Windows 应用中的凝视交互和眼动跟踪

根据用户眼睛的位置和移动，为跟踪用户的凝视、注意力和状态提供支持。

重要 API：Windows.Devices.Input.Preview、GazeDevicePreview、GazePointPreview、GazeInputSourcePreview

概述

凝视输入是一种强大的方式，可以与 Windows 应用程序互动并使用，对于患有神经肌肉疾病（例如肌萎缩侧索硬化症，ALS）以及其他涉及肌肉或神经功能受损的用户来说，特别有用。

此外，凝视输入为游戏（包括目标获取和跟踪）以及传统生产力应用、信息亭和其他交互情境提供了同样引人注目的机会，尤其是在传统输入设备（如键盘、鼠标、触屏）不可用的情况，或在某些情况下，能够解放用户的双手用于其他任务（例如拿购物袋）可能非常有用或有帮助。

隐私

由于眼动跟踪设备收集的可能敏感的个人数据，需要在应用程序的应用清单中声明 gazeInput 功能（请参阅以下 安装 部分）。 声明后，Windows 会自动提示用户提供同意对话框（首次运行应用时），用户必须授予应用与眼动跟踪设备通信的权限并访问此数据。

此外，如果你的应用收集、存储或传输眼动跟踪数据，则必须在应用的隐私声明中对此进行描述，并遵循应用开发人员协议和Microsoft应用商店策略中个人信息的其他所有要求。

设置

若要在 Windows 应用中使用凝视输入 API，需要：

• 请在应用清单中指定gazeInput功能。

  使用 Visual Studio 清单设计器打开 Package.appxmanifest 文件，或通过选择“查看代码”并将以下内容DeviceCapabilityCapabilities插入节点来手动添加该功能：

  <Capabilities>
     <DeviceCapability Name="gazeInput" />
  </Capabilities>
  

• 连接到您的系统且已打开的 Windows 兼容的眼动跟踪设备（内置或外围设备）。

  有关受支持的眼动跟踪设备列表，请参阅 Windows 10 中的目视控制入门 。

基本眼动跟踪

在此示例中，我们演示了如何在 Windows 应用中跟踪用户的凝视，并使用计时函数进行基本的命中测试，以指示他们可以如何保持对特定元素的凝视焦点。

小型椭圆用于显示凝视点在应用程序视口中的位置，而 Windows 社区工具包中的 RadialProgressBar 则随机放置在画布上。 当在进度栏上检测到凝视焦点时，将启动计时器，当进度栏达到 100%时，进度栏会在画布上随机重新定位。

使用计时器示例进行凝视跟踪

从 凝视输入示例下载此示例（基本）

1. 首先，我们设置 UI（MainPage.xaml）。

   <Page
       x:Class="gazeinput.MainPage"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
       xmlns:local="using:gazeinput"
       xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
       xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
       xmlns:controls="using:Microsoft.Toolkit.Uwp.UI.Controls"    
       mc:Ignorable="d">
   
       <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
           <Grid x:Name="containerGrid">
               <Grid.RowDefinitions>
                   <RowDefinition Height="Auto"/>
                   <RowDefinition Height="*"/>
               </Grid.RowDefinitions>
               <StackPanel x:Name="HeaderPanel" 
                       Orientation="Horizontal" 
                       Grid.Row="0">
                   <StackPanel.Transitions>
                       <TransitionCollection>
                           <AddDeleteThemeTransition/>
                       </TransitionCollection>
                   </StackPanel.Transitions>
                   <TextBlock x:Name="Header" 
                          Text="Gaze tracking sample" 
                          Style="{ThemeResource HeaderTextBlockStyle}" 
                          Margin="10,0,0,0" />
                   <TextBlock x:Name="TrackerCounterLabel"
                          VerticalAlignment="Center"                 
                          Style="{ThemeResource BodyTextBlockStyle}"
                          Text="Number of trackers: " 
                          Margin="50,0,0,0"/>
                   <TextBlock x:Name="TrackerCounter"
                          VerticalAlignment="Center"                 
                          Style="{ThemeResource BodyTextBlockStyle}"
                          Text="0" 
                          Margin="10,0,0,0"/>
                   <TextBlock x:Name="TrackerStateLabel"
                          VerticalAlignment="Center"                 
                          Style="{ThemeResource BodyTextBlockStyle}"
                          Text="State: " 
                          Margin="50,0,0,0"/>
                   <TextBlock x:Name="TrackerState"
                          VerticalAlignment="Center"                 
                          Style="{ThemeResource BodyTextBlockStyle}"
                          Text="n/a" 
                          Margin="10,0,0,0"/>
               </StackPanel>
               <Canvas x:Name="gazePositionCanvas" Grid.Row="1">
                   <controls:RadialProgressBar
                       x:Name="GazeRadialProgressBar" 
                       Value="0"
                       Foreground="Blue" 
                       Background="White"
                       Thickness="4"
                       Minimum="0"
                       Maximum="100"
                       Width="100"
                       Height="100"
                       Outline="Gray"
                       Visibility="Collapsed"/>
                   <Ellipse 
                       x:Name="eyeGazePositionEllipse"
                       Width="20" Height="20"
                       Fill="Blue" 
                       Opacity="0.5" 
                       Visibility="Collapsed">
                   </Ellipse>
               </Canvas>
           </Grid>
       </Grid>
   </Page>
   

