WPF界面设计技巧（5）—自定义列表项呈现内容

 

 

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。

 

源代码下载