Stroke.OnInvalidated Method (EventArgs)


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Raises the Invalidated event.

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

Protected Overridable Sub OnInvalidated (
	e As EventArgs


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
End Enum 'DrawingMode
Private strokeMode As DrawingMode = DrawingMode.Solid

' Property that specifies whether to draw a solid stroke or the stylus points
Public Property Mode() As DrawingMode

        Return strokeMode
    End Get

    Set(ByVal value As DrawingMode)
        If strokeMode <> value Then
            strokeMode = value
            Me.OnInvalidated(New EventArgs())
        End If
    End Set

End Property

Protected Overrides Sub DrawCore(ByVal context As System.Windows.Media.DrawingContext, _
            ByVal overridedAttributes As DrawingAttributes)
    Dim strokeBrush As New SolidColorBrush(overridedAttributes.Color)

    ' If strokeMode it set to Solid, draw the strokes regularly.
    ' Otherwise, draw the stylus points.
    If strokeMode = DrawingMode.Solid Then
        Dim geometry As Geometry = GetGeometry(overridedAttributes)
        context.DrawGeometry(strokeBrush, Nothing, geometry)
        ' strokeMode == DrawingMode.StylusPoints
        Dim points As StylusPointCollection

        ' Get the stylus points used to draw the stroke.  The points used depends on
        ' the value of FitToCurve.
        If Me.DrawingAttributes.FitToCurve Then
            points = Me.GetBezierStylusPoints()
            points = Me.StylusPoints
        End If

        ' Draw a circle at each stylus point.
        Dim p As StylusPoint
        For Each p In points
            context.DrawEllipse(Nothing, New Pen(strokeBrush, 1), CType(p, Point), 5, 5)
        Next p
    End If

End Sub 'DrawCore

.NET Framework
Available since 3.0
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