c# - 控件模板 Storyboard ，在同一模板内的其他控件中设置值

Question

有人要求我围绕现有的 DateTimePicker 控件创建一个 hack。通常，日期/时间选择器有一个精美的日历图像，然后是它旁边的文本框，用于显示实际日期。用户可以单击图像并弹出日历，选择后，日期会刷新到文本框区域。

我遇到的问题是其他设计师不喜欢日历图形，只想要一个普通的文本框控件，但如果用户双击，打开弹出式日历，获取日期并刷新它。多亏了在 S/O 上找到的其他帮助，我非常接近这一点。

所以，描述我的控件模板，并保持简单(非自定义控件，除非我需要根据建议)。控件模板基于文本框控件。我们有一个带有文本框 PART_ContentHost 的边框，然后是一个标准日历控件的弹出窗口。

对于控件模板触发器，我有一个链接到 ScrollViewer(文本框输入区域)的 MouseDoubleClick 事件。如果触发，则将弹出窗口的 IsOpen 设置为 true 并公开日历。这很好用。

现在，完成它。如果用户从日历中选择一个日期，下一个触发器将关闭弹出窗口(IsOpen 设置为 false)。这也行。

我的问题。我还希望在选择时采用所选日期并将其 ToString() 日期表示形式放入 ScrollViewer.Content (x:Name="PART_ContentHost)。

<ControlTemplate TargetType="{x:Type TextBox}" x:Key="CTTextBox" >
   <StackPanel>
      <Border x:Name="targetBorder" 
         BorderBrush="{TemplateBinding BorderBrush}"
         SnapsToDevicePixels="true">

         <ScrollViewer x:Name="PART_ContentHost"
            Background="{TemplateBinding Background}"
            BorderBrush="{TemplateBinding BorderBrush}"
            Foreground="{TemplateBinding Foreground}" />
      </Border>
      <Popup PlacementTarget="{Binding ElementName=PART_ContentHost}" x:Name="PopCal">
         <Calendar x:Name="ActualCalendar"/>
      </Popup>
   </StackPanel>

   <ControlTemplate.Triggers>
      <EventTrigger RoutedEvent="ScrollViewer.MouseDoubleClick" SourceName="PART_ContentHost">
         <BeginStoryboard>
            <Storyboard>
               <BooleanAnimationUsingKeyFrames 
                  Storyboard.TargetName="PopCal" 
                  Storyboard.TargetProperty="(Popup.IsOpen)">
                  <DiscreteBooleanKeyFrame KeyTime="00:00:00" Value="True"/>
               </BooleanAnimationUsingKeyFrames>
            </Storyboard>
         </BeginStoryboard>
      </EventTrigger>

      <EventTrigger RoutedEvent="Calendar.SelectedDatesChanged" SourceName="ActualCalendar">
         <BeginStoryboard>
            <Storyboard>
               <BooleanAnimationUsingKeyFrames 
                  Storyboard.TargetName="PopCal" 
                  Storyboard.TargetProperty="(Popup.IsOpen)">
                  <DiscreteBooleanKeyFrame KeyTime="00:00:00" Value="False"/>
               </BooleanAnimationUsingKeyFrames>
            </Storyboard>


            WHAT WOULD I PUT HERE to have the selected date of the popup calendar
            inserted into the content of the PART_ContentHost...
            <Storyboard>
               <BooleanAnimationUsingKeyFrames 
                  Storyboard.TargetName="PART_ContentHost" 
                  Storyboard.TargetProperty="(Content)">
                  <DiscreteBooleanKeyFrame KeyTime="00:00:00" Value=" ????? "/>
               </BooleanAnimationUsingKeyFrames>
            </Storyboard>

         </BeginStoryboard>
      </EventTrigger>
   </ControlTemplate.Triggers>
</ControlTemplate>

