silverlight 对ChildWindow返回给父窗体值的理解

这篇文章是我对ChildWindow的理解，举例说明：

有时候在项目中需要弹出子窗体进行一些操作，然后将操作的值返回到父窗体中。

下图是子窗体的界面（比较粗糙。。。。）

下面贴出其代码：

<controls:ChildWindow x:Class="FineMmarketing.Controls.SelectChild"
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
           xmlns:controls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls"
           Width="365" Height="226" 
           Title="请选择纬度">
    <Grid x:Name="LayoutRoot" Margin="2" >
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <StackPanel Margin="0,0,0,37">            
            <TextBlock Width="100" Height="30" Text="请输入纬度：" Margin="83 35 0 0" HorizontalAlignment="Left" />
            <TextBox x:Name="Txt" Width="200" Height="30" HorizontalAlignment="Center" Margin="24 0 0 0"/>
        </StackPanel>
        
        <Button x:Name="CancelButton" Content="取消" Click="CancelButton_Click" Width="75" Height="23" HorizontalAlignment="Right" Margin="0,12,0,0" Grid.Row="1" />
        <Button x:Name="OKButton" Content="确定" Click="OKButton_Click" Width="75" Height="23" HorizontalAlignment="Right" Margin="0,12,79,0" Grid.Row="1" />
    </Grid>
</controls:ChildWindow>

 /// <summary>
        /// 确定按钮
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void OKButton_Click(object sender, RoutedEventArgs e)
        {            
            if (!String.IsNullOrEmpty(this.Txt.Text))
            {
                Regex reg = new Regex("^[0-9]+$");
                Match ma = reg.Match(this.Txt.Text.ToString());
                if (ma.Success)
                {
                    Num = Convert.ToInt32(this.Txt.Text.ToString());
                    if (Num > 10)
                    {
                        MessageBox.Show("纬度不能超过10！");
                        return;
                    }
                    else
                    {
                        this.Tag = Num;
                    }           
                }
                else
                {
                    MessageBox.Show("请输入正确的纬度！");
                }
            }
            else
            {
                MessageBox.Show("请输入纬度！");
            }
            this.DialogResult = true;
        }
 /// <summary>
        /// 取消按钮
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CancelButton_Click(object sender, RoutedEventArgs e)
        {
            this.DialogResult = false;
        }

然后看一下在父窗体中如何调用子窗体，然后后台定义事件执行子窗体关闭事件。

SelectChild myChild = new SelectChild();//申明子窗体对象
////定义子窗体关闭事件
myChild.Closed += new EventHandler(win_Closed);


 /// <summary>
        /// 子窗口关闭返回值事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void win_Closed(object sender,EventArgs e)
        {
            bool? result = myChild.DialogResult;
            //判断是否是顶级确定按钮关闭并且有返回值
            if (result.HasValue && result.Value)
            {
                //是定义在子窗体中的公有的全局变量
                MessageBox.Show(myChild.txt);
            }
        }