Frustrated, Bothered and Bewildered (Form AutoScroll Broken)

[eBob.com]

I have a nearly empty form. In the designer I set Autoscroll to True. At
run time I dynamically add a DataGridView which is larger than the form.
That should result in Form scroll bars (the DataGridView is larger than the
form) but does not. Unless I squeeze the form down to a really small size.

All of many attempts to reproduce the problem in a really simple program
have failed. But the code that fails is fairly brief and simple. So I have
included it below and hope that someone who is bored today might take a look
and see if they spot anything, or maybe even try it.

In the designer I create a button named btnSpecifyFolder (drive/folder info
is used to populate the DataGridView), a FolderBrowserDiaglog (default name)
and set the form AutoScroll to True. I also set the size of the form so
that once the
DataGridView is added the scroll bars will be required.

Thanks for any help you can give me. Code's below. Bob

Option Strict On
Option Explicit On

Imports System.IO
Imports System.ComponentModel


Public Class Form1

Class MasterDGVRowTag ' used for rows in the MasterDGV

End Class

Dim DriveFolder As String
Dim di As DirectoryInfo
Dim MasterDGV As DataGridView
Dim diArray As DirectoryInfo()

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

End Sub

Private Sub btnSpecifyFolder_Click(ByVal sender As System.Object, ByVal
e As System.EventArgs) Handles btnSpecifyFolder.Click
Dim FBDresult As Integer = FolderBrowserDialog1.ShowDialog()
If FBDresult = DialogResult.OK Then
DriveFolder = FolderBrowserDialog1.SelectedPath
'MsgBox("selectedpath is """ & DriveFolder & """")
di = New DirectoryInfo(DriveFolder)
End If

diArray = di.GetDirectories
CreateMasterDGV() ' go create and populate the MasterDGV

Me.Controls.Add(MasterDGV)
End Sub

Sub CreateMasterDGV()

'
' create empty DGV
'

MasterDGV = New DataGridView

With MasterDGV
.Anchor = DirectCast(AnchorStyles.Bottom + AnchorStyles.Left +
AnchorStyles.Right + AnchorStyles.Top, AnchorStyles)

End With

SetupMasterDGV(MasterDGV)

AddHandler MasterDGV.CellMouseClick, AddressOf
MasterDGV_CellMouseClick

'
' now populate the MasterDGV
'

For Each directory As DirectoryInfo In diArray
Try
AddRow2(directory.Name, directory.LastAccessTime,
directory.CreationTime, directory.LastWriteTime)
Catch
End Try
Next

MasterDGV.Height = MasterDGV.Rows.Item(0).Height *
MasterDGV.Rows.Count _
+ MasterDGV.ColumnHeadersHeight ' set height of Master seg.
we've been working on
End Sub

Sub AddRow2(ByRef dirname As String, _
ByRef lat As Date, ByRef law As Date, ByRef cd As Date)

Dim AddedRowIndex As Integer

Dim dgvr As New DataGridViewRow
dgvr.CreateCells(MasterDGV)
dgvr.Cells(0).Value = "+"
dgvr.Cells(1).Value = dirname
'dgvr.Cells(2).Value = filename
dgvr.Cells(3).Value = lat
dgvr.Cells(4).Value = cd
dgvr.Cells(5).Value = law
'dgvr.Cells(6).Value = length
AddedRowIndex = MasterDGV.Rows.Add(dgvr) ' add row, get newly added
row's index
'MasterDGV.Rows.Item(AddedRowIndex).Tag = New MasterDGVRowTag(True,
False)
MasterDGV(1, 1).ToolTipText = "detail data"

End Sub 'AddRow2

Private Sub MasterDGV_CellMouseClick(ByVal sender As Object, ByVal e As
DataGridViewCellMouseEventArgs)

If e.RowIndex = -1 Then Exit Sub ' ignore clicks in header row

End Sub

Sub SetupMasterDGV(ByVal dgv As DataGridView)