<Style TargetType="{x:Type TextBox}" x:Key="STextBox" >
   <!--<Setter Property="OverridesDefaultStyle" Value="True"/>-->
   <Setter Property="FontFamily" Value="Arial" />
   <Setter Property="FontSize" Value="12" />
   <Setter Property="Height" Value="20" />
   <Setter Property="Width" Value="100" />
   <Setter Property="VerticalContentAlignment" Value="Bottom" />
   <Setter Property="HorizontalContentAlignment" Value="Left" />
   <Setter Property="HorizontalAlignment" Value="Left" />
   <!-- Padding is Left, Top, Right, Bottom -->
   <Setter Property="Padding" Value="2,0,0,2" />
   <Setter Property="Margin" Value="0,0,0,0" />

   <Setter Property="Visibility" Value="Visible" />
   <Setter Property="IsEnabled" Value="True" />

   <Setter Property="CharacterCasing" Value="Upper" />
   <Setter Property="BorderThickness" Value="1" />

   <Setter Property="BorderBrush" Value="Black" />
   <Setter Property="Background" Value="White" />
   <Setter Property="Foreground" Value="Black" />

   <Setter Property="Template" Value="{StaticResource CTTextBox}" />
</Style>

Answer 1

我确信可以通过多种方式解决问题，但在这些情况下我通常会执行附加行为。但是while情况不太正常，因为这里实现了一个模板控件。无论如何，我认为附加行为适合这种情况，在你的位置我会这样做。

附加行为是非常强大和方便的解决方案，完全满足 MVVM 模式，也可以在 Blend 中使用(具有预定义的接口(interface))。附加行为 - 是一个附加属性，它有一个事件处理程序来更改此属性，并且所有逻辑都在此处理程序中实现。

在开始意识到行为之前，我会考虑对您的模板所做的一些更改。

我有点不明白你为什么要使用PART_ContentHost ScrollViewer 控件，也许会有几个日期需要滚动显示。在 WPF 中，显示内容需要两个控件:

1. 内容展示器
2. 内容控制

这是他们的主要目标。 first lightest 通常用在模板中，但它不支持事件，我们需要协调工作，所以我选择了ContentControl。在小东西上为模板添加绑定(bind)属性，设置为Popup:

AllowsTransparency="True"
VerticalOffset="4"
HorizontalOffset="-5" 

为了更好的可视化。现在转到行为示例。

XAML

<Window.Resources>
    <ControlTemplate x:Key="CTTextBox" TargetType="{x:Type TextBox}">
        <StackPanel AttachedBehaviors:SelectDateBehavior.IsEnabled="True"> <!-- Here is determined behaviour -->
            <Border x:Name="targetBorder" 
                    Width="{TemplateBinding Width}"
                    Height="{TemplateBinding Height}"
                    BorderBrush="{TemplateBinding BorderBrush}"
                    BorderThickness="{TemplateBinding BorderThickness}"
                    Background="{TemplateBinding Background}"
                    TextBlock.Foreground="{TemplateBinding Foreground}"
                    SnapsToDevicePixels="True">

                <ContentControl x:Name="ContentHost"
                                Content="{TemplateBinding Text}"
                                HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                VerticalAlignment="{TemplateBinding VerticalContentAlignment}" 
                                Margin="4,0,0,0" />
            </Border>

            <Popup x:Name="PopCal" 
                   AllowsTransparency="True"
                   VerticalOffset="4"
                   HorizontalOffset="-5"
                   PlacementTarget="{Binding ElementName=ContentHost}">

                <Calendar x:Name="ActualCalendar" />
            </Popup>
        </StackPanel>
    </ControlTemplate>

    <Style TargetType="{x:Type TextBox}" x:Key="STextBox">
        <Setter Property="FontFamily" Value="Arial" />
        <Setter Property="FontSize" Value="12" />
        <Setter Property="Height" Value="25" />
        <Setter Property="Width" Value="100" />
        <Setter Property="VerticalContentAlignment" Value="Center" />
        <Setter Property="HorizontalContentAlignment" Value="Left" />
        <Setter Property="HorizontalAlignment" Value="Center" />       
        <Setter Property="CharacterCasing" Value="Upper" />
        <Setter Property="BorderThickness" Value="1" />
        <Setter Property="BorderBrush" Value="Gray" />
        <Setter Property="Background" Value="AliceBlue" />
        <Setter Property="Foreground" Value="Black" />
        <Setter Property="Template" Value="{StaticResource CTTextBox}" />
    </Style>
</Window.Resources>

