WPF 之 自定义Shape

AMindMap需要一个Line，用以连接父ANode和子ANode，

简单说，就是一头大一头小的线，Wpf自带的Line是没这个功能。

Path可以画，不过，我的想法仍旧是绑定。那只能自己做咯。

图例

正文

既然Line,Rectangle等都是继承自Shape的,直接新建一个类继承自Sharp.

 1 Public Class ALine
 2     Inherits Shape
 3 
 4     Protected Overrides ReadOnly Property DefiningGeometry As System.Windows.Media.Geometry
 5         Get
 6 
 7         End Get
 8     End Property
 9 End Class
10 

继承完Shape，ALine中自动添加了一个需要重写的只读属性，从字面上就可以理解

为自定义shape的内容了。返回一个Geometry，那岂不是嗯嗯嗯？

ALine的属性

一头大一头小的Line也是Line，那就要有两个端点，并且，端点的数值是需要被

绑定的，大声一起说，“DependencyProperty”

  1 
  2 #Region "   X1  DependencyProperty "
  3     ''' <summary>
  4     ''' PropertyComment
  5     ''' </summary>
  6     ''' <remarks></remarks>
  7     Public Shared ReadOnly X1Property As DependencyProperty = _
  8         DependencyProperty.Register(
  9             "X1", GetType(Double), GetType(ALine), New FrameworkPropertyMetadata( _
 10                 0.0, FrameworkPropertyMetadataOptions.AffectsMeasure))
 11 
 12     Public Property X1() As Double
 13         Get
 14             Return GetValue(X1Property)
 15         End Get
 16         Set(ByVal Value As Double)
 17             SetValue(X1Property, Value)
 18         End Set
 19     End Property
 20 #End Region
 21 
 22 #Region "   Y1  DependencyProperty "
 23     ''' <summary>
 24     ''' PropertyComment
 25     ''' </summary>
 26     ''' <remarks></remarks>
 27     Public Shared ReadOnly Y1Property As DependencyProperty = _
 28         DependencyProperty.Register(
 29             "Y1", GetType(Double), GetType(ALine), New FrameworkPropertyMetadata( _
 30                 0.0, FrameworkPropertyMetadataOptions.AffectsMeasure))
 31 
 32     Public Property Y1() As Double
 33         Get
 34             Return GetValue(Y1Property)
 35         End Get
 36         Set(ByVal Value As Double)
 37             SetValue(Y1Property, Value)
 38         End Set
 39     End Property
 40 
 41 #End Region
 42 
 43 #Region "   X2  DependencyProperty "
 44     ''' <summary>
 45     ''' PropertyComment
 46     ''' </summary>
 47     ''' <remarks></remarks>
 48     Public Shared ReadOnly X2Property As DependencyProperty = _
 49         DependencyProperty.Register(
 50             "X2", GetType(Double), GetType(ALine), New FrameworkPropertyMetadata( _
 51                 0.0, FrameworkPropertyMetadataOptions.AffectsMeasure))
 52 
 53     Public Property X2() As Double
 54         Get
 55             Return GetValue(X2Property)
 56         End Get
 57         Set(ByVal Value As Double)
 58             SetValue(X2Property, Value)
 59         End Set
 60     End Property
 61 
 62 #End Region
 63 
 64 #Region "   Y2  DependencyProperty "
 65     ''' <summary>
 66     ''' PropertyComment
 67     ''' </summary>
 68     ''' <remarks></remarks>
 69     Public Shared ReadOnly Y2Property As DependencyProperty = _
 70         DependencyProperty.Register(
 71             "Y2", GetType(Double), GetType(ALine), New FrameworkPropertyMetadata( _
 72                 0.0, FrameworkPropertyMetadataOptions.AffectsMeasure))
 73 
 74     Public Property Y2() As Double
 75         Get
 76             Return GetValue(Y2Property)
 77         End Get
 78         Set(ByVal Value As Double)
 79             SetValue(Y2Property, Value)
 80         End Set
 81     End Property
 82 
 83 #End Region
 84 
 85 #Region "   TailWidth  DependencyProperty "
 86     ''' <summary>
 87     ''' PropertyComment
 88     ''' </summary>
 89     ''' <remarks></remarks>
 90     Public Shared ReadOnly TailWidthProperty As DependencyProperty = _
 91         DependencyProperty.Register(
 92             "TailWidth", GetType(Double), GetType(ALine), New FrameworkPropertyMetadata( _
 93                 3.0, FrameworkPropertyMetadataOptions.AffectsMeasure))
 94     Public Property TailWidth() As Double
 95         Get
 96             Return GetValue(TailWidthProperty)
 97         End Get
 98         Set(ByVal Value As Double)
 99             SetValue(TailWidthProperty, Value)
100         End Set
101     End Property
102 
103 #End Region

这里定义了X1,Y1,X2,Y2,TailWidth,这些属性足够说明，线的位置和尾部粗细。

ALine的内容

一个楔形是怎么画的呢？这只是一个几何问题，还是画一张图说明吧。

Sorry哈，反正就是Atan，sin，cos一通算，画图太费劲了，我就歇了哈。

代码 强制重载的DefiningGeometry

 1 
 2     Protected Overrides ReadOnly Property DefiningGeometry As System.Windows.Media.Geometry
 3         Get
 4             Dim mGeometry As New StreamGeometry
 5             mGeometry.FillRule = FillRule.EvenOdd
 6 
 7             Using context As StreamGeometryContext = mGeometry.Open
 8                 DrawLineGeometry(context)
 9             End Using
10             mGeometry.Freeze()
11             Return mGeometry
12         End Get
13     End Property
14 
15     Private Sub DrawLineGeometry(ByVal context As StreamGeometryContext)
16         Dim theta As Double = Math.Atan2(Y1 - Y2, X1 - X2)
17         Dim sint As Double = Math.Sin(theta)
18         Dim cost As Double = Math.Cos(theta)
19         Dim pt1 As Point = New Point(X2, Y2)
20         Dim pt2 As Point = New Point(X1 - TailWidth * sint, Y1 + TailWidth * cost)
21         Dim pt3 As Point = New Point(X1 + TailWidth * sint, Y1 - TailWidth * cost)
22         context.BeginFigure(pt1, True, True)
23         context.LineTo(pt2, True, True)
24         context.LineTo(pt3, True, True)
25     End Sub

实例

在一个空白窗口中，像使用Line一样。

1 <local:ALine X1="10" Y1="10" X2="100" Y2="100" TailWidth="10" 
2              Fill="LightBlue" 
3              Canvas.Left="93" Canvas.Top="76"
4              >
5 </local:ALine>

就这个效果

我不得不说，这个思路是在网上找到的，既然找到了，给大家分享一下，是一件好事儿。