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；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)：
/// <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；width: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；width: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; } }
五．图片列表样式，支持大数据量的虚拟化
先看看效果图（gif图，有点大）：
用的是ListView作为列表容器，因为Listview支持灵活的扩展，为了实现上面的效果，集合容器ItemsPanel只能使用WrapPanel，样式本身并不复杂：
<Page.Resources> <DataTemplate x:Key="ThumbImageItem"> <Grid Width="140" Height="120" ToolTip="{Binding Path=DataContext.FullPath}"> <Grid.RowDefinitions> <RowDefinition Height="*"/> <RowDefinition Height="20"/> </Grid.RowDefinitions> <core:ThumbnailImage ThumbnailSource="{Binding File}" Width="140" Height="100" CacheEnable="True" AsyncEnable="True" VerticalAlignment="Center" HorizontalAlignment="Center" Stretch="None"/> <TextBlock Grid.Row="1" Text="{Binding Name}" FontSize="12" Height="20" HorizontalAlignment="Center" VerticalAlignment="Center" TextAlignment="Center" TextTrimming="CharacterEllipsis"/> <!--<CheckBox VerticalAlignment="Top" HorizontalAlignment="Right" xly:ControlAttachProperty.FIconSize="20"/>--> </Grid> </DataTemplate> <Style x:Key="ImageListViewItem" TargetType="{x:Type ListViewItem}"> <Setter Property="Foreground" Value="{StaticResource TextForeground}" /> <Setter Property="HorizontalContentAlignment" Value="Stretch" /> <Setter Property="VerticalContentAlignment" Value="Center" /> <Setter Property="Margin" Value="2" /> <Setter Property="SnapsToDevicePixels" Value="True" /> <Setter Property="Background" Value="Transparent"></Setter> <Setter Property="Padding" Value="2,0,2,0"></Setter> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type ListViewItem}"> <Border x:Name="Bd" Background="{TemplateBinding Background}" SnapsToDevicePixels="true" BorderThickness="1" BorderBrush="Transparent" Margin="{TemplateBinding Margin}"> <ContentPresenter x:Name="contentPresenter" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Margin="{TemplateBinding Padding}" /> </Border> <ControlTemplate.Triggers> <Trigger Property="IsSelected" Value="true"> <Setter TargetName="Bd" Property="Background" Value="{StaticResource ItemSelectedBackground}" /> <Setter Property="Foreground" Value="{StaticResource ItemSelectedForeground}" /> <Setter TargetName="Bd" Property="BorderBrush" Value="{StaticResource FocusBorderBrush}" /> </Trigger> <Trigger Property="IsMouseOver" Value="True"> <Setter TargetName="Bd" Property="Background" Value="{StaticResource ItemMouseOverBackground}" /> <Setter Property="Foreground" Value="{StaticResource ItemMouseOverForeground}" /> <Setter TargetName="Bd" Property="BorderBrush" Value="{StaticResource MouseOverBorderBrush}" /> </Trigger> <MultiTrigger> <MultiTrigger.Conditions> <Condition Property="IsSelected" Value="true" /> <Condition Property="Selector.IsSelectionActive" Value="True" /> </MultiTrigger.Conditions> <Setter Property="Background" Value="{StaticResource ItemSelectedBackground}" /> <Setter Property="Foreground" Value="{StaticResource ItemSelectedForeground}" /> <Setter TargetName="Bd" Property="BorderBrush" Value="{StaticResource FocusBorderBrush}" /> </MultiTrigger> </ControlTemplate.Triggers> </ControlTemplate> </Setter.Value> </Setter> </Style> </Page.Resources> <Grid Margin="3"> <Grid.RowDefinitions> <RowDefinition Height="50"/> <RowDefinition Height="*"/> </Grid.RowDefinitions> <StackPanel Orientation="Horizontal"> <TextBox x:Name="txtFolder" Style="{StaticResource LabelOpenFolderTextBox}" Height="30" Width="400" Margin="5">D:\Doc\Resource</TextBox> <core:FButton Content="绑定" Margin="5" Click="FButton_Click"></core:FButton> </StackPanel> <ListView Grid.Row="1" x:Name="timgViewer" AlternationCount="0" ScrollViewer.IsDeferredScrollingEnabled="True" SelectionMode="Multiple" ItemTemplate="{StaticResource ThumbImageItem}" ItemContainerStyle="{StaticResource ImageListViewItem}"> <ListView.ItemsPanel> <ItemsPanelTemplate> <core:VirtualizingWrapPanel ItemHeight="200" ItemWidth="240" Orientation="Horizontal" VirtualizingStackPanel.IsVirtualizing="True" VirtualizingStackPanel.VirtualizationMode="Recycling" CanVerticallyScroll="True" CanHorizontallyScroll="False" /> </ItemsPanelTemplate> </ListView.ItemsPanel> </ListView> </Grid>
