StrokeCollection.Draw(DrawingContext) Methode

Definition

Namespace:

System.Windows.Ink

Assembly:

PresentationCore.dll

Zeichnet die Striche in der StrokeCollection.

public:
 void Draw(System::Windows::Media::DrawingContext ^ context);

public void Draw (System.Windows.Media.DrawingContext context);

member this.Draw : System.Windows.Media.DrawingContext -> unit

Public Sub Draw (context As DrawingContext)

Parameter

context

DrawingContext

Die DrawingContext, auf der der StrokeCollection gezeichnet werden soll.

Beispiele

Im folgenden Beispiel wird ein benutzerdefiniertes Element erstellt, das eine Miniaturansicht eines InkCanvasanzeigt. Das benutzerdefinierte Element behält einen Verweis auf ein InkCanvas und zeichnet sich neu, wenn das StrokeCollected Ereignis auftritt.

public class InkThumbnail : FrameworkElement
{
    private InkCanvas sourceInkCanvas = null;
    
    // Get the InkCanvas that the user draws on.
    public InkCanvas Source
    {

        get 
        { 
            return sourceInkCanvas; 
        }

        set
        {
            
            if (sourceInkCanvas != null)
            {
                // Detach the event handler from the former InkCanvas.
                sourceInkCanvas.StrokeCollected -= new InkCanvasStrokeCollectedEventHandler(SourceChanged);
            }

            sourceInkCanvas = value;

            if (sourceInkCanvas != null)
            {
                // Attach the even handler to the InkCannvas
                sourceInkCanvas.StrokeCollected += new InkCanvasStrokeCollectedEventHandler(SourceChanged);
            }
        }
    }

    // Handle the StrokeCollection event of the InkCanvas.
    private void SourceChanged(object sender, InkCanvasStrokeCollectedEventArgs e)
    {

        // Cause the thumbnail to be redrawn.
        this.InvalidateVisual();
    }

    protected override void OnRender(DrawingContext drawingContext)
    {
        
        base.OnRender(drawingContext);

        // Draw the strokes from the InkCanvas at 1/4 of their size.
        drawingContext.PushTransform(new ScaleTransform(0.25, 0.25));

        if (sourceInkCanvas != null)
        {
            sourceInkCanvas.Strokes.Draw(drawingContext);
        }
    }
}

Public Class InkThumbnail
    Inherits FrameworkElement

    Private sourceInkCanvas As InkCanvas = Nothing

    ' Get the InkCanvas that the user draws on.
    Public Property Source() As InkCanvas
        Get
            Return sourceInkCanvas
        End Get

        Set(ByVal Value As InkCanvas)

            If Not sourceInkCanvas Is Nothing Then

                ' Detach the event handler from the former InkCanvas.
                RemoveHandler sourceInkCanvas.StrokeCollected, AddressOf SourceChanged
            End If

            sourceInkCanvas = Value


            If Not sourceInkCanvas Is Nothing Then

                ' Attach the even handler to the InkCannvas
                AddHandler sourceInkCanvas.StrokeCollected, AddressOf SourceChanged
            End If

        End Set
    End Property

    ' Handle the StrokeCollection event of the InkCanvas.
    Private Sub SourceChanged(ByVal sender As Object, ByVal e As InkCanvasStrokeCollectedEventArgs)

        ' Cause the thumbnail to be redrawn.
        Me.InvalidateVisual()
    End Sub


    Protected Overrides Sub OnRender(ByVal drawingContext As DrawingContext)

        MyBase.OnRender(drawingContext)

        ' Draw the strokes from the InkCanvas at 1/4 of their size.
        drawingContext.PushTransform(New ScaleTransform(0.25, 0.25))

        If Not sourceInkCanvas Is Nothing Then
            sourceInkCanvas.Strokes.Draw(drawingContext)
        End If

    End Sub

End Class