Draw the perimiter of a PointF collection?

[troupm]

My brain hurts again.

I want to take a collection of PointF objects and crate a path that is the outer perimiter of the collection, so that I don't get a criss-cross problem. I'm assuming no wierd shapes with undercuts; just a collection of 'border' points. The best I could come up with is a 'Clock Hand' type radial sorting function (below). There HAS to be a better way. Anyone?

(Note: The seGpsPoint object contains a .DrawingPoint property that is a PointF object, everything else is standard)

''' <summary>
''' Sorts the DrawingPoints ofa a collection
''' of seGpsPoints in a clockwise direction
''' for use in drawing a path or polygon around
''' the outer perimeter of the collection
''' </summary>
''' <param name="GPSPointCollection">Collection of seGpsPoints to sort</param>
''' <param name="Bounds">Rectale defining sort area</param>
''' <param name="GraphicsObject">System.Graphics object to scan</param>
''' <returns></returns>
''' <remarks></remarks>

Public Function RadialSort(ByVal GPSPointCollection As Collection, ByVal Bounds As RectangleF, ByVal GraphicsObject As Graphics) As PointF()
Dim oPoint As New Point
Dim oGPS As New seGpsPoint
Dim oColl As New Collection
Dim oTemp As New Collection 'Collection of Points already captured
Dim CenterPt As New Point
Dim oMatrix As New Matrix
Dim iAngle As Integer = 0
'Set Sweep Centerpoint
CenterPt.X = CInt(Bounds.X + Bounds.Width / 2)
CenterPt.Y = CInt(Bounds.Y + Bounds.Height / 2)
Dim oSweepRect As New RectangleF
'Define Sweep Arm rectangle
oSweepRect.Y = CenterPt.Y
'Conservatively define Sweep Arm
oSweepRect.Width = Convert.ToSingle(Math.Max(10, Bounds.Width / 20))
oSweepRect.X = (CenterPt.X - oSweepRect.Width / 2)
'Trig to make sure all points are in Sweep Radius
oSweepRect.Height = Convert.ToSingle(Math.Sqrt(((Bounds.Height / 2) ^ 2 + (Bounds.Width / 2) ^ 2))) + 10
Dim oSweepRegion As New Region(oSweepRect)
'Collection of seGpsPoint Objects, each with a PointF
oColl = GPSPointCollection
'Target PointF Array to be returned length = Collection Count
Dim aryPoints(oColl.Count - 1) As PointF
'Dim return array index counter
Dim iCtr As Integer = 0
'Dim index counter for Rectange Objects
'that will approximate the Sweep Arm using
'the GetRegionScans method
Dim iIndex As Integer = 0
'Define rotation as 1 degree
oMatrix.RotateAt(1, CenterPt)
GraphicsObject.FillRegion(Brushes.Transparent, oSweepRegion)
'Make sure all 360 degrees are covered
For iAngle = 0 To 361
'This will rotate the Matrix by 1 degree
oSweepRegion.Transform(oMatrix)
GraphicsObject.FillRegion(Brushes.Transparent, oSweepRegion)
Dim aryArm() As RectangleF = oSweepRegion.GetRegionScans(oMatrix)
'This is a processor intensive bit
For iIndex = 0 To aryArm.Length - 1
For Each oGPS In GPSPointCollection
If aryArm(iIndex).Contains(oGPS.DrawingPoint) Then
Dim strKey As String
strKey = oGPS.GpsID.ToString
'Don't duplicate points, in case arms
'recapture a point on this iteration
If Not oTemp.Contains(strKey) Then
'Add seGpsPoint object and key to 'already captured' Collection
oTemp.Add(oGPS, oGPS.GpsID.ToString)
aryPoints(iCtr) = oGPS.DrawingPoint
'Increment array index when new point is captured
iCtr += 1
If iCtr = oColl.Count Then
'Commit array and exit when array is full
RadialSort = aryPoints
Exit Function
End If
End If
End If
Next
Next
Next
'This code should never be executed if all is well:
RadialSort = aryPoints
End Function

[Plaguemonkey]

<EDIT>
No wonder it looked familiar. I seriously need sleep.
</EDIT>

Eerie. Too eerie.