2. 接下来，初始化应用。

   在此代码片段中，我们声明全局对象并重写 OnNavigatedTo 页面事件以启动 凝视设备观察程序 以及 OnNavigatedFrom 页面事件以停止 凝视设备观察程序。

   using System;
   using Windows.Devices.Input.Preview;
   using Windows.UI.Xaml.Controls;
   using Windows.UI.Xaml;
   using Windows.Foundation;
   using System.Collections.Generic;
   using Windows.UI.Xaml.Media;
   using Windows.UI.Xaml.Navigation;
   
   namespace gazeinput
   {
       public sealed partial class MainPage : Page
       {
           /// <summary>
           /// Reference to the user's eyes and head as detected
           /// by the eye-tracking device.
           /// </summary>
           private GazeInputSourcePreview gazeInputSource;
   
           /// <summary>
           /// Dynamic store of eye-tracking devices.
           /// </summary>
           /// <remarks>
           /// Receives event notifications when a device is added, removed, 
           /// or updated after the initial enumeration.
           /// </remarks>
           private GazeDeviceWatcherPreview gazeDeviceWatcher;
   
           /// <summary>
           /// Eye-tracking device counter.
           /// </summary>
           private int deviceCounter = 0;
   
           /// <summary>
           /// Timer for gaze focus on RadialProgressBar.
           /// </summary>
           DispatcherTimer timerGaze = new DispatcherTimer();
   
           /// <summary>
           /// Tracker used to prevent gaze timer restarts.
           /// </summary>
           bool timerStarted = false;
   
           /// <summary>
           /// Initialize the app.
           /// </summary>
           public MainPage()
           {
               InitializeComponent();
           }
   
           /// <summary>
           /// Override of OnNavigatedTo page event starts GazeDeviceWatcher.
           /// </summary>
           /// <param name="e">Event args for the NavigatedTo event</param>
           protected override void OnNavigatedTo(NavigationEventArgs e)
           {
               // Start listening for device events on navigation to eye-tracking page.
               StartGazeDeviceWatcher();
           }
   
           /// <summary>
           /// Override of OnNavigatedFrom page event stops GazeDeviceWatcher.
           /// </summary>
           /// <param name="e">Event args for the NavigatedFrom event</param>
           protected override void OnNavigatedFrom(NavigationEventArgs e)
           {
               // Stop listening for device events on navigation from eye-tracking page.
               StopGazeDeviceWatcher();
           }
       }
   }
   

3. 接下来，添加我们的凝视设备监听方法。

   在 StartGazeDeviceWatcher中，我们调用 CreateWatcher 并声明眼动跟踪设备事件侦听器（DeviceAdded、 DeviceUpdated 和 DeviceRemoved）。

   在 DeviceAdded中，我们检查眼动跟踪设备的状态。 如果设备可用，我们会递增设备计数并启用视线跟踪。 有关详细信息，请参阅下一步。

   在中 DeviceUpdated，我们还启用凝视跟踪，因为如果重新校准设备，则会触发此事件。

   在DeviceRemoved中，我们递减我们的设备计数器并移除设备事件处理器。

   在 StopGazeDeviceWatcher 中，我们关闭凝视设备监视器。

    /// <summary>
    /// Start gaze watcher and declare watcher event handlers.
    /// </summary>
    private void StartGazeDeviceWatcher()
    {
        if (gazeDeviceWatcher == null)
        {
            gazeDeviceWatcher = GazeInputSourcePreview.CreateWatcher();
            gazeDeviceWatcher.Added += this.DeviceAdded;
            gazeDeviceWatcher.Updated += this.DeviceUpdated;
            gazeDeviceWatcher.Removed += this.DeviceRemoved;
            gazeDeviceWatcher.Start();
        }
    }

