[转帖]MO自定义符号之二（将点显示为水池符号）

这里再讲一个VB下自定义符号的应用实例，那就是将点显示为一个水池，如下图所示。
<P><a href="http://edu.bjenv.com/blog/uploadfile/2005516184544481.jpg" target="_blank" ><IMG src="http://edu.bjenv.com/blog/uploadfile/2005516184544481.jpg" border=0></A></P>
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<P>罗嗦的话就不说了，直接贴代码：</P>
<P>Option Explicit</P>
<P>Implements AFCustom.ICustomMarker</P>
<P>' data members<BR>Private m_pen As Long<BR>Private m_oldPen As Long<BR>Private m_size As Long<BR>Private m_Style As WsNodeStyle</P>
<P>' win32 api functions<BR>Private Declare Function SelectObject Lib "gdi32" (ByVal hDC As Long, ByVal hObject As Long) As Long<BR>Private Declare Function CreatePen Lib "gdi32" (ByVal nPenStyle As Long, ByVal nWidth As Long, ByVal crColor As Long) As Long<BR>Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long</P>
<P>Private Declare Function LineTo Lib "gdi32" (ByVal hDC As Long, ByVal x As Long, ByVal y As Long) As Long<BR>Private Declare Function MoveToEx Lib "gdi32" (ByVal hDC As Long, ByVal x As Long, ByVal y As Long, lpPoint As Long) As Long<BR>Private Declare Function Ellipse Lib "gdi32" (ByVal hDC As Long, ByVal x1 As Long, ByVal y1 As Long, ByVal x2 As Long, ByVal y2 As Long) As Long</P>
<P>Private Sub Class_Initialize()<BR>  m_Style = WsWaterTankNode<BR>End Sub</P>
<P>Public Property Let SymbolStyle(ByVal vData As WsNodeStyle)<BR>    m_Style = vData<BR>End Property</P>
<P>Public Property Get SymbolStyle() As WsNodeStyle<BR>    SymbolStyle = m_Style<BR>End Property</P>
<P>Public Sub ICustomMarker_Draw(ByVal hDC As Long, ByVal x As Long, ByVal y As Long)<BR>  Select Case m_Style<BR>  Case WsWaterTankNode '水池<BR>    MoveToEx hDC, x - m_size, y - m_size, 0<BR>    LineTo hDC, x - m_size, y<BR>    LineTo hDC, x + m_size, y<BR>    LineTo hDC, x + m_size, y - m_size<BR>    MoveToEx hDC, x - m_size, Int(y - m_size * 2 / 5), 0<BR>    LineTo hDC, x + m_size, Int(y - m_size * 2 / 5)<BR>  Case Else<BR>    Ellipse hDC, x - m_size, y - m_size, x + m_size, y + m_size<BR>  End Select<BR>End Sub</P>
<P>Public Sub ICustomMarker_ResetDC(ByVal hDC As Long)<BR>  SelectObject hDC, m_oldPen<BR>  DeleteObject m_pen<BR>End Sub</P>
<P>Public Sub ICustomMarker_SetupDC(ByVal hDC As Long, ByVal dpi As Double, ByVal pBaseSym As Object)<BR>  m_pen = CreatePen(0, 1, pBaseSym.Color)<BR>  m_oldPen = SelectObject(hDC, m_pen)<BR>  m_size = pBaseSym.Size<BR>End Sub</P>

用位图表示时，如果点很多，两三万个，会出现刷新很慢，不知道有什么好的解决方法没有？

<P>这个东东不错，顶一下</P>

这个东西很好，很实用，版主能给点设计思路吗？

不错，MO中也有这样的自定义特征符号的例子，但是如果特征点的符号差别变化不大时VB中用位图来表示最方便。