缩略图创建服务接口 IThumbnailProvider { 创建缩略图。fileName:文件路径；width:图片宽度；height:高度 /// </summary> ImageSource GenereateThumbnail(object fileSource, double width, double height); }

　　如上面的代码视图，有三个实现，视频缩略图VedioThumbnailProvider没有实现完成，基本方法是利用一个第三方工具ffmpeg来获取第一帧图像然后创建ImageSource。

　　ImageThumbnailProvider：普通图片缩略图实现(调用的2.2方法)：

本地图片缩略图创建服务 ImageThumbnailProvider : IThumbnailProvider { 创建缩略图。fileName:文件路径；width:图片宽度；height:高度 ImageSource GenereateThumbnail(object fileName, double width, double height) { try { var path = fileName.ToSafeString(); if (path.IsInvalid()) return null; return System.Utility.Helper.Images.CreateImageSourceThumbnia(path, width, height); } catch { return null; } } }

　　WebImageThumbnailProvider：网络图片缩略图实现（下载图片数据后调用2.1方法）：  

网络图片缩略图创建服务 WebImageThumbnailProvider : IThumbnailProvider { 创建缩略图。fileName:文件路径；width:图片宽度；height:高度 ImageSource GenereateThumbnail(object fileName, double width, double height) { try { var path = fileName.ToSafeString(); if (path.IsInvalid()) return null; var request = WebRequest.Create(path); request.Timeout = 20000; var stream = request.GetResponse().GetResponseStream(); var img = System.Drawing.Image.FromStream(stream); return System.Utility.Helper.Images.CreateImageSourceThumbnia(img, width, height); } catch { return null; } } }

　　简单工厂ThumbnailProviderFactory实现：  

缩略图创建服务简单工厂 ThumbnailProviderFactory : System.Utility.Patterns.ISimpleFactory<EnumThumbnail, IThumbnailProvider> { 根据key获取实例 IThumbnailProvider GetInstance(EnumThumbnail key) { switch (key) { case EnumThumbnail.Image: return Singleton<ImageThumbnailProvider>.GetInstance(); case EnumThumbnail.Vedio: return Singleton<VedioThumbnailProvider>.GetInstance(); case EnumThumbnail.WebImage: return Singleton<WebImageThumbnailProvider>.GetInstance(); } return null; } }

3.2 缩略图控件ThumbnailImage

　　先看看效果图吧，下面三张图片，图1是本地图片，图2是网络图片，图3也是网络图片，为什么没显示呢，这张图片用的是国外的图片链接地址，异步加载（加载比较慢，还没出来的！）

　　ThumbnailImage实际是继承在微软的图片控件Image，因此没有样式代码，继承之后，主要的目的就是重写Imagesource的处理过程，详细代码：

/* * 较大的图片，视频，网络图片要做缓存处理：缓存缩略图为本地文件，或内存缩略图对象。 缩略图图片显示控件，同时支持图片和视频缩略图 ThumbnailImage : Image { 是否启用缓存,默认false不启用 CacheEnable { get { return (bool)GetValue(CacheEnableProperty); } set { SetValue(CacheEnableProperty, value); } } 是否启用缓存,默认false不启用.默认缓存时间是180秒 DependencyProperty CacheEnableProperty = DependencyProperty.Register(, typeof(bool), typeof(ThumbnailImage), new PropertyMetadata(false)); 缓存时间，单位秒。默认180秒 CacheTime { get { return (int)GetValue(CacheTimeProperty); } set { SetValue(CacheTimeProperty, value); } } DependencyProperty CacheTimeProperty = DependencyProperty.Register(, typeof(int), typeof(ThumbnailImage), new PropertyMetadata(180)); 是否启用异步加载，网络图片建议启用，本地图可以不需要。默认不起用异步 AsyncEnable { get { return (bool)GetValue(AsyncEnableProperty); } set { SetValue(AsyncEnableProperty, value); } } DependencyProperty AsyncEnableProperty = DependencyProperty.Register(, typeof(bool), typeof(ThumbnailImage), new PropertyMetadata(false)); 缩略图类型，默认Image图片 EnumThumbnail ThumbnailType { get { return (EnumThumbnail)GetValue(ThumbnailTypeProperty); } set { SetValue(ThumbnailTypeProperty, value); } } DependencyProperty ThumbnailTypeProperty = DependencyProperty.Register(, typeof(EnumThumbnail), typeof(ThumbnailImage), new PropertyMetadata(EnumThumbnail.Image)); 缩略图数据源：文件物理路径 ThumbnailSource { get { return GetValue(ThumbnailSourceProperty); } set { SetValue(ThumbnailSourceProperty, value); } } DependencyProperty ThumbnailSourceProperty = DependencyProperty.Register(, typeof(object), typeof(ThumbnailImage), new PropertyMetadata(OnSourcePropertyChanged)); 缩略图 ThumbnailProviderFactory ThumbnailProviderFactory = new ThumbnailProviderFactory(); OnInitialized(EventArgs e) { base.OnInitialized(e); this.Loaded += ThumbnailImage_Loaded; } void ThumbnailImage_Loaded(object sender, RoutedEventArgs e) { BindSource(this); } 属性更改处理事件 OnSourcePropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args) { ThumbnailImage img = sender as ThumbnailImage; if (img == null) return; if (!img.IsLoaded) return; BindSource(img); } BindSource(ThumbnailImage image) { var w = image.Width; var h = image.Height; object source = image.ThumbnailSource; (image.AsyncEnable) { BindThumbnialAync(image, source, w, h); } else { BindThumbnial(image, source, w, h); } } 绑定缩略图 BindThumbnial(ThumbnailImage image, object fileSource, double w, double h) { IThumbnailProvider thumbnailProvider = ThumbnailProviderFactory.GetInstance(image.ThumbnailType); image.Dispatcher.BeginInvoke(new Action(() => { var cache = image.CacheEnable; var time = image.CacheTime; ImageSource img = null; if (cache) { img = CacheManager.GetCache<ImageSource>(fileSource.GetHashCode().ToString(), time, () => { return thumbnailProvider.GenereateThumbnail(fileSource, w, h); }); } else img = thumbnailProvider.GenereateThumbnail(fileSource, w, h); image.Source = img; }), DispatcherPriority.ApplicationIdle); } 异步线程池绑定缩略图 BindThumbnialAync(ThumbnailImage image, object fileSource, double w, double h) { IThumbnailProvider thumbnailProvider = ThumbnailProviderFactory.GetInstance(image.ThumbnailType); var cache = image.CacheEnable; var time = image.CacheTime; System.Utility.Executer.TryRunByThreadPool(() => { ImageSource img = null; if (cache) { img = CacheManager.GetCache<ImageSource>(fileSource.GetHashCode().ToString(), time, () => { return thumbnailProvider.GenereateThumbnail(fileSource, w, h); }); } else img = thumbnailProvider.GenereateThumbnail(fileSource, w, h); image.Dispatcher.BeginInvoke(new Action(() => { image.Source = img; }), DispatcherPriority.ApplicationIdle); }); } }