    /// <summary>
    /// Shut down gaze watcher and stop listening for events.
    /// </summary>
    private void StopGazeDeviceWatcher()
    {
        if (gazeDeviceWatcher != null)
        {
            gazeDeviceWatcher.Stop();
            gazeDeviceWatcher.Added -= this.DeviceAdded;
            gazeDeviceWatcher.Updated -= this.DeviceUpdated;
            gazeDeviceWatcher.Removed -= this.DeviceRemoved;
            gazeDeviceWatcher = null;
        }
    }

    /// <summary>
    /// Eye-tracking device connected (added, or available when watcher is initialized).
    /// </summary>
    /// <param name="sender">Source of the device added event</param>
    /// <param name="e">Event args for the device added event</param>
    private void DeviceAdded(GazeDeviceWatcherPreview source, 
        GazeDeviceWatcherAddedPreviewEventArgs args)
    {
        if (IsSupportedDevice(args.Device))
        {
            deviceCounter++;
            TrackerCounter.Text = deviceCounter.ToString();
        }
        // Set up gaze tracking.
        TryEnableGazeTrackingAsync(args.Device);
    }

    /// <summary>
    /// Initial device state might be uncalibrated, 
    /// but device was subsequently calibrated.
    /// </summary>
    /// <param name="sender">Source of the device updated event</param>
    /// <param name="e">Event args for the device updated event</param>
    private void DeviceUpdated(GazeDeviceWatcherPreview source,
        GazeDeviceWatcherUpdatedPreviewEventArgs args)
    {
        // Set up gaze tracking.
        TryEnableGazeTrackingAsync(args.Device);
    }

    /// <summary>
    /// Handles disconnection of eye-tracking devices.
    /// </summary>
    /// <param name="sender">Source of the device removed event</param>
    /// <param name="e">Event args for the device removed event</param>
    private void DeviceRemoved(GazeDeviceWatcherPreview source,
        GazeDeviceWatcherRemovedPreviewEventArgs args)
    {
        // Decrement gaze device counter and remove event handlers.
        if (IsSupportedDevice(args.Device))
        {
            deviceCounter--;
            TrackerCounter.Text = deviceCounter.ToString();

            if (deviceCounter == 0)
            {
                gazeInputSource.GazeEntered -= this.GazeEntered;
                gazeInputSource.GazeMoved -= this.GazeMoved;
                gazeInputSource.GazeExited -= this.GazeExited;
            }
        }
    }

4. 在这里，我们检查设备在IsSupportedDevice中是否可用，如果是，则尝试在TryEnableGazeTrackingAsync中启用凝视跟踪。

   在 TryEnableGazeTrackingAsync中，我们声明凝视事件处理程序，并调用 GazeInputSourcePreview.GetForCurrentView（） 来获取对输入源的引用（这必须在 UI 线程上调用，请参阅 保持 UI 线程响应）。

   注释

   仅当应用程序连接并需要兼容的眼动跟踪设备时，才应调用 GazeInputSourcePreview.GetForCurrentView 。 否则，不需要同意对话框。

    /// <summary>
    /// Initialize gaze tracking.
    /// </summary>
    /// <param name="gazeDevice"></param>
    private async void TryEnableGazeTrackingAsync(GazeDevicePreview gazeDevice)
    {
        // If eye-tracking device is ready, declare event handlers and start tracking.
        if (IsSupportedDevice(gazeDevice))
        {
            timerGaze.Interval = new TimeSpan(0, 0, 0, 0, 20);
            timerGaze.Tick += TimerGaze_Tick;

            SetGazeTargetLocation();

