Question

我有一个自定义Image类，用于存储图库应用程序的单个图像信息：

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;
 }
}

为了管理三种不同大小的位图，我创建了以下基类（BitmapType）和三个子类（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);
   }
  }
 }

这就是我实现上述目的的方法：

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));

有更简单的方法吗？我觉得BitmapType子类中有很多重复的代码。

至少，这有助于避免一堆for循环试图找到所请求的大小，并且在需要更多或更少大小的位图的情况下它似乎是可移植的。

Answer 1

您可以简单地使用缓存并按需填充它。这是草图：

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);
    }
}

假设示例用法：

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

是否有更简单的方法来管理位图的多个尺寸（尺寸）？

1 个答案: