重新想象 Windows 8 Store Apps (51) - 输入: 涂鸦板

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重新想象 Windows 8 Store Apps (51) - 输入: 涂鸦板

作者：webabcd


介绍
重新想象 Windows 8 Store Apps 之 涂鸦板

• 通过 Pointer 相关事件实现一个具有基本功能的涂鸦板
• 通过 InkManager 实现一个功能完善的涂鸦板

示例
1、演示如何通过 Pointer 相关事件实现一个只有基本功能的涂鸦板
Input/Ink/Simple.xaml

<Page
    x:Class="XamlDemo.Input.Ink.Simple"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Input.Ink"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="Transparent">
        <StackPanel Margin="120 0 0 0">

            <Button Name="btnClear" Content="清除" Click="btnClear_Click_1" />

            <Canvas Name="canvas" Background="Blue" Width="800" Height="480" HorizontalAlignment="Left" Margin="0 10 0 0" />

        </StackPanel>
    </Grid>
</Page>

Input/Ink/Simple.xaml.cs

/*
 * 通过 Pointer 相关事件实现一个只有基本功能的涂鸦板
 */

using System;
using System.Collections.Generic;
using Windows.Foundation;
using Windows.UI;
using Windows.UI.Input;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Shapes;

namespace XamlDemo.Input.Ink
{
    public sealed partial class Simple : Page
    {
        // 用于保存触摸点（PointerId - Point）
        private Dictionary<uint, Point?> _dicPoint;

        public Simple()
        {
            this.InitializeComponent();

            canvas.PointerPressed += canvas_PointerPressed;
            canvas.PointerMoved += canvas_PointerMoved;
            canvas.PointerReleased += canvas_PointerReleased;
            canvas.PointerExited += canvas_PointerExited;

            _dicPoint = new Dictionary<uint, Point?>();
        }

        void canvas_PointerPressed(object sender, PointerRoutedEventArgs e)
        {
            // 指针按下后，保存此触摸点
            PointerPoint pointerPoint = e.GetCurrentPoint(canvas);
            _dicPoint[pointerPoint.PointerId] = pointerPoint.Position;
        }

        void canvas_PointerMoved(object sender, PointerRoutedEventArgs e)
        {
            PointerPoint pointerPoint = e.GetCurrentPoint(canvas);

            if (_dicPoint.ContainsKey(pointerPoint.PointerId) && _dicPoint[pointerPoint.PointerId].HasValue)
            {
                Point currentPoint = pointerPoint.Position;
                Point previousPoint = _dicPoint[pointerPoint.PointerId].Value;

                // 如果指针移动过程中，两个点间的距离超过 4 则在两点间绘制一条直线，以完成涂鸦
                if (ComputeDistance(currentPoint, previousPoint) > 4)
                {
                    Line line = new Line()
                    {
                        X1 = previousPoint.X,
                        Y1 = previousPoint.Y,
                        X2 = currentPoint.X,
                        Y2 = currentPoint.Y,
                        StrokeThickness = 5,
                        Stroke = new SolidColorBrush(Colors.Orange),
                        StrokeEndLineCap = PenLineCap.Round
                    };

                    _dicPoint[pointerPoint.PointerId] = currentPoint;
                    canvas.Children.Add(line);
                }
            }
        }

        void canvas_PointerReleased(object sender, PointerRoutedEventArgs e)
        {
            // 指针释放后，从字典中删除此 PointerId 的数据
            PointerPoint pointerPoint = e.GetCurrentPoint(canvas);
            if (_dicPoint.ContainsKey(pointerPoint.PointerId))
                _dicPoint.Remove(pointerPoint.PointerId);
        }

        void canvas_PointerExited(object sender, PointerRoutedEventArgs e)
        {
            // 指针离开相当于指针释放
            canvas_PointerReleased(sender, e);
        }

        // 清除涂鸦
        private void btnClear_Click_1(object sender, RoutedEventArgs e)
        {
            canvas.Children.Clear();
            _dicPoint.Clear();
        }

        // 计算两个点（Point）之间的距离
        private double ComputeDistance(Point point1, Point point2)
        {
            return Math.Sqrt(Math.Pow(point1.X - point2.X, 2) + Math.Pow(point1.Y - point2.Y, 2));
        }
    }
}