            // This must be called from the UI thread.
            gazeInputSource = GazeInputSourcePreview.GetForCurrentView();

            gazeInputSource.GazeEntered += GazeEntered;
            gazeInputSource.GazeMoved += GazeMoved;
            gazeInputSource.GazeExited += GazeExited;
        }
        // Notify if device calibration required.
        else if (gazeDevice.ConfigurationState ==
                    GazeDeviceConfigurationStatePreview.UserCalibrationNeeded ||
                    gazeDevice.ConfigurationState ==
                    GazeDeviceConfigurationStatePreview.ScreenSetupNeeded)
        {
            // Device isn't calibrated, so invoke the calibration handler.
            System.Diagnostics.Debug.WriteLine(
                "Your device needs to calibrate. Please wait for it to finish.");
            await gazeDevice.RequestCalibrationAsync();
        }
        // Notify if device calibration underway.
        else if (gazeDevice.ConfigurationState == 
            GazeDeviceConfigurationStatePreview.Configuring)
        {
            // Device is currently undergoing calibration.  
            // A device update is sent when calibration complete.
            System.Diagnostics.Debug.WriteLine(
                "Your device is being configured. Please wait for it to finish"); 
        }
        // Device is not viable.
        else if (gazeDevice.ConfigurationState == GazeDeviceConfigurationStatePreview.Unknown)
        {
            // Notify if device is in unknown state.  
            // Reconfigure/recalbirate the device.  
            System.Diagnostics.Debug.WriteLine(
                "Your device is not ready. Please set up your device or reconfigure it."); 
        }
    }

    /// <summary>
    /// Check if eye-tracking device is viable.
    /// </summary>
    /// <param name="gazeDevice">Reference to eye-tracking device.</param>
    /// <returns>True, if device is viable; otherwise, false.</returns>
    private bool IsSupportedDevice(GazeDevicePreview gazeDevice)
    {
        TrackerState.Text = gazeDevice.ConfigurationState.ToString();
        return (gazeDevice.CanTrackEyes &&
                    gazeDevice.ConfigurationState == 
                    GazeDeviceConfigurationStatePreview.Ready);
    }

5. 接下来，我们将设置凝视事件处理程序。

   我们在 GazeEntered 分别显示凝视跟踪椭圆，并在 GazeExited 隐藏。

   在GazeMoved中，我们根据GazeEnteredPreviewEventArgs的CurrentPoint提供的EyeGazePosition来移动凝视跟踪椭圆。 我们还管理 RadialProgressBar 上的凝视焦点计时器，这会触发进度栏的重新定位。 有关详细信息，请参阅下一步。

   /// <summary>
   /// GazeEntered handler.
   /// </summary>
   /// <param name="sender">Source of the gaze entered event</param>
   /// <param name="e">Event args for the gaze entered event</param>
   private void GazeEntered(
       GazeInputSourcePreview sender, 
       GazeEnteredPreviewEventArgs args)
   {
       // Show ellipse representing gaze point.
       eyeGazePositionEllipse.Visibility = Visibility.Visible;
   
       // Mark the event handled.
       args.Handled = true;
   }
   
   /// <summary>
   /// GazeExited handler.
   /// Call DisplayRequest.RequestRelease to conclude the 
   /// RequestActive called in GazeEntered.
   /// </summary>
   /// <param name="sender">Source of the gaze exited event</param>
   /// <param name="e">Event args for the gaze exited event</param>
   private void GazeExited(
       GazeInputSourcePreview sender, 
       GazeExitedPreviewEventArgs args)
   {
       // Hide gaze tracking ellipse.
       eyeGazePositionEllipse.Visibility = Visibility.Collapsed;
   
       // Mark the event handled.
       args.Handled = true;
   }
   
   /// <summary>
   /// GazeMoved handler translates the ellipse on the canvas to reflect gaze point.
   /// </summary>
   /// <param name="sender">Source of the gaze moved event</param>
   /// <param name="e">Event args for the gaze moved event</param>
   private void GazeMoved(GazeInputSourcePreview sender, GazeMovedPreviewEventArgs args)
   {
       // Update the position of the ellipse corresponding to gaze point.
       if (args.CurrentPoint.EyeGazePosition != null)
       {
           double gazePointX = args.CurrentPoint.EyeGazePosition.Value.X;
           double gazePointY = args.CurrentPoint.EyeGazePosition.Value.Y;
   
           double ellipseLeft = 
               gazePointX - 
               (eyeGazePositionEllipse.Width / 2.0f);
           double ellipseTop = 
               gazePointY - 
               (eyeGazePositionEllipse.Height / 2.0f) - 
               (int)Header.ActualHeight;
   
