使用 Caliburn 绑定 TextboxHelper.ButtonCommand答案

【问题标题】：TextboxHelper.ButtonCommand Binding using Caliburn使用 Caliburn 绑定 TextboxHelper.ButtonCommand
【发布时间】：2014-01-29 06:46:10
【问题描述】：

我在使用 caliburn 将 TextboxHelper.ButtonCommand（来自 mahapps.metro）绑定到我的视图模型时遇到问题。

目前我正在使用委托命令进行这项工作。

查看：

<TextBox Name="TextBoxContent"
             mui:TextboxHelper.ButtonContent="s"
             mui:TextboxHelper.ButtonCommand="{Binding DelCommand, Mode=OneWay}"
             Style="{DynamicResource ButtonCommandMuiTextBox}" />

查看模式：

ICommand DelCommand
{
    get {return new Command();}
}

void Command() { //Handle press here }

但是我真的很想使用 caliburn 而不是委托命令来实现这一点。我试过使用文本框上的事件触发器无济于事，就像这样......

<TextBox Name="TextBoxContent" mui:TextboxHelper.ButtonContent="s"
             Style="{DynamicResource ButtonCommandMuiTextBox}">
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="mui:TextboxHelper.ButtonCommand">
                <i:EventTrigger.Actions>
                    <cal:ActionMessage MethodName="Command"/>
                </i:EventTrigger.Actions>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </TextBox>

这有什么不能做到的原因吗？

谢谢

【问题讨论】：

标签： c# wpf mvvm caliburn.micro mahapps.metro

【解决方案1】：

我创建了一个附加属性，将 Caliburn 消息附加到 MahApps 文本框按钮。

public static class MahappsHelper
{
    /// <summary>
    /// Attach Caliburn cal:Message.Attach for the Mahapps TextBoxHelper.Button
    /// </summary>
    public static readonly DependencyProperty ButtonMessageProperty =
        DependencyProperty.RegisterAttached("ButtonMessage", typeof(string), typeof(MahappsHelper), new PropertyMetadata(null, ButtonMessageChanged));

    public static string GetButtonMessage(DependencyObject obj)
    {
        return (string)obj.GetValue(ButtonMessageProperty);
    }

    public static void SetButtonMessage(DependencyObject obj, string value)
    {
        obj.SetValue(ButtonMessageProperty, value);
    }

    private static void ButtonMessageChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        FrameworkElement textBox = d as TextBox;
        if (d == null)
            textBox = d as PasswordBox;
        if (d == null)
            textBox = d as ComboBox;
        if (textBox == null)
            throw new ArgumentException("ButtonMessage does not work with control " + d.GetType());

        textBox.Loaded -= ButtonMessageTextBox_Loaded;

        Button button = GetTextBoxButton(textBox);
        if (button != null)
        {
            SetButtonMessage(textBox, button);
            return;
        }

        // cannot get button, try it in the Loaded event
        textBox.Loaded += ButtonMessageTextBox_Loaded;
    }

    private static Button GetTextBoxButton(FrameworkElement textBox)
    {
        return TreeHelper.FindChild<Button>(textBox, "PART_ClearText");
    }

    private static void ButtonMessageTextBox_Loaded(object sender, RoutedEventArgs e)
    {
        FrameworkElement textBox = (FrameworkElement)sender;
        textBox.Loaded -= ButtonMessageTextBox_Loaded;

        Button button = GetTextBoxButton(textBox);
        SetButtonMessage(textBox, button);
    }

    /// <summary>
    /// Set Caliburn Message to the TextBox button.
    /// </summary>
    private static void SetButtonMessage(FrameworkElement textBox, Button button)
    {
        if (button == null)
            return;

        string message = GetButtonMessage(textBox);
        Caliburn.Micro.Message.SetAttach(button, message);
    }
}

及用法：

    <TextBox x:Name="SearchBox" mahapps:TextBoxHelper.Watermark="Search ..."
             cal:Message.Attach="[KeyDown] = [Search(SearchBox.Text, $eventArgs)]"
             my:MahappsHelper.ButtonMessage="Search(SearchBox.Text)" />

【讨论】：

【解决方案2】：

这是因为它不是事件，您可以通过将对命令的调用转换为附加事件来解决此问题，然后让 caliburn 监视该事件。

我将省略附加的事件代码，因为它很长但可以在这里找到：Custom attached events in WPF

有点像

public class MyControlExtension
{
    public static readonly DependencyProperty SendMahAppsCommandAsEventProperty = DependencyProperty.RegisterAttached("SendMahAppsCommandAsEvent", typeof(bool), ... etc ... );

    public static SetSendMahAppsCommandAsEvent(DependencyObject element, bool value)
    {
        if (value) 
               TextboxHelper.SetButtonCommand(element, CreateCommand(element));
        else 
               TextboxHelper.SetButtonCommand(null);
    }

    public static bool GetHeaderSizingGroup(DependencyObject element)
    {
        return (bool) element.GetValue(SendMahAppsCommandAsEventProperty);
    }

    private static ICommand CreateCommand(DependencyObject element) 
    {
          return new MyCommandThatRaisesAttachedEvent(element);
    }
}

【讨论】：