<Grid>
    <TextBox Style="{StaticResource STextBox}"
             Text="Select date" />
</Grid>

附加行为

public class SelectDateBehavior
{
    #region IsEnabled Dependency Property

    public static readonly DependencyProperty IsEnabledProperty;

    public static void SetIsEnabled(DependencyObject DepObject, bool value)
    {
        DepObject.SetValue(IsEnabledProperty, value);
    }

    public static bool GetIsEnabled(DependencyObject DepObject)
    {
        return (bool)DepObject.GetValue(IsEnabledProperty);
    }

    static SelectDateBehavior()
    {
        IsEnabledProperty = DependencyProperty.RegisterAttached("IsEnabled",
                                                            typeof(bool),
                                                            typeof(SelectDateBehavior),
                                                            new UIPropertyMetadata(false, IsEnabledChanged));
    }

    #endregion

    #region IsEnabledChanged Handler

    private static void IsEnabledChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e) 
    {
        Panel panel = sender as Panel;

        if (panel != null)
        {
            if (e.NewValue is bool && ((bool)e.NewValue) == true)
            {
                panel.Loaded += new RoutedEventHandler(panelLoaded);
            }
            else
            {
                panel.Loaded -= new RoutedEventHandler(panelLoaded);
            }
        }
    }

    #endregion

    #region Panel Loaded Handler

    private static void panelLoaded(object sender, RoutedEventArgs e) 
    {
        Panel panel = sender as Panel;
        Border border = panel.FindName("targetBorder") as Border;
        ContentControl contentHost = border.FindName("ContentHost") as ContentControl;
        Popup popup = panel.FindName("PopCal") as Popup;

        if (popup != null)
        {
            Calendar calendar = popup.FindName("ActualCalendar") as Calendar;                
            calendar.SelectedDatesChanged += new EventHandler<SelectionChangedEventArgs>(calendarSelectedDatesChanged);
        }

        if (contentHost != null)
        {
            contentHost.MouseDoubleClick += new MouseButtonEventHandler(contentHostMouseDoubleClick);
        }          
    }

    #endregion

    #region ContentHost MouseDoubleClick Handler

    private static void contentHostMouseDoubleClick(object sender, MouseButtonEventArgs e) 
    {
        ContentControl contentHost = sender as ContentControl;
        Border border = contentHost.Parent as Border;
        Panel panel = border.Parent as Panel;
        Popup popup = panel.FindName("PopCal") as Popup;

        if (popup != null) 
        {
            popup.IsOpen = true;
        }
    }

    #endregion

    #region Calendar SelectedDatesChanged Handler

    private static void calendarSelectedDatesChanged(object sender, SelectionChangedEventArgs e) 
    {
        Calendar calendar = sender as Calendar;
        Popup popup = calendar.Parent as Popup;
        Panel panel = popup.Parent as Panel;
        Border border = panel.FindName("targetBorder") as Border;
        ContentControl contentHost = border.FindName("ContentHost") as ContentControl;

        if (popup != null) 
        {
            contentHost.Content = calendar.SelectedDate;
            popup.IsOpen = false;
        }
    }

    #endregion
}

输出

设置当前日期在这里进行:

private static void calendarSelectedDatesChanged(object sender, SelectionChangedEventArgs e) 
{
    // Skipped a few lines of code
    if (popup != null) 
    {
        contentHost.Content = calendar.SelectedDate;
        popup.IsOpen = false;
    }
}

一些注意事项

让我提请注意一些功能。首先，我们必须摆脱 EventTrigger Storyboard，因为在 WPF 动画中设置最高优先级值 ，这意味着如果一旦我们在动画中设置值 IsOpen，从其他来源访问(代码等)是不可能的。所以我把所有的触发器/事件放在一边。

其次，解决方案与模板和控件的结构密切相关。这意味着如果必须更改模板的结构，则必须更改行为(可能不多)。

This example is available here.