I registered just to reply to your post. I will post again if I figure it out before you do . Meanwhile, check out this [V][C]- scratchbuilt for the same issue, straight from my current project:

Public Function RadialSort(ByVal GPSPointCollection As Collection, ByVal Bounds As RectangleF, ByVal GraphicsObject As Graphics, Optional ByVal SweepResolution As Integer = 1, Optional ByVal CloseFigure As Boolean = True) As PointF()
        'On Error Resume Next 'TODO: This is crap

        If GraphicsObject Is Nothing Then Return Nothing


        Dim oPoint As New Point
        Dim oFirstPoint As New Point
        Dim oGPS As New seGpsPoint
        Dim oColl As New Collection
        Dim oTemp As New Collection 'Collection of Points already captured
        Dim CenterPt As New Point
        Dim oMatrix As New System.Drawing.Drawing2D.Matrix
        Dim iAngle As Integer = 0
        'Set Sweep Centerpoint
        CenterPt.X = CInt(Bounds.X + Bounds.Width / 2)
        CenterPt.Y = CInt(Bounds.Y + Bounds.Height / 2)
        Dim oSweepRect As New RectangleF
        'Define Sweep Arm rectangle
        oSweepRect.Y = CenterPt.Y
        'Conservatively define Sweep Arm
        oSweepRect.Width = Convert.ToSingle(Math.Max(10, Bounds.Width / 20))
        oSweepRect.X = (CenterPt.X - oSweepRect.Width / 2)
        'Trig to make sure all points are in Sweep Radius
        oSweepRect.Height = Convert.ToSingle(Math.Sqrt(((Bounds.Height / 2) ^ 2 + (Bounds.Width / 2) ^ 2))) + 10
        Dim oSweepRegion As New Region(oSweepRect)
        'Collection of seGpsPoint Objects, each with a PointF
        oColl = GPSPointCollection
        'Target PointF Array to be returned length = Collection Count
        Dim aryPoints(oColl.Count) As PointF
        If Not CloseFigure Then
            ReDim aryPoints(oColl.Count - 1)
        End If
        Dim iCtr As Integer = 0
        Dim iIndex As Integer = 0
        'Define rotation as [SweepResolution] degrees
        oMatrix.RotateAt(SweepResolution, CenterPt)
        GraphicsObject.FillRegion(Brushes.Transparent, oSweepRegion)
        'Make sure all 360 degrees are covered
        For iAngle = 0 To 361
            'This will rotate the system.drawing.drawing2d.matrix by 1 degree
            oSweepRegion.Transform(oMatrix)
            GraphicsObject.FillRegion(Brushes.Transparent, oSweepRegion)
            Dim aryArm() As RectangleF = oSweepRegion.GetRegionScans(oMatrix)
            'This is a processor intensive bit
            For iIndex = 0 To aryArm.Length - 1
                For Each oGPS In GPSPointCollection
                    If aryArm(iIndex).Contains(oGPS.DrawingPoint) Then
                        Dim strKey As String
                        strKey = oGPS.GpsID.ToString
                        'Don't duplicate points, in case arms overlap on this iteration
                        If Not oTemp.Contains(strKey) Then
                            'Add seGpsPoint object and key to 'already captured' Collection
                            oTemp.Add(oGPS, oGPS.GpsID.ToString)
                            aryPoints(iCtr) = oGPS.DrawingPoint
                            'Increment array index when new point is captured
                            iCtr += 1
                            If iCtr = oColl.Count Then
                                'Set Last Point to FirstPoint to for Closed Figure
                                If CloseFigure Then
                                    aryPoints(iCtr) = aryPoints(0)
                                End If
                                'Commit array and exit when array is full
                                Return aryPoints
                                'RadialSort = aryPoints
                                Exit Function
                            End If
                        End If
                    End If
                Next
            Next
        Next
        'This code should never be executed if all is well:
        RadialSort = aryPoints
    End Function

[kvprajapati]

Welcome Plaguemonkey.

Please read before posting- http://www.daniweb.com/forums/thread78223.html

Thread Closed.