Esta documentación está archivada y no tiene mantenimiento.

DrawingContext (Clase)

Describes visual content using draw, push, and pop commands.

Espacio de nombres: System.Windows.Media
Ensamblado: PresentationCore (en presentationcore.dll)
Espacio de nombres XML:  http://schemas.microsoft.com/winfx/2006/xaml/presentation

public abstract class DrawingContext : DispatcherObject, IDisposable
public abstract class DrawingContext extends DispatcherObject implements IDisposable
public abstract class DrawingContext extends DispatcherObject implements IDisposable
Esta clase es abstracta; vea en Jerarquía de herencia las clases derivadas no abstractas utilizables en XAML.

Use a DrawingContext to populate a Visual or a Drawing with visual content.

Although the DrawingContext draw methods appear similar to the draw methods of the System.Drawing.Graphics type, they function very differently: DrawingContext is used with a retained mode graphics system, while the System.Drawing.Graphics type is used with an immediate mode graphics system. When you use a DrawingContext object's draw commands, you are actually storing a set of rendering instructions (although the exact storage mechanism depends on the type of object that supplies the DrawingContext) that will later be used by the graphics system; you are not drawing to the screen in real-time. For more information about how the Windows Presentation Foundation (WPF) graphics system works, see the Visual Layer Overview.

You never directly instantiate a DrawingContext; you can, however, acquire a drawing context from certain methods, such as DrawingGroup.Open and DrawingVisual.RenderOpen.

The following example retrieves a DrawingContext from a DrawingVisual and uses it to draw a rectangle.

// Create a DrawingVisual that contains a rectangle.
private DrawingVisual CreateDrawingVisualRectangle()
{
    DrawingVisual drawingVisual = new DrawingVisual();

    // Retrieve the DrawingContext in order to create new drawing content.
    DrawingContext drawingContext = drawingVisual.RenderOpen();

    // Create a rectangle and draw it in the DrawingContext.
    Rect rect = new Rect(new Point(160, 100), new Size(320, 80));
    drawingContext.DrawRectangle(Brushes.LightBlue, (Pen)null, rect);

    // Persist the drawing content.
    drawingContext.Close();

    return drawingVisual;
}

The next example demonstrates the PushOpacity, PushEffect, and Pop commands. The DrawingContext is obtained from a DrawingGroup and displayed using an Image control.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Navigation;
using System.Windows.Media.Effects;

namespace SDKSample
{


    public class PushEffectExample : Page
    {

        public PushEffectExample()
        {
            Pen shapeOutlinePen = new Pen(Brushes.Black, 2);
            shapeOutlinePen.Freeze();

            // Create a DrawingGroup
            DrawingGroup dGroup = new DrawingGroup();

            // Obtain a DrawingContext from 
            // the DrawingGroup.
            using (DrawingContext dc = dGroup.Open())
            {
                // Draw a rectangle at full opacity.
                dc.DrawRectangle(Brushes.Blue, shapeOutlinePen, new Rect(0, 0, 25, 25));

                // Push an opacity change of 0.5. 
                // The opacity of each subsequent drawing will
                // will be multiplied by 0.5.
                dc.PushOpacity(0.5);

                // This rectangle is drawn at 50% opacity.
                dc.DrawRectangle(Brushes.Blue, shapeOutlinePen, new Rect(25, 25, 25, 25));

                // Blurs subsquent drawings. 
                dc.PushEffect(new BlurBitmapEffect(), null);

                // This rectangle is blurred and drawn at 50% opacity (0.5 x 0.5). 
                dc.DrawRectangle(Brushes.Blue, shapeOutlinePen, new Rect(50, 50, 25, 25));

                // This rectangle is also blurred and drawn at 50% opacity.
                dc.DrawRectangle(Brushes.Blue, shapeOutlinePen, new Rect(75, 75, 25, 25));

                // Stop applying the blur to subsquent drawings.
                dc.Pop();

                // This rectangle is drawn at 50% opacity with no blur effect.
                dc.DrawRectangle(Brushes.Blue, shapeOutlinePen, new Rect(100, 100, 25, 25));
            }

            // Display the drawing using an image control.
            Image theImage = new Image();
            DrawingImage dImageSource = new DrawingImage(dGroup);
            theImage.Source = dImageSource;

            this.Content = theImage;

        }




    }

}

Más código

How to: Draw Text to a Visual

The following example shows how to draw text to a DrawingVisual using a DrawingContext object. A drawing context is returned by calling the RenderOpen method of a DrawingVisual object. You can draw graphics and text into a drawing context.

System.Object
   System.Windows.Threading.DispatcherObject
    System.Windows.Media.DrawingContext

Los miembros estáticos públicos (Shared en Visual Basic) de este tipo son seguros para la ejecución de subprocesos. No se garantiza que los miembros de instancias sean seguros para la ejecución de subprocesos.

Microsoft .NET Framework 3.0 es compatible con Windows Vista, Microsoft Windows XP SP2 y Windows Server 2003 SP1.

.NET Framework

Compatible con: 3.0
Mostrar: