如何在UWP ScrollViewer中限制单指滚动和平移并启用双指？
目前，没有内置的API可以直接跟踪一次有多少手指接触。但是你可以通过指针事件对restrict scrolling and panning with single finger and enable with two fingers in UWP ScrollViewer做你想做的事情。
请处理UIElement.PointerExited事件和UIElement.PointerCaptureLost事件。现在代码应该在开始时做你想做的事情。在我的测试中，它将禁用单指滚动和平移，并启用两个或多个手指。

public MainPage()
    {
        this.InitializeComponent();
        this.scrollView.AddHandler(UIElement.PointerPressedEvent, new PointerEventHandler(scrollView_PointerPressed), true);
        this.scrollView.AddHandler(UIElement.PointerReleasedEvent, new PointerEventHandler(scrollView_PointerReleased), true);
        this.scrollView.AddHandler(UIElement.PointerCanceledEvent, new PointerEventHandler(scrollView_PointerCanceled), true);
        this.scrollView.AddHandler(UIElement.PointerCaptureLostEvent, new PointerEventHandler(scrollView_PointerCaptureLost), true);
        this.scrollView.AddHandler(UIElement.PointerExitedEvent, new PointerEventHandler(scrollView_PointerExited), true);
        
    }

    int numberOfContacts = 0;
    private void scrollView_PointerPressed(object sender, PointerRoutedEventArgs e)
    {
        if (e.Pointer.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Touch)
        {
            numberOfContacts++;
            System.Diagnostics.Debug.WriteLine($"Pressed -> {numberOfContacts}");
            if (numberOfContacts == 1)
            {
                (scrollView.Content as UIElement).ManipulationMode &= ~ManipulationModes.System;
            }
            else if (numberOfContacts > 1)
            {
                (scrollView.Content as UIElement).ManipulationMode |= ManipulationModes.System;
            }
        }
    }

    private void scrollView_PointerReleased(object sender, PointerRoutedEventArgs e)
    {
        if (e.Pointer.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Touch)
        {
            if (numberOfContacts > 0)
            {
                numberOfContacts--;
            }
            System.Diagnostics.Debug.WriteLine($"Released -> {numberOfContacts}");
            (scrollView.Content as UIElement).ManipulationMode |= ManipulationModes.System;
        }
    }

    private void scrollView_PointerCanceled(object sender, PointerRoutedEventArgs e)
    {
        if (e.Pointer.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Touch)
        {
            if (numberOfContacts > 0)
            {
                numberOfContacts--;
            }
            System.Diagnostics.Debug.WriteLine($"Cancelled -> {numberOfContacts}");
            (scrollView.Content as UIElement).ManipulationMode |= ManipulationModes.System;
        }
    }

    private void scrollView_PointerCaptureLost(object sender, PointerRoutedEventArgs e)
    {
        if (e.Pointer.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Touch)
        {
            if (numberOfContacts > 0)
            {
                numberOfContacts--;
            }
            System.Diagnostics.Debug.WriteLine($"Capture lost -> {numberOfContacts}");
            (scrollView.Content as UIElement).ManipulationMode |= ManipulationModes.System;
        }
    }

    private void scrollView_PointerExited(object sender, PointerRoutedEventArgs e)
    {
        if (e.Pointer.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Touch)
        {
            if (numberOfContacts>0) 
            {
                numberOfContacts--;
            }
            System.Diagnostics.Debug.WriteLine($"Pointer Exited -> {numberOfContacts}");
            (scrollView.Content as UIElement).ManipulationMode |= ManipulationModes.System;
        }
    }