接续上次的程序，稍微改动一下原有样式，并添加一个数据模板，我们就可以达成下面这样的显示功能：
鼠标悬停于文件列表项上，会在工具提示中显示图像缩略图及文件名、文件大小信息。
选中一个列表项，该列表项会扩大，并动态显示出一个小缩略图及文件的所在路径。
代码如下：
Code
<Application x:Class="自定义列表项.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:c="clr-namespace:System.IO;assembly=mscorlib"
StartupUri="Window1.xaml">
<Application.Resources>
<!--FileInfo数据模板-->
<DataTemplate DataType="{x:Type c:FileInfo}">
<WrapPanel VerticalAlignment="Center">
<WrapPanel.ToolTip>
<WrapPanel Width="164">
<Image Margin="2,4" MaxHeight="160" MaxWidth="160" Source="{Binding FullName}"/>
<TextBlock Text="{Binding Name}" Width="160" Margin="2"/>
<TextBlock Margin="2" Text="{Binding Length}"/><TextBlock Margin="2">字节</TextBlock>
</WrapPanel>
</WrapPanel.ToolTip>
<Image x:Name="pic" Margin="2" Opacity="0" MaxHeight="0" MaxWidth="0" Source="{Binding FullName}" />
<StackPanel VerticalAlignment="Center">
<TextBlock x:Name="title" Height="24" Margin="2,0" Text="{Binding Name}"/>
<TextBlock x:Name="path" Opacity="0" Height="0" Margin="2,0" Text="{Binding FullName}"/>
</StackPanel>
</WrapPanel>
<DataTemplate.Triggers>
<Trigger Property="Height" Value="68">
<Setter TargetName="path" Property="Height" Value="24"/>
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation To="1" BeginTime="0:0:0.1" Duration="0:0:0.1" Storyboard.TargetName="pic" Storyboard.TargetProperty="Opacity" />
<DoubleAnimation To="64" BeginTime="0:0:0.1" Duration="0:0:0.1" Storyboard.TargetName="pic" Storyboard.TargetProperty="MaxHeight" />
<DoubleAnimation To="64" BeginTime="0:0:0.1" Duration="0:0:0.1" Storyboard.TargetName="pic" Storyboard.TargetProperty="MaxWidth" />
<DoubleAnimation To="0.4" BeginTime="0:0:0.1" Duration="0:0:0.1" Storyboard.TargetName="path" Storyboard.TargetProperty="Opacity" />
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation BeginTime="0:0:0.4" Duration="0:0:0.1" Storyboard.TargetName="pic" Storyboard.TargetProperty="Opacity" />
<DoubleAnimation BeginTime="0:0:0.3" Duration="0:0:0.1" Storyboard.TargetName="pic" Storyboard.TargetProperty="MaxHeight" />
<DoubleAnimation BeginTime="0:0:0.3" Duration="0:0:0.1" Storyboard.TargetName="pic" Storyboard.TargetProperty="MaxWidth" />
<DoubleAnimation BeginTime="0:0:0.4" Duration="0:0:0.1" Storyboard.TargetName="path" Storyboard.TargetProperty="Opacity" />
</Storyboard>
</BeginStoryboard>
</Trigger.ExitActions>
</Trigger>
</DataTemplate.Triggers>
</DataTemplate>
<!--ListBox样式-->
<Style TargetType="ListBox">
<Setter Property="BorderBrush" Value="#BDD4F1"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Background" Value="#F8F7F5"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Hidden"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
</Style>
<!--ListBoxItem样式-->
<Style TargetType="ListBoxItem">
<Setter Property="Foreground" Value="#B5BABF"/>
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="Height" Value="28"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<Border Name="back" BorderBrush="#F8F7F5" BorderThickness="0,1,0,1">
<Border.Background>
<LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
<GradientBrush.GradientStops>
<GradientStopCollection>
<GradientStop Color="#F8F7F5" Offset="0.0"/>
<GradientStop Color="#F8F7F5" Offset="0.5"/>
<GradientStop Color="#F8F7F5" Offset="0.51"/>
<GradientStop Color="#F8F7F5" Offset="1"/>
</GradientStopCollection>
</GradientBrush.GradientStops>
</LinearGradientBrush>
</Border.Background>
<ContentPresenter x:Name="content" Height="28" Margin="2" VerticalAlignment="Center"/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSelected" Value="True">
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation To="68" Duration="0:0:0.3" Storyboard.TargetName="content" Storyboard.TargetProperty="Height"/>
<DoubleAnimation To="68" Duration="0:0:0.3" Storyboard.TargetProperty="Height"/>
<ColorAnimation To="#F3C37C" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" />
<ColorAnimation To="#952B00" Duration="0:0:0.2" Storyboard.TargetProperty="(ListBoxItem.Foreground).(SolidColorBrush.Color)" />
<ColorAnimation To="#FFF" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation To="#FFEF99" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