主要难道在于 WrapPanel是不支持虚拟化的，网上找了一个开源的WrapPanel虚拟化实现=VirtualizingWrapPanel，它有点小bug（滑动条长度计算有时候不是很准确），不过完全不影响使用，代码：
public class VirtualizingWrapPanel : VirtualizingPanel, IScrollInfo { #region Fields UIElementCollection _children; ItemsControl _itemsControl; IItemContainerGenerator _generator; private Point _offset = new Point(0, 0); private Size _extent = new Size(0, 0); private Size _viewport = new Size(0, 0); private int firstIndex = 0; private Size childSize; private Size _pixelMeasuredViewport = new Size(0, 0); Dictionary<UIElement, Rect> _realizedChildLayout = new Dictionary<UIElement, Rect>(); WrapPanelAbstraction _abstractPanel; #endregion #region Properties private Size ChildSlotSize { get { return new Size(ItemWidth, ItemHeight); } } #endregion #region Dependency Properties [TypeConverter(typeof(LengthConverter))] public double ItemHeight { get { return (double)base.GetValue(ItemHeightProperty); } set { base.SetValue(ItemHeightProperty, value); } } [TypeConverter(typeof(LengthConverter))] public double ItemWidth { get { return (double)base.GetValue(ItemWidthProperty); } set { base.SetValue(ItemWidthProperty, value); } } public Orientation Orientation { get { return (Orientation)GetValue(OrientationProperty); } set { SetValue(OrientationProperty, value); } } public static readonly DependencyProperty ItemHeightProperty = DependencyProperty.Register("ItemHeight", typeof(double), typeof(VirtualizingWrapPanel), new FrameworkPropertyMetadata(double.PositiveInfinity)); public static readonly DependencyProperty ItemWidthProperty = DependencyProperty.Register("ItemWidth", typeof(double), typeof(VirtualizingWrapPanel), new FrameworkPropertyMetadata(double.PositiveInfinity)); public static readonly DependencyProperty OrientationProperty = StackPanel.OrientationProperty.AddOwner(typeof(VirtualizingWrapPanel), new FrameworkPropertyMetadata(Orientation.Horizontal)); #endregion #region Methods public void SetFirstRowViewItemIndex(int index) { SetVerticalOffset((index) / Math.Floor((_viewport.Width) / childSize.Width)); SetHorizontalOffset((index) / Math.Floor((_viewport.Height) / childSize.Height)); } private void Resizing(object sender, EventArgs e) { if (_viewport.Width != 0) { int firstIndexCache = firstIndex; _abstractPanel = null; MeasureOverride(_viewport); SetFirstRowViewItemIndex(firstIndex); firstIndex = firstIndexCache; } } public int GetFirstVisibleSection() { int section; if (_abstractPanel == null) return 0; var maxSection = _abstractPanel.Max(x => x.Section); if (Orientation == Orientation.Horizontal) { section = (int)_offset.Y; } else { section = (int)_offset.X; } if (section > maxSection) section = maxSection; return section; } public int GetFirstVisibleIndex() { if (_abstractPanel == null) return 0; int section = GetFirstVisibleSection(); var item = _abstractPanel.Where(x => x.Section == section).FirstOrDefault(); if (item != null) return item._index; return 0; } private void CleanUpItems(int minDesiredGenerated, int maxDesiredGenerated) { for (int i = _children.Count - 1; i >= 0; i--) { GeneratorPosition childGeneratorPos = new GeneratorPosition(i, 0); int itemIndex = _generator.IndexFromGeneratorPosition(childGeneratorPos); if (itemIndex < minDesiredGenerated || itemIndex > maxDesiredGenerated) { _generator.Remove(childGeneratorPos, 1); RemoveInternalChildRange(i, 1); } } } private void ComputeExtentAndViewport(Size