WPF设计の画刷（Brush）

一、什么是画刷

        画刷是是一种渲染方式，用于填充图形形状，如矩形、椭圆、扇形、多边形和封闭路径。在GDI+中，画刷分为以下几种：SolidBrush，TextureBrush，HatchBrush，LinearGradientBrush和PathGradientBrush。在层次关系上，它们都位于System.Drawing空间下，继承自System.Drawing.Brush类。

       画刷主要分为三大类：

1、SolidBrush（实心画刷）我们最常用

    实心画刷是我们用的最多的，也是最简单的一个，其实也就是填充色的意思，一个很简单的例子：

其实这里的Background=Red使用的就是SolidColorBrush，xaml进行解析时，发现Background是Brush类型，刚才我也说了

Brush具有图形转换的能力，最后xaml就会通过Transform把”Red"字符串解析成SolidColorBrush，更直观一点的话，我们可以

用C#代码来描述。

1     public partial class MainWindow : Window
2     {
3         public MainWindow()
4         {
5             InitializeComponent();
6 
7             button1.Background = new SolidColorBrush(Colors.Red);
8         }
9     }

2、GradientBrush(梯度画刷、渐变画刷)

a、线性渐进画刷

<Window x:Class="WpfApplication2.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Canvas>
<Rectangle Canvas.Left="51" Canvas.Top="187" Height="101" Name="rectangle2" Stroke="Black" Width="325">
<Rectangle.Fill>
<LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
<GradientStop Color="Yellow" Offset="0.5"/>
<GradientStop Color="Green" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
</Canvas>
</Window>

得到的效果：

b、圆形梯度画刷

  <Ellipse x:Name="ellipseWithRadialGradientBrush" Height="113.56" Stroke="#FF000000">
   <Ellipse.Fill>
    <RadialGradientBrush>
     <GradientStop Color="#FFA21212" Offset="1"/>
     <GradientStop Color="#FFF8C906" Offset="0"/>
    </RadialGradientBrush>
   </Ellipse.Fill>
  </Ellipse>

效果：

中心偏移：

  <Ellipse x:Name="ellipseWithRadialGradientBrushCenterOffset" Stroke="#FF000000">
   <Ellipse.Fill>
    <RadialGradientBrush GradientOrigin="0.399,0.149">
     <GradientStop Color="#FFA21212" Offset="1"/>
     <GradientStop Color="#FFF8C906" Offset="0"/>
    </RadialGradientBrush>
   </Ellipse.Fill>
  </Ellipse>

3、ImageBrush（图像画刷） 

     顾名思义，就是把图像转换为画刷的方式渲染。

<Window x:Class="WpfApplication7.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:my="clr-namespace:WpfApplication1"
        Title="MainWindow" Height="400" Width="600">
    <Grid>
        <Grid.Background>
            <ImageBrush x:Name="landBrush" ImageSource="C:UsersjohnDesktop	est.gif"/>
        </Grid.Background>
    </Grid>
</Window>

4、VisualBrush（控件画刷）

这个我们可以用来做水印。

首先作为windows资源引入：

        <Window.Resources>
            <VisualBrush x:Key="test" TileMode="Tile" Opacity="0.8">
                <VisualBrush.Visual>
                    <StackPanel>
                        <TextBlock Foreground="Gold">
                       昨夜星辰昨夜风
                        </TextBlock>
                        <TextBlock Foreground="LightBlue">
                       画楼西畔桂堂东
                        </TextBlock>
                        <TextBlock Foreground="LightGray">
                       身无彩凤双飞翼
                        </TextBlock>
                        <TextBlock Foreground="Pink">
                      心有灵犀一点通
                        </TextBlock>
                    </StackPanel>
                </VisualBrush.Visual>
            </VisualBrush>
        </Window.Resources>

5、DrawingBrush（自定义画刷）

<Window x:Class="WpfApplication4.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <DrawingBrush x:Key="test">
            <DrawingBrush.Drawing>
                <DrawingGroup>
                    <DrawingGroup.Children>
                        <GeometryDrawing>
                            <!-- 绘制矩形 -->
                            <GeometryDrawing.Geometry>
                                <RectangleGeometry RadiusX="0.2" RadiusY="0.5"
                                                       Rect="0.02,0.02,0.96,0.96" />
                            </GeometryDrawing.Geometry>
                            <!-- 矩形填充色 -->
                            <GeometryDrawing.Brush>
                                <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
                                    <GradientStop Color="Green" Offset="0" />
                                    <GradientStop Color="Red" Offset="1" />
                                </LinearGradientBrush>
                            </GeometryDrawing.Brush>
                            <!-- 矩形边框 -->
                            <GeometryDrawing.Pen>
                                <Pen Thickness="0.02">
                                    <Pen.Brush>
                                        <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
                                            <GradientStop Color="AliceBlue" Offset="0" />
                                            <GradientStop Color="Black" Offset="1" />
                                        </LinearGradientBrush>
                                    </Pen.Brush>
                                </Pen>
                            </GeometryDrawing.Pen>
                        </GeometryDrawing>
                    </DrawingGroup.Children>
                </DrawingGroup>
            </DrawingBrush.Drawing>
        </DrawingBrush>
    </Window.Resources>
    <Grid>
        <Button Background="{StaticResource ResourceKey=test}" FontSize="40" Content="Button" Height="113" HorizontalAlignment="Left" Margin="89,80,0,0" Name="button1" VerticalAlignment="Top" Width="292" />
    </Grid>
</Window>

6、常见效果举例：

a、头像：

    <Grid>
        <Ellipse x:Name="ellipseWithImageBrush" Stroke="#FF000000" Width="113" Height="113">
            <Ellipse.Fill>
                <ImageBrush ImageSource="Resources/wx_camera_1504279469046.jpg"/>
            </Ellipse.Fill>
        </Ellipse>
    </Grid>

效果：

 b、对称：

XAML代码：
<Ellipse x:Name="ellipseWithDrawingBrush" Stroke="#FF000000" Width="113" Height="113">
  <Ellipse.Fill>
  <DrawingBrush Viewport="0,0,0.5,0.5" TileMode="Tile">
          <DrawingBrush.Drawing>
            <GeometryDrawing Brush="Red">
              <GeometryDrawing.Geometry>
                <GeometryGroup>
                  <EllipseGeometry RadiusX="20" RadiusY="45" Center="50,50" />
                  <EllipseGeometry RadiusX="45" RadiusY="20" Center="50,50" />
                </GeometryGroup>
              </GeometryDrawing.Geometry>
              <GeometryDrawing.Pen>
                <Pen Thickness="10">
                  <Pen.Brush>
                    <LinearGradientBrush>
                      <GradientStop Offset="0.0" Color="Black" />
                      <GradientStop Offset="1.0" Color="Gray" />
                    </LinearGradientBrush>
                  </Pen.Brush>
                </Pen>
              </GeometryDrawing.Pen>
            </GeometryDrawing>
          </DrawingBrush.Drawing>
        </DrawingBrush>
</Ellipse.Fill>
  </Ellipse>

注意ImageBrush中属性的设置和不同的效果

     TileMode="FlipX"
     AlignmentX="Left"
     AlignmentY="Top"
     Viewport="0,0,0.3,0.3"