Hi,

 I've been programmatically formatting some ultragrids using visibleposition and have been noticing some odd side effects, particularly with calculated object properties and button controls.

Does the Band insist the columns have a sequential VisiblePosition order under the hood? If I set a column to VisiblePosition 1000 will the Visible Position change to (maxcolumns-1)? If I change column 1's visible position to the same visible position of column 2, will column 2's visible position change to that of column 1? Is it safe to set visible positions starting with the left most column and working forwards?

Thanks

Jim

Spodgy said:

Does the Band insist the columns have a sequential VisiblePosition order under the hood?

Yes.

Spodgy said:

If I set a column to VisiblePosition 1000 will the Visible Position change to (maxcolumns-1)?

I'm not certain what actually happens here.  What you've described is the most likely scenario; otherwise, I'd expect the grid to throw an exception.

Spodgy said:

If I change column 1's visible position to the same visible position of column 2, will column 2's visible position change to that of column 1?

I believe so, but I'd have to test it to be certain, and I don't have an environment set up to do so right away.  The way I recall this is by picturing "removing" the column from its current position, shifting all the columns between it and the destination to fill the space, then putting the column in the destination.  However, I don't recall with 100% certainty what happens when you move a column toward the "right" (increasing its visible position), and it's not a suggested approach.

Spodgy said:

Is it safe to set visible positions starting with the left most column and working forwards?

Not only is this safe, this is the suggested approach.  By doing this, as you set subsequent column header positions, you won't "clobber" any positions you've already set.

Should it work if positions are not 0 1 2 3 4 5 6 and so on, but 0 4 5 6 2 3 1 ?

I have a problem that VisiblePosition doesn't work. May be here is the problem?

Thank you!

You need to set the positions in order from 0 up. Otherwise, a later position change might affect a previous one. For example, suppose you have 4 columns:

ABCD

And you want to arrange them like this:

DCAB

If you set the VisiblePositions in order of the columns like so:

columns["A"].Header.VisiblePosition = 2;
columns["B"].Header.VisiblePosition = 3;
columns["C"].Header.VisiblePosition = 1;
columns["D"].Header.VisiblePosition = 0;

This will not work right. To understand why, let's go through the process step-by-step:

ABCD

A = 2

BCAD

B = 3

CADB - We already run into a problem here, because column A has been shifted out of position by the movement of column B.

If we do in the position order, it works correctly:

ABCD

D = 0

DABC

C = 1

DCAB

A = 2 ( no change)

B = 3 ( no change)

What I have done in the past to make this easier for myself is create a class that stores the column and the position that I want without affecting the grid. Then sort the list in position order and apply them to the grid in order.

I have attached a sample project here with a class called WinGridColumnPositioner that does this. You just add the columns to the Positoner class itself and call the position method and it takes care of positioning the columns in order by position.

The WinGridColumnPositioner Class in VB for anyone still stuck in the ice age such as myself.

Private Class WinGridColumnPositioner

Private band As UltraGridBand
Private columnPositions As Dictionary(Of Integer, UltraGridColumn) = New Dictionary(Of Integer, UltraGridColumn)

Public Sub AddColumnPosition(column As UltraGridColumn, visiblePosition As Integer)

If Me.band Is Nothing Then
Me.band = column.Band
End If

If column.Band IsNot Me.band Then
Throw New ArgumentException("All columns added to the positioner must be from the same band")
End If

If Me.columnPositions.Values.Contains(column) Then
Throw New ArgumentException("Cannot add the same column to the list twice")
End If

Me.columnPositions.Add(visiblePosition, column)
End Sub

Public Sub Position()
Dim columnCount As Integer = Me.columnPositions.Count
If columnCount = 0 Then
Throw New InvalidOperationException("There are no columns to position")
End If

Dim proccessed As Integer = 0
Dim visiblePosition As Integer = 0

While (proccessed < columnCount)
Dim column As UltraGridColumn
Dim success As Boolean = Me.columnPositions.TryGetValue(visiblePosition, column)
If success Then
column.Header.VisiblePosition = visiblePosition
proccessed += 1
End If
visiblePosition += 1
End While
End Sub
End Class

Private Sub ArrangeMyUltraGridColumns()
Dim columns As ColumnsCollection = Me.myUltraGrid.DisplayLayout.Bands(0).Columns
Dim winGridColumnPositioner As WinGridColumnPositioner = New WinGridColumnPositioner()
winGridColumnPositioner.AddColumnPosition(columns("A"), 0)
winGridColumnPositioner.AddColumnPosition(columns("B"), 1)
winGridColumnPositioner.AddColumnPosition(columns("C"), 2)
winGridColumnPositioner.Position()
End Sub