pixelMeasuredViewportSize, int visibleSections) { if (Orientation == Orientation.Horizontal) { _viewport.Height = visibleSections; _viewport.Width = pixelMeasuredViewportSize.Width; } else { _viewport.Width = visibleSections; _viewport.Height = pixelMeasuredViewportSize.Height; } if (Orientation == Orientation.Horizontal) { _extent.Height = _abstractPanel.SectionCount + ViewportHeight - 1; } else { _extent.Width = _abstractPanel.SectionCount + ViewportWidth - 1; } _owner.InvalidateScrollInfo(); } private void ResetScrollInfo() { _offset.X = 0; _offset.Y = 0; } private int GetNextSectionClosestIndex(int itemIndex) { var abstractItem = _abstractPanel[itemIndex]; if (abstractItem.Section < _abstractPanel.SectionCount - 1) { var ret = _abstractPanel. Where(x => x.Section == abstractItem.Section + 1). OrderBy(x => Math.Abs(x.SectionIndex - abstractItem.SectionIndex)). First(); return ret._index; } else return itemIndex; } private int GetLastSectionClosestIndex(int itemIndex) { var abstractItem = _abstractPanel[itemIndex]; if (abstractItem.Section > 0) { var ret = _abstractPanel. Where(x => x.Section == abstractItem.Section - 1). OrderBy(x => Math.Abs(x.SectionIndex - abstractItem.SectionIndex)). First(); return ret._index; } else return itemIndex; } private void NavigateDown() { var gen = _generator.GetItemContainerGeneratorForPanel(this); UIElement selected = (UIElement)Keyboard.FocusedElement; int itemIndex = gen.IndexFromContainer(selected); int depth = 0; while (itemIndex == -1) { selected = (UIElement)VisualTreeHelper.GetParent(selected); itemIndex = gen.IndexFromContainer(selected); depth++; } DependencyObject next = null; if (Orientation == Orientation.Horizontal) { int nextIndex = GetNextSectionClosestIndex(itemIndex); next = gen.ContainerFromIndex(nextIndex); while (next == null) { SetVerticalOffset(VerticalOffset + 1); UpdateLayout(); next = gen.ContainerFromIndex(nextIndex); } } else { if (itemIndex == _abstractPanel._itemCount - 1) return; next = gen.ContainerFromIndex(itemIndex + 1); while (next == null) { SetHorizontalOffset(HorizontalOffset + 1); UpdateLayout(); next = gen.ContainerFromIndex(itemIndex + 1); } } while (depth != 0) { next = VisualTreeHelper.GetChild(next, 0); depth--; } (next as UIElement).Focus(); } private void NavigateLeft() { var gen = _generator.GetItemContainerGeneratorForPanel(this); UIElement selected = (UIElement)Keyboard.FocusedElement; int itemIndex = gen.IndexFromContainer(selected); int depth = 0; while (itemIndex == -1) { selected = (UIElement)VisualTreeHelper.GetParent(selected); itemIndex = gen.IndexFromContainer(selected); depth++; } DependencyObject next = null; if (Orientation == Orientation.Vertical) { int nextIndex = GetLastSectionClosestIndex(itemIndex); next = gen.ContainerFromIndex(nextIndex); while (next == null) { SetHorizontalOffset(HorizontalOffset - 1); UpdateLayout(); next = gen.ContainerFromIndex(nextIndex); } } else { if (itemIndex == 0) return; next = gen.ContainerFromIndex(itemIndex - 1); while (next == null) { SetVerticalOffset(VerticalOffset - 1); UpdateLayout(); next = gen.ContainerFromIndex(itemIndex - 1); } } while (depth != 0) { next = VisualTreeHelper.GetChild(next, 0); depth--; } (next as UIElement).Focus(); } private void NavigateRight() { var gen = _generator.GetItemContainerGeneratorForPanel(this); UIElement selected = (UIElement)Keyboard.FocusedElement; int itemIndex = gen.IndexFromContainer(selected); int depth = 0; while (itemIndex == -1) { selected = (UIElement)VisualTreeHelper.GetParent(selected); itemIndex = gen.IndexFromContainer(selected); depth++; } DependencyObject next = null; if (Orientation == Orientation.Vertical) { int nextIndex = GetNextSectionClosestIndex(itemIndex); next = gen.ContainerFromIndex(nextIndex); while (next == null) { SetHorizontalOffset(HorizontalOffset + 