Conditional formatting of DataGridView cell data - Change color on negative - vb.net

Question

I was hoping to be able to use color based conditional formatting in the DefaultCellStyle.Format field for DataGridView cells, in a similar way to how Excel handles this.
For example in Excel, a format string of £#,##0.00;[Red]-£#,##0.00 will display negative values in red.
Is this supported in VB.NET ?
I am aware I can use the .CellFormatting event to conditionally change cell text color but was looking for a less bulky and restrictive way of doing this.

Answer 1

By creating the following CellFormatting addition, I am able to use Excel style conditional colour formatting in the cells format field. Setting the colour for negative/positive/zero values is supported.
Format string is expected to be in the following format (all colours optional) :
[colour]<format for +value> ; [colour]<format for -value> ; [colour]<format for zero value>
..a test DGV column with conditional formatting
c = New DataGridViewColumn
c.Name = "AmountOUT"
c.DataPropertyName = c.Name
c.HeaderText = "AmountOUT"
c.CellTemplate = New DataGridViewTextBoxCell
c.DefaultCellStyle.Format = "[Green]£0.00;[Red]-£0.00;[Blue]zero"
.Columns.Add(c)
..
Private Sub DataGridView1_CellFormatting(sender As Object, e As DataGridViewCellFormattingEventArgs) Handles DataGridView1.CellFormatting
'Split format string to positive / negative / zero components
Dim posnegzero As List(Of String)
posnegzero = e.CellStyle.Format.Split(CChar(";")).ToList
Dim coloursPNZ As New List(Of String)
Dim remainderformatPNZ As String = ""
For Each s As String In posnegzero
If s.Contains("[") And s.Contains("]") Then
'Extract [xxx] contents
coloursPNZ.Add(s.Substring(s.IndexOf("[") + 1, s.IndexOf("]") - s.IndexOf("[") - 1))
'Append rebuilt format excluding [xxx]
remainderformatPNZ &= s.Substring(0, s.IndexOf("[")) & s.Substring(s.IndexOf("]") + 1, s.Length - s.IndexOf("]") - 1) & ";"
Else
coloursPNZ.Add("")
remainderformatPNZ &= s & ";"
End If
Next
'Set format excluding any [xxx] components
e.CellStyle.Format = remainderformatPNZ
'Check for positive value
If Val(e.Value) > 0 And coloursPNZ.Count >= 1 Then
If coloursPNZ(0) <> "" Then
e.CellStyle.ForeColor = Color.FromName(coloursPNZ(0))
End If
End If
'Check for negative value
If Val(e.Value) < 0 And coloursPNZ.Count >= 2 Then
If coloursPNZ(1) <> "" Then
e.CellStyle.ForeColor = Color.FromName(coloursPNZ(1))
End If
End If
'Check for zero value
If Val(e.Value) = 0 And coloursPNZ.Count >= 3 Then
If coloursPNZ(2) <> "" Then
e.CellStyle.ForeColor = Color.FromName(coloursPNZ(2))
End If
End If
End Sub

Answer 2

Dim dgv As DataGridView = Me.DataGridView1
For i As Integer = 0 To dgv.Rows.Count - 1
For ColNo As Integer = 4 To 7 ' number columns
If Not dgv.Rows(i).Cells(ColNo).Value < 0 Then
dgv.Rows(i).Cells(ColNo).Style.BackColor = vbcolor.Red
End If
Next
Next
checking for negative values lookout for strings format and check accordingly
Tryparse will convert the input to an integer if it succeeds - you don't need both the comps and value variables. Here's an example of how it works:
Dim comps As Integer
Dim input As String = "im not an integer"
Dim input2 As String = "2"
'tryparse fails, doesn't get into comps < 0 comparison
If Integer.TryParse(input, comps) Then
If comps < 0 Then
'do something
End If
Else
'I'm not an integer!
End If
'tryparse works, goes into comps < 0 comparison
If Integer.TryParse(input2, comps) Then
If comps < 0 Then
'do something
End If
End If