flash.display.BitmapData; 
    public class BitmapThumbnail extends BitmapType 
    { 
    public function BitmapThumbnail(bitmapData:BitmapData = null, pixelSnapping:String = 'auto', smoothing:Boolean = false) 
    { 
    super(bitmapData, pixelSnapping, smoothing); 
    } 
    } 
} 

這是我將如何實現以上：

var image:Image = new Image(); 

//I would be loading external bitmaps but for the example I'll just create new ones: 
image[BitmapThumbnail] = new BitmapThumbnail(new BitmapData(65,65,false,0x000000)); 
image[BitmapMediumSize] = new BitmapMediumSize(new BitmapData(200,200,false,0x000000)); 
image[BitmapFullSize] = new BitmapFullSize(new BitmapData(500,500,false,0x000000)); 

有沒有更簡單的方法來做到這一點？我覺得在BitmapType子類中有很多重複的代碼。

至少，這有助於避免一堆的for循環試圖找到所請求的大小，似乎移植到那裏需要更多或更少的位圖的大小的情況。

Answer 1

您可以簡單地使用緩存並按需求填充它。這裏有一個素描：

class Image { 
    var url:String; 
    //... other stuff 
    var cache:Object = {}; 
    function getImage(size:int, onDone:Function, onProgress:Function = null, onError:Function = null):void { 
     if (onProgress == null) onProgress = function (loaded:int, total:int):void {}; 
     var cached:* = this.cache[size]; 
     if (cache == null) { 
      var l:Loader = new Loader(); 
        var req:URLRequest = new URLRequest(url) 
      //add parameters here, depending on size 
      l.load(); 
      l.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, function (e:IOErrorEvent):void { 
       onError(cache[size] = e); 
      }); 
      l.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, function (p:ProgressEvent):void { 
       onProgress(p.byteLoaded, p.byteTotal); 
      }); 
      l.contentLoaderInfo.addEventListener(Event.COMPLETE, function (e:Event):void { 
       onDone(cache[size] = l.content); 
      }); 
     } 
     else if (cache is DisplayObject) { 
      onDone(cache); 
     } 
     else onError(cache); 
    } 
} 

假設的例子用法：

myImage.getImage(ImageSize.THUMB, displayImage, updateLoader, displayBroken);