1); UpdateLayout(); next = gen.ContainerFromIndex(nextIndex); } } else { if (itemIndex == _abstractPanel._itemCount - 1) return; next = gen.ContainerFromIndex(itemIndex + 1); while (next == null) { SetVerticalOffset(VerticalOffset + 1); UpdateLayout(); next = gen.ContainerFromIndex(itemIndex + 1); } } while (depth != 0) { next = VisualTreeHelper.GetChild(next, 0); depth--; } (next as UIElement).Focus(); } private void NavigateUp() { var gen = _generator.GetItemContainerGeneratorForPanel(this); UIElement selected = (UIElement)Keyboard.FocusedElement; int itemIndex = gen.IndexFromContainer(selected); int depth = 0; while (itemIndex == -1) { selected = (UIElement)VisualTreeHelper.GetParent(selected); itemIndex = gen.IndexFromContainer(selected); depth++; } DependencyObject next = null; if (Orientation == Orientation.Horizontal) { int nextIndex = GetLastSectionClosestIndex(itemIndex); next = gen.ContainerFromIndex(nextIndex); while (next == null) { SetVerticalOffset(VerticalOffset - 1); UpdateLayout(); next = gen.ContainerFromIndex(nextIndex); } } else { if (itemIndex == 0) return; next = gen.ContainerFromIndex(itemIndex - 1); while (next == null) { SetHorizontalOffset(HorizontalOffset - 1); UpdateLayout(); next = gen.ContainerFromIndex(itemIndex - 1); } } while (depth != 0) { next = VisualTreeHelper.GetChild(next, 0); depth--; } (next as UIElement).Focus(); } #endregion #region Override protected override void OnKeyDown(KeyEventArgs e) { switch (e.Key) { case Key.Down: NavigateDown(); e.Handled = true; break; case Key.Left: NavigateLeft(); e.Handled = true; break; case Key.Right: NavigateRight(); e.Handled = true; break; case Key.Up: NavigateUp(); e.Handled = true; break; default: base.OnKeyDown(e); break; } } protected override void OnItemsChanged(object sender, ItemsChangedEventArgs args) { base.OnItemsChanged(sender, args); _abstractPanel = null; ResetScrollInfo(); } protected override void OnInitialized(EventArgs e) { this.SizeChanged += new SizeChangedEventHandler(this.Resizing); base.OnInitialized(e); _itemsControl = ItemsControl.GetItemsOwner(this); _children = InternalChildren; _generator = ItemContainerGenerator; } protected override Size MeasureOverride(Size availableSize) { if (_itemsControl == null || _itemsControl.Items.Count == 0) return availableSize; if (_abstractPanel == null) _abstractPanel = new WrapPanelAbstraction(_itemsControl.Items.Count); _pixelMeasuredViewport = availableSize; _realizedChildLayout.Clear(); Size realizedFrameSize = availableSize; int itemCount = _itemsControl.Items.Count; int firstVisibleIndex = GetFirstVisibleIndex(); GeneratorPosition startPos = _generator.GeneratorPositionFromIndex(firstVisibleIndex); int childIndex = (startPos.Offset == 0) ? startPos.Index : startPos.Index + 1; int current = firstVisibleIndex; int visibleSections = 1; using (_generator.StartAt(startPos, GeneratorDirection.Forward, true)) { bool stop = false; bool isHorizontal = Orientation == Orientation.Horizontal; double currentX = 0; double currentY = 0; double maxItemSize = 0; int currentSection = GetFirstVisibleSection(); while (current < itemCount) { bool newlyRealized; // Get or create the child UIElement child = _generator.GenerateNext(out newlyRealized) as UIElement; if (newlyRealized) { // Figure out if we need to insert the child at the end or somewhere in the middle if (childIndex >= _children.Count) { base.AddInternalChild(child); } else { base.InsertInternalChild(childIndex, child); } _generator.PrepareItemContainer(child); child.Measure(ChildSlotSize); } else { // The child has already been created, let's be sure it's in the right spot Debug.Assert(child == _children[childIndex], "Wrong child was generated"); } childSize = child.DesiredSize; Rect childRect = new Rect(new Point(currentX, currentY), childSize); if (isHorizontal) { maxItemSize = Math.Max(maxItemSize, childRect.Height); if (childRect.Right > realizedFrameSize.Width) //wrap to a new line { currentY = currentY + maxItemSize; currentX = 0; maxItemSize = childRect.Height; childRect.X = currentX; childRect.Y = currentY; currentSection++; visibleSections++; } if (currentY > realizedFrameSize.Height) stop = true; currentX = childRect.Right; } else { maxItemSize = Math.Max(maxItemSize, childRect.Width); if (childRect.Bottom > realizedFrameSize.Height) //wrap to a new column { currentX = currentX + maxItemSize; currentY = 0; maxItemSize = childRect.Width; childRect.X = currentX; childRect.Y = currentY; currentSection++; visibleSections++; } if (currentX > realizedFrameSize.Width) stop = true; currentY = childRect.Bottom; } _realizedChildLayout.Add(child, childRect); _abstractPanel.SetItemSection(current, currentSection); if (stop) break; current++; childIndex++; } } CleanUpItems(firstVisibleIndex, current - 1); ComputeExtentAndViewport(availableSize, visibleSections); return availableSize; } protected override Size ArrangeOverride(Size finalSize) { if (_children != null) { foreach (UIElement child in _children) { var layoutInfo = _realizedChildLayout[child]; child.Arrange(layoutInfo); } } return finalSize; } #endregion #region IScrollInfo Members private bool _canHScroll = false; public bool CanHorizontallyScroll { get { return _canHScroll; } set { _canHScroll = value; } } private bool _canVScroll = false; public bool CanVerticallyScroll { get { return _canVScroll; } set { _canVScroll = value; } } public double ExtentHeight { get { return _extent.Height; } } public double ExtentWidth { get { return _extent.Width; } } public double HorizontalOffset { get { return _offset.X; } } public double VerticalOffset { get { return _offset.Y; } } public void LineDown() { if (Orientation == Orientation.Vertical) SetVerticalOffset(VerticalOffset + 20); else SetVerticalOffset(VerticalOffset + 1); } public void LineLeft() { if (Orientation == Orientation.Horizontal) SetHorizontalOffset(HorizontalOffset - 20); else SetHorizontalOffset(HorizontalOffset - 1); } public void LineRight() { if (Orientation == Orientation.Horizontal) SetHorizontalOffset(HorizontalOffset + 20); else SetHorizontalOffset(HorizontalOffset + 1); } public void LineUp() { if (Orientation == Orientation.Vertical) SetVerticalOffset(VerticalOffset - 20); else SetVerticalOffset(VerticalOffset - 1); } public Rect MakeVisible(Visual visual, Rect rectangle) { var gen = (ItemContainerGenerator)_generator.GetItemContainerGeneratorForPanel(this); var element = (UIElement)visual; int itemIndex = gen.IndexFromContainer(element); while (itemIndex == -1) { element = (UIElement)VisualTreeHelper.GetParent(element); itemIndex = gen.IndexFromContainer(element); } int section = _abstractPanel[itemIndex].Section; Rect elementRect = _realizedChildLayout[element]; if (Orientation == Orientation.Horizontal) { double viewportHeight = _pixelMeasuredViewport.Height; if (elementRect.Bottom > viewportHeight) _offset.Y += 1; else if (elementRect.Top < 0) _offset.Y -= 1; } else { double viewportWidth = _pixelMeasuredViewport.Width; if (elementRect.Right > viewportWidth) _offset.X += 1; else if (elementRect.Left < 0) _offset.X -= 1; } InvalidateMeasure(); return elementRect; } public void MouseWheelDown() { PageDown(); } public void MouseWheelLeft() { PageLeft(); } public void MouseWheelRight() { PageRight(); } public void MouseWheelUp() { PageUp(); } public void PageDown() { SetVerticalOffset(VerticalOffset + _viewport.Height * 0.8); } public void PageLeft() { SetHorizontalOffset(HorizontalOffset - _viewport.Width * 0.8); } public void PageRight() { SetHorizontalOffset(HorizontalOffset + _viewport.Width * 0.8); } public void PageUp() { SetVerticalOffset(VerticalOffset - _viewport.Height * 0.8); } private