WPF and Silverlight 学习笔记(三十):Brush(2)

上一篇文章主要绍介的是Brush中的SolidColorBrush、渐变Brush及TileBrush,本篇将详细探讨TileBrush的三种子类型:ImageBrush、DrawingBrush和VisualBrush。

一、ImageBrush

ImageBrush通过一幅位图填充区域,定义一种Brush。其主要属性即ImageSource指定一幅位图图片。

二、DrawingBrush

DrawingBrush以矢量为源填充区域,与ImageBrush的区别在于其与分辨率无关,在放大时不会出现位图的失真。使用DrawingBrush时通常使用其Drawing属性,其类型为System.Windows.Media.Drawing类对象,Drawing类是一个抽象类,其继承关系如下:

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使用GeometryDrawing绘制几何图形,使用ImageDrawing和VideoDrawing利用图片和视频填充,使用GlyphRunDrawing利用文本填充,使用DrawingGroup可以组合各种Drawing对象。

例如,定义一个完整的Brush,填充后的效果类似于上一篇中线性渐变组合后的效果:

   1: <Window x:Class="WPF_30.Window1"
   2:     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
   3:     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
   4:     Title="Window1" Height="227" Width="444">
   5:     <Window.Resources>
   6:         <DrawingBrush x:Key="MyDrawingBrush">
   7:             <DrawingBrush.Drawing>
   8:                 <DrawingGroup>
   9:                     <DrawingGroup.Children>
  10:                         <GeometryDrawing>
  11:                             <GeometryDrawing.Brush>
  12:                                 <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
  13:                                     <GradientStop Color="Green" Offset="0" />
  14:                                     <GradientStop Color="DarkGreen" Offset="1" />
  15:                                 </LinearGradientBrush>
  16:                             </GeometryDrawing.Brush>
  17:  
  18:                             <GeometryDrawing.Pen>
  19:                                 <Pen Thickness="0.02">
  20:                                     <Pen.Brush>
  21:                                         <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
  22:                                             <GradientStop Color="Black" Offset="0" />
  23:                                             <GradientStop Color="LightGray" Offset="1" />
  24:                                         </LinearGradientBrush>
  25:                                     </Pen.Brush>
  26:                                 </Pen>
  27:                             </GeometryDrawing.Pen>
  28:                             <GeometryDrawing.Geometry>
  29:                                 <RectangleGeometry RadiusX="0.2" RadiusY="0.5"
  30:                                                        Rect="0.02,0.02,0.96,0.96" />
  31:                             </GeometryDrawing.Geometry>
  32:                         </GeometryDrawing>
  33:  
  34:                         <GeometryDrawing>
  35:                             <GeometryDrawing.Brush>
  36:                                 <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
  37:                                     <GradientStop Color="#dfff" Offset="0" />
  38:                                     <GradientStop Color="#0fff" Offset="1" />
  39:                                 </LinearGradientBrush>
  40:                             </GeometryDrawing.Brush>
  41:                             <GeometryDrawing.Geometry>
  42:                                 <RectangleGeometry RadiusX="0.1" RadiusY="0.5"
  43:                                                        Rect="0.1,0.07,0.8,0.5" />
  44:                             </GeometryDrawing.Geometry>
  45:                         </GeometryDrawing>
  46:                     </DrawingGroup.Children>
  47:                 </DrawingGroup>
  48:             </DrawingBrush.Drawing>
  49:         </DrawingBrush>
  50:     </Window.Resources>
  51:     <Grid>
  52:         <Button Content="我的按钮" Margin="10" Background="{StaticResource MyDrawingBrush}"
  53:                 FontSize="78" FontFamily="微软雅黑" FontWeight="Bold">
  54:             <Button.Foreground>
  55:                 <ImageBrush ImageSource="bg.jpg" />
  56:             </Button.Foreground>
  57:         </Button>
  58:     </Grid>
  59: </Window>

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在这个DrawingBrush中,使用到的线性渐变,但它不像上篇例子中的多个图形的组全,它是一个完整的Brush,可以直接作为一个Resource使用。

