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Handwriting Recognition

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This section discusses the fundamentals of recognition as it pertains to digital ink in the WPF platform.

Recognition Solutions

The following example shows how to recognize ink using the Microsoft.Ink.InkCollector class.

Note

This sample requires that handwriting recognizers be installed on the system.

Create a new WPF application project in Visual Studio called InkRecognition. Replace the contents of the Window1.xaml file with the following XAML code. This code renders the application's user interface.

<Window x:Class="InkRecognition.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="InkRecognition" 
    >
  <Canvas Name="theRootCanvas">
    <Border
      Background="White"
      BorderBrush="Black"
      BorderThickness="2"
      Height="300"
      Width="300"
      Canvas.Top="10"
      Canvas.Left="10">
      <InkCanvas Name="theInkCanvas"></InkCanvas>
    </Border>
    <TextBox Name="textBox1"
      Height="25"
      Width="225"
      Canvas.Top="325"
      Canvas.Left="10"></TextBox>
    <Button
      Height="25"
      Width="75"
      Canvas.Top="325"
      Canvas.Left="235"
      Click="buttonClick">Recognize</Button>
        <Button x:Name="btnClear" Content="Clear Canvas" Canvas.Left="10" Canvas.Top="367" Width="75" Click="btnClear_Click"/>
    </Canvas>
</Window>

Add a reference to the Microsoft Ink assembly, Microsoft.Ink.dll, which can be found in \Program Files\Common Files\Microsoft Shared\Ink. Replace the contents of the code behind file with the following code.

using System.Windows;
using Microsoft.Ink;
using System.IO;

namespace InkRecognition
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>

    public partial class Window1 : Window
    {

        public Window1()
        {
            InitializeComponent();
        }

        // Recognizes handwriting by using RecognizerContext
        private void buttonClick(object sender, RoutedEventArgs e)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                theInkCanvas.Strokes.Save(ms);
                var myInkCollector = new InkCollector();
                var ink = new Ink();
                ink.Load(ms.ToArray());

                using (RecognizerContext context = new RecognizerContext())
                {
                    if (ink.Strokes.Count > 0)
                    {
                        context.Strokes = ink.Strokes;
                        RecognitionStatus status;

                        var result = context.Recognize(out status);

                        if (status == RecognitionStatus.NoError)
                            textBox1.Text = result.TopString;
                        else
                            MessageBox.Show("Recognition failed");
                    }
                    else
                    {
                        MessageBox.Show("No stroke detected");
                    }
                }
            }
        }

        private void btnClear_Click(object sender, RoutedEventArgs e) {
            theInkCanvas.Strokes.Clear();
        }
    }
}

Imports System.Windows
Imports Microsoft.Ink
Imports System.IO

'/ <summary>
'/ Interaction logic for Window1.xaml
'/ </summary>

Namespace InkRecognition

    Class Window1
        Inherits Window

        Public Sub New()
            InitializeComponent()
        End Sub


        ' Recognizes handwriting by using RecognizerContext
        Private Sub buttonClick(ByVal sender As Object, ByVal e As RoutedEventArgs)

            Using ms As New MemoryStream()
                theInkCanvas.Strokes.Save(ms)
                Dim myInkCollector As InkCollector = New InkCollector()
                Dim ink As Ink = New Ink()
                ink.Load(ms.ToArray())

                Using context As New RecognizerContext()
                    If ink.Strokes.Count > 0 Then
                        context.Strokes = ink.Strokes
                        Dim status As RecognitionStatus

                        Dim result As RecognitionResult = context.Recognize(status)

                        If status = RecognitionStatus.NoError Then
                            textBox1.Text = result.TopString
                        Else
                            MessageBox.Show("Recognition failed")
                        End If
                    Else
                        MessageBox.Show("No stroke detected")
                    End If
                End Using
            End Using
        End Sub

        Private Sub btnClear_Click(sender As Object, e As RoutedEventArgs)
            theInkCanvas.Strokes.Clear()
        End Sub
    End Class
End Namespace

See also