2、演示如何通过 InkManager 实现一个功能完善的涂鸦板
Input/Ink/InkRenderer.cs

/*
 * 开发一个 InkRenderer 类，用于呈现 InkManager 中的内容
 * 
 * 注：InkManager 用于 ink 的管理，但并不负责呈现
 * 
 * 
 * InkStroke - ink 画笔
 *     DrawingAttributes - 画笔的相关属性，一个 InkDrawingAttributes 类型的对象
 *         Color - 颜色
 *         FitToCurve - 使用贝塞尔曲线则为 true，使用直线则为 false，默认值为 true
 *         PenTip - 笔尖的形状（Circle, Rectangle）
 *         Size - 笔尖的尺寸
 *         IgnorePressure - 是否忽略笔尖在触摸屏上的压力
 *     BoundingRect - ink 画笔的边界框
 *     Recognized - 该画笔是否已被文字识别
 *     Selected - 该画笔是否被选中
 *     Clone() - 克隆这个画笔，并返回克隆后的新的 InkStroke 对象
 *     GetRenderingSegments() - 返回 ink 的线段集合，即 InkStrokeRenderingSegment 集合
 *     
 * InkStrokeRenderingSegment - ink 的线段
 *     BezierControlPoint1 - 贝塞尔曲线的第一个控制点的位置
 *     BezierControlPoint2 - 贝塞尔曲线的第二个控制点的位置
 *     Position - 贝塞尔曲线的终点的位置
 */

using System.Collections.Generic;
using Windows.UI;
using Windows.UI.Input;
using Windows.UI.Input.Inking;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Shapes;

namespace XamlDemo.Input.Ink
{
    public class InkRenderer
    {
        /// <summary>
        /// 呈现 ink 的容器
        /// </summary>
        private readonly Panel _container = null;

        /// <summary>
        /// ink 的实时路径（PointerId - Path）
        /// </summary>
        private readonly Dictionary<uint, Path> _dicLivePath = null;
        /// <summary>
        /// ink 的实时路径中所包含的 PolyLineSegment（PointerId - PolyLineSegment）
        /// </summary>
        private readonly Dictionary<uint, PolyLineSegment> _dicLivePolyLine = null;

        /// <summary>
        /// InkStroke 所对应三次贝塞尔曲线，用于保存全部涂鸦曲线（包括未被选中的和被选中的）
        /// </summary>
        private readonly Dictionary<InkStroke, Path> _dicInkPath = null;
        /// <summary>
        /// InkStroke 所对应三次贝塞尔曲线，用于保存被选中的涂鸦曲线
        /// </summary>
        private readonly Dictionary<InkStroke, Path> _dicSelectionPath = null;

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="panel">用于呈现 ink 的容器</param>
        public InkRenderer(Panel panel)
        {
            _container = panel;

            _dicLivePath = new Dictionary<uint, Path>();
            _dicLivePolyLine = new Dictionary<uint, PolyLineSegment>();

            _dicInkPath = new Dictionary<InkStroke, Path>();
            _dicSelectionPath = new Dictionary<InkStroke, Path>();
        }

        /// <summary>
        /// 开始实时绘制 ink
        /// </summary>
        /// <param name="pointerPoint">当前的触摸点</param>
        /// <param name="inkDrawingAttributes">ink 的 InkDrawingAttributes 数据</param>
        public void EnterLiveRendering(PointerPoint pointerPoint, InkDrawingAttributes inkDrawingAttributes)
        {
            uint pointerId = pointerPoint.PointerId;

            var polyLine = new PolyLineSegment();
            polyLine.Points.Add(pointerPoint.Position);
            var figure = new PathFigure();
            figure.StartPoint = pointerPoint.Position;
            figure.Segments.Add(polyLine);
            var geometry = new PathGeometry();
            geometry.Figures.Add(figure);
            var path = new Path();
            path.Data = geometry;

            path.Stroke = new SolidColorBrush(inkDrawingAttributes.Color);
            path.StrokeThickness = inkDrawingAttributes.Size.Width;
            path.StrokeLineJoin = PenLineJoin.Round;
            path.StrokeStartLineCap = PenLineCap.Round;

            _dicLivePolyLine.Add(pointerId, polyLine);
            _dicLivePath.Add(pointerId, path);

