WPF之图像、图形和视觉画刷的使用

图像画刷
  ImageBrush常用于渲染图片，其属性ImageSource由ImageSource类定义而成，用于设置图像信息。但ImageSource是一个抽象类，因此设置图像信息的任务落到了其子类BitmapImage身上。ImageBrush还有另外一个常用属性Stretch用于图片填充模式，默认值为Fill。
ImageBrush在XAML中示例代码如下：

<Canvas Height="200" Width="200">
    <Canvas.Background>
        <ImageBrush Stretch="Fill">
            <ImageBrush.ImageSource>
                <BitmapImage UriSource="/Picture/帽子.jpg"/>
            </ImageBrush.ImageSource>
        </ImageBrush>
    </Canvas.Background>
</Canvas>

C#：

Canvas canvas = new Canvas();
canvas.Height = 200;
canvas.Width = 200;
ImageBrush imageBrush = new ImageBrush();
imageBrush.ImageSource = new BitmapImage(new Uri("Picture/帽子.jpg", UriKind.Relative));
canvas.Background = imageBrush;

绘图画刷
  DrawingBrush用途比较多，可以用于绘制形状、文本、图像以及视频。各绘制对象如下：

1、GeometryDrawing：绘制形状
2、ImageDrawing：绘制图像
3、GlyphRunDrawing：绘制文字
4、VideoDrawing：音频和视频的播放
5、DrawingGroup：绘图组，将其它图形合并到单个复合图形

  下面将展示一个按钮，按钮内部有三个连着的站着的椭圆，椭圆的边缘线宽度为2，示例代码如下：
XAML：

<Button Content="A Button" Width="100" Height="50">
    <Button.Background>
        <DrawingBrush>
            <DrawingBrush.Drawing>
                <GeometryDrawing Brush="AliceBlue">
                    <GeometryDrawing.Geometry>
                        <GeometryGroup>
                            <EllipseGeometry RadiusX="12.5" RadiusY="25" Center="25, 50"/>
                            <EllipseGeometry RadiusX="12.5" RadiusY="25" Center="50, 50"/>
                            <EllipseGeometry RadiusX="12.5" RadiusY="25" Center="75, 50"/>
                        </GeometryGroup>
                    </GeometryDrawing.Geometry>
                    <GeometryDrawing.Pen>
                        <Pen Thickness="2" Brush="Gray"/>
                    </GeometryDrawing.Pen>
                </GeometryDrawing>
            </DrawingBrush.Drawing>
        </DrawingBrush>
    </Button.Background>
</Button>

C#：

Button btn = new Button();
btn.Height = 50;
btn.Width = 100;
btn.Content = "A Button";
DrawingBrush drawingBrush = new DrawingBrush();
GeometryDrawing geometryDrawing = new GeometryDrawing();
GeometryGroup geometryGroup = new GeometryGroup();
geometryGroup.Children.Add(new EllipseGeometry(new Point(25, 50), 12.5, 25));
geometryGroup.Children.Add(new EllipseGeometry(new Point(50, 50), 12.5, 25));
geometryGroup.Children.Add(new EllipseGeometry(new Point(70, 50), 12.5, 25));
geometryDrawing.Geometry = geometryGroup;
geometryDrawing.Pen = new Pen(new SolidColorBrush(Colors.Gray), 2);
geometryDrawing.Brush = new SolidColorBrush(Colors.AliceBlue);
drawingBrush.Drawing = geometryDrawing;
btn.Background = drawingBrush;

视觉画刷
  视觉画刷在所有画刷中，属于低层次的画刷，因为属性Visual是所有UI元素的祖先，因此VisualBrush可以使用WPF中所有UI元素进行渲染。以下代码将显示StackPanel、Ellipse、TextBlock以及Button组合的渲染效果。
XAML：

<Rectangle Height="50" Width="200" Stroke="AliceBlue">
    <Rectangle.Fill>
        <VisualBrush>
            <VisualBrush.Visual>
                <StackPanel Background="White" Orientation="Horizontal">
                    <Ellipse Fill="Blue" Height="10" Width="10"/>
                    <TextBlock Text="VisualBrush"/>
                    <Button Content="按钮"/>
                </StackPanel>
            </VisualBrush.Visual>
        </VisualBrush>
    </Rectangle.Fill>
</Rectangle>

C#：

Rectangle rectangle = new Rectangle();
rectangle.Height = 50;
rectangle.Width = 200;
VisualBrush visualBrush = new VisualBrush();
StackPanel stackPanel = new StackPanel();
stackPanel.Orientation = Orientation.Horizontal;
Ellipse ellipse = new Ellipse();
ellipse.Height = 10;
ellipse.Width = 10;
ellipse.Fill = new SolidColorBrush(Colors.Blue);
stackPanel.Children.Add(ellipse);
TextBlock textBlock = new TextBlock();
textBlock.Text = "VisualBrush";
stackPanel.Children.Add(textBlock);
Button button = new Button();
button.Content = "按钮";
stackPanel.Children.Add(button);
stackPanel.Background = new SolidColorBrush(Colors.White);
visualBrush.Visual = stackPanel;
rectangle.Fill = visualBrush;

  以上是ImageBrush、DrawingBrush以及VisualBrush三种画刷的示例用法，在实际的应用中，当然不止这么简单的用法，因此这里只算是一个简单的总结，如有错误，欢迎留言指正。