' the Height is not set here as that has to be set after it is
populated

dgv.ColumnCount = 7

With dgv

.Location = New Point(0, 40)

.AllowUserToOrderColumns = False ' because this doesn't work
when the master table is segmented

.Width = 500

.ColumnHeadersBorderStyle = DataGridViewHeaderBorderStyle.Single

With .ColumnHeadersDefaultCellStyle
.BackColor = Color.Navy
.ForeColor = Color.White
.Font = New Font(MasterDGV.Font, FontStyle.Bold)
End With

.CellBorderStyle = DataGridViewCellBorderStyle.Single
.GridColor = Color.Black
.RowHeadersVisible = False
.ScrollBars = ScrollBars.Horizontal

.AllowUserToAddRows = False
.AllowUserToDeleteRows = False
.AllowUserToOrderColumns = True
.ReadOnly = True

With .Columns(0)
.Width = 20
.ValueType = GetType(String)
End With

With .Columns(1)
.Name = "Directory"
.ValueType = GetType(String)
.Width = 200
End With

With .Columns(2)
.Name = "FileName"
.ValueType = GetType(String)
End With

With .Columns(3)
.Name = "Last Accessed"
.ValueType = GetType(Date)
.Width = 150
End With

With .Columns(4)
.Name = "Create Date"
.ValueType = GetType(Date)
.Width = 150
.Visible = False
End With

With .Columns(5)
.Name = "Last Written"
.ValueType = GetType(Date)
.Width = 150
.Visible = False
End With

With .Columns(6)
.Name = "Size"
.ValueType = GetType(Long)
.DefaultCellStyle.Format = "n0"
.HeaderCell.Style.Alignment =
DataGridViewContentAlignment.MiddleRight
.DefaultCellStyle.Alignment =
DataGridViewContentAlignment.MiddleRight
End With

.SelectionMode = DataGridViewSelectionMode.FullRowSelect
.MultiSelect = False

End With

End Sub 'SetupMasterDGV

End Class

 

[Armin Zingler]

MasterDGV = New DataGridView

With MasterDGV
.Anchor = DirectCast(AnchorStyles.Bottom +
AnchorStyles.Left + AnchorStyles.Right + AnchorStyles.Top,
AnchorStyles)
End With

If you anchor the control, it is automatically resized and is never larger
than the Form. Consequently, no scrollbars are shown.

(BTW, if you replace "+" by "Or", you can remove DirectCast; because
the AnchorStyles Enum has an attached Flags-attribute)


Armin

 

[eBob.com]

If you anchor the control, it is automatically resized and is never larger
than the Form. Consequently, no scrollbars are shown.

(BTW, if you replace "+" by "Or", you can remove DirectCast; because
the AnchorStyles Enum has an attached Flags-attribute)


Armin

Thank you Armin. I suspected something along those lines but commented out
the Anchor setting and got the same result. Of course I didn't realize that
I was setting the Anchor property in two places!!!!

If I have my head correctly wrapped around this, then there is no way for a
DataGridView, via anchoring, to take advantage of the user making the form
larger without paying a penalty when the user makes the form smaller. The
form is not going to provide a scroll bar when the form is made too small
because the control is anchored. And it doesn't do any good to specify
scroll bars for the DataGridView because it's been resized to the point
where a scroll bar is not necessary. That's what I conclude since I have a
horizontal scroll bar for the DataGridView which I never see when it is
anchored and I make the form too small.

BTW, a hack which gets the result I'd like to see is to place an invisible
label just to the lower, right of the DataGridView. (There's already a
button in the upper, left.)

When I have a chance I will have to investigate docking. Maybe that will
work the way I'd like it too. Otherwise, if I decide it's really worth it,
I can do whatever my little heart pleases in a Form.SizeChanged event
handler.

Thanks for the tip re Or'ing the AnchorStyles Enums. I was surprised when I
needed, or thought I needed, the DirectCast but didn't take the time to
investigate. I have never looked into the Flags-attribute.

Thanks again, Bob