            _container.Children.Add(path);
        }

        /// <summary>
        /// 更新 ink 的实时绘制
        /// </summary>
        /// <param name="pointerPoint"></param>
        public void UpdateLiveRender(PointerPoint pointerPoint)
        {
            uint pointerId = pointerPoint.PointerId;

            _dicLivePolyLine[pointerId].Points.Add(pointerPoint.Position);
        }

        /// <summary>
        /// 停止此次 ink 的实时绘制
        /// </summary>
        /// <param name="pointerPoint">涂鸦的停止点</param>
        public void ExitLiveRendering(PointerPoint pointerPoint)
        {
            uint pointerId = pointerPoint.PointerId;

            _container.Children.Remove(_dicLivePath[pointerId]);

            _dicLivePolyLine.Remove(pointerId);
            _dicLivePath.Remove(pointerId);
        }

        /// <summary>
        /// 将 InkStroke 绘制成一条三次贝塞尔曲线
        /// </summary>
        /// <param name="inkStroke">InkStroke 对象</param>
        public void UpdateInkRender(InkStroke inkStroke)
        {
            Path bezierPath = InkStroke2BezierPath(inkStroke);
            _dicInkPath.Add(inkStroke, bezierPath);
            _container.Children.Add(bezierPath);
        }

        /// <summary>
        /// 将每一个 InkStroke 都绘制成一条三次贝塞尔曲线
        /// </summary>
        /// <param name="inkStrokes">InkStroke 集合</param>
        public void UpdateInkRender(IEnumerable<InkStroke> inkStrokes)
        {
            foreach (InkStroke inkStroke in inkStrokes)
            {
                UpdateInkRender(inkStroke);
            }
        }

        /// <summary>
        /// 将被选中的 InkStroke 以被选中的样式绘制出来
        /// </summary>
        public void UpdateSelectionRender()
        {
            foreach (var inkPath in _dicInkPath)
            {
                Path selectionPath = null;
                bool selectionPathExists = _dicSelectionPath.TryGetValue(inkPath.Key, out selectionPath);

                // 如果 InkStroke 是被选中的状态，但是并没有呈现出选中状态，则呈现这个选中状态
                if (inkPath.Key.Selected && !selectionPathExists)
                {
                    inkPath.Value.StrokeThickness = inkPath.Key.DrawingAttributes.Size.Width + 2;

                    selectionPath = InkStroke2BezierPath(inkPath.Key);
                    selectionPath.Stroke = new SolidColorBrush(Colors.White);
                    selectionPath.StrokeThickness = inkPath.Key.DrawingAttributes.Size.Width;
                    _dicSelectionPath.Add(inkPath.Key, selectionPath);

                    _container.Children.Add(selectionPath);
                }
                // 如果 InkStroke 是未被选中的状态，但是却呈现出选中状态，则去掉这个选中状态的呈现
                else if (selectionPathExists)
                {
                    inkPath.Value.StrokeThickness = inkPath.Key.DrawingAttributes.Size.Width;
                    _dicSelectionPath.Remove(inkPath.Key);
                    _container.Children.Remove(selectionPath);
                }
            }
        }

        /// <summary>
        /// 清除全部呈现
        /// </summary>
        public void Clear()
        {
            foreach (var path in _dicInkPath.Values)
            {
                _container.Children.Remove(path);
            }
            foreach (var path in _dicSelectionPath.Values)
            {
                _container.Children.Remove(path);
            }
            foreach (var path in _dicLivePath.Values)
            {
                _container.Children.Remove(path);
            }

            _dicInkPath.Clear();
            _dicSelectionPath.Clear();
            _dicLivePath.Clear();
            _dicLivePolyLine.Clear();
        }



