用VB和MapX实现各种专题图的示例代码

Private Function GetThemeLayerName() As String
'获得专题图层名称
Dim strLayerName As String
Dim nIndex As Integer

nIndex = Combo2.ListIndex
If nIndex < 0 Then
strLayerName = ""
Else
strLayerName = Combo2.List(nIndex)
End If

GetThemeLayerName = strLayerName

End Function

Private Sub Command5_Click()
'创建专题图层

Dim oDs As MapXLib.Dataset
Dim oLayer As MapXLib.Layer
Dim oTheme As MapXLib.Theme
Dim oFields As New MapXLib.Fields
Dim oField As MapXLib.Field
Dim oCoordSys As MapXLib.CoordSys

Dim strLayerName As String
Dim nType As Integer

Dim s As Integer

'改变投影系
Set oCoordSys = Map1.DisplayCoordSys.Clone
SetCoordsys

'设置专题图层
strLayerName = GetThemeLayerName()
If strLayerName = "" Then
MsgBox "请选择绑定图层"
Exit Sub
End If

'设置专题绑定数据集
Set oLayer = Map1.Layers.Item(strLayerName)
Map1.DataSets.RemoveAll
Set oDs = Map1.DataSets.Add(miDataSetLayer, oLayer, oLayer.KeyField)

'获得专题图类型
nType = GetThemeType
If nType = -1 Or nType = 9 Then
MsgBox "请选择专题类型"
Exit Sub
End If

'设置专题图
oFields.RemoveAll
Set oField = oFields.Add(oDs.Fields.Item(2), "data1"

oDs.Themes.RemoveAll
If nType = 1 Or nType = 2 Then
oFields.Add oDs.Fields.Item(3), "data2"

Set oTheme = oDs.Themes.Add(nType, oFields)
ElseIf nType = 9 Then
'Set oTheme = oDs.Themes.Add(nType)
Else
Set oTheme = oDs.Themes.Add(nType, oField)
End If

'还原投影系

Set Map1.DisplayCoordSys = oCoordSys
'Set Map1.NumericCoordSys = oCoordSys
Set Map1.NumericCoordSys = Map1.DisplayCoordSys

End Sub
Sub SetCoordsys()
'设置投影系
Dim oDatum As New MapXLib.Datum

oDatum.Set 0, 0, 0, 0, 0, 0, 0, 0, 0
Map1.DisplayCoordSys.Set miLongLat, oDatum, miUnitDegree
Set Map1.NumericCoordSys = Map1.DisplayCoordSys

End Sub

Private Function GetThemeType() As Integer
'获得专题图类型
Dim nType As Integer, nIndex As Integer

nIndex = Combo1.ListIndex

Select Case nIndex

Case 0 '范围图
nType = 0
Case 1 '柱状图
nType = 1
Case 2 '饼状图
nType = 2
Case 3 '等级符号图
nType = 3
Case 4 '点密度图
nType = 4
Case 5 '独立值图
nType = 5
Case 6 '自动专题图
nType = 6
Case 7 '标注范围专题图
nType = 7
Case 8 '标注独立值专题图
nType = 8
Case 9 '非专题图
nType = 9

Case Else '提示用户选择专题类型
nType = -1

End Select

GetThemeType = nType

End Function

Private Sub Form_Load()

Dim i As Integer, nLayerCount As Integer

'加载专题图类型
Combo1.AddItem "范围图", 0
Combo1.AddItem "柱状图", 1
Combo1.AddItem "饼状图", 2
Combo1.AddItem "等级符号图", 3
Combo1.AddItem "点密度图", 4
Combo1.AddItem "独立值图", 5
Combo1.AddItem "自动专题图", 6
Combo1.AddItem "标注范围专题图", 7
Combo1.AddItem "标注独立值专题图", 8
Combo1.AddItem "非专题图", 9

'加载图层列表

If Map1.Layers.Count > 0 Then
nLayerCount = Map1.Layers.Count
For i = 1 To nLayerCount
Combo2.AddItem Map1.Layers.Item(i).Name, i - 1
Next
End If

End Sub