我如何添加一个提示文字，WPF文本框？

问题描述：

例如，Facebook已经在搜索文本框中输入搜索的提示文本时的文本框为空。

For example, Facebook has a "Search" hint text in the Search text box when the textbox is empty.

如何使用WPF文本框实现这一目标？

How to achieve this with WPF text boxes??

答

您可以更轻松地完成这项具有的VisualBrush ，并在风格：

You can accomplish this much more easily with a VisualBrush and some triggers in a Style:

<TextBox>
    <TextBox.Style>
        <Style TargetType="TextBox" xmlns:sys="clr-namespace:System;assembly=mscorlib">
            <Style.Resources>
                <VisualBrush x:Key="CueBannerBrush" AlignmentX="Left" AlignmentY="Center" Stretch="None">
                    <VisualBrush.Visual>
                        <Label Content="Search" Foreground="LightGray" />
                    </VisualBrush.Visual>
                </VisualBrush>
            </Style.Resources>
            <Style.Triggers>
                <Trigger Property="Text" Value="{x:Static sys:String.Empty}">
                    <Setter Property="Background" Value="{StaticResource CueBannerBrush}" />
                </Trigger>
                <Trigger Property="Text" Value="{x:Null}">
                    <Setter Property="Background" Value="{StaticResource CueBannerBrush}" />
                </Trigger>
                <Trigger Property="IsKeyboardFocused" Value="True">
                    <Setter Property="Background" Value="White" />
                </Trigger>
            </Style.Triggers>
        </Style>
    </TextBox.Style>
</TextBox>

要增加可重用性这个风格，也可以创建一组附加属性来控制实际的提示标语文本，颜色，方位等。

To increase the re-usability of this Style, you can also create a set of attached properties to control the actual cue banner text, color, orientation etc.

我如何添加一个提示文字，WPF文本框？

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