flex 图片展示效果

DisplayShelf.as文件如下：
package file
{
import flash.events.Event;
import flash.events.EventDispatcher;
import flash.events.KeyboardEvent;
import flash.events.MouseEvent;
import flash.events.TimerEvent;
import flash.filters.DropShadowFilter;
import flash.geom.Matrix;
import flash.ui.Keyboard;
import flash.utils.Dictionary;
import flash.utils.Timer;

import mx.collections.ArrayCollection;
import mx.collections.ICollectionView;
import mx.collections.IList;
import mx.collections.XMLListCollection;
import mx.controls.Image;
import mx.core.ClassFactory;
import mx.core.IDataRenderer;
import mx.core.IFactory;
import mx.core.UIComponent;
import mx.effects.AnimateProperty;
import mx.effects.easing.Quadratic;
import mx.events.CollectionEvent;
import mx.managers.HistoryManager;
import mx.managers.IFocusManagerComponent;
import mx.managers.IHistoryManagerClient;
// defining styles on the DisplayShelf. By defining these styles here in metadata, developers will be allowed
// to specify values for these styles as attributes on the MXML tag. Note that this component doesn't actually
// use these styles...instead, the TiltingTiles it contains use them. But this component assigns _itself_ as the
// stylename for those TiltingTile instances. That makes the tiltingTile inherit all the style values defined on this component.
// Thus by defining the styles on this component, we are automatically passing them through to the contained subcomponent.
// this is a common practice for aggregating subcomponents.
[Style(name="borderThickness", type="Number")]
[Style(name="borderColor", type="Number")]
// defining the change event. This event is dispatched whenever the selectedIndex of this component changes. By declaring it
// here, in metadata, we allow developers to specify a change handler on our MXML tag.
[Event("change")]
// defining the default property. By declaring dataProvider as our defaultProperty,