        /// <summary>
        /// 如果 InkStroke 是一个贝塞尔曲线画笔，则可将其转换成 Path（一条贝塞尔曲线）
        /// </summary>
        /// <param name="inkStroke">InkStroke 对象</param>
        /// <returns>转换后的 Path 对象</returns>
        public static Path InkStroke2BezierPath(InkStroke inkStroke)
        {
            var figure = new PathFigure();
            var segments = inkStroke.GetRenderingSegments().GetEnumerator();
            segments.MoveNext();

            figure.StartPoint = segments.Current.Position;

            while (segments.MoveNext())
            {
                var bs = new BezierSegment();
                bs.Point1 = segments.Current.BezierControlPoint1;
                bs.Point2 = segments.Current.BezierControlPoint2;
                bs.Point3 = segments.Current.Position;
                figure.Segments.Add(bs);
            }

            var geometry = new PathGeometry();
            geometry.Figures.Add(figure);
            var path = new Path();
            path.Data = geometry;

            path.Stroke = new SolidColorBrush(inkStroke.DrawingAttributes.Color);
            path.StrokeThickness = inkStroke.DrawingAttributes.Size.Width;
            path.StrokeLineJoin = PenLineJoin.Round;
            path.StrokeStartLineCap = PenLineCap.Round;

            return path;
        }
    }
}

Input/Ink/Demo.xaml

<Page
    x:Class="XamlDemo.Input.Ink.Demo"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Input.Ink"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="Transparent">
        <StackPanel Margin="120 0 0 0">

            <TextBlock Name="lblMsg" FontSize="14.667" />
            
            <StackPanel Orientation="Horizontal" Margin="0 10 0 0">
                <RadioButton Name="radInk" GroupName="mode" Content="涂鸦模式" Checked="radInk_Checked_1" IsChecked="True" />
                <RadioButton Name="radSelect" GroupName="mode" Content="选择模式" Checked="radSelect_Checked_1" Margin="10 0 0 0" />
                <RadioButton Name="radErase" GroupName="mode" Content="删除模式" Checked="radErase_Checked_1" Margin="10 0 0 0" />
            </StackPanel>

            <StackPanel Orientation="Horizontal" Margin="0 10 0 0">
                <Button Name="btnClearAll" Content="清除全部内容" Click="btnClearAll_Click_1" />
                <Button Name="btnClearSelectedInk" Content="清除被选中的内容" Click="btnClearSelectedInk_Click_1" Margin="10 0 0 0" />
                <Button Name="btnClearSelectedState" Content="清除选中状态" Click="btnClearSelectedState_Click_1" Margin="10 0 0 0" />
                <Button Name="btnMoveSelectedInk" Content="移动被选中的内容" Click="btnMoveSelectedInk_Click_1" Margin="10 0 0 0" />
            </StackPanel>
            
            <StackPanel Orientation="Horizontal" Margin="0 10 0 0">
                <Button Name="btnCut" Content="剪切" Click="btnCut_Click_1" />
                <Button Name="btnCopy" Content="复制" Click="btnCopy_Click_1" Margin="10 0 0 0" />
                <Button Name="btnPaste" Content="粘贴" Click="btnPaste_Click_1" Margin="10 0 0 0" />
            </StackPanel>

            <StackPanel Orientation="Horizontal" Margin="0 10 0 0">
                <Button Name="btnSave" Content="保存到文件" Click="btnSave_Click_1" />
                <Button Name="btnLoad" Content="从文件加载" Click="btnLoad_Click_1" Margin="10 0 0 0" />
                <Button Name="btnRecognize" Content="文字识别" Click="btnRecognize_Click_1" Margin="10 0 0 0" />
            </StackPanel>

            <Canvas x:Name="canvas" Background="Blue" Width="800" Height="360" Margin="0 10 0 0" HorizontalAlignment="Left"
                    PointerPressed="canvas_PointerPressed_1"
                    PointerMoved="canvas_PointerMoved_1"
                    PointerReleased="canvas_PointerReleased_1" />

