GestureRecognizer.Recognize(StrokeCollection) Method

Definition

Namespace:

System.Windows.Ink

Assembly:

PresentationCore.dll

Looks for gestures in the specified StrokeCollection.

public:
 System::Collections::ObjectModel::ReadOnlyCollection<System::Windows::Ink::GestureRecognitionResult ^> ^ Recognize(System::Windows::Ink::StrokeCollection ^ strokes);

public System.Collections.ObjectModel.ReadOnlyCollection<System.Windows.Ink.GestureRecognitionResult> Recognize (System.Windows.Ink.StrokeCollection strokes);

member this.Recognize : System.Windows.Ink.StrokeCollection -> System.Collections.ObjectModel.ReadOnlyCollection<System.Windows.Ink.GestureRecognitionResult>

Public Function Recognize (strokes As StrokeCollection) As ReadOnlyCollection(Of GestureRecognitionResult)

Parameters

strokes

StrokeCollection

The StrokeCollection to search for gestures.

Returns

ReadOnlyCollection<GestureRecognitionResult>

An array of type GestureRecognitionResult that contains application gestures that the GestureRecognizer recognized.

Examples

The following example demonstrates how to determine whether a Stroke is a ScratchOut gesture.

private bool InterpretScratchoutGesture(Stroke stroke)
{
    // Attempt to instantiate a recognizer for scratchout gestures.
    ApplicationGesture[] gestures = { ApplicationGesture.ScratchOut };
    GestureRecognizer recognizer = new GestureRecognizer(gestures);

    if (!recognizer.IsRecognizerAvailable)
        return false;

    // Determine if the stroke was a scratchout gesture.
    StrokeCollection gestureStrokes = new StrokeCollection();
    gestureStrokes.Add(stroke);

    ReadOnlyCollection<GestureRecognitionResult> results = recognizer.Recognize(gestureStrokes);

    if (results.Count == 0)
        return false;

    // Results are returned sorted in order strongest-to-weakest; 
    // we need only analyze the first (strongest) result.
    if (results[0].ApplicationGesture == ApplicationGesture.ScratchOut &&
          results[0].RecognitionConfidence == RecognitionConfidence.Strong)
    {
        // Use the scratchout stroke to perform hit-testing and 
        // erase existing strokes, as necessary.
        return true;
    }
    else
    {
        // Not a gesture: display the stroke normally.
        return false;
    }
}

Private Function InterpretScratchoutGesture(ByVal stroke As Stroke) As Boolean
    ' Attempt to instantiate a recognizer for scratchout gestures.
    Dim gestures() As ApplicationGesture = {ApplicationGesture.ScratchOut}

    Dim recognizer As New GestureRecognizer(gestures)

    If Not recognizer.IsRecognizerAvailable Then
        Return False
    End If

    ' Determine if the stroke was a scratchout gesture.
    Dim gestureStrokes As StrokeCollection = New StrokeCollection()
    gestureStrokes.Add(stroke)

    Dim results As ReadOnlyCollection(Of GestureRecognitionResult)
    results = recognizer.Recognize(gestureStrokes)

    If results.Count = 0 Then
        Return False
    End If

    ' Results are returned sorted in order strongest-to-weakest; 
    ' we need only analyze the first (strongest) result.
    If (results(0).ApplicationGesture = ApplicationGesture.ScratchOut) Then

        ' Use the scratchout stroke to perform hit-testing and 
        ' erase existing strokes, as necessary.
        Return True
    Else
        ' Not a gesture: display the stroke normally.
        Return False
    End If
End Function

Remarks

The array returned by the Recognize method is sorted by the GestureRecognitionResult.RecognitionConfidence property. For example, Recognize may return a GestureRecognitionResult array with the following values:

Index	ApplicationGesture	RecognitionConfidence
0	Check	Strong
1	NoGesture	Intermediate
2	Curlicue	Poor
3	DoubleCurlicue	Poor

This means that the GestureRecognizer recognizes that it is very likely that the Stroke is a check mark, relatively likely that the Stroke in not a gesture, and not at all likely that the Stroke is a curlicue or a double curlicue.

Note

The Recognize method can return an array with NoGesture at a higher RecognitionConfidence than other application gestures. This means that it is more likely that the Stroke is not a gesture, as opposed to a gesture that has a lower RecognitionConfidence.