<ColorAnimation To="#FFE13F" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[2].(GradientStop.Color)" />
<ColorAnimation To="#FFF3B0" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[3].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation BeginTime="0:0:0.4" Duration="0:0:0.2" Storyboard.TargetName="content" Storyboard.TargetProperty="Height"/>
<DoubleAnimation BeginTime="0:0:0.4" Duration="0:0:0.2" Storyboard.TargetProperty="Height"/>
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetProperty="(ListBoxItem.Foreground).(SolidColorBrush.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[2].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[3].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.ExitActions>
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<ColorAnimation To="#D8E6F5" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" />
<ColorAnimation To="#617A98" Duration="0:0:0.2" Storyboard.TargetProperty="(ListBoxItem.Foreground).(SolidColorBrush.Color)" />
<ColorAnimation To="#F6F9FD" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation To="#E0EBF7" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
<ColorAnimation To="#D7E5F6" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[2].(GradientStop.Color)" />
<ColorAnimation To="#F6F9FD" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[3].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetProperty="(ListBoxItem.Foreground).(SolidColorBrush.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[2].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[3].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.ExitActions>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<!--以前教程中使用的按钮样式-->
<Style TargetType="Button">
<Setter Property="Foreground" Value="Black"/>
<!--修改模板属性-->
<Setter Property="Template">
<Setter.Value>
<!--控件模板-->
<ControlTemplate TargetType="Button">
<!--背景色-->
<Border x:Name="back" Opacity="0.8" CornerRadius="3">
<Border.BitmapEffect>
<OuterGlowBitmapEffect Opacity="0.7" GlowSize="0" GlowColor="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(Button.Background).(SolidColorBrush.Color)}" />
</Border.BitmapEffect>
<Border.Background>
<LinearGradientBrush StartPoint="0,0" EndPoint="0,1.5">
<GradientBrush.GradientStops>
<GradientStopCollection>
<GradientStop Color="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(Button.Background).(SolidColorBrush.Color)}" Offset="0"/>
<GradientStop Color="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(Button.Background).(SolidColorBrush.Color)}" Offset="0.4"/>
<GradientStop Color="#FFF" Offset="1"/>
</GradientStopCollection>
</GradientBrush.GradientStops>
</LinearGradientBrush>
</Border.Background>
<!--前景色及边框-->
<Border x:Name="fore" BorderThickness="1" CornerRadius="3" BorderBrush="#5555">
<Border.Background>
<LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
<GradientBrush.GradientStops>
<GradientStopCollection>
<GradientStop Color="#6FFF" Offset="0.5"/>
<GradientStop Color="#1111" Offset="0.51"/>
</GradientStopCollection>
</GradientBrush.GradientStops>
</LinearGradientBrush>
</Border.Background>
<!--按钮内容-->
<ContentPresenter x:Name="content" HorizontalAlignment="Center" VerticalAlignment="Center" Content="{TemplateBinding Content}">
<ContentPresenter.BitmapEffect>
<DropShadowBitmapEffect Color="#000" Direction="-90" ShadowDepth="2" Softness="0.1" Opacity="0.3" />
</ContentPresenter.BitmapEffect>
</ContentPresenter>
</Border>
</Border>
<!--触发器-->
<ControlTemplate.Triggers>
<!--鼠标移入移出-->
<Trigger Property="IsMouseOver" Value="True">
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation To="6" Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BitmapEffect).(OuterGlowBitmapEffect.GlowSize)" />
<ColorAnimation To="#AFFF" BeginTime="0:0:0.2" Duration="0:0:0.2" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation To="#3FFF" BeginTime="0:0:0.2" Duration="0:0:0.2" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation Duration="0:0:0.2" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BitmapEffect).(OuterGlowBitmapEffect.GlowSize)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.2" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.ExitActions>