        </StackPanel>
    </Grid>
</Page>

Input/Ink/Demo.xaml.cs

/*
 * 通过 InkManager 实现一个功能完善的涂鸦板
 * 
 * 注：InkManager 用于 ink 的管理，但并不负责呈现，需要自己开发呈现 ink 的类，请参见 InkRenderer.cs
 * 
 * 
 * InkManager - ink 的管理类
 *     包括 ink 的输入模式，复制/粘贴，移动，保存到文件，从文件加载，文字识别等功能
 *     详细说明请参见本 Demo 中的相关代码的注释
 * 
 * InkStroke - ink 画笔
 *     DrawingAttributes - 画笔的相关属性，一个 InkDrawingAttributes 类型的对象
 *         Color - 颜色
 *         FitToCurve - 使用贝塞尔曲线则为 true，使用直线则为 false，默认值为 true
 *         PenTip - 笔尖的形状（Circle, Rectangle）
 *         Size - 笔尖的尺寸
 *         IgnorePressure - 是否忽略笔尖在触摸屏上的压力
 *     BoundingRect - ink 画笔的边界框
 *     Recognized - 该画笔是否已被文字识别
 *     Selected - 该画笔是否被选中
 *     Clone() - 克隆这个画笔，并返回克隆后的新的 InkStroke 对象
 *     GetRenderingSegments() - 返回 ink 的线段集合，即 InkStrokeRenderingSegment 集合
 *     
 * InkStrokeRenderingSegment - ink 的线段
 *     BezierControlPoint1 - 贝塞尔曲线的第一个控制点的位置
 *     BezierControlPoint2 - 贝塞尔曲线的第二个控制点的位置
 *     Position - 贝塞尔曲线的终点的位置
 */

using System;
using System.Linq;
using System.Collections.Generic;
using Windows.Foundation;
using Windows.Storage;
using Windows.Storage.Pickers;
using Windows.UI;
using Windows.UI.Input;
using Windows.UI.Input.Inking;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Input;
using XamlDemo.Common;

namespace XamlDemo.Input.Ink
{
    public sealed partial class Demo : Page
    {
        // 自己开发的用于呈现 ink 的类
        private InkRenderer _renderer = null;

        private InkManager _inkManager = null;
        private InkDrawingAttributes _inkDrawingAttributes = null; // 涂鸦 ink 的样式
        private InkDrawingAttributes _inkDrawingAttributesForSelect = null; // 选择模式时，用于呈现用户的选择路径的 ink 的样式

        private int _pointerId = -1; // 当前指针的 pointerId

        public Demo()
        {
            this.InitializeComponent();

            _inkDrawingAttributes = new InkDrawingAttributes();
            _inkDrawingAttributes.Color = Colors.Orange;
            _inkDrawingAttributes.Size = new Size(5, 5);
            _inkDrawingAttributes.IgnorePressure = true;
            _inkDrawingAttributes.FitToCurve = true;

            _inkDrawingAttributesForSelect = new InkDrawingAttributes();
            _inkDrawingAttributesForSelect.Color = Colors.White;
            _inkDrawingAttributesForSelect.Size = new Size(1, 1);
            _inkDrawingAttributesForSelect.PenTip = PenTipShape.Circle;
           

            _inkManager = new InkManager();
            // InkManager 一共有三种模式：Inking - 涂鸦；Erasing - 擦除；Selecting - 选择
            _inkManager.Mode = InkManipulationMode.Inking;
            // 设置 InkManager 的默认的画笔属性
            _inkManager.SetDefaultDrawingAttributes(_inkDrawingAttributes);
            // 获取 InkManager 所支持的文字识别的种类
            var inkRecognizers = _inkManager.GetRecognizers();
            var inkRecognizer = inkRecognizers.SingleOrDefault(p => p.Name.Equals("Microsoft 中文(简体)手写识别器"));
            if (inkRecognizer != null)
            {
                // 设置 InkManager 的默认的文字识别器为“Microsoft 中文(简体)手写识别器”
                _inkManager.SetDefaultRecognizer(inkRecognizer);
            }

            _renderer = new InkRenderer(canvas);
        }

        private void canvas_PointerPressed_1(object sender, PointerRoutedEventArgs e)
        {
            PointerPoint pointerPoint = e.GetCurrentPoint(canvas);
            _pointerId = (int)pointerPoint.PointerId;

            switch (_inkManager.Mode)
            {
                case InkManipulationMode.Erasing: // 擦除模式
                    break;
                case InkManipulationMode.Inking: // 涂鸦模式
                    _renderer.EnterLiveRendering(pointerPoint, _inkDrawingAttributes);
                    break;
                case InkManipulationMode.Selecting: // 选择模式
                    _renderer.EnterLiveRendering(pointerPoint, _inkDrawingAttributesForSelect);
                    break;
                default:
                    break;
            }

            // 通知 InkManager 指针已按下
            _inkManager.ProcessPointerDown(pointerPoint);
        }

        private void canvas_PointerMoved_1(object sender, PointerRoutedEventArgs e)
        {
            PointerPoint pointerPoint = e.GetCurrentPoint(canvas);

            if (_pointerId == (int)pointerPoint.PointerId)
            {
                switch (_inkManager.Mode)
                {
                    case InkManipulationMode.Erasing:
                        // 通知 InkManager 指针移动中，然后会返回一个 Rect 对象，其代表被 Erasing 的矩形范围
                        var erasingRect = (Rect)_inkManager.ProcessPointerUpdate(e.GetCurrentPoint(canvas));
                        if (erasingRect.Height != 0 && erasingRect.Width != 0)
                        {
                            _renderer.Clear();
                            // 通过 InkManager.GetStrokes() 获取 InkManager 包含的全部 InkStroke 对象集合
                            _renderer.UpdateInkRender(_inkManager.GetStrokes());
                        }
                        break;
                    case InkManipulationMode.Inking:
                    case InkManipulationMode.Selecting:
                        if (_inkManager.Mode == InkManipulationMode.Inking || _inkManager.Mode == InkManipulationMode.Selecting)
                        {
                            var intermediatePoints = e.GetIntermediatePoints(canvas);
                            for (int i = intermediatePoints.Count - 1; i >= 0; i--)
                            {
                                // 通知 InkManager 指针移动中
                                _inkManager.ProcessPointerUpdate(intermediatePoints[i]);
                            }

                            _renderer.UpdateLiveRender(pointerPoint);
                        }
                        break;
                    default:
                        break;
                }
            }
        }

        private void canvas_PointerReleased_1(object sender, PointerRoutedEventArgs e)
        {
            PointerPoint pointerPoint = e.GetCurrentPoint(canvas);

            if (_pointerId == (int)pointerPoint.PointerId)
            {
                _pointerId = -1;

                // 通知 InkManager 指针释放了，返回值：当 Inking 或 Selecting 时返回值为用户此次操作的矩形范围；当 Erasing 时返回值为 0,0,0,0
                var rect = _inkManager.ProcessPointerUp(pointerPoint);
                // var inkManagerRect = _inkManager.BoundingRect; // InkManager 所管理 InkStroke 集合的矩形范围（矩形边框）

                switch (_inkManager.Mode)
                {
                    case InkManipulationMode.Inking:
                        _renderer.ExitLiveRendering(pointerPoint);
                        _renderer.UpdateInkRender(_inkManager.GetStrokes()[_inkManager.GetStrokes().Count - 1]);
                        break;
                    case InkManipulationMode.Selecting:
                        _renderer.ExitLiveRendering(pointerPoint);
                        _renderer.UpdateSelectionRender();
                        break;
                    default:
                        break;
                }
            }
        }

        private async void btnSave_Click_1(object sender, RoutedEventArgs e)
        {
            if (_inkManager.GetStrokes().Count > 0)
            {
                if (Helper.EnsureUnsnapped())
                {
                    var savePicker = new FileSavePicker();
                    savePicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
                    savePicker.FileTypeChoices.Add("GIF", new List<string> { ".gif" });

                    StorageFile file = await savePicker.PickSaveFileAsync();
                    if (null != file)
                    {
                        using (var stream = await file.OpenAsync(FileAccessMode.ReadWrite))
                        {
                            // 将 InkManager 中的 InkStroke 对象集合保存为文件
                            await _inkManager.SaveAsync(stream);
                        }
                    }
                }
            }
        }

        private async void btnLoad_Click_1(object sender, RoutedEventArgs e)
        {
            if (Helper.EnsureUnsnapped())
            {
                var openPicker = new Windows.Storage.Pickers.FileOpenPicker();
                openPicker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.PicturesLibrary;
                openPicker.FileTypeFilter.Add(".gif");
                StorageFile file = await openPicker.PickSingleFileAsync();
                if (null != file)
                {
                    using (var stream = await file.OpenSequentialReadAsync())
                    {
                        // 加载一个文件，从中获取 InkStroke 对象集合，并将其交由 InkManager 管理
                        await _inkManager.LoadAsync(stream);
                    }

