DrawingContext.Pop Method

Definition

Namespace:

System.Windows.Media

Assembly:

PresentationCore.dll

Pops the last opacity mask, opacity, clip, effect, or transform operation that was pushed onto the drawing context.

C#

public abstract void Pop();

Examples

The following example shows the effect of the Pop command.

C#

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

namespace SDKSample
{

    public class PopExample : Page
    {

        public PopExample()
        {
            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));

                // Push an opacity change of 0.5. 
                // The opacity of each subsequent drawing will
                // will be multiplied by 0.5. Note that
                // push operations are cumulative (until they are
                // popped). 
                dc.PushOpacity(0.5);

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

                // Changes the opacity back to 0.5.
                dc.Pop();

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

                // Changes the opacity back to 1.0.
                dc.Pop();

                // This rectangle is drawn at 100% opacity.
                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;
        }
    }
}

The following illustration shows this example's output:

Remarks

Once an operation is popped, it is no longer applied to subsequent drawing commands.

Applies to