DrawingGroup.OpacityMask 属性
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
获取或设置用于改变此 DrawingGroup 的选区不透明度的画笔。
public:
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, setPublic Property OpacityMask As Brush属性值
描述此 DrawingGroup 透明度的 Brush；null 指示不存在不透明蒙板且不透明度统一。 默认值为 null。
示例
此示例演示如何将不透明度掩码应用于 .Drawing 类 DrawingGroup 是支持不透明度掩码的唯一 Drawing 对象类型。
若要向 Drawing 对象应用不透明度掩码，请将其添加到对象 DrawingGroup 并设置 OpacityMask 该对象的属性 DrawingGroup 。
下图显示了三个 DrawingGroup视图：不透明度掩码的绘图、仅不透明度掩码以及 DrawingGroup 应用不透明度掩码之后。
以下示例使用 a RadialGradientBrush 作为不透明度掩码。DrawingGroup
备注
虽然此示例使用RadialGradientBrush不透明度掩码、LinearGradientBrush、DrawingBrushImageBrush对象和VisualBrush对象也可以进行良好的不透明度掩码。 有关不透明度掩码及其工作原理的详细信息，请参阅 不透明度掩码概述。
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));
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);
//
// 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.
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"
Margin="20" Background="White">
<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 DrawingGroup with a RadialGradientBrush as its opacity mask. -->
<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>
<DrawingGroup.OpacityMask>
<!-- The opacity mask. -->
<RadialGradientBrush>
<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" />
</RadialGradientBrush>
</DrawingGroup.OpacityMask>
</DrawingGroup>
</DrawingImage.Drawing>
</DrawingImage>
</Image.Source>
</Image>
</Border>
</Page>
注解
映射到 Brush .DrawingGroup 映射 Brush 的每个像素的不透明度值用于确定每个相应像素的 DrawingGroup不透明度。 只有画笔中每个颜色的不透明度值才用于此处理;将忽略所有其他颜色信息。
此属性指定的不透明度与 Opacity 对象的值 DrawingGroup 相乘。 有关不透明度掩码及其工作原理的详细信息，请参阅 不透明度掩码概述。
DrawingGroup 操作按以下顺序应用：
依赖项属性信息
| 标识符字段 | OpacityMaskProperty |
元数据属性设置为 true |
无 |