ScrollViewer _owner; public ScrollViewer ScrollOwner { get { return _owner; } set { _owner = value; } } public void SetHorizontalOffset(double offset) { if (offset < 0 || _viewport.Width >= _extent.Width) { offset = 0; } else { if (offset + _viewport.Width >= _extent.Width) { offset = _extent.Width - _viewport.Width; } } _offset.X = offset; if (_owner != null) _owner.InvalidateScrollInfo(); InvalidateMeasure(); firstIndex = GetFirstVisibleIndex(); } public void SetVerticalOffset(double offset) { if (offset < 0 || _viewport.Height >= _extent.Height) { offset = 0; } else { if (offset + _viewport.Height >= _extent.Height) { offset = _extent.Height - _viewport.Height; } } _offset.Y = offset; if (_owner != null) _owner.InvalidateScrollInfo(); //_trans.Y = -offset; InvalidateMeasure(); firstIndex = GetFirstVisibleIndex(); } public double ViewportHeight { get { return _viewport.Height; } } public double ViewportWidth { get { return _viewport.Width; } } #endregion #region helper data structures class ItemAbstraction { public ItemAbstraction(WrapPanelAbstraction panel, int index) { _panel = panel; _index = index; } WrapPanelAbstraction _panel; public readonly int _index; int _sectionIndex = -1; public int SectionIndex { get { if (_sectionIndex == -1) { return _index % _panel._averageItemsPerSection - 1; } return _sectionIndex; } set { if (_sectionIndex == -1) _sectionIndex = value; } } int _section = -1; public int Section { get { if (_section == -1) { return _index / _panel._averageItemsPerSection; } return _section; } set { if (_section == -1) _section = value; } } } class WrapPanelAbstraction : IEnumerable<ItemAbstraction> { public WrapPanelAbstraction(int itemCount) { List<ItemAbstraction> items = new List<ItemAbstraction>(itemCount); for (int i = 0; i < itemCount; i++) { ItemAbstraction item = new ItemAbstraction(this, i); items.Add(item); } Items = new ReadOnlyCollection<ItemAbstraction>(items); _averageItemsPerSection = itemCount; _itemCount = itemCount; } public readonly int _itemCount; public int _averageItemsPerSection; private int _currentSetSection = -1; private int _currentSetItemIndex = -1; private int _itemsInCurrentSecction = 0; private object _syncRoot = new object(); public int SectionCount { get { int ret = _currentSetSection + 1; if (_currentSetItemIndex + 1 < Items.Count) { int itemsLeft = Items.Count - _currentSetItemIndex; ret += itemsLeft / _averageItemsPerSection + 1; } return ret; } } private ReadOnlyCollection<ItemAbstraction> Items { get; set; } public void SetItemSection(int index, int section) { lock (_syncRoot) { if (section <= _currentSetSection + 1 && index == _currentSetItemIndex + 1) { _currentSetItemIndex++; Items[index].Section = section; if (section == _currentSetSection + 1) { _currentSetSection = section; if (section > 0) { _averageItemsPerSection = (index) / (section); } _itemsInCurrentSecction = 1; } else _itemsInCurrentSecction++; Items[index].SectionIndex = _itemsInCurrentSecction - 1; } } } public ItemAbstraction this[int index] { get { return Items[index]; } } #region IEnumerable<ItemAbstraction> Members public IEnumerator<ItemAbstraction> GetEnumerator() { return Items.GetEnumerator(); } #endregion #region IEnumerable Members System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return GetEnumerator(); } #endregion } #endregion }
附录：参考引用
WPF自定义控件与样式(1)-矢量字体图标(iconfont)
WPF自定义控件与样式(3)-TextBox & RichTextBox & PasswordBox样式、水印、Label标签、功能扩展
WPF自定义控件与样式(4)-CheckBox/RadioButton自定义样式
WPF自定义控件与样式(5)-Calendar/DatePicker日期控件自定义样式及扩展
WPF自定义控件与样式(6)-ScrollViewer与ListBox自定义样式
WPF自定义控件与样式(7)-列表控件DataGrid与ListView自定义样式
WPF自定义控件与样式(8)-ComboBox与自定义多选控件MultComboBox
WPF自定义控件与样式(9)-树控件TreeView与菜单Menu-ContextMenu
WPF自定义控件与样式(10)-进度控件ProcessBar自定义样
WPF自定义控件与样式(11)-等待/忙/正在加载状态-控件实现
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