Export (0) Print
Expand All

RawStylusInput.NotifyWhenProcessed Method

Subscribes to the application thread's corresponding stylus methods.

Namespace:  System.Windows.Input.StylusPlugIns
Assembly:  PresentationCore (in PresentationCore.dll)

public void NotifyWhenProcessed(
	Object callbackData
)
You cannot use methods in XAML.

Parameters

callbackData
Type: System.Object

The data to pass to the application thread.

The pen's input is routed to an element's StylusPlugIn on the pen thread. Because accurate hit-testing cannot be performed on the pen thread, some elements might occasionally receive stylus input intended for other elements. If you need to be sure the input was routed correctly before performing an operation, call the NotifyWhenProcessed method in the method that occurs on the pen thread. The following table lists where to call NotifyWhenProcessed to subscribe to the application thread's method.

Call NotifyWhenProcessed in this method

To subscribe to this method

OnStylusDown

OnStylusDownProcessed

OnStylusMove

OnStylusMoveProcessed

OnStylusUp

OnStylusUpProcessed

The following example creates a StylusPlugIn that checks for the Down gesture. The StylusPlugIn calls NotifyWhenProcessed in OnStylusUp to subscribe to the OnStylusUpProcessed method, which is called from the application thread.

class RecognizerPlugin : StylusPlugIn
{
    GestureRecognizer recognizer;

    // StylusPointCollection that contains the stylus points of the current 
    // stroke.
    StylusPointCollection points;

    // Keeps track of the stylus to check whether two styluses are used on the 
    // digitizer. 
    int currentStylus;

    public RecognizerPlugin()
        : base()
    {
        recognizer = new GestureRecognizer();
    }

    // Collect the points as the user draws the stroke. 
    protected override void OnStylusDown(RawStylusInput rawStylusInput)
    {
        // If points is not null, there is already a stroke taking place 
        // on the digitizer, so don't create a new StylusPointsCollection. 
        if (points == null)
        {
            points = new StylusPointCollection(rawStylusInput.GetStylusPoints().Description);
            points.Add(rawStylusInput.GetStylusPoints());
            currentStylus = rawStylusInput.StylusDeviceId;
        }
    }

    // Collect the points as the user draws the stroke. 
    protected override void OnStylusMove(RawStylusInput rawStylusInput)
    {
        // Check whether the stylus that started the stroke is the same, and 
        // that the element hasn't lost focus since the stroke began. 
            if (points != null && currentStylus == rawStylusInput.StylusDeviceId)
        {
            points.Add(rawStylusInput.GetStylusPoints());
        }
    }

    // Collect the points as the user draws the stroke. 
    protected override void OnStylusUp(RawStylusInput rawStylusInput)
    {
        // Check whether the stylus that started the stroke is the same, and 
        // that the element hasn't lost focus since the stroke began. 
        if (points != null && currentStylus == rawStylusInput.StylusDeviceId)
        {
            points.Add(rawStylusInput.GetStylusPoints());

            // Subscribe to the OnStylusUpProcessed method.
            rawStylusInput.NotifyWhenProcessed(points);
        }

        points = null;
        currentStylus = 0;
    }

    // If the element loses focus, stop collecting the points and don't 
    // perform gesture recognition. 
    protected override void OnStylusLeave(RawStylusInput rawStylusInput, bool confirmed)
    {
        if (confirmed)
        {
            // Clear the StylusPointCollection
            points = null;
            currentStylus = 0;
        }
    }

    // This method is called on the application thread. 
    protected override void OnStylusUpProcessed(object callbackData, bool targetVerified)
    {
        // Check that the element actually receive the OnStylusUp input. 
        if (targetVerified && recognizer.IsRecognizerAvailable)
        {
            StylusPointCollection strokePoints = callbackData as StylusPointCollection;

            if (strokePoints == null)
            {
                return;
            }

            // Create a StrokeCollection to pass to the GestureRecognizer.
            Stroke newStroke = new Stroke(strokePoints);
            StrokeCollection strokes = new StrokeCollection();
            strokes.Add(newStroke);

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

            // If the GestureRecognizer recognizes the stroke as a Down 
            // gesture with strong confidence, raise an event. 
            if (results[0].ApplicationGesture == ApplicationGesture.Down &&
                results[0].RecognitionConfidence == RecognitionConfidence.Strong)
            {
                //raise event
            }
        }
    }
}

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0

Community Additions

ADD
Show:
© 2014 Microsoft