DrawingGroup.ClipGeometry 属性

定义

命名空间:

System.Windows.Media

程序集:

PresentationCore.dll

获取或设置此 DrawingGroup 的剪裁区域。

public:
 property System::Windows::Media::Geometry ^ ClipGeometry { System::Windows::Media::Geometry ^ get(); void set(System::Windows::Media::Geometry ^ value); };

public System.Windows.Media.Geometry ClipGeometry { get; set; }

member this.ClipGeometry : System.Windows.Media.Geometry with get, set

Public Property ClipGeometry As Geometry

属性值

Geometry

用于剪裁此 Geometry 的 DrawingGroup。 默认值为 null。

示例

This example shows how to define a clip region for a Drawing.

使用 a DrawingGroup 定义剪辑 Drawing。 该 DrawingGroup 类是唯一一种 Drawing 对象类型，可用于定义自己的剪辑区域。

使用 a Geometry 描述剪辑并将其应用于 ClipGeometry 对象的属性 DrawingGroup 。

此图显示了 DrawingGroup 应用椭圆剪辑前后。

以下示例使用一个DrawingGroupClipGeometry应用于多个GeometryDrawing对象。

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

namespace SDKSample
{
    /// <summary>
    /// Shows how to define a clip region for a DrawingGroup.
    /// </summary>
    public class ClipExample : Page
    {
        public ClipExample()
        {

            //
            // Create several GeometryDrawing objects.
            //

            // Create a rectangle.
            GeometryDrawing drawing1 = new GeometryDrawing(
                Brushes.Pink,
                null, 
                new RectangleGeometry(new Rect(0,0,50,85))
                );

            //
            // Create a polygon.
            //
            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 drawing2 = new GeometryDrawing(
                    Brushes.Lime,
                    new Pen(Brushes.Black, 10),
                    pGeometry
                );

            //
            // Create a circle.
            //
            GeometryDrawing drawing3 = 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);
            aDrawingGroup.Children.Add(drawing3);

            //
            // Create an EllipseGeometry and use it to
            // clip the DrawingGroup.
            //
            EllipseGeometry clipGeometry = 
                new EllipseGeometry(new Point(25,50), 25, 50);
            aDrawingGroup.ClipGeometry = clipGeometry;

            // 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="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" HorizontalAlignment="Left">
      <Image.Source>
        <DrawingImage PresentationOptions:Freeze="True">
          <DrawingImage.Drawing>

            <!-- A DrawingGeometry with an elliptical clip region. -->
            <DrawingGroup>
              <GeometryDrawing Brush="Pink">
                <GeometryDrawing.Geometry>
                  <RectangleGeometry Rect="0,0,50,85" />
                </GeometryDrawing.Geometry>
              </GeometryDrawing>
              <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>

              <DrawingGroup.ClipGeometry>
                <EllipseGeometry Center="25,50" RadiusX="25" RadiusY="50" />
              </DrawingGroup.ClipGeometry>
            </DrawingGroup>
          </DrawingImage.Drawing>
        </DrawingImage>
      </Image.Source>
    </Image>
  </Border>


</Page>

注解

几何图形外部的绘图从呈现几何图形时剪裁 DrawingGroup 。 几何图形不必是矩形;例如，可以使用一个 EllipseGeometry 剪裁到椭圆形状。

DrawingGroup 操作按以下顺序应用：

1. OpacityMask

2. Opacity

3. BitmapEffect

4. ClipGeometry

5. GuidelineSet

6. Transform

依赖项属性信息

标识符字段	ClipGeometryProperty
元数据属性设置为 true	无