C# - WinRT 信息：元素已经是另一个元素的子元素。附加信息：未检测到已安装的组件

Question

我是 C# 新手，我一直在尝试设置一个基本游戏（来自一本书），但是由于以下错误，我正处于无法运行的地步

在 mscorlib.dll 中发生了“System.Exception”类型的异常，但是 未在用户代码中处理

WinRT 信息：元素已经是另一个元素的子元素。

附加信息：未检测到已安装的组件。

查看代码我看不出有什么问题；

    private void StartGame()
    {
        human.IsHitTestVisible = true;
        humanCaptured = false;
        progressBar.Value = 0;
        startButton.Visibility = Visibility.Collapsed;
        playArea.Children.Add(target);
        playArea.Children.Add(human);
        enemyTimer.Start();
        tagetTimer.Start();
    }

查看文档大纲，这似乎也是正确的顺序；
对我来说唯一的东西似乎是 Xaml；

<Canvas x:Name="playArea" Grid.RowSpan="3" Margin="10,77,10,0" >
            <StackPanel x:Name="human" Orientation="Vertical">
                <Ellipse Fill="Purple" Height="10"  Width="10" />
                <Rectangle Fill="Purple" Height="25" Width="10"/>
            </StackPanel>
            <Rectangle x:Name="target" Height="53.149" Canvas.Left="1202.196" Stroke="Black" Canvas.Top="419.937" Width="56.008" RenderTransformOrigin="0.5,0.5" UseLayoutRounding="False" d:LayoutRounding="Auto">
                <Rectangle.Fill>
                    <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                        <GradientStop Color="Black"/>
                        <GradientStop Color="#FF4860F7" Offset="0.508"/>
                    </LinearGradientBrush>
                </Rectangle.Fill>
                <Rectangle.RenderTransform>
                    <CompositeTransform Rotation="46.097"/>
                </Rectangle.RenderTransform>
            </Rectangle>
            <TextBox x:Name="gameOverText" TextWrapping="Wrap" Text="Game Over" Canvas.Left="428" Canvas.Top="248" Height="107" Width="413" FontSize="72" FontWeight="Bold" FontStyle="Italic"/>
            <Canvas.Background>
                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                    <GradientStop Color="#FF1BAE78" Offset="1"/>
                    <GradientStop Color="#FFDCEE3B"/>
                </LinearGradientBrush>
            </Canvas.Background>
</Canvas>

有什么想法吗？

Answer 1

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using Windows.UI.Popups; //This is used for massage box within a blank applocation. 

using Windows.UI.Xaml.Media.Animation;

// The Basic Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234237

namespace Save_The_Humans
{
    /// <summary>
    /// A basic page that provides characteristics common to most applications.
    /// </summary>
    public sealed partial class MainPage : Save_The_Humans.Common.LayoutAwarePage
    {
        Random random = new Random();
        DispatcherTimer enemyTimer = new DispatcherTimer();
        DispatcherTimer tagetTimer = new DispatcherTimer();
        bool humanCaptured = false;

        public MainPage()
        {
            this.InitializeComponent();

            enemyTimer.Tick += enemyTimer_Tick;
            enemyTimer.Interval = TimeSpan.FromSeconds(2);

            tagetTimer.Tick += tagetTimer_Tick;
            tagetTimer.Interval = TimeSpan.FromSeconds(.1);
        }

        void tagetTimer_Tick(object sender, object e)
        {
            progressBar.Value += 1;
            if (progressBar.Value >= progressBar.Maximum)
                EndTheGame();

        }

        private void EndTheGame()
        {
            if (!playArea.Children.Contains(gameOverText))
            {
                enemyTimer.Stop();
                tagetTimer.Stop();
                humanCaptured = false;
                startButton.Visibility = Visibility.Visible;
                playArea.Children.Add(gameOverText);
            }
        }

        void enemyTimer_Tick(object sender, object e)
        {
            AddEnemy();
        }

        /// <summary>
        /// Populates the page with content passed during navigation.  Any saved state is also
        /// provided when recreating a page from a prior session.
        /// </summary>
        /// <param name="navigationParameter">The parameter value passed to
        /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested.
        /// </param>
        /// <param name="pageState">A dictionary of state preserved by this page during an earlier
        /// session.  This will be null the first time a page is visited.</param>
        protected override void LoadState(Object navigationParameter, Dictionary<String, Object> pageState)
        {
        }

        /// <summary>
        /// Preserves state associated with this page in case the application is suspended or the
        /// page is discarded from the navigation cache.  Values must conform to the serialization
        /// requirements of <see cref="SuspensionManager.SessionState"/>.
        /// </summary>
        /// <param name="pageState">An empty dictionary to be populated with serializable state.</param>
        protected override void SaveState(Dictionary<String, Object> pageState)
        {
        }
        private void startButton_Click(object sender, RoutedEventArgs e)
        {
            StartGame();
        }
        /// <summary>
        /// Starts the game.
        /// </summary>
        public void StartGame()
        {
            human.IsHitTestVisible = true;
            humanCaptured = false;
            progressBar.Value = 0;
            startButton.Visibility = Visibility.Collapsed;
            /*playArea.Children.Add(target);
            playArea.Children.Add(human);*/
            enemyTimer.Start();
            tagetTimer.Start();
        }
        /// <summary>
        /// Starts the animation, below is the enemy method.
        /// </summary>
        private void AddEnemy()
        {
            ContentControl enemy = new ContentControl();
            enemy.Template = Resources["EnemyTemplate"] as ControlTemplate;
            AnimateEnemy(enemy, 0, playArea.ActualWidth - 100, "(Canvas.Left)");
            AnimateEnemy(enemy, random.Next((int)playArea.ActualHeight - 100),
                random.Next((int)playArea.ActualHeight - 100), "(Canvas.Top)");
            playArea.Children.Add(enemy);
        }

        private void AnimateEnemy(ContentControl enemy, double from, double to, string properyToAnimate)
        {
            Storyboard storyboard = new Storyboard() { AutoReverse = true, RepeatBehavior = RepeatBehavior.Forever };
            DoubleAnimation animation = new DoubleAnimation()
            {
                From = from,
                To = to,
                Duration = new Duration(TimeSpan.FromSeconds(random.Next(4, 6)))
            };
            Storyboard.SetTarget(animation, enemy);
            Storyboard.SetTargetProperty(animation, properyToAnimate);
            storyboard.Children.Add(animation);
            storyboard.Begin();
        }
        /// <summary>
        /// async needs to be a part of the method to show message box!
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private async void About_Click(object sender, RoutedEventArgs e)
        {
            //Creating instance for the MessageDialog Class  
            //and passing the message in it's Constructor
            MessageDialog msgbox = new MessageDialog("Created by");
            //Calling the Show method of MessageDialog class  
            //which will show the MessageBox  
            await msgbox.ShowAsync();
        }
    }
}