                    _renderer.Clear();
                    _renderer.UpdateInkRender(_inkManager.GetStrokes());
                }
            }
        }

        private void radInk_Checked_1(object sender, RoutedEventArgs e)
        {
            if (_inkManager != null)
                _inkManager.Mode = InkManipulationMode.Inking; // 涂鸦模式
        }

        private void radSelect_Checked_1(object sender, RoutedEventArgs e)
        {
            if (_inkManager != null)
                _inkManager.Mode = InkManipulationMode.Selecting; // 选择模式
        }

        private void radErase_Checked_1(object sender, RoutedEventArgs e)
        {
            if (_inkManager != null)
                _inkManager.Mode = InkManipulationMode.Erasing; // 擦除模式
        }

        private void btnCut_Click_1(object sender, RoutedEventArgs e)
        {
            // 将 InkManager 中的被选中的 InkStroke 对象集合复制到剪切板
            _inkManager.CopySelectedToClipboard();
            // 将 InkManager 中的被选中的 InkStroke 对象集合删除掉
            _inkManager.DeleteSelected();

            _renderer.Clear();
            _renderer.UpdateInkRender(_inkManager.GetStrokes());
        }

        private void btnCopy_Click_1(object sender, RoutedEventArgs e)
        {
            // 将 InkManager 中的被选中的 InkStroke 对象集合复制到剪切板
            _inkManager.CopySelectedToClipboard();
        }

        private void btnPaste_Click_1(object sender, RoutedEventArgs e)
        {
            // 剪切板中的数据是否是 InkStroke 对象集合
            if (_inkManager.CanPasteFromClipboard())
            {
                // 将剪切板中的 InkStroke 对象集合粘贴到指定位置，并将此 InkStroke 对象集合交由 InkManager 管理
                _inkManager.PasteFromClipboard(new Point(10, 10));

                _renderer.Clear();
                _renderer.UpdateInkRender(_inkManager.GetStrokes());
                _renderer.UpdateSelectionRender();
            }
        }

        private void btnClearAll_Click_1(object sender, RoutedEventArgs e)
        {
            // 通过 InkManager.GetStrokes() 获取 InkManager 包含的全部 InkStroke 对象集合
            foreach (var inkStroke in _inkManager.GetStrokes())
            {
                // InkStroke 是否被选中
                inkStroke.Selected = true;
            }
            // 将 InkManager 中的被选中的 InkStroke 对象集合删除掉
            _inkManager.DeleteSelected();

            _renderer.Clear();
        }

        private void btnClearSelectedInk_Click_1(object sender, RoutedEventArgs e)
        {
            // 将 InkManager 中的被选中的 InkStroke 对象集合删除掉
            _inkManager.DeleteSelected();

            _renderer.Clear();
            _renderer.UpdateInkRender(_inkManager.GetStrokes());
        }

        private void btnClearSelectedState_Click_1(object sender, RoutedEventArgs e)
        {
            foreach (var inkStroke in _inkManager.GetStrokes())
            {
                // InkStroke 是否被选中
                inkStroke.Selected = false;
            }

            _renderer.Clear();
            _renderer.UpdateInkRender(_inkManager.GetStrokes());
        }

        private void btnMoveSelectedInk_Click_1(object sender, RoutedEventArgs e)
        {
            // 将 InkManager 中的被选中的 InkStroke 对象集合移动指定的距离（本例为向下移动 5 个像素，向右移动 50 个像素）
            _inkManager.MoveSelected(new Point(50, 5));

            _renderer.Clear();
            _renderer.UpdateInkRender(_inkManager.GetStrokes());
            _renderer.UpdateSelectionRender();
        }

        private async void btnRecognize_Click_1(object sender, RoutedEventArgs e)
        {
            // 对 InkManager 中的内容做文字识别
            //     InkRecognitionTarget.All - 识别全部; 
            //     InkRecognitionTarget.Selected - 识别选中的 InkStroke 集合; 
            //     InkRecognitionTarget.Recent - 识别最近的 InkStroke
            var recognitionResults = await _inkManager.RecognizeAsync(InkRecognitionTarget.All);
            // 将文字识别的结果更新到 InkManager
            _inkManager.UpdateRecognitionResults(recognitionResults);
            // _inkManager.GetRecognitionResults(); 获取 InkManager 中的文字识别的结果

            string result = "文字识别的结果：";
            foreach (InkRecognitionResult recognitionResult in recognitionResults)
            {
                // 获取此文字识别的所有可能的结果集合，集合的第一条数据为最匹配的结果
                result += " " + recognitionResult.GetTextCandidates()[0];
            }

            lblMsg.Text = result;
        }
    }
}

OK
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