WPF自定义WaterTextBox

今天在看javaScript中发现有onblur和onfocus事件，很轻松了实现了有水印的TextBox，寻思着wpf中是不是也有类似的方法，查找官网api，发现了有LostFocus和GotFocus两个方法，不过，要实现类似效果，你的重写他。代码很简单，直接上：

public class WaterTextBox : TextBox

    {

        public WaterTextBox()

        { 

            this.Text = "输入内容";

            this.Foreground = Brushes.Gray;

        }

        protected override void OnLostFocus(System.Windows.RoutedEventArgs e)

        {

            base.OnLostFocus(e);

            if (string.IsNullOrEmpty(this.Text))

            {

                this.Text = "输入内容";

                this.Foreground = Brushes.Gray;

            }

        }

        protected override void OnGotFocus(System.Windows.RoutedEventArgs e)

        {

            base.OnGotFocus(e);

            if (this.Text == "输入内容" && this.Foreground == Brushes.Gray)

            {

                this.Clear();

                this.Foreground = Brushes.Black;

            }

        }

    }

定义一个WaterTextBox继承TextBox，重写OnLostFocus和OnGotFocus，前台代码更简单，如下：

<Window x:Class="wpfLostFocus.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        xmlns:my="clr-namespace:wpfLostFocus"

        Title="MainWindow" Height="350" Width="525">

    <Grid>

        <my:WaterTextBox Width="100" Height="25"></my:WaterTextBox>

        <TextBox Margin="208,198,209,92" Text="nihao"/>

    </Grid>

</Window>