I have three text boxes.
txtBox1 - Enabled=True - TabIndex=1
txtBox2 - Enabled=False - TabIndex=2
txtBox3 - Enabled=True - TabIndex=3
I have an event handler that sets Enabled=True for txtBox2 when txtBox1 is validating. My problem is that the cursor doesn't go to txtBox2 after leaving txtBox1, it jumps to txtBox3.
Private Sub Example(ByVal sender As Object, _
ByVal e As System.ComponentModel.CancelEventArgs) Handles txtBox1.Validating
txtBox2.Enabled = True
End Sub
Is there a way to have the TabIndex respected after a field is enabled in a validating event handler? I can use Select() but that breaks reverse tabbing through the fields (SHIFT+TAB).
Thank you!
It is a simple chicken-and-egg problem. The Validating event fires because the textbox lost the focus. Which happened because you tabbed to the next control. Which was of course txtBox3, enabling txtBox2 does not change that.
Easy to fix, the ActiveControl property tells you which control is active. So write it like this:
txtBox2.Enabled = True
If Me.ActiveControl Is txtBox3 Then txtBox2.Focus()
Back-tabbing works properly as long as you have more than 3 controls that can receive the focus.
Ok so I posted the wrong solution so here is the correct one. Hans got me thinking and this is what I came up with that works for my needs:
Public Class Form1
' First you have to declare a variable
Dim m_TabForward As Boolean
' Capture the keystrokes to check for direction.
Private Sub GetTabDirection(ByVal sender As Object, _
ByVal e As PreviewKeyDownEventArgs) Handles _
txtBox1.PreviewKeyDown
If (e.KeyCode = Keys.Tab AndAlso e.Modifiers = Keys.Shift) Then
m_TabForward = False
ElseIf e.KeyCode = Keys.Tab Then
m_TabForward = True
End If
End Sub
' Enable the next textbox and select it. Because SelectNextControl
' takes a direction argument you don't have a problem with reversing order
' like you would using txtBox2.Select()
Private Sub ValidateFields(ByVal Sender As Object, _
ByVal e As System.ComponentModel.CancelEventArgs) _
Handles txtBox1.Validating
Dim ctl As Control = Sender
If Sender Is txtBox1 Then
txtBox2.Enabled = True
End If
SelectNextControl(ctl, m_TabForward, True, True, True)
End Sub
End Class
Related
Fellows, I am having this problem - the DateTimePicker won't trigger KeyDown and KeyPress events with the tab key (other keys are working fine, and the keyUp event as well, although it triggers after "arriving" at the DateTimePicker after pressing tab at the previous control focused). I'm using .net 4.6.1, Visual Basic and VS 2017.
What I'm trying to do -> Go to month and year directly on DateTimePicker in C# (Go to month and year directly on DateTimePicker)
Code I'm using:
Private Sub DateTimePicker1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles DateTimePicker1.KeyDown
If e.KeyCode = Keys.Tab Then
e.Handled = True
MsgBox("TAB DOWN")
End If
End Sub
Private Sub DateTimePicker1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles DateTimePicker1.KeyPress
e.Handled = True
MsgBox("tab press")
End Sub
Private Sub DateTimePicker1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles DateTimePicker1.KeyUp
If e.KeyCode = Keys.Tab Then
MsgBox("TAB UP")
e.Handled = True
End If
End Sub
Any clues?
The Tab key is used for navigation. Moving the focus from one control to another. So your KeyDown event handler can never see it, the keystroke is intercepted and used before that. You could subscribe the PreviewKeyDown event and set the e.IsInputKey = true as a workaround, check the MSDN sample code in the linked article for code.
But it is the wrong event to use anyway, you'd still want this to work when the user changes focus with the mouse instead of the keyboard. So use the Enter event instead.
Do beware that both approaches have the same problem, the focus might already be on the month part from previous usage of the control so now your code will incorrectly move it to the year part. And you can't find out what part has the focus, that is up a creek without a good paddle. A very ugly workaround for that is to change the Format property, and back, that forces the control to re-create the control window and that always resets the focus. Use BeginInvoke() to run that code. Perhaps more constructively, consider to just not display the day if you are only interested in month+year, CustomFormat property.
Sample code that implements the focus hack:
Private Sub DateTimePicker1_Enter(sender As Object, e As EventArgs) Handles DateTimePicker1.Enter
Me.BeginInvoke(
New Action(Sub()
'' Hack to reset focus
DateTimePicker1.Format = DateTimePickerFormat.Long
DateTimePicker1.Format = DateTimePickerFormat.Short
DateTimePicker1.Focus()
SendKeys.Send("{Right}")
End Sub))
End Sub
It's not the right answer to this question, although it helps as well. If you want to just make the tab behave as the right key when inside a DateTimePicker, a good (sketchy) way to do is:
Private i = 2
Protected Overrides Function ProcessTabKey(ByVal forward As Boolean) As Boolean
Dim ctl As Control = Me.ActiveControl
If ctl IsNot Nothing AndAlso TypeOf ctl Is DateTimePicker And i <> 0 Then
SendKeys.Send("{Right}")
i -= 1