如何在 WP8 中获取元素的绝对位置并使用它将元素移动到新位置

Question

如何在 WP8 中获取元素的绝对位置并使用它将该元素移动到新位置

我正在尝试使用以下代码在屏幕上点按来移动图像，但出现了意外行为。

        private void SetGame()
    {
        ScreenWidth = Application.Current.Host.Content.ActualWidth;
        ScreenHeight = Application.Current.Host.Content.ActualHeight;

        var transform = littleMan.TransformToVisual(Application.Current.RootVisual);
        System.Windows.Point absolutePosition = transform.Transform(new System.Windows.Point(0, 0));

        manLocY = absolutePosition.Y; //vert
        manLocX = absolutePosition.X; //hori

        leftControlArea = (ScreenWidth / 2);
        rightControlArea = (ScreenWidth / 2); // answer to the screen width;
        topControlArea = (ScreenHeight / 3);
        bottomControlArea = (ScreenHeight / 3) * 2; // answer to the screen height

        littleManWidth = littleMan.ActualWidth;
        littleManHeight = littleMan.ActualHeight;

    }

    private void MoveLittleMan(Vector2 tappedWhere)
    {
        double tapX, tapY;
        tapX = tappedWhere.X; // represent where user tapped on screen width wise
        tapY = tappedWhere.Y; // represent where user tapped on screen height wise


        if(tapY <= topControlArea)
        {
            // move top
            Debug.WriteLine("Move TOP - X: " + tapX + " - Y: " + tapY);
            if (manLocY > littleManHeight)
            {
                manLocY = manLocY - skippingSteps;
                Canvas.SetTop(littleMan, manLocY);
            }
        }

        else if(tapY >= bottomControlArea)
        {
            //move bottom
            Debug.WriteLine("Move BOTTOM - X: " + tapX + " - Y: " + tapY);
            if (manLocY < (ScreenHeight - littleManHeight))
            {
                manLocY = manLocY + skippingSteps;
                Canvas.SetTop(littleMan, manLocY);
            }
        }

        else if (tapX <= leftControlArea && tapY > topControlArea && tapY < bottomControlArea)
        { 
            //move left
            Debug.WriteLine("Move LEFT - X: " + tapX + " - Y: " + tapY);
            if (manLocX > littleManWidth)
            {
                manLocX = manLocX - skippingSteps;
                Canvas.SetLeft(littleMan, manLocX);
            }
        }
        else if (tapX > rightControlArea && tapY > topControlArea && tapY < bottomControlArea)
        { 
            //move right
            Debug.WriteLine("Move RIGHT - X: " + tapX + " - Y: " + tapY);
            if (manLocX < (ScreenWidth - littleManWidth))
            {
                manLocX = manLocX + skippingSteps;
                Canvas.SetLeft(littleMan, manLocX);
            }

        }

    }

预期的行为是，在点击时，系统将确定屏幕的哪一侧被点击，并将小人移动到那个方向。

skippingSteps = 40;

当应用程序启动时setGame() 函数运行。我遇到的问题是，当应用程序启动并且我点击屏幕右侧时，littleMan 跳出屏幕右边界太远。当我按左键时，它开始回来。有了断点，我收集的数据看起来还不错，但是当 Canvas.SetLeft 或 Canvas.SetTop 被称为 littleMan 时，它是一个 20x20 的 gif 图像，会跳转到 X 平面中 520 的位置。

谁能帮我理解我做错了什么。

Answer 1

好的，所以我通过以下方式解决了我的问题。

我的 XAML

    <Grid x:Name="LayoutRoot" Background="Transparent">
    <Canvas Margin="0" HorizontalAlignment="Left" VerticalAlignment="Top">
        <Image Name="littleMan" Source="images/smileyFace.gif" Stretch="None"></Image>
    </Canvas>
    </Grid>

我的代码在后面

    public Game()
    {
        InitializeComponent();
        this.Loaded += Game_Loaded;
    }

    void Game_Loaded(object sender, RoutedEventArgs e)
    {
        SetGame();
        TouchPanel.EnabledGestures = GestureType.Tap;
        LayoutRoot.ManipulationCompleted += new EventHandler<ManipulationCompletedEventArgs>(LayoutRoot_ManipulationCompleted);
    }

    void LayoutRoot_ManipulationCompleted(object sender, ManipulationCompletedEventArgs e)
    {
        while (TouchPanel.IsGestureAvailable)
        {
            GestureSample gesture = TouchPanel.ReadGesture();

            switch (gesture.GestureType)
            {
                case GestureType.Tap:
                    Dispatcher.BeginInvoke(() => MoveLittleMan(gesture.Position));
                    break;
            }
        }
    }

    private void SetGame()
    {
        ScreenWidth = Application.Current.Host.Content.ActualWidth;
        ScreenHeight = Application.Current.Host.Content.ActualHeight;

        // littleman image is in 20 * 20
        littleManWidth = 20;
        littleManHeight = 20; 

        manLocY = (ScreenHeight / 2) + littleManHeight; //vert
        manLocX = (ScreenWidth / 2) + littleManWidth; //hori

        littleMan.Margin = new Thickness(manLocX, manLocY, 0, 0);

        leftControlArea = (ScreenWidth / 2);
        rightControlArea = (ScreenWidth / 2); // answer to the screen width;
        topControlArea = (ScreenHeight / 3);
        bottomControlArea = (ScreenHeight / 3) * 2; // answer to the screen height
    }

    private void MoveLittleMan(Vector2 tappedWhere)
    {
        double tapX, tapY;
        tapX = tappedWhere.X; // represent where user tapped on screen width wise
        tapY = tappedWhere.Y; // represent where user tapped on screen height wise


        if(tapY <= topControlArea)
        {
            // move top
            Debug.WriteLine("Move TOP - X: " + tapX + " - Y: " + tapY);
            if (manLocY > littleManHeight)
            {
                manLocY = manLocY - skippingSteps;
                littleMan.Margin = new Thickness(manLocX, manLocY, 0, 0);
            }
        }

        else if(tapY >= bottomControlArea)
        {
            //move bottom
            Debug.WriteLine("Move BOTTOM - X: " + tapX + " - Y: " + tapY);
            if (manLocY < (ScreenHeight - littleManHeight -50))
            {
                manLocY = manLocY + skippingSteps;
                littleMan.Margin = new Thickness(manLocX, manLocY, 0, 0);
            }
        }

        else if (tapX <= leftControlArea && tapY > topControlArea && tapY < bottomControlArea)
        { 
            //move left
            Debug.WriteLine("Move LEFT - X: " + tapX + " - Y: " + tapY);
            if (manLocX > littleManWidth)
            {
                manLocX = manLocX - skippingSteps;
                littleMan.Margin = new Thickness(manLocX, manLocY, 0, 0);
            }
        }
        else if (tapX > rightControlArea && tapY > topControlArea && tapY < bottomControlArea)
        { 
            //move right
            Debug.WriteLine("Move RIGHT - X: " + tapX + " - Y: " + tapY);
            if (manLocX < (ScreenWidth - littleManWidth))
            {
                manLocX = manLocX + skippingSteps;
                littleMan.Margin = new Thickness(manLocX, manLocY, 0, 0);
            }
        }

    }