从 WPF 中的 TextBox 触发事件的工作来完成

Question

您好，我正在尝试将我正在做的事情放在代码背后的事件中，该触发器正在应用于文本框的样式的触发器中。我想要的是防止使用背后的代码来做到这一点并使用触发器。有没有办法做到这一点？

我的文本框

<TextBox Name="myTextBox"  Style="{StaticResource txtBoxStyle}"/>

我的风格

<Style x:Key="txtBoxStyle" TargetType="{x:Type TextBox}">
    <Setter Property="Foreground" Value="Silver"/>
    <Setter Property="MaxLength" Value="6"/>
</Style>

代码背后的事件

private void myTextBox_LostFocus(object sender, RoutedEventArgs e)
{
    if (myTextBox.Text.Length == 0)
        myTextBox.Text = "000000";
}

private void myTextBox_GotFocus(object sender, RoutedEventArgs e)
{
    if (myTextBox.Text == "000000")
        myTextBox.Clear();
}

private void myTextBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
    if (!(e.Key >= Key.D0 && e.Key <= Key.D9) && e.Key != Key.Back)
        e.Handled = true;
}

private void myTextBox_TextChanged(object sender, TextChangedEventArgs e)
{
    if (myTextBox.Text == "000000")
        myTextBox.Foreground = Brushes.Silver;
    else
    {                
        myTextBox.Foreground = Brushes.Black;

        if(myTextBox.Text.Length == 6)
            myButton.Visibility = Visibility.Visible;
        else
            myButton.Visibility = Visibility.Hidden;
    }
}

提前致谢！

Answer 1

编辑：为此逻辑使用触发器不是一个好主意，并且由于其自引用（导致堆栈溢出）而很可能会失败，值转换器也有点问题。要封装复杂的逻辑并通过样式应用它，请使用attached behavior。

---

<Style TargetType="{x:Type TextBox}">
    <Style.Triggers>
        <MultiDataTrigger>
            <MultiDataTrigger.Conditions>
                <Condition Binding="{Binding IsFocused, RelativeSource={RelativeSource Self}}" Value="False"/>
                <Condition Binding="{Binding Text, RelativeSource={RelativeSource Self}}" Value=""/>
            </MultiDataTrigger.Conditions>
            <MultiDataTrigger.Setters>
                <Setter Property="Text" Value="000000"/>
            </MultiDataTrigger.Setters>
        </MultiDataTrigger>
        <MultiDataTrigger>
            <MultiDataTrigger.Conditions>
                <Condition Binding="{Binding IsFocused, RelativeSource={RelativeSource Self}}" Value="True"/>
                <Condition Binding="{Binding Text, RelativeSource={RelativeSource Self}}" Value="000000"/>
            </MultiDataTrigger.Conditions>
            <MultiDataTrigger.Setters>
                <Setter Property="Text" Value=""/>
            </MultiDataTrigger.Setters>
        </MultiDataTrigger>
        <Trigger Property="Text" Value="000000">
            <Setter Property="Foreground" Value="Silver"/>
        </Trigger>
    </Style.Triggers>
    <!-- If (Text != "000000") Foreground = Brushes.Black -->
    <Setter Property="Foreground" Value="Black"/>
</Style>

设置按钮可见性的逻辑不应以这种样式处理，而应由按钮处理。无法翻译按键事件。

按钮样式：

<Style TargetType="{x:Type Button}">
    <Setter Property="Visibility" Value="Hidden"/> <!-- Normal state -->
    <Style.Triggers>
        <DataTrigger Binding="{Binding Text.Length, ElementName=myButton}" Value="6">
            <Setter Property="Visibility" Value="Visible"/>
        </DataTrigger>
    </Style.Triggers>
</Style>