DrawingGroup.OpacityMask プロパティ


この DrawingGroup について、選択した領域の不透明度を変更するために使用するブラシを取得または設定します。Gets or sets the brush used to alter the opacity of select regions of this DrawingGroup.

 property System::Windows::Media::Brush ^ OpacityMask { System::Windows::Media::Brush ^ get(); void set(System::Windows::Media::Brush ^ value); };
public System.Windows.Media.Brush OpacityMask { get; set; }
member this.OpacityMask : System.Windows.Media.Brush with get, set
Public Property OpacityMask As Brush


この DrawingGroup の不透明度を表す Brushnull は、不透明マスクが存在せず、不透明度が均一であることを示します。A Brush that describes the opacity of this DrawingGroup; null indicates that no opacity mask exists and the opacity is uniform. 既定値は、null です。The default is null.

この例では、 Drawingに不透明度マスクを適用する方法を示します。This example shows how to apply an opacity mask to a Drawing. クラスは、不透明マスクをサポートDrawingする唯一の種類のオブジェクトです。 DrawingGroupThe DrawingGroup class is the only type of Drawing object that supports opacity masks.

Drawingオブジェクトに不透明度マスクを適用するにはDrawingGroup 、オブジェクトをに追加しOpacityMaskDrawingGroupオブジェクトのプロパティを設定します。To apply an opacity mask to a Drawing object, add it to a DrawingGroup and set the OpacityMask property of the DrawingGroup object.

次の図は、 DrawingGroupの3つのビューを示しています。不透明度マスクのない描画、不透明度マスクのみ、 DrawingGroupおよび不透明度マスクが適用された後の。The following illustration shows three views of the DrawingGroup: the drawing without an opacity mask, the opacity mask alone, and the DrawingGroup after the opacity mask is applied.

不透明度マスクを持つ図面グループA DrawingGroup with an opacity mask

次の例ではRadialGradientBrush 、をDrawingGroupの不透明度マスクとして使用します。The following example uses a RadialGradientBrush as an opacity mask for a DrawingGroup.


この例では、 RadialGradientBrushを不透明度LinearGradientBrushマスクDrawingBrush ImageBrushとして使用しVisualBrushていますが、、、、およびの各オブジェクトは、適切な不透明マスクを作成することもできます。Although this example uses a RadialGradientBrush as an opacity mask, LinearGradientBrush, DrawingBrush, ImageBrush, and VisualBrush objects can also make good opacity masks. 不透明度マスクとその動作の詳細については、「不透明度マスクの概要」を参照してください。For more information about opacity masks and how they work, see the Opacity Masks Overview.

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 create and apply an OpacityMask to
    /// a DrawinGroup.
    /// </summary>
    public class OpacityMaskExample : Page
        public OpacityMaskExample()

            // 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));
            PathGeometry pGeometry = new PathGeometry();

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

            // Create another GeometryDrawing.
            GeometryDrawing drawing2 = new GeometryDrawing(
                    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();

            // Define an opacity mask and apply it to the
            // drawing group.
            RadialGradientBrush opacityMask = new RadialGradientBrush();
            opacityMask.GradientStops.Add(new GradientStop(Color.FromArgb(255, 0, 0, 0), 0.0));
            opacityMask.GradientStops.Add(new GradientStop(Color.FromArgb(0, 0, 0, 0), 0.55));
            opacityMask.GradientStops.Add(new GradientStop(Color.FromArgb(255, 0, 0, 0), 0.65));
            opacityMask.GradientStops.Add(new GradientStop(Color.FromArgb(0, 0, 0, 0), 0.75));
            opacityMask.GradientStops.Add(new GradientStop(Color.FromArgb(255, 0, 0, 0), 0.80));
            opacityMask.GradientStops.Add(new GradientStop(Color.FromArgb(0, 0, 0, 0), 0.90));
            opacityMask.GradientStops.Add(new GradientStop(Color.FromArgb(255, 0, 0, 0), 1.0));

            aDrawingGroup.OpacityMask = opacityMask;

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

            // Freeze the DrawingImage for performance benefits.

            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;

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

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

                <!-- The opacity mask. -->
                  <GradientStop Offset="0.0" Color="#FF000000" />
                  <GradientStop Offset="0.55" Color="#00000000" />
                  <GradientStop Offset="0.65" Color="#FF000000" />
                  <GradientStop Offset="0.75" Color="#00000000" />
                  <GradientStop Offset="0.80" Color="#FF000000" />
                  <GradientStop Offset="0.90" Color="#00000000" />
                  <GradientStop Offset="1.0" Color="#FF000000" />



はにマップされます。 DrawingGroup BrushThe Brush is mapped to the DrawingGroup. マップBrushされたの各ピクセルの不透明度の値は、 DrawingGroupの対応する各ピクセルの不透明度を決定するために使用されます。The opacity value of each pixel of the mapped Brush is used to determine the resulting opacity of each corresponding pixel of the DrawingGroup. この処理には、ブラシの各色の不透明度の値のみが使用されます。その他の色情報はすべて無視されます。Only the opacity value of each color in the brush is used for this processing; all other color information is ignored.

このプロパティが指定する不透明度は、 Opacity DrawingGroupオブジェクトの値と乗算されます。The opacity that this property specifies is multiplied with the Opacity value of the DrawingGroup object. 不透明度マスクとその動作の詳細については、「不透明度マスクの概要」を参照してください。For more information about opacity masks and how they work, see Opacity Masks Overview.

DrawingGroup操作は次の順序で適用されます。DrawingGroup operations are applied in the following order:

  1. OpacityMask

  2. Opacity

  3. BitmapEffect

  4. ClipGeometry

  5. GuidelineSet

  6. Transform

依存プロパティ情報Dependency Property Information

識別子フィールドIdentifier field OpacityMaskProperty
メタデータプロパティがに設定されるtrueMetadata properties set to true NoneNone