</Trigger>
<!--按钮按下弹起-->
<Trigger Property="IsPressed" Value="True">
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation To="3" Duration="0:0:0.1" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BitmapEffect).(OuterGlowBitmapEffect.GlowSize)" />
<ColorAnimation To="#3AAA" Duration="0:0:0.1" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation To="#2111" Duration="0:0:0.1" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation Duration="0:0:0.1" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BitmapEffect).(OuterGlowBitmapEffect.GlowSize)" />
<ColorAnimation Duration="0:0:0.1" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.1" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.ExitActions>
</Trigger>
<!--按钮失效-->
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Foreground" Value="#B444"/>
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation To="0" Duration="0:0:0.3" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BitmapEffect).(OuterGlowBitmapEffect.GlowSize)" />
<DoubleAnimation To="1" Duration="0:0:0.1" Storyboard.TargetName="content" Storyboard.TargetProperty="(ContentPresenter.BitmapEffect).(DropShadowBitmapEffect.Opacity)" />
<DoubleAnimation To="-135" Duration="0:0:0.1" Storyboard.TargetName="content" Storyboard.TargetProperty="(ContentPresenter.BitmapEffect).(DropShadowBitmapEffect.Direction)" />
<ColorAnimation To="#FFF" Duration="0:0:0.3" Storyboard.TargetName="content" Storyboard.TargetProperty="(ContentPresenter.BitmapEffect).(DropShadowBitmapEffect.Color)" />
<ColorAnimation To="#D555" Duration="0:0:0.3" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" />
<ColorAnimation To="#CEEE" Duration="0:0:0.3" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation To="#CDDD" Duration="0:0:0.3" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation Duration="0:0:0.1" Storyboard.TargetName="back" Storyboard.TargetProperty="(Border.BitmapEffect).(OuterGlowBitmapEffect.GlowSize)" />
<DoubleAnimation Duration="0:0:0.1" Storyboard.TargetName="content" Storyboard.TargetProperty="(ContentPresenter.BitmapEffect).(DropShadowBitmapEffect.Opacity)" />
<DoubleAnimation Duration="0:0:0.1" Storyboard.TargetName="content" Storyboard.TargetProperty="(ContentPresenter.BitmapEffect).(DropShadowBitmapEffect.Direction)" />
<ColorAnimation Duration="0:0:0.1" Storyboard.TargetName="content" Storyboard.TargetProperty="(ContentPresenter.BitmapEffect).(DropShadowBitmapEffect.Color)" />
<ColorAnimation Duration="0:0:0.1" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.BorderBrush).(SolidColorBrush.Color)" />
<ColorAnimation Duration="0:0:0.1" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)" />
<ColorAnimation Duration="0:0:0.1" Storyboard.TargetName="fore" Storyboard.TargetProperty="(Border.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)" />
</Storyboard>
</BeginStoryboard>
</Trigger.ExitActions>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Application.Resources>
</Application>
下面逐步讲解一下代码。
首先需要引入一个命名空间，就是 FileInfo 类所在的 System.IO 命名空间，我们将它的别名定义为“c”。
DataTemplate 标记是为界面中出现的数据类型定义的显示模板，如果不指定 x:Key 的话，那么界面上不管何处出现此类型的对象，都会转为这样的显示方式。
WrapPanel 是一种简单的容器元素，它会把它里面的所有元素都横着排列，排不下了就换一行接着排，这类似网页的默认布局模式，很容易掌握。
WrapPanel.ToolTip 内定义的就是工具提示里的那个缩略图和文字了，其他代码都很简单就不多说了。
很多人觉得工具提示里可以放图片是一件很神奇的事，的确很让人惊喜，但是其实WPF元素的内容格式基本都是 Object 类型的，也就是说，你可以放一切你能想到的东西进去！按钮、视频、文档乃至3D模型，都可以哦。
我们来看触发器，这个触发器定义的 Height 是谁的属性呢？记得以前我们自定义样式时怎么显示元素的内容吗？对，ContentPresenter，这就是所有内容的总容器。
为什么要在 ContentPresenter 高度为 68 的时候触发动画呢？这其实我是使了个歪点子～我没找到数据内容相应上层元素属性变化的方法，所以就用 ContentPresenter 高度变化与这边产生联动，从而间接响应 ListBox 那边的 IsSelected 属性变化。
动画的内容就是把先前隐藏的图片和一行文字显示并放大出来，没什么难点的。
行了，代码部分讲解完了，我们来谈谈如何完善这个程序。
这程序模样不错，但是有几点很不爽：
1 显示文件的大小的单位是字节，这让人很晕。
2 选择了非图片文件不会显示任何提示，只是图片处空了。
3 FileInfo对象的内容在后台被更改不会及时反映到界面上。
对应的解决办法：
1 采用自定义类，获取必要的 FileInfo 对象的部分属性值，定义专门用于以其它单位显示文件大小的属性。
2 还是采用自定义类，获取 FileInfo 对象的扩展名属性，将之赋予自定义的一个依赖属性上，依赖属性可以被触发器 Trigger 识别，这样我们就可以依据扩展名来显示不同的布局结构，并控制元素的隐现，比如选中视频文件可以播放视频预览，而选中一个普通文件只会显示一种替代图标。
3 依然是自定义类，只有实现 INotifyPropertyChanged 接口的类型才可以提供更改通知，以维护双向实时绑定。
WPF是个大舞台，我们可以做的还有很多。