如何使用 C# ArcObjects 获取鼠标单击的地理坐标

Question

我在 ArcGIS 中有一个 ArcObjects C# 工具（大部分代码可在 Stack Exchange 上找到），当用户单击地图中的某个位置时，它可以识别地图坐标。这是我使用的代码：

    public override void OnMouseDown(int Button, int Shift, int X, int Y)
    {
        if (Button == 1)
        {
            ESRI.ArcGIS.Display.IScreenDisplay screenDisplay = (m_application.Document as IMxDocument).ActiveView.ScreenDisplay;
            ESRI.ArcGIS.Geometry.IPoint point = screenDisplay.DisplayTransformation.ToMapPoint(X, Y);

            MessageBox.Show("X position is " + point.X.ToString() + " Y position is " + point.Y.ToString());
        }
    }

我们的地图使用英尺单位，因此该工具会显示英尺坐标。我怎样才能让这个工具返回度-分-秒？ ESRI 的标准识别工具可以做到这一点，这也是我希望获得类似结果的工具。

Answer 1

您必须首先将屏幕点转换为地图当前坐标系，然后您需要将该点投影到 WGS84 中，然后转换为度分秒。我在下面创建了一个类。不客气，伙计。

实施

Public Overrides Sub OnMouseDown(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Integer, ByVal Y As Integer)
    Dim getMethod As New DecimalDegreesToDegreesMinutesSeconds
    getMethod.PointFromScreenPoint(X, Y)
End Sub

    Public Class DecimalDegreesToDegreesMinutesSeconds
' Used by both
Private pSpRFc As ESRI.ArcGIS.Geometry.SpatialReferenceEnvironment

' WGS1984
Private pSpRef1 As ESRI.ArcGIS.Geometry.ISpatialReference
Private pGCS As ESRI.ArcGIS.Geometry.IGeographicCoordinateSystem

'' NAD83 FEET STATEPLANES NC 
'Private pSpRef2 As ESRI.ArcGIS.Geometry.ISpatialReference
'Private pPCS As ESRI.ArcGIS.Geometry.IProjectedCoordinateSystem

Private ReadOnly Property WGS84() As ESRI.ArcGIS.Geometry.ISpatialReference
    Get
        ' WGS1984
        pSpRFc = New ESRI.ArcGIS.Geometry.SpatialReferenceEnvironment
        pGCS = pSpRFc.CreateGeographicCoordinateSystem(4326)
        pSpRef1 = pGCS
        pSpRef1.SetFalseOriginAndUnits(-180, -90, 1000000)
        Return pSpRef1
    End Get
End Property

' pass the original screen point into this function
Public Sub PointFromScreenPoint(pX As Double, pY As Double)
    Dim scrDisp As ESRI.ArcGIS.Display.IScreenDisplay = Nothing
    Dim pnt As ESRI.ArcGIS.Geometry.IPoint = Nothing
    Dim pGeoSpRef As ESRI.ArcGIS.Geometry.IGeometry = Nothing

    Try
        '
        scrDisp = New ESRI.ArcGIS.Display.ScreenDisplay
        scrDisp = SGProperties.pActiveView.ScreenDisplay ' the activeview
        scrDisp.StartDrawing(scrDisp.hDC, CShort(ESRI.ArcGIS.Display.esriScreenCache.esriNoScreenCache))
        '
        pnt = scrDisp.DisplayTransformation.ToMapPoint(pX, pY)
        '
        pGeoSpRef = pnt
        pGeoSpRef.SpatialReference = SGProperties.pMap.SpatialReference ' the current maps
        pGeoSpRef.Project(WGS84())

        Windows.Forms.MessageBox.Show("X position is " + ConvertDegrees(pnt.X, DegreesType.Longitude).ToString() + " Y position is " + ConvertDegrees(pnt.Y, DegreesType.Latitude).ToString())
    Catch ex As Exception

    Finally
        If scrDisp IsNot Nothing Then System.Runtime.InteropServices.Marshal.ReleaseComObject(scrDisp)
        scrDisp = Nothing
        If pnt IsNot Nothing Then System.Runtime.InteropServices.Marshal.ReleaseComObject(pnt)
        pnt = Nothing
        If pGeoSpRef IsNot Nothing Then System.Runtime.InteropServices.Marshal.ReleaseComObject(pGeoSpRef)
        pGeoSpRef = Nothing
    End Try
End Sub

Enum DegreesType
    Latitude
    Longitude
End Enum

Private Function ConvertDegrees(pInDegrees As Double, pInType As DegreesType)
    Dim degrees As Integer
    Dim submin As Double
    Dim minutes As Double
    Dim subsecsonds As Double
    Dim direction As String
    Dim output As String

    Try

        degrees = Math.Truncate(pInDegrees)
        submin = Math.Abs((pInDegrees - Math.Truncate(pInDegrees)) * 60)
        minutes = Math.Truncate(submin)
        subsecsonds = Math.Abs((submin - Math.Truncate(submin)) * 60)
        direction = ""

        If pInType.ToString().Trim().ToUpper() = "Latitude".ToUpper() Then
            If degrees < 0 Then
                direction = "S"
            ElseIf (degrees > 0) Then
                direction = "N"
            Else
                direction = ""
            End If
        ElseIf pInType.ToString().Trim().ToUpper() = "Longitude".ToUpper() Then
            If degrees < 0 Then
                direction = "W"
            ElseIf (degrees > 0) Then
                direction = "E"
            Else
                direction = ""
            End If
        End If

        output = degrees.ToString() + ":" + minutes.ToString() + ":" + subsecsonds.ToString().Substring(0, 5) + direction

        Return output
    Catch ex As Exception
        Return Nothing
    End Try
End Function

结束类

Answer 2

在获取坐标之前，您可以轻松更改 IDisplayTransformation 对象的地图单位：

        ESRI.ArcGIS.Display.IDisplayTransformation displayTransformation = screenDisplay.DisplayTransformation;
        displayTransformation.Units = ESRI.ArcGIS.esriSystem.esriUnits.esriMeters; // or another unit
        ESRI.ArcGIS.Geometry.IPoint point = displayTransformation.ToMapPoint(X, Y);

您可以获取有关不同 ESRI 单位的信息here