OnInvalidated Method

Stroke.OnInvalidated Method (EventArgs)

 

Raises the Invalidated event.

Namespace:   System.Windows.Ink
Assembly:  PresentationCore (in PresentationCore.dll)

protected virtual void OnInvalidated(
	EventArgs e
)

Parameters

e
Type: System.EventArgs

An EventArgs that contains the event data.

If you inherit from the Stroke class and your stroke's appearance is based on a custom state, you must call the OnInvalidated method to raise the Invalidated event. The InkPresenter handles the Invalidated event and calls the DrawCore method.

The following example draws a Stroke either as a solid stroke or as a series of StylusPoint objects, depending on the Mode property. The example calls the OnInvalidated method, which in turn calls the DrawCore where the stroke is drawn.

// Enumerator that specifies the drawing mode of the stroke.
public enum DrawingMode
{
    Solid,
    StyulusPoints
}
private DrawingMode strokeMode = DrawingMode.Solid;

// Property that specifies whether to draw a solid stroke or the stylus points
public DrawingMode Mode
{
    get
    {
        return strokeMode;
    }

     set
    {
        if (strokeMode != value)
        {
            strokeMode = value;
            this.OnInvalidated(new EventArgs());
        }
    }
}

protected override void DrawCore(System.Windows.Media.DrawingContext context, DrawingAttributes overrides)
{
    SolidColorBrush strokeBrush = new SolidColorBrush(overrides.Color);

    // If strokeMode it set to Solid, draw the strokes regularly.
    // Otherwise, draw the stylus points.
    if (strokeMode == DrawingMode.Solid)
    {
        Geometry geometry = GetGeometry(overrides);
        context.DrawGeometry(strokeBrush, null, geometry);
    }
    else // strokeMode == DrawingMode.StylusPoints
    {
        StylusPointCollection points;

        // Get the stylus points used to draw the stroke.  The points used depends on
        // the value of FitToCurve.
        if (this.DrawingAttributes.FitToCurve)
        {
            points = this.GetBezierStylusPoints();
        }
        else
        {
            points = this.StylusPoints;
        }

        // Draw a circle at each stylus point.
        foreach (StylusPoint p in points)
        {
            context.DrawEllipse(null, new Pen(strokeBrush, 1), (Point)p, 5, 5);
        }
    }
}

.NET Framework
Available since 3.0
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