WPF自定义控件与样式(12)-缩略图ThumbnailImage /gif动画图/图片列表
一．前言
申明：WPF自定义控件与样式是一个系列文章，前后是有些关联的，但大多是按照由简到繁的顺序逐步发布的等，若有不明白的地方可以参考本系列前面的文章，文末附有部分文章链接。
本文主要针对WPF项目开发中图片的各种使用问题，经过总结，把一些经验分享一下。内容包括：
- WPF常用图像数据源ImageSource的创建；
- 自定义缩略图控件ThumbnailImage，支持网络图片、大图片、图片异步加载等特性；
- 动态图片gif播放控件；
- 图片列表样式，支持大数据量的虚拟化；
二． WPF常用图像数据源ImageSource的创建
<Image Source="../Images/qq.png"></Image>
这是一个普通Image控件的使用，Source的数据类型是ImageSource，在XAML中可以使用文件绝对路径或相对路径，ImageSource是一个抽象类，我们一般使用BitmapSource、BitmapImage等。
但在实际项目中，有各种各样的需求，比如：
-
- 从Bitmap创建ImageSource对象；
- 从数据流byte[]创建ImageSource对象；
- 从System.Drawing.Image创建ImageSource对象；
- 从一个大图片文件创建一个指定大小的ImageSource对象；
2.1 从System.Drawing.Image创建指定大小ImageSource对象
/// <summary> /// 使用System.Drawing.Image创建WPF使用的ImageSource类型缩略图（不放大小图） /// </summary> /// <param name="sourceImage">System.Drawing.Image 对象</param> /// <param name="width">指定宽度</param> /// <param name="height">指定高度</param> public static ImageSource CreateImageSourceThumbnia(System.Drawing.Image sourceImage, double width, double height) { if (sourceImage == null) return null; double rw = width / sourceImage.Width; double rh = height / sourceImage.Height; var aspect = (float)Math.Min(rw, rh); int w = sourceImage.Width, h = sourceImage.Height; if (aspect < 1) { w = (int)Math.Round(sourceImage.Width * aspect); h = (int)Math.Round(sourceImage.Height * aspect); } Bitmap sourceBmp = new Bitmap(sourceImage, w, h); IntPtr hBitmap = sourceBmp.GetHbitmap(); BitmapSource bitmapSource = Imaging.CreateBitmapSourceFromHBitmap(hBitmap, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions()); bitmapSource.Freeze(); System.Utility.Win32.Win32.DeleteObject(hBitmap); sourceImage.Dispose(); sourceBmp.Dispose(); return bitmapSource; }
2.2 从一个大图片文件创建一个指定大小的ImageSource对象
/// <summary> /// 创建WPF使用的ImageSource类型缩略图（不放大小图） /// </summary> /// <param name="fileName">本地图片路径</param> /// <param name="width">指定宽度</param> /// <param name="height">指定高度</param> public static ImageSource CreateImageSourceThumbnia(string fileName, double width, double height) { System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(fileName); double rw = width / sourceImage.Width; double rh = height / sourceImage.Height; var aspect = (float)Math.Min(rw, rh); int w = sourceImage.Width, h = sourceImage.Height; if (aspect < 1) { w = (int)Math.Round(sourceImage.Width * aspect); h = (int)Math.Round(sourceImage.Height * aspect); } Bitmap sourceBmp = new Bitmap(sourceImage, w, h); IntPtr hBitmap = sourceBmp.GetHbitmap(); BitmapSource bitmapSource = Imaging.CreateBitmapSourceFromHBitmap(hBitmap, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions()); bitmapSource.Freeze(); System.Utility.Win32.Win32.DeleteObject(hBitmap); sourceImage.Dispose(); sourceBmp.Dispose(); return bitmapSource; }
2.3 从Bitmap创建指定大小的ImageSource对象
/// <summary> /// 从一个Bitmap创建ImageSource /// </summary> /// <param name="image">Bitmap对象</param> /// <returns></returns> public static ImageSource CreateImageSourceFromImage(Bitmap image) { if (image == null) return null; try { IntPtr ptr = image.GetHbitmap(); BitmapSource bs = Imaging.CreateBitmapSourceFromHBitmap(ptr, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions()); bs.Freeze(); image.Dispose(); System.Utility.Win32.Win32.DeleteObject(ptr); return bs; } catch (Exception) { return null; } }
2.4 从数据流byte[]创建指定大小的ImageSource对象
/// <summary>
/// 从数据流创建缩略图
/// </summary>
public static ImageSource CreateImageSourceThumbnia(byte[] data, double width, double height)
{
using (Stream stream = new MemoryStream(data, true))
{
using (Image img = Image.FromStream(stream))
{
return CreateImageSourceThumbnia(img, width, height);
}
}
}
三．自定义缩略图控件ThumbnailImage
ThumbnailImage控件的主要解决的问题：
为了能扩展支持多种类型的缩略图，设计了一个简单的模式，用VS自带的工具生成的代码视图：
3.1 多种类型的缩略图扩展
首先定义一个图片类型枚举：
/// <summary> /// 缩略图数据源源类型 /// </summary> public enum EnumThumbnail { Image, Vedio, WebImage, Auto, FileX, }
然后定义了一个接口，生成图片数据源ImageSource
/// <summary> /// 缩略图创建服务接口 /// </summary> public interface IThumbnailProvider { /// <summary> /// 创建缩略图。fileName:文件路径；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)：
