<b>用VB写的创建椭圆区域的原代码
</b>// FeatureFactory.CreateEllipticalRegion Method
 void CSampleProjectView::CreateEllipse() {
  // Create a new ellipse region and add it to a temporary features layer
  CMapXRectangle rect;
  CMapXFeature createdEllipse;
  if(!rect.CreateDispatch(rect.GetClsid())) {
   TRACE0("Failed to Create rectangle object");
   return;
  }
  try {
   rect.Set(m_Map.GetCenterX(),m_Map.GetCenterY(),m_Map.GetCenterX()+30,m_Map.GetCenterY()+10);
   createdEllipse = m_Map.GetFeatureFactory().CreateEllipticalRegion(rect);
<P>   m_Map.GetLayers().Item("Temp Layer").AddFeature(createdEllipse);
  } catch(COleDispatchException* e) {
   e->ReportError();
   e->Delete();
  } catch(COleException* e) {
   e->ReportError();
   e->Delete();
  }
 }</P>

<P>在VB+Mapx5.0中新建图层及属性的源代码
Private Sub Command1_Click()
 'this sample used the new AddField methods and the LayerInfo object to </P><P>make a new tab
 'file.  for each record in the Us_Cust table (found in mapstats.mdb) </P><P>it adds a point
 'feature to the new table.  for each feature added to the table, </P><P>selected attribute
 'data from Us_Cust is associated with that point (the company name, </P><P>order ammount, city
 'and state).
  Dim rs As DAO.Recordset
      Dim db As DAO.Database
    
      Dim flds As New MapXLib.Fields</P><P>      Dim lyrNew As MapXLib.Layer
      Dim ptNew As New MapXLib.Point
      Dim ftrNew As MapXLib.Feature
      Dim ff As MapXLib.FeatureFactory
      Dim li As New MapXLib.LayerInfo
      Dim rvs As New MapXLib.Rowvalues
      Dim ds As MapXLib.Dataset
    
      'make database connection and get a recordset
      Set db = DBEngine.OpenDatabase("C:\Program Files\MapInfo\MapX </P><P>5.0\data\mapstats.mdb")
      Set rs = db.OpenRecordset("US_Cust")
    
      'we'll use feature factory later</P><P>      Set ff = Map1.FeatureFactory
    
      'define the columnar structure of the new table we're going to </P><P>create
      flds.AddStringField "Company", 50
      flds.AddStringField "City", 50
      flds.AddStringField "State", 2
      flds.AddNumericField "Order_Amt", 12, 2
 
      'define the LayerInfo object
      li.Type = miLayerInfoTypeNewTable
      li.AddParameter "FileSpec", App.Path ; "\custtab.tab"
      li.AddParameter "Name", "mycustomers"
      li.AddParameter "Fields", flds</P><P>    
      'add the new layer to the top of the map
      Map1.Layers.Add li, 1
    
      'make a dataset from the new layer and get its Rowvalues </P><P>collection
      Set lyrNew = Map1.Layers(1)
      Set ds = Map1.Datasets.Add(miDataSetLayer, lyrNew)
      Set rvs = ds.Rowvalues(0)
    
      'for each records in the Us_Cust table we'll make a point feature </P><P>and add it
      'to the newly created layer.  Using the Rowvalues object from </P><P>that layer's
      'dataset we'll supply attribute data for each point feature added</P><P>      rs.MoveFirst
     Do While Not rs.EOF
           rvs.Item("Company").value = rs.Fields("Company")
           rvs.Item("City").value = rs.Fields("City")
           rvs.Item("State").value = rs.Fields("State")
           rvs.Item("Order_Amt").value = rs.Fields("Order_Amt")
        
           ptNew.Set rs.Fields("X"), rs.Fields("Y")
           Set ftrNew = ff.CreateSymbol(ptNew)
           Set ftrNew = lyrNew.AddFeature(ftrNew, rvs)
        
           rs.MoveNext</P><P>      Loop
    
     'close database connection
      Set rs = Nothing
     Set db = Nothing
 End Sub
</P>

不错！！
<img src="images/post/smile/dvbbs/em01.gif" />

<P>下面是简单的绑定X/Y的例子，</P>
<P>Dim BindLayerObject As New MapXLib.BindLayer</P>
<P>  Dim flds As New MapXLib.Fields
  Dim conn As New ADODB.Connection
  Dim rst As New ADODB.Recordset
  Dim connstring As String
  Dim sqlstr As String
  </P>
<P>  Dim ds As MapXLib.Dataset
  ' Get the recordset to map</P>
<P>  ' MapStats Access database</P>
<P>  ' Has Longitude, Latitude columns</P>
<P>  connstring = "Provider=SQLOLEDB.1;Persist Security Info=False;User ID=sa" _
                ; ";Initial Catalog=数据库名;Data Source=计算机名"
  conn.Open connstring</P>
<P>  sqlstr = "select * from US_Cust"
  rst.CursorLocation = adUseClient
  rst.Open sqlstr, conn, adOpenStatic, adLockOptimistic</P>
<P>
  rst.MoveLast</P>
<P>    Debug.Print "Record Set has " ; rst.RecordCount ; " records."</P>
<P>  ' Fill in the Bindlayer object</P>
<P>  BindLayerObject.layername = "US Customers"  'Name of new layer</P>
<P>  BindLayerObject.RefColumn1 = "X" ' "Longitude"</P>
<P>  ' Use Column number (one'based!) or Column name</P>
<P>  BindLayerObject.RefColumn2 = "Y" ' "Latitude"</P>
<P>  BindLayerObject.LayerType = miBindLayerTypeXY
  BindLayerObject.FileSpec = App.Path ; "\map\US Customers" ; ".tab"
  'Type for X/Y binding</P>
<P>  Debug.Print "Finished setting up Bind Layer"
  If Dir(App.Path ; "\map\US Customers.*") <> "" Then Kill (App.Path ; "\map\US Customers.*")
  Set ds = Map1.DataSets.Add(miDataSetADO, rst, "testname", "City", , BindLayerObject)</P>
<P>  Debug.Print "Finished adding dataset"
  
  
    Dim ftrs As MapXLib.Features</P>
<P>
  rst.Close
</P>

<img src="images/post/smile/dvbbs/em02.gif" /><img src="images/post/smile/dvbbs/em02.gif" /><img src="images/post/smile/dvbbs/em02.gif" /><img src="images/post/smile/dvbbs/em02.gif" />

谢谢！

<P>比较鼠标当前点和当前屏幕顶点之间X and Y的差距，到达制定范围后就把移动地图</P><P>车辆监控 『轨迹回放』功能用的很多的</P>

<img src="images/post/smile/dvbbs/em01.gif" /><img src="images/post/smile/dvbbs/em02.gif" />

<P>鼠标的坐标超出了当前窗口，给当前窗口的矩形的坐标进行赋值增加，然后移动窗口显示区</P><img src="images/post/smile/dvbbs/em08.gif" /><img src="images/post/smile/dvbbs/em08.gif" />

<img src="images/post/smile/dvbbs/em03.gif" />