深入解析:打造自动消失的对话框

原理：使用Popup控件，并且设置Popup控件的位置居中。

1：新建自定义控件PopupBorder,作为Popup的child。代码如下：


代码如下:

<UserControl x:Class="SLStudy.PopupBorder"
   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <UserControl.Resources>
        <Storyboard x:Name="myStoryboard">
            <DoubleAnimation
                Storyboard.TargetName="LayoutRoot"
                Storyboard.TargetProperty="Opacity"
                    From="1.0" To="0" Duration="0:0:1"
                    AutoReverse="True" />
        </Storyboard>
    </UserControl.Resources>

<Grid x:Name="LayoutRoot" >
        <!--<Border Background="#FFCC0D0D" BorderThickness="0" CornerRadius="5">-->
        <Border BorderThickness="0" CornerRadius="5">
            <Border.Background>
                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                    <GradientStop Color="#FF27A3D7" Offset="0.51"/>
                    <GradientStop Color="#FF76C2E1" Offset="0.004"/>
                    <GradientStop Color="#FF27A3D7" Offset="1"/>
                </LinearGradientBrush>
            </Border.Background>
            <Border.Effect>
                <DropShadowEffect BlurRadius="10" Color="#FFCC0D0D" ShadowDepth="0"/>
            </Border.Effect>
            <TextBlock x:Name="txtMessage" HorizontalAlignment="Center" Margin="10" VerticalAlignment="Center"
                       FontSize="28" Foreground="White" FontFamily="Comic Sans MS"
                       >This is a Simple Example</TextBlock>
        </Border>
    </Grid>
</UserControl>

新建PopupDemo页面，代码如下：

 代码如下:
<Grid x:Name="LayoutRoot">
        <StackPanel>
            <Button Content="Show" Click="ShowPopup_Clicked"></Button>
        </StackPanel>
    </Grid>
后台cs代码为：



 代码如下:
private void ShowPopup_Clicked(object sender, RoutedEventArgs e)
        {
            Popup popup = new Popup();
//设置popup的Child属性为自定义的用户控件。
             popup.Child = new PopupBorder();
            popup.IsOpen = true;
        }


 代码如下:
popUp.LayoutUpdated += delegate
            {
                popUp.Margin = new Thickness(
                        (App.Current.Host.Content.ActualWidth - pborder.ActualWidth) / 2,
                        (App.Current.Host.Content.ActualHeight - pborder.ActualHeight) / 2,
                        0,
                        0);
            };
完整的代码如下： 



 代码如下:
PopupBorder pborder = new PopupBorder();
Popup popUp = new Popup();
//设置popup的Child属性为自定义的用户控件。
popUp.Child = pborder;
popUp.LayoutUpdated += delegate
{
    popUp.Margin = new Thickness(
            (App.Current.Host.Content.ActualWidth - pborder.ActualWidth) / 2,
            (App.Current.Host.Content.ActualHeight - pborder.ActualHeight) / 2,
            0,
            0);
};
popUp.IsOpen = true;
运行可以发现弹出的消息已经居中了，那么如何让它自动消失呢？？,
要想自动消失还得使用定时器，过了一段时间后定时器将popUp控件的 IsOpen属性设置为false，这样窗口就关闭了。
于是在LayoutUpdated中增加定时器代码：



 代码如下:
popUp.LayoutUpdated += delegate
            {
                popUp.Margin = new Thickness(
                        (App.Current.Host.Content.ActualWidth - pborder.ActualWidth) / 2,
                        (App.Current.Host.Content.ActualHeight - pborder.ActualHeight) / 2,
                        0,
                        0);
System.Threading.Timer timer = new System.Threading.Timer(
                    (state) =>
                    {
                        popUp.Dispatcher.BeginInvoke(() =>
                        {
                            popUp.IsOpen = false;
                        });
                    }, null, 500, 500);
            };
在过了500秒后，将popUp. IsOpen设置为false。
运行可以发现窗口可以自动消失了。
可以看到弹出窗口一下就关闭了，那么能不能慢慢的渐变的消失呢？？
为了实现渐变的消失，那么就应该使用动画了。
首先在PopupBorder中增加



 代码如下:
<UserControl.Resources>
        <Storyboard x:Name="myStoryboard">
            <DoubleAnimation
                Storyboard.TargetName="LayoutRoot"
                Storyboard.TargetProperty="Opacity"
                    From="1.0" To="0" Duration="0:0:1"
                    AutoReverse="True" />
        </Storyboard>
    </UserControl.Resources>
当然上面的PopupBorder代码中已经有了这段代码了，动画使用了DoubleAnimation,设置LayoutRoot 对象的Opacity属性在1秒的时间内从1，变到0。
接着在PopupDemo页面的按钮事件里面在popUp.Child = pborder;后面增加如下代码来执行动画：



 代码如下:
//设置popup的Child属性为自定义的用户控件。
popUp.Child = pborder;
pborder.myStoryboard.Completed += delegate
{
    popUp.IsOpen = false;
};
pborder.myStoryboard.Begin();
然后将Clicked中的代码进行重构。
新建MessageBoxHelper类：
代码如下：



 代码如下:
public class MessageBoxHelper
{
    #region 提示消?息¡é
/// <summary>
    /// 弹出提示消息标题为提示，按钮为确定
    /// </summary>
    /// <param name="msg"></param>
    public static void ShowMessage(string msg)
    {
        //ShowFriendMessage(msg, "提示", MessageBoxButton.OK);
PopupBorder pborder = new PopupBorder();
        pborder.txtMessage.Text = " " + msg + " ";
pborder.UpdateLayout();
Popup popUp = new Popup();
        popUp.Child = pborder;
pborder.myStoryboard.Completed += delegate
        {
            popUp.IsOpen = false;
        };
        pborder.myStoryboard.Begin();
popUp.InvokeOnLayoutUpdated(() =>
        {
            popUp.Margin = new Thickness(
                (App.Current.Host.Content.ActualWidth - pborder.ActualWidth) / 2,
                (App.Current.Host.Content.ActualHeight - pborder.ActualHeight) / 2,
                0,
                0);
System.Threading.Timer timer = new System.Threading.Timer(
                (state) =>
                {
                    popUp.Dispatcher.BeginInvoke(() =>
                    {
                        popUp.IsOpen = false;
                    });
                }, null, 500, 500);
        });
        popUp.IsOpen = true;
}
/// <summary>
    /// 弹出提示消息按钮为确定
    /// </summary>
    /// <param name="msg"></param>
    public static void ShowMessage(string msg, string title)
    {
        ShowMessage(msg, title, MessageBoxButton.OK);
    }
/// <summary>
    /// 弹出提示消息
    /// </summary>
    /// <param name="msg"></param>
    public static void ShowMessage(string msg, string title, MessageBoxButton buttons)
    {
        MessageBox.Show(msg, title, buttons);
    }
#endregion
}
使用的时候只需要MessageBoxHelper.ShowMessage(“Hello World”);就可以了。注意别忘记了PopupBorder控件。