在WPF中自定义你的绘制（二）

                                                   在WPF中自定义你的绘制（二）
                                                                   周银辉

1，绘制几何图形
也许你在使用WPF进行开发的时候已经注意到一个很有意思的现象，要在屏幕上显示一个圆形（椭圆），你可以使用Ellipse对象，如下面的代码所示：

< Grid >
           < Ellipse  Fill ="#FFFFFFFF"  Stroke ="#FF000000"  Margin ="61,36,100,0"  VerticalAlignment ="Top"  Height ="33" />        
     </ Grid >

< GeometryDrawing   Brush ="Blue" >
          < GeometryDrawing .Geometry >
                     < EllipseGeometry  Center ="50,50"  RadiusX ="20"  RadiusY ="45"   />
          </ GeometryDrawing.Geometry >             
          < GeometryDrawing .Pen >
                       < Pen  Thickness ="1"  Brush ="Black"   />
          </ GeometryDrawing.Pen >
</ GeometryDrawing >

protected   override   void  OnRender(DrawingContext dc)
         {
            base.OnRender(dc);

            Geometry ellipse = new EllipseGeometry(new Point(100, 70), 100, 50);
            GeometryDrawing drawing = new GeometryDrawing(Brushes.LightBlue, new Pen(Brushes.Green,1), ellipse);

            dc.DrawDrawing(drawing);
        }

效果如下图：

其他基本几何图形（如RectangleGeometry,LineGeometry等）与此类似。

2, 绘制图片
最简单的使用图片的方式当然是利用Image控件，就像以前我们使用PictureBox一样，但更多的我们是使用自定义方式来绘制，ImageDrawing 对象为我们绘制图片提供了方便。

  protected   override   void  OnRender(DrawingContext dc)
         {
            base.OnRender(dc);
            BitmapImage bmp = new BitmapImage(new Uri("http://images.cnblogs.com/logo.gif", UriKind.Absolute));
            ImageDrawing drawing = new ImageDrawing(bmp, new Rect(10, 10, 326, 43));
            dc.DrawDrawing(drawing);
        }

< 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" >
    
     <!--  The example shows how to use different property settings of Glyphs objects.  -->
     < Canvas
         xmlns ="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x ="http://schemas.microsoft.com/winfx/2006/xaml"
        Background ="PowderBlue"
     >
        
         < Glyphs
             FontUri              = "C:\WINDOWS\Fonts\ARIAL.TTF"
            FontRenderingEmSize  = "36"
            StyleSimulations     = "ItalicSimulation"
            UnicodeString        = "Hello World!"
            Fill                 = "SteelBlue"
            OriginX              = "50"
            OriginY              = "75"
         />
        
         <!--  "Hello World!" with default kerning  -->
         < Glyphs
             FontUri              = "C:\WINDOWS\Fonts\ARIAL.TTF"
            FontRenderingEmSize  = "36"
            UnicodeString        = "Hello World!"
            Fill                 = "Maroon"
            OriginX              = "50"
            OriginY              = "150"
         />
        
         <!--  "Hello World!" with explicit character widths for proportional font  -->
         < Glyphs
             FontUri              = "C:\WINDOWS\Fonts\ARIAL.TTF"
            FontRenderingEmSize  = "36"
            UnicodeString        = "Hello World!"
            Indices              = ",80;,80;,80;,80;,80;,80;,80;,80;,80;,80;,80"
            Fill                 = "Maroon"
            OriginX              = "50"
            OriginY              = "225"
         />
        
         <!--  "Hello World!" with fixed-width font  -->
         < Glyphs
             FontUri              = "C:\WINDOWS\Fonts\COUR.TTF"
            FontRenderingEmSize  = "36"
            StyleSimulations     = "BoldSimulation"
            UnicodeString        = "Hello World!"
            Fill                 = "Maroon"
            OriginX              = "50"
            OriginY              = "300"
         />
        
         <!--  "Open file" without "fi" ligature  -->
         < Glyphs
             FontUri              = "C:\WINDOWS\Fonts\TIMES.TTF"
            FontRenderingEmSize  = "36"
            StyleSimulations     = "BoldSimulation"
            UnicodeString        = "Open file"
            Fill                 = "SlateGray"
            OriginX              = "400"
            OriginY              = "75"
         />
        
         <!--  "Open file" with "fi" ligature  -->
         < Glyphs
             FontUri              = "C:\WINDOWS\Fonts\TIMES.TTF"
            FontRenderingEmSize  = "36"
            StyleSimulations     = "BoldSimulation"
            UnicodeString        = "Open file"
            Indices              = ";;;;;(2:1)191"
            Fill                 = "SlateGray"
            OriginX              = "400"
            OriginY              = "150"
         />
    
     </ Canvas >


</ Page >

在《在WPF中自定义你的绘制（三）》中我们会继续讨论自定义绘制中更深入的话题：合并绘制、利用路径绘制图形、将我们的绘制转变为画刷，谢谢！