Graphics drawline scaling vb.net - vb.net

Question

I'm trying to develop a program that has been made by another person.
What I develop is just for showing the measurement point like the picture below.
There are min and max data that appear in the form and it's showing from the smallest to the largest value and every time the mouse moves from left to right, the measuring point value will adjust to the graph value that has been determined as above.
The problem is data accuracy at the measuring point does not match with the value that has been determined, this is because the graphic is out of frame.
Here is the code for showing graphics;
Private Sub UpdateDiaGraph()
Call Me.ClearGraph(Me.gDia, Me.PicDiaGraph)
Call Me.InitializeGraph(Me.gDia, Me.PicDiaGraph, Me.recDia)
If Me.dsData.Tables("Dia").Rows.Count = 0 Then
Exit Sub
End If
Dim drs() As DataRow = Me.dsData.Tables("Dia").Select("", "[PathNo],[EquipmentNo],[Point]")
Dim pathNo As Integer = 0
Dim equipmentNo As Integer = 0
Dim diaCount As Integer = 0
Dim maxPoint As Integer = 0
Dim longestDiaCount As Integer = 0
Dim upper As New List(Of Decimal)
Dim lower As New List(Of Decimal)
For Each dr As DataRow In drs
If pathNo <> dr("PathNo") Or equipmentNo <> dr("EquipmentNo") Then
pathNo = dr("PathNo")
equipmentNo = dr("EquipmentNo")
'Count the graphics
diaCount += 1
' Get standard width
upper.Add(dr("Upper"))
lower.Add(dr("Lower"))
End If
' Get the max number of graph points and the number of graphs at that time
If maxPoint < dr("Point") Then
maxPoint = dr("Point")
longestDiaCount = diaCount
End If
Next
Dim x1, x2 As Decimal
Dim y1, y2 As Decimal
' Get the width to draw the reference line
Dim oneHeight As Decimal = Me.recDia.Height / (diaCount + 1)
'Initialize the graph
For i As Integer = 1 To diaCount
x1 = Me.recDia.Left + 1
x2 = Me.recDia.Left + Me.recDia.Width - 1
y1 = Me.recDia.Top + oneHeight * i
' Tolerance range
'※0.01mm/1 Point
Me.gDia.FillRectangle(New SolidBrush(Me.toleranceRecColor) _
, x1 _
, y1 - upper(diaCount - i) * 100 _
, Me.recDia.Width - 1 _
, (upper(diaCount - i) - lower(diaCount - i)) * 100)
' reference line
Me.gDia.DrawLine(New Pen(Me.centerLineColor), x1, y1, x2, y1)
Next
' Determine the drawing magnification of the X-axis so that the max number of points can be displayed
Dim xMag As Decimal = Me.recDia.Width / maxPoint
'Draw a graph
Dim counter As Integer = 0
Dim centerLineY As Decimal
Dim center As Decimal = 0
Dim p As Integer = -1
pathNo = 0 : equipmentNo = 0
For Each dr As DataRow In drs
' Get reference line and reference value
If pathNo <> dr("PathNo") Or equipmentNo <> dr("EquipmentNo") Then
pathNo = dr("PathNo")
equipmentNo = dr("EquipmentNo")
counter += 1
centerLineY = Me.recDia.Top + oneHeight * (diaCount - (counter - 1))
center = dr("Center")
'Draw chart title and reference value
Dim num As New Common.Numeric
Dim numFormat As String = num.GetNumericFormat(1, 2)
Dim s As String = dr("MeasuringTarget").ToString & ControlChars.CrLf
Dim sSize As Size = TextRenderer.MeasureText(Me.gDia, s, Me.Font)
Me.gDia.DrawString(s, Me.Font, Brushes.White, Me.recDia.Left - sSize.Width - 2, centerLineY - sSize.Height / 2)
s = ControlChars.CrLf & Format(center, numFormat)
sSize = TextRenderer.MeasureText(Me.gDia, s, Me.Font)
Me.gDia.DrawString(s, Me.Font, Brushes.White, Me.recDia.Left - sSize.Width - 2, centerLineY - sSize.Height / 2)
x1 = 0 : x2 = 0 : y1 = 0 : y2 = 0 : p = -1
End If
p += 1
'Change the drawing direction and starting point of the graph depending on the number of direction changes
If Me.extRevCnt.Item(pathNo) Mod 2 = 0 Then
x2 = Me.recDia.Left + p * xMag
Else
x2 = Me.recDia.Left + Me.recDia.Width - p * xMag
End If
y2 = centerLineY - (dr("Data") - center) * 100
If p <> 0 Then
'graph drawing
If Me.recDia.Top < y2 And y2 < Me.recDia.Top + Me.recDia.Height Then
' Change the drawing color of the graph for each outer diameter
If counter < Me.diaGraphColor.Count Then
Me.gDia.DrawLine(New Pen(Me.diaGraphColor(counter)), x1, y1, x2, y2)
Else
Me.gDia.DrawLine(New Pen(Me.graphColor), x1, y1, x2, y2)
End If
End If
' out of tolerance
