Q: Sending messages

  • Thread starter Thread starter Geoff Jones
  • Start date Start date
G

Geoff Jones

Hiya

I have overriden a DataGrid in Vb.net. During some calculations within this
DataGrid, I would like to be able to send a signal to the form that hosts
the DataGrid e.g. update a progress control in the form as the calculations
in the DataGrid proceed.

I'm uncertain how to proceed. That is, how can I send a signal to the host
form from within the DataGrid?

Thanks in advance

Geoff
 
Hi,

Add a ProgressChanged event to the datagrid. Raise the event when
you want to update the progressbar's value. In the event procedure on the
form update the progressbar.

Ken
-------------------
Hiya

I have overriden a DataGrid in Vb.net. During some calculations within this
DataGrid, I would like to be able to send a signal to the form that hosts
the DataGrid e.g. update a progress control in the form as the calculations
in the DataGrid proceed.

I'm uncertain how to proceed. That is, how can I send a signal to the host
form from within the DataGrid?

Thanks in advance

Geoff
 
Hi Ken

Sorry, you've lost me. I'm uncertain how to "raise" events. Could you give
some example code?

Geoff
 
Hi,

Here is the code for datagrid that will raise an event to let you
the user is about to delete a row. Also prevents the user from resizing a
row or column.


Public Class ConfirmDeleteDataGrid

Inherits DataGrid

Public Event DeletedRow(ByVal sender As Object, ByVal e As EventArgs)

Private Const WM_KEYDOWN = &H100



Public Overrides Function PreProcessMessage(ByRef msg As
System.Windows.Forms.Message) As Boolean

Dim keyCode As Keys = CType((msg.WParam.ToInt32 And Keys.KeyCode), Keys)

If msg.Msg = WM_KEYDOWN And keyCode = Keys.Delete Then

If MessageBox.Show("Delete This Row?", "Confirm Delete", _

MessageBoxButtons.YesNo) = DialogResult.No Then

Return True

Else

RaiseEvent DeletedRow(Me, New EventArgs)

End If

End If

Return MyBase.PreProcessMessage(msg)

End Function

Protected Overrides Function ProcessDialogKey(ByVal keyData As
System.Windows.Forms.Keys) As Boolean

Dim pt As Point

Dim hti As DataGrid.HitTestInfo

pt = Me.PointToClient(Cursor.Position)

hti = Me.HitTest(pt)

If keyData = Keys.Delete Then

If hti.Type = Me.HitTestType.RowHeader Then

If MessageBox.Show("Delete this row?", "Confirm Delete", _

MessageBoxButtons.YesNo) = DialogResult.No Then

Return True

Else

RaiseEvent DeletedRow(Me, New EventArgs)

End If

End If

End If

Return MyBase.ProcessDialogKey(keyData)

End Function



Protected Overrides Sub OnMouseDown(ByVal e As
System.Windows.Forms.MouseEventArgs)

Dim hti As DataGrid.HitTestInfo = Me.HitTest(New Point(e.X, e.Y))

If hti.Type = DataGrid.HitTestType.ColumnResize Or hti.Type =
DataGrid.HitTestType.RowResize Then

Return 'no baseclass call

End If

MyBase.OnMouseDown(e)

End Sub

Public Sub New()

Trace.WriteLine(Me.VertScrollBar.Visible.ToString)

End Sub

Protected Overrides Sub OnMouseMove(ByVal e As
System.Windows.Forms.MouseEventArgs)

Dim hti As DataGrid.HitTestInfo = Me.HitTest(New Point(e.X, e.Y))

If hti.Type = DataGrid.HitTestType.ColumnResize Or hti.Type =
DataGrid.HitTestType.RowResize Then

Return 'no baseclass call

End If

MyBase.OnMouseMove(e)

End Sub


End Class



Ken

-------------------------------
Hi Ken

Sorry, you've lost me. I'm uncertain how to "raise" events. Could you give
some example code?

Geoff
 
Thanks Ken

Ken Tucker said:
Hi,

Here is the code for datagrid that will raise an event to let you
the user is about to delete a row. Also prevents the user from resizing a
row or column.


Public Class ConfirmDeleteDataGrid

Inherits DataGrid

Public Event DeletedRow(ByVal sender As Object, ByVal e As EventArgs)

Private Const WM_KEYDOWN = &H100



Public Overrides Function PreProcessMessage(ByRef msg As
System.Windows.Forms.Message) As Boolean

Dim keyCode As Keys = CType((msg.WParam.ToInt32 And Keys.KeyCode), Keys)

If msg.Msg = WM_KEYDOWN And keyCode = Keys.Delete Then

If MessageBox.Show("Delete This Row?", "Confirm Delete", _

MessageBoxButtons.YesNo) = DialogResult.No Then

Return True

Else

RaiseEvent DeletedRow(Me, New EventArgs)

End If

End If

Return MyBase.PreProcessMessage(msg)

End Function

Protected Overrides Function ProcessDialogKey(ByVal keyData As
System.Windows.Forms.Keys) As Boolean

Dim pt As Point

Dim hti As DataGrid.HitTestInfo

pt = Me.PointToClient(Cursor.Position)

hti = Me.HitTest(pt)

If keyData = Keys.Delete Then

If hti.Type = Me.HitTestType.RowHeader Then

If MessageBox.Show("Delete this row?", "Confirm Delete", _

MessageBoxButtons.YesNo) = DialogResult.No Then

Return True

Else

RaiseEvent DeletedRow(Me, New EventArgs)

End If

End If

End If

Return MyBase.ProcessDialogKey(keyData)

End Function



Protected Overrides Sub OnMouseDown(ByVal e As
System.Windows.Forms.MouseEventArgs)

Dim hti As DataGrid.HitTestInfo = Me.HitTest(New Point(e.X, e.Y))

If hti.Type = DataGrid.HitTestType.ColumnResize Or hti.Type =
DataGrid.HitTestType.RowResize Then

Return 'no baseclass call

End If

MyBase.OnMouseDown(e)

End Sub

Public Sub New()

Trace.WriteLine(Me.VertScrollBar.Visible.ToString)

End Sub

Protected Overrides Sub OnMouseMove(ByVal e As
System.Windows.Forms.MouseEventArgs)

Dim hti As DataGrid.HitTestInfo = Me.HitTest(New Point(e.X, e.Y))

If hti.Type = DataGrid.HitTestType.ColumnResize Or hti.Type =
DataGrid.HitTestType.RowResize Then

Return 'no baseclass call

End If

MyBase.OnMouseMove(e)

End Sub


End Class



Ken

-------------------------------
Hi Ken

Sorry, you've lost me. I'm uncertain how to "raise" events. Could you give
some example code?

Geoff
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