How to: Apply a Transform to a Drawing

This example shows how to apply a Transform to a Drawing. To transform a Drawing object, you add it to a DrawingGroup and set the Transform property of the DrawingGroup object.

The DrawingGroup class is the only type of Drawing object that supports transforms. To apply multiple transforms to a single DrawingGroup, use a TransformGroup.

Example

The following example uses a DrawingGroup to combine several GeometryDrawing objects and then transforms them by using a RotateTransform.

The illustration shows the DrawingGroup before and after the RotateTransform is applied.

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

namespace SDKSample
{
    public class TransformExample : Page
    {

        public TransformExample()
        {

            // 
            // Create a GeometryDrawing. 
            // 

            // Define the drawing's contents.
            PathFigure pLineFigure = new PathFigure();
            pLineFigure.StartPoint = new Point(25, 25);
            PolyLineSegment pLineSegment = new PolyLineSegment();
            pLineSegment.Points.Add(new Point(0, 50));
            pLineSegment.Points.Add(new Point(25, 75));
            pLineSegment.Points.Add(new Point(50, 50));
            pLineSegment.Points.Add(new Point(25, 25));
            pLineSegment.Points.Add(new Point(25, 0));
            pLineFigure.Segments.Add(pLineSegment);
            PathGeometry pGeometry = new PathGeometry();
            pGeometry.Figures.Add(pLineFigure);

            GeometryDrawing drawing1 = new GeometryDrawing(
                    Brushes.Lime,
                    new Pen(Brushes.Black, 10),
                    pGeometry
                );

            // 
            // Create another GeometryDrawing. 
            //
            GeometryDrawing drawing2 = new GeometryDrawing(
                    Brushes.Lime,
                    new Pen(Brushes.Black, 2),
                    new EllipseGeometry(new Point(10, 10), 5, 5)
                );

            // Create the DrawingGroup and add the 
            // geometry drawings.
            DrawingGroup aDrawingGroup = new DrawingGroup();
            aDrawingGroup.Children.Add(drawing1);
            aDrawingGroup.Children.Add(drawing2);

            // 
            // Create a RotateTransform and apply it to the 
            // drawing group. 
            //
            RotateTransform rotation = new RotateTransform(
                45, // Angle 
                50, // CenterX
                75  // CenterY
                );
            aDrawingGroup.Transform = rotation;


            // Use an Image control and a DrawingImage to 
            // display the drawing.
            DrawingImage aDrawingImage = new DrawingImage(aDrawingGroup);

            // Freeze the DrawingImage for performance benefits.
            aDrawingImage.Freeze();

            Image anImage = new Image();
            anImage.Source = aDrawingImage;
            anImage.Stretch = Stretch.None;
            anImage.HorizontalAlignment = HorizontalAlignment.Left;

            // Create a border around the images and add it to the 
            // page.
            Border imageBorder = new Border();
            imageBorder.BorderBrush = Brushes.Gray;
            imageBorder.BorderThickness = new Thickness(1);
            imageBorder.VerticalAlignment = VerticalAlignment.Top;
            imageBorder.HorizontalAlignment = HorizontalAlignment.Left;
            imageBorder.Margin = new Thickness(20);
            imageBorder.Child = anImage;

            this.Background = Brushes.White;
            this.Margin = new Thickness(20);
            this.Content = imageBorder;

        }

    }
}

<Page 
  xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:PresentationOptions="https://schemas.microsoft.com/winfx/2006/xaml/presentation/options" 
  xmlns:mc="https://schemas.openxmlformats.org/markup-compatibility/2006"
  mc:Ignorable="PresentationOptions"
  Background="White" Margin="20">

  <Border BorderBrush="Gray" BorderThickness="1" 
    HorizontalAlignment="Left" VerticalAlignment="Top"
    Margin="20">
    <Image Stretch="None" HorizontalAlignment="Left">
      <Image.Source>
        <DrawingImage PresentationOptions:Freeze="True">
          <DrawingImage.Drawing>

            <!-- A drawing group with a RotateTransform. -->
            <DrawingGroup>
              <GeometryDrawing Brush="Lime" Geometry="M 25,25 L 0,50 25,75 50,50 25,25 25,0">
                <GeometryDrawing.Pen>
                  <Pen Thickness="10" Brush="Black" />
                </GeometryDrawing.Pen>
              </GeometryDrawing>
              <GeometryDrawing Brush="Lime">
                <GeometryDrawing.Geometry>
                  <EllipseGeometry Center="10,10" RadiusX="5" RadiusY="5" />
                </GeometryDrawing.Geometry>
                <GeometryDrawing.Pen>
                  <Pen Thickness="2" Brush="Black" />
                </GeometryDrawing.Pen>
              </GeometryDrawing>

              <!-- Rotate the drawing 45 degrees about (50,75). -->
              <DrawingGroup.Transform>
                <RotateTransform CenterX="50" CenterY="75" Angle="45" />
              </DrawingGroup.Transform>

            </DrawingGroup>
          </DrawingImage.Drawing>
        </DrawingImage>
      </Image.Source>
    </Image>
  </Border>


</Page>

See Also

Concepts

Drawing Objects Overview

Transforms Overview

Reference

RotateTransform

ScaleTransform

SkewTransform

TranslateTransform

MatrixTransform