鹤翔庄气功:VB+MapX编程实现地图数据查询

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VB+MapX编程实现地图数据查询

2004-06-01 14:00作者:citylamp出处:论坛责任编辑:方舟

  综述

  应用MapX控件实现查询的功能并不太难。MapX为我们提供了Find、FindFeature等对象,可以用来实现我们需要的功能。



  1、本程序实现从下列表中选择一个节点,并以此节点为中心进行进行定位的功能(实例以第一层RTUName属性的值进行查询)

Private Sub Command1_Click()
Dim FindObj As MapXLib.Find
Dim FoundFeature As FindFeature
'从要查询的RTU图层生成Find对象,并为这个对象设置要查询的FindDataSet、FindField属性
Set FindObj = Form1.Map1.Layers.Item(1).Find
Set FindObj.FindDataset = Form1.Map1.DataSets("RTU节点" & " dataset")
Set FindObj.FindField = FindObj.FindDataset.Fields("RTUName")

Set FoundFeature = FindObj.Search(Combo1.Text)

Me.Hide
' 关掉AutoRedraw是因为CenterX(Y)的改变就要刷新图层,AutoRedraw打开的话会造成二次刷新
Form1.Map1.AutoRedraw = False
Form1.Map1.CenterX = FoundFeature.CenterX
Form1.Map1.CenterY = FoundFeature.CenterY
Form1.Show

End Sub
  2、把上面的程序稍微改写一下,实现按照用户输入的字段进行查询定位的功能:

Private Sub Command2_Click()

Dim FindObj As MapXLib.Find
Dim FoundFeature As FindFeature
'从要查询的RTU图层生成Find对象,并为这个对象设置要查询的FindDataSet、FindField属性
Set FindObj = Form1.Map1.Layers.Item(1).Find
Set FindObj.FindDataset = Form1.Map1.DataSets("RTU节点" & " dataset")
Set FindObj.FindField = FindObj.FindDataset.Fields("RTUName")

Set FoundFeature = FindObj.Search(Text1.Text)

If FoundFeature.FindRC Mod 10 = 1 Or FoundFeature.FindRC Mod 10 = 2 Then
Me.Hide
' 关掉AutoRedraw是因为CenterX(Y)的改变就要刷新图层,AutoRedraw打开的话会造成二次刷新
Form1.Map1.AutoRedraw = False
Form1.Map1.CenterX = FoundFeature.CenterX
Form1.Map1.CenterY = FoundFeature.CenterY
Form1.Show
Else
MsgBox "不存在该RTU节点!"
End If

End Sub

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