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Cómo: Dibujar una imagen usando un objeto ImageDrawing

  • Artículo

En este ejemplo se muestra cómo usar un objeto ImageDrawing para dibujar una imagen. ImageDrawing le permite mostrar un objeto ImageSource con DrawingBrush, DrawingImage o Visual. Para dibujar una imagen, debe crear ImageDrawing y establecer sus propiedades ImageDrawing.ImageSource y ImageDrawing.Rect. La propiedad ImageDrawing.ImageSource especifica la imagen que se va a dibujar, y la propiedad ImageDrawing.Rect especifica la posición y el tamaño de cada imagen.

Ejemplo

En el ejemplo siguiente se crea un dibujo compuesto mediante cuatro objetos ImageDrawing. En este ejemplo se produce la imagen siguiente:

Varios objetos DrawingImage
Cuatro objetos ImageDrawing

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

namespace SDKSample
{
    public class ImageDrawingExample : Page
    {
        public ImageDrawingExample()
        {
            // Create a DrawingGroup to combine the ImageDrawing objects.
            DrawingGroup imageDrawings = new DrawingGroup();

            // Create a 100 by 100 image with an upper-left point of (75,75).
            ImageDrawing bigKiwi = new ImageDrawing();
            bigKiwi.Rect = new Rect(75, 75, 100, 100);
            bigKiwi.ImageSource = new BitmapImage(
                new Uri(@"sampleImages\kiwi.png", UriKind.Relative));

            imageDrawings.Children.Add(bigKiwi);

            // Create a 25 by 25 image with an upper-left point of (0,150).
            ImageDrawing smallKiwi1 = new ImageDrawing();
            smallKiwi1.Rect = new Rect(0, 150, 25, 25);
            smallKiwi1.ImageSource = new BitmapImage(new Uri(@"sampleImages\kiwi.png", UriKind.Relative));
            imageDrawings.Children.Add(smallKiwi1);

            // Create a 25 by 25 image with an upper-left point of (150,0).
            ImageDrawing smallKiwi2 = new ImageDrawing();
            smallKiwi2.Rect = new Rect(150, 0, 25, 25);
            smallKiwi2.ImageSource = new BitmapImage(new Uri(@"sampleImages\kiwi.png", UriKind.Relative));
            imageDrawings.Children.Add(smallKiwi2);

            // Create a 75 by 75 image with an upper-left point of (0,0).
            ImageDrawing wholeKiwi = new ImageDrawing();
            wholeKiwi.Rect = new Rect(0, 0, 75, 75);
            wholeKiwi.ImageSource = new BitmapImage(new Uri(@"sampleImages\wholekiwi.png", UriKind.Relative));
            imageDrawings.Children.Add(wholeKiwi);

            //
            // Use a DrawingImage and an Image control to
            // display the drawings.
            //
            DrawingImage drawingImageSource = new DrawingImage(imageDrawings);

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

            Image imageControl = new Image();
            imageControl.Stretch = Stretch.None;
            imageControl.Source = drawingImageSource;

            // Create a border to contain the Image control.
            Border imageBorder = new Border();
            imageBorder.BorderBrush = Brushes.Gray;
            imageBorder.BorderThickness = new Thickness(1);
            imageBorder.HorizontalAlignment = HorizontalAlignment.Left;
            imageBorder.VerticalAlignment = VerticalAlignment.Top;
            imageBorder.Margin = new Thickness(20);
            imageBorder.Child = imageControl;

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

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
  xmlns:PresentationOptions="http://schemas.microsoft.com/winfx/2006/xaml/presentation/options" 
  xmlns:mc="http://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">
      <Image.Source>
        <DrawingImage PresentationOptions:Freeze="True">
          <DrawingImage.Drawing>
            <DrawingGroup>

              <!-- The Rect property specifies that the image only fill a 100 by 100
                   rectangular area. -->
              <ImageDrawing Rect="75,75,100,100" ImageSource="sampleImages\kiwi.png"/>

              <!-- This image is set to fill a 25 by 25 rectangular area. -->
              <ImageDrawing Rect="0,150,25,25" ImageSource="sampleImages\kiwi.png"/>

              <!-- This image is set to fill a 25 by 25 rectangular area. -->
              <ImageDrawing Rect="150,0,25,25" ImageSource="sampleImages\kiwi.png"/>

              <!-- This image is set to fill a 75 by 75 rectangular area. -->
              <ImageDrawing Rect="0,0,75,75" ImageSource="sampleImages\wholekiwi.png"/>

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

Para ver un ejemplo en el que se muestra una manera sencilla de mostrar una imagen sin usar ImageDrawing, consulte Uso del elemento Image.

Vea también