/// <summary> /// 本地图片缩略图创建服务 /// </summary> internal class ImageThumbnailProvider : IThumbnailProvider { /// <summary> /// 创建缩略图。fileName:文件路径；图片宽度；height:高度 /// </summary> public 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）：
/// <summary> /// 网络图片缩略图创建服务 /// </summary> internal class WebImageThumbnailProvider : IThumbnailProvider { /// <summary> /// 创建缩略图。fileName:文件路径；图片宽度；height:高度 /// </summary> public 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：
/// <summary> /// 缩略图创建服务简单工厂 /// </summary> public class ThumbnailProviderFactory : System.Utility.Patterns.ISimpleFactory<EnumThumbnail, IThumbnailProvider> { /// <summary> /// 根据key获取实例 /// </summary> public virtual 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。 */ /// <summary> /// 缩略图图片显示控件，同时支持图片和视频缩略图 /// </summary> public class ThumbnailImage : Image { /// <summary> /// 是否启用缓存,默认false不启用 /// </summary> public bool CacheEnable { get { return (bool)GetValue(CacheEnableProperty); } set { SetValue(CacheEnableProperty, value); } } /// <summary> /// 是否启用缓存,默认false不启用.默认缓存时间是180秒 /// </summary> public static readonly DependencyProperty CacheEnableProperty = DependencyProperty.Register("CacheEnable", typeof(bool), typeof(ThumbnailImage), new PropertyMetadata(false)); /// <summary> /// 缓存时间，单位秒。默认180秒 /// </summary> public int CacheTime { get { return (int)GetValue(CacheTimeProperty); } set { SetValue(CacheTimeProperty, value); } } public static readonly DependencyProperty CacheTimeProperty = DependencyProperty.Register("CacheTime", typeof(int), typeof(ThumbnailImage), new PropertyMetadata(180)); /// <summary> /// 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 /// </summary> public bool AsyncEnable { get { return (bool)GetValue(AsyncEnableProperty); } set { SetValue(AsyncEnableProperty, value); } } public static readonly DependencyProperty AsyncEnableProperty = DependencyProperty.Register("AsyncEnable", typeof(bool), typeof(ThumbnailImage), new PropertyMetadata(false)); /// <summary> /// 缩略图类型，默认Image图片 /// </summary> public EnumThumbnail ThumbnailType { get { return (EnumThumbnail)GetValue(ThumbnailTypeProperty); } set { SetValue(ThumbnailTypeProperty, value); } } public static readonly DependencyProperty ThumbnailTypeProperty = DependencyProperty.Register("ThumbnailType", typeof(EnumThumbnail), typeof(ThumbnailImage), new PropertyMetadata(EnumThumbnail.Image)); /// <summary> /// 缩略图数据源：文件物理路径 /// </summary> public object ThumbnailSource { get { return GetValue(ThumbnailSourceProperty); } set { SetValue(ThumbnailSourceProperty, value); } } public static readonly DependencyProperty ThumbnailSourceProperty = DependencyProperty.Register("ThumbnailSource", typeof(object), typeof(ThumbnailImage), new PropertyMetadata(OnSourcePropertyChanged)); /// <summary> /// 缩略图 /// </summary> protected static ThumbnailProviderFactory ThumbnailProviderFactory = new ThumbnailProviderFactory(); protected override void OnInitialized(EventArgs e) { base.OnInitialized(e); this.Loaded += ThumbnailImage_Loaded; } void ThumbnailImage_Loaded(object sender, RoutedEventArgs e) { BindSource(this); } /// <summary> /// 属性更改处理事件 /// </summary> private static void OnSourcePropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args) { ThumbnailImage img = sender as ThumbnailImage; if (img == null) return; if (!img.IsLoaded) return; BindSource(img); } private static void BindSource(ThumbnailImage image) { var w = image.Width; var h = image.Height; object source = image.ThumbnailSource; //bind if (image.AsyncEnable) { BindThumbnialAync(image, source, w, h); } else { BindThumbnial(image, source, w, h); } } /// <summary> /// 绑定缩略图 /// </summary> private static void 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); } /// <summary> /// 异步线程池绑定缩略图 /// </summary> private static void 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); }); } }
其中异步用的线程池执行图片加载， Executer.TryRunByThreadPool是一个辅助方法，用于在线程池中执行一个委托方法。缓存的实现用的是另外一个轻量级内存缓存组建（使用微软HttpRuntime.Cache的缓存机制），关于缓存的方案网上很多，这里就不介绍了。
示例代码：
<core:ThumbnailImage Width="120" Height="120" Margin="3" ThumbnailSource="Images/qq.png" /> <core:ThumbnailImage Width="120" Height="120" Margin="3" ThumbnailType="WebImage" AsyncEnable="True" ThumbnailSource="http://img0.bdstatic.com/img/image/shouye/fsxzqnghbxzzzz.jpg" /> <core:ThumbnailImage Width="160" Height="120" Margin="3" CacheEnable="True" ThumbnailType="WebImage" AsyncEnable="True" ThumbnailSource="http://www.wallsave.com/wallpapers/1920x1080/beautiful-girl/733941/beautiful-girl-girls-hd-733941.jpg" /> <core:ThumbnailImage Width="160" Height="120" Margin="3" ThumbnailType="WebImage" AsyncEnable="True" ThumbnailSource="http://wallpaperpassion.com/upload_puzzle_thumb/16047/hot-girl-hd-wallpaper.jpg" /> <core:FButton Width="120" Click="FButton_Click">CacheEnable</core:FButton> <core:ThumbnailImage x:Name="ImageCache" Width="160" CacheEnable="True" Height="120" Margin="3" ThumbnailType="WebImage" AsyncEnable="True" />
四．动态图片gif播放控件
由于WPF没有提供Gif的播放控件，网上有不少开源的方案，这里实现的Gif播放也是来自网上的开源代码（代码地址：http://1code.codeplex.com/）。效果不错哦！：
实现代码：
/// <summary> /// 支持GIF动画图片播放的图片控件，GIF图片源GIFSource /// </summary> public class AnimatedGIF : Image { public static readonly DependencyProperty GIFSourceProperty = DependencyProperty.Register( "GIFSource", typeof(string), typeof(AnimatedGIF), new PropertyMetadata(OnSourcePropertyChanged)); /// <summary> /// GIF图片源，支持相对路径、绝对路径 /// </summary> public string GIFSource { get { return (string)GetValue(GIFSourceProperty); } set { SetValue(GIFSourceProperty, value); } } internal Bitmap Bitmap; // Local bitmap member to cache image resource internal BitmapSource BitmapSource; public delegate void FrameUpdatedEventHandler(); /// <summary> /// Delete local bitmap resource /// Reference: http://msdn.microsoft.com/en-us/library/dd183539(VS.85).aspx /// </summary> [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)] static extern bool DeleteObject(IntPtr hObject); protected override void OnInitialized(EventArgs e) { base.OnInitialized(e); this.Loaded += AnimatedGIF_Loaded; this.Unloaded += AnimatedGIF_Unloaded; } void AnimatedGIF_Unloaded(object sender, RoutedEventArgs e) { this.StopAnimate(); } void AnimatedGIF_Loaded(object sender, RoutedEventArgs e) { BindSource(this); } /// <summary> /// Start animation /// </summary> public void StartAnimate() { ImageAnimator.Animate(Bitmap, OnFrameChanged); } /// <summary> /// Stop animation /// </summary> public void StopAnimate() { ImageAnimator.StopAnimate(Bitmap, OnFrameChanged); } /// <summary> /// Event handler for the frame changed /// </summary> private void OnFrameChanged(object sender, EventArgs e) { Dispatcher.BeginInvoke(DispatcherPriority.Normal, new FrameUpdatedEventHandler(FrameUpdatedCallback)); } private void FrameUpdatedCallback() { ImageAnimator.UpdateFrames(); if (BitmapSource != null) BitmapSource.Freeze(); // Convert the bitmap to BitmapSource that can be display in WPF Visual Tree BitmapSource = GetBitmapSource(this.Bitmap, this.BitmapSource); Source = BitmapSource; InvalidateVisual(); } /// <summary> /// 属性更改处理事件 /// </summary> private static void OnSourcePropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args) { AnimatedGIF gif = sender as AnimatedGIF; if (gif == null) return; if (!gif.IsLoaded) return; BindSource(gif); } private static void BindSource(AnimatedGIF gif) { gif.StopAnimate(); if (gif.Bitmap != null) gif.Bitmap.Dispose(); var path = gif.GIFSource; if (path.IsInvalid()) return; if (!Path.IsPathRooted(path)) { path = File.GetPhysicalPath(path); } gif.Bitmap = new Bitmap(path); gif.BitmapSource = GetBitmapSource(gif.Bitmap, gif.BitmapSource); gif.StartAnimate(); } private static BitmapSource GetBitmapSource(Bitmap bmap, BitmapSource bimg) { IntPtr handle = IntPtr.Zero; try { handle = bmap.GetHbitmap(); bimg = Imaging.CreateBitmapSourceFromHBitmap( handle, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions()); } finally { if (handle != IntPtr.Zero) DeleteObject(handle); } return bimg; } }