WPF自定义控件Textbox 带水印 以及错误信息显示_02

  public partial class SelfWateMarkTextbox : System.Windows.Controls.UserControl
    {
        private const string defaultText = "";

        private const string IsInputText = "";

        private const string IsErrorText = "";

        private const string IsMaxLength = "30";

        public string TextValue = string.Empty;

        public SelfWateMarkTextbox()
        {
            InitializeComponent();

            this.Loaded += new RoutedEventHandler(WateMarkTextbox_Loaded);

            this.GotFocus += new RoutedEventHandler(WateMarkTextbox_GotFocus);

            this.LostFocus += new RoutedEventHandler(WateMarkTextbox_LostFocus);

            this.textBox1.TextChanged += new TextChangedEventHandler(TextBox1_TextChanged);

            this.txtErrorShow.TextChanged += new TextChangedEventHandler(txtErrorShow_TextChanged);
        }

        void txtErrorShow_TextChanged(object sender, TextChangedEventArgs e)
        {
            if (!string.IsNullOrEmpty(this.txtErrorShow.Text) && txtErrorShow.Text.ToLower() == "true")
            {
                IsErrorShowBorder.Visibility = Visibility.Visible;
            }
            else
            {
                IsErrorShowBorder.Visibility = Visibility.Hidden;
            }
        }

        void TextBox1_TextChanged(object sender, TextChangedEventArgs e)
        {
            if (TextValue != null && TextValue.Length > 0 && !this.textBox1.IsFocused)
            {
                this.textBox1.Text = TextValue;
            }
            else if (!string.IsNullOrEmpty(this.textBox1.Text) || this.textBox1.IsFocused)
            {
                this.textBox1.Text = this.textBox1.Text;
            }
            else
            {
                this.textBox1.Text = Watermark;
            }

            if (this.textBox1.Text != Watermark)
            {
                TextValue = this.textBox1.Text;
            }
            if (this.textBox1.Text != Watermark && this.textBox1.IsFocused)
            {
                IsErrorShowBorder.Visibility = Visibility.Hidden;
            }
        }

        void WateMarkTextbox_LostFocus(object sender, RoutedEventArgs e)
        {
            if (string.IsNullOrEmpty(this.textBox1.Text))
            {
                this.textBox1.Text = Watermark;
            }
        }

        void WateMarkTextbox_GotFocus(object sender, RoutedEventArgs e)
        {
            if (this.textBox1.Text.Equals(Watermark))
            {
                this.textBox1.Text = string.Empty;
            }
        }

        void WateMarkTextbox_Loaded(object sender, RoutedEventArgs e)
        {

            this.textBox1.Text = Watermark;
            this.IsInput.Content = IsRequired;
            this.IsError.Content = IsErrorMessage;
            this.textBox1.MaxLength = Convert.ToInt32(MaxLength);
        }

        public string Watermark
        {
            get
            {
                string result = (string)GetValue(WatermarkProperty);

                if (string.IsNullOrEmpty(result))
                {
                    result = defaultText;
                }

                return result;
            }

            set { SetValue(WatermarkProperty, value); }
        }

        public string IsRequired
        {
            get
            {
                string result = (string)GetValue(IsRequiredProperty);

                if (string.IsNullOrEmpty(result))
                {
                    result = IsInputText;
                }

                return result;
            }

            set { SetValue(IsRequiredProperty, value); }
        }

        public string IsErrorMessage
        {
            get
            {
                string result = (string)GetValue(IsErrorMessageProperty);

                if (string.IsNullOrEmpty(result))
                {
                    result = IsErrorText;
                }

                return result;
            }

            set { SetValue(IsErrorMessageProperty, value); }
        }

        public string MaxLength
        {
            get
            {
                string result = (string)GetValue(IsMaxLengthProperty);

                if (string.IsNullOrEmpty(result))
                {
                    result = IsMaxLength;
                }

                return result;
            }

            set { SetValue(IsMaxLengthProperty, value); }
        }

        public string IsErrorShow
        {

            set
            {
                txtErrorShow.Text = null;
                txtErrorShow.Text = value;
            }

        }

        public static readonly DependencyProperty WatermarkProperty =
            DependencyProperty.Register("Watermark", typeof(string), typeof(SelfWateMarkTextbox), new UIPropertyMetadata(defaultText));

        public static readonly DependencyProperty IsRequiredProperty =
                DependencyProperty.Register("IsRequired", typeof(string), typeof(SelfWateMarkTextbox), new UIPropertyMetadata(IsInputText));

        public static readonly DependencyProperty IsErrorMessageProperty =
            DependencyProperty.Register("IsErrorMessage", typeof(string), typeof(SelfWateMarkTextbox), new UIPropertyMetadata(IsErrorText));

        public static readonly DependencyProperty IsMaxLengthProperty =
           DependencyProperty.Register("MaxLength", typeof(string), typeof(SelfWateMarkTextbox), new UIPropertyMetadata(IsMaxLength));

    }

 <Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" >
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" MaxWidth="20"></ColumnDefinition>
            <ColumnDefinition Width="1.5*"></ColumnDefinition>
            <ColumnDefinition Width="*"></ColumnDefinition>
            <ColumnDefinition Width="1"></ColumnDefinition>
        </Grid.ColumnDefinitions>
        <Label Grid.Column="0" Name="IsInput" Foreground="Red" VerticalContentAlignment="Center"   HorizontalContentAlignment="Center">*</Label>
        <TextBox Grid.Column="1" VerticalContentAlignment="Center" x:Name="textBox1" TextWrapping="Wrap" />
        <Border Grid.Column="2" Name="IsErrorShowBorder" BorderThickness="1"  Background="LightPink"  CornerRadius="10"  Visibility="Hidden">
            <Label Name="IsError"  Foreground="Red" VerticalContentAlignment="Top" HorizontalContentAlignment="Center"></Label>
        </Border>
        <TextBox Grid.Column="3" VerticalContentAlignment="Center" Text="{Binding IsErroShow}"  x:Name="txtErrorShow"   Visibility="Hidden"/>
    </Grid>

<Grid>
        <StackPanel>
            <my:SelfWateMarkTextbox x:Name="txtAccount"  Height="30" Width="300" IsErrorMessage="请输入账号" MaxLength="16"  IsRequired="*" Margin="5" />
            <my:SelfWateMarkTextbox  x:Name="txtName" Height="30" Width="300" IsErrorMessage="请输入姓名" MaxLength="8"  IsRequired="*" Margin="5" />
            <Button  Content="显示错误" Width="75" Height="21" Margin="5" Click="Button_Click"></Button>
        </StackPanel>
      
    </Grid>