StrokeCollection.Draw(DrawingContext) Metodo

Definizione

Spazio dei nomi:

System.Windows.Ink

Assembly:

PresentationCore.dll

Disegna i tratti in 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)

Parametri

context

DrawingContext

Oggetto DrawingContext sul quale creare l'oggetto StrokeCollection.

Esempio

Nell'esempio seguente viene creato un elemento personalizzato che visualizza una visualizzazione di anteprima di un oggetto InkCanvas. L'elemento personalizzato mantiene un riferimento a un oggetto InkCanvas e si ridisegna quando si verifica l'evento StrokeCollected .

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