If dr("DataFlag") = Common.Constant.DataFlag.NG Then
Me.gDia.DrawLine(New Pen(Me.ngColor), x1, centerLineY, x2, centerLineY)
End If
'Draw a scale every 10m * However, only when drawing the longest graph
'Drawn for the first graph (normal mandrel diameter)
If counter = 1 Then
If p Mod 100 = 0 Then
Me.gDia.DrawLine(Pens.White, x2, Me.recDia.Top + Me.recDia.Height, x2, Me.recDia.Top + Me.recDia.Height - 3)
Dim s As String = (p \ 10).ToString & "m"
Dim sSize As Size = TextRenderer.MeasureText(Me.gDia, s, Me.Font)
Me.gDia.DrawString(s, Me.Font, Brushes.White, x2 - sSize.Width / 2, Me.recDia.Top + Me.recDia.Height + 2)
End If
End If
Else
' determine the corners of a polygon
Dim points As Point() = {New Point(x2, centerLineY - 10), New Point(x2 - 10, centerLineY - 40), New Point(x2 + 10, centerLineY - 40)}
Me.gDia.FillPolygon(Brushes.Blue, points, System.Drawing.Drawing2D.FillMode.Alternate)
' Display the division number in the circle above
Dim s As String = dr("DivNo").ToString
Dim sSize As Size = TextRenderer.MeasureText(Me.gDia, s, Me.Font)
Me.gDia.DrawString(s, New Font(Me.Font, FontStyle.Regular), Brushes.White, x2 - sSize.Width / 2 + 2, centerLineY - 35)
End If
x1 = x2
y1 = y2
Next
Type.Variable.divideTargetDia = Me.DGVDataDia.SelectedRows.Item(0).Index
Call Me.DrawingGraphDia(Me.DGVDataDia.SelectedRows.Item(0).Index)
Me.PicDiaGraph.Refresh()
End Sub
Here is the code for showing data pointer
Private Sub PicDiaGraph_Paint(ByVal gDia As Graphics)
If IsNothing(tblDataDia) = True Then Exit Sub
If tblDataDia.Rows.Count = 0 Then Exit Sub
If IsNothing(tblEquipmentNoDia) = True Then Exit Sub
If tblEquipmentNoDia.Rows.Count = 0 Then Exit Sub
' Allocate the drawing range according to the number of device numbers
Dim allHeight As Integer = Me.PicDiaGraph.Size.Height
'Drawing range per device number
Dim heightPerEN As Integer = allHeight / (tblEquipmentNoDia.Rows.Count + 1)
' Device number count
Dim count As Integer = 0
' Draw a graph for each device number
For Each rEN As DataRow In tblEquipmentNoDia.Rows
Dim eNo As Integer = rEN("EquipmentNo")
Dim tblSource As DataTable = tblDataDia.Clone
For Each r As DataRow In tblDataDia.Select("EquipmentNo = '" & eNo & "'", "Point ASC")
tblSource.ImportRow(r)
Next
' Acquisition of standard value
Dim tblStandard As New DataTable
If Me.Today = False Then
Dim SQL As String = ""
SQL &= "SELECT Standard.Center "
SQL &= "FROM Standard "
SQL &= "WHERE Standard.EquipmentNo = " & eNo & " And Standard.MfgID = '" & barcodeNo.Trim & "' "
SQL &= "GROUP BY Standard.Center;"
daDia = New OleDb.OleDbDataAdapter(SQL, cnMdbDia)
daDia.Fill(tblStandard)
Else
'
End If
Dim center As Single = Format(tblStandard.Rows(0)("center"), "0.00")
' Drawing start position (height)
Dim shift As Integer = heightPerEN * count
'get width of data
Dim margin As Integer = 0
_xMaxDia = tblSource.Select("Point = MAX(Point)")(0)("Point")
_xMinDia = tblSource.Select("Point = MIN(Point)")(0)("Point")
Dim yMax As Single = tblSource.Select("Data = MAX(Data)")(0)("Data")
Dim yMin As Single = tblSource.Select("Data = MIN(Data)")(0)("Data")
'Width on X-axis data
Dim xRange As Integer = _xMaxDia - _xMinDia
'Width on Y-axis data
Dim yRange As Single = yMax - yMin
'Get size of control
Dim height As Integer = heightPerEN - (margin * 2)
Dim width As Integer = Me.PicDiaGraph.Size.Width - 21
' Nominal length per unit
_xUnitDia = width / xRange
Dim yUnit As Single = 200
'graph drawing
For i As Integer = 0 To tblSource.Rows.Count - 2
Dim x1 As Decimal = Me.recDia.Left + 1
' starting point data
Dim row1 As DataRow = tblSource.Rows(i)
Dim point1 As Integer = row1("Point")
Dim data1 As Single = row1("Data")
' end point data
Dim row2 As DataRow = tblSource.Rows(i + 1)
Dim point2 As Integer = row2("Point")
Dim data2 As Single = row2("Data")
If point2 < point1 Then MessageBox.Show("X")
Me.gDia.DrawLine(Pens.White, _
CInt((point1 - _xMinDia) * _xUnitDia), _
height - (data1 - center) * yUnit + margin + shift, _
CInt(point2 - _xMinDia) * _xUnitDia, _
height - (data2 - center) * yUnit + margin + shift)
Next
count += 1
Next
End Sub
The problem might appear in this code