三、VisualBrush

使用VisualBrush可以将任意的WPF元素(Visual类的子类)组合在一起,从而形成一个Brush。例如实现上例中DrawingBrush实现的效果:

   1: <Window x:Class="WPF_30.Window2"
   2:     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
   3:     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
   4:     Title="Window2" Height="135" Width="300">
   5:     <Window.Resources>
   6:         <VisualBrush x:Key="MyVisualBrush">
   7:             <VisualBrush.Visual>
   8:                 <Grid Width="80" Height="26">
   9:                     <Grid.RowDefinitions>
  10:                         <RowDefinition Height="2*" />
  11:                         <RowDefinition Height="*" />
  12:                     </Grid.RowDefinitions>
  13:                     <Rectangle Grid.RowSpan="2" RadiusX="13" RadiusY="13">
  14:                         <Rectangle.Fill>
  15:                             <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
  16:                                 <GradientStop Color="Green" Offset="0" />
  17:                                 <GradientStop Color="DarkGreen" Offset="1" />
  18:                             </LinearGradientBrush>
  19:                         </Rectangle.Fill>
  20:                         <Rectangle.Stroke>
  21:                             <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
  22:                                 <GradientStop Color="Black" Offset="0" />
  23:                                 <GradientStop Color="LightGray" Offset="1" />
  24:                             </LinearGradientBrush>
  25:                         </Rectangle.Stroke>
  26:                     </Rectangle>
  27:  
  28:                     <Rectangle Margin="3,2" RadiusX="8" RadiusY="12">
  29:                         <Rectangle.Fill>
  30:                             <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
  31:                                 <GradientStop Color="#dfff" Offset="0" />
  32:                                 <GradientStop Color="#0fff" Offset="1" />
  33:                             </LinearGradientBrush>
  34:                         </Rectangle.Fill>
  35:                     </Rectangle>
  36:  
  37:                 </Grid>
  38:             </VisualBrush.Visual>
  39:         </VisualBrush>
  40:     </Window.Resources>
  41:     <Grid>
  42:         <Rectangle Fill="{StaticResource MyVisualBrush}" />
  43:     </Grid>
  44: </Window>

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需注意的是,如果使用DrawingBrush可以实现的效果,尽量使用DrawingBrush而不是VisualBrush,以提高应用程序的性能。

再例如定义一个带“镜面”效果的Brush。

 

 

   1: <Window x:Class="WPF_30.Window3"
   2:     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
   3:     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
   4:     Title="Window3" Height="224" Width="300">
   5:     <Grid>
   6:         <Grid.RowDefinitions>
   7:             <RowDefinition />
   8:             <RowDefinition Height="60"/>
   9:         </Grid.RowDefinitions>
  10:  
  11:         <Grid x:Name="mainUI" IsSharedSizeScope="True" Background="#EEE">
  12:             <Grid.RowDefinitions>
  13:                 <RowDefinition Height="Auto" />
  14:                 <RowDefinition Height="Auto"/>
  15:             </Grid.RowDefinitions>
  16:             <Image Source="cnblogs.gif" Grid.Row="0" />
  17:             <TextBox Text="http://www.cnblogs.com/DragonInSea" Grid.Row="1" />
  18:         </Grid>
  19:  
  20:         <Rectangle Grid.Row="1">
  21:             <Rectangle.LayoutTransform>
  22:                 <ScaleTransform ScaleY="-1" />
  23:             </Rectangle.LayoutTransform>
  24:  
  25:             <Rectangle.Fill>
  26:                 <VisualBrush Visual="{Binding ElementName=mainUI}" />
  27:             </Rectangle.Fill>
  28:  
  29:             <Rectangle.OpacityMask>
  30:                 <LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
  31:                     <GradientStop Offset="0" Color="Transparent" />
  32:                     <GradientStop Offset="1" Color="White" />
  33:                 </LinearGradientBrush>
  34:             </Rectangle.OpacityMask>
  35:         </Rectangle>
  36:  
  37:     </Grid>
  38: </Window>

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