           // Translate transform for moving gaze ellipse.
           TranslateTransform translateEllipse = new TranslateTransform
           {
               X = ellipseLeft,
               Y = ellipseTop
           };
   
           eyeGazePositionEllipse.RenderTransform = translateEllipse;
   
           // The gaze point screen location.
           Point gazePoint = new Point(gazePointX, gazePointY);
   
           // Basic hit test to determine if gaze point is on progress bar.
           bool hitRadialProgressBar = 
               DoesElementContainPoint(
                   gazePoint, 
                   GazeRadialProgressBar.Name, 
                   GazeRadialProgressBar); 
   
           // Use progress bar thickness for visual feedback.
           if (hitRadialProgressBar)
           {
               GazeRadialProgressBar.Thickness = 10;
           }
           else
           {
               GazeRadialProgressBar.Thickness = 4;
           }
   
           // Mark the event handled.
           args.Handled = true;
       }
   }
   

6. 最后，下面是用于管理此应用的凝视焦点计时器的方法。

   DoesElementContainPoint 检查凝视指针是否位于进度栏上。 如果是这样，它将启动凝视计时器，并在每次计时器的滴答中增加进度条。

   SetGazeTargetLocation 设置进度栏的初始位置，如果进度栏完成（具体取决于凝视焦点计时器），将进度栏移动到随机位置。

   /// <summary>
   /// Return whether the gaze point is over the progress bar.
   /// </summary>
   /// <param name="gazePoint">The gaze point screen location</param>
   /// <param name="elementName">The progress bar name</param>
   /// <param name="uiElement">The progress bar UI element</param>
   /// <returns></returns>
   private bool DoesElementContainPoint(
       Point gazePoint, string elementName, UIElement uiElement)
   {
       // Use entire visual tree of progress bar.
       IEnumerable<UIElement> elementStack = 
           VisualTreeHelper.FindElementsInHostCoordinates(gazePoint, uiElement, true);
       foreach (UIElement item in elementStack)
       {
           //Cast to FrameworkElement and get element name.
           if (item is FrameworkElement feItem)
           {
               if (feItem.Name.Equals(elementName))
               {
                   if (!timerStarted)
                   {
                       // Start gaze timer if gaze over element.
                       timerGaze.Start();
                       timerStarted = true;
                   }
                   return true;
               }
           }
       }
   
       // Stop gaze timer and reset progress bar if gaze leaves element.
       timerGaze.Stop();
       GazeRadialProgressBar.Value = 0;
       timerStarted = false;
       return false;
   }
   
   /// <summary>
   /// Tick handler for gaze focus timer.
   /// </summary>
   /// <param name="sender">Source of the gaze entered event</param>
   /// <param name="e">Event args for the gaze entered event</param>
   private void TimerGaze_Tick(object sender, object e)
   {
       // Increment progress bar.
       GazeRadialProgressBar.Value += 1;
   
       // If progress bar reaches maximum value, reset and relocate.
       if (GazeRadialProgressBar.Value == 100)
       {
           SetGazeTargetLocation();
       }
   }
   
   /// <summary>
   /// Set/reset the screen location of the progress bar.
   /// </summary>
   private void SetGazeTargetLocation()
   {
       // Ensure the gaze timer restarts on new progress bar location.
       timerGaze.Stop();
       timerStarted = false;
   
       // Get the bounding rectangle of the app window.
       Rect appBounds = Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().VisibleBounds;
   
       // Translate transform for moving progress bar.
       TranslateTransform translateTarget = new TranslateTransform();
   
       // Calculate random location within gaze canvas.
           Random random = new Random();
           int randomX = 
               random.Next(
                   0, 
                   (int)appBounds.Width - (int)GazeRadialProgressBar.Width);
           int randomY = 
               random.Next(
                   0, 
                   (int)appBounds.Height - (int)GazeRadialProgressBar.Height - (int)Header.ActualHeight);
   
       translateTarget.X = randomX;
       translateTarget.Y = randomY;
   
       GazeRadialProgressBar.RenderTransform = translateTarget;
   
       // Show progress bar.
       GazeRadialProgressBar.Visibility = Visibility.Visible;
       GazeRadialProgressBar.Value = 0;
   }
   

另请参阅

资源

• Windows 社区工具包凝视库

主题示例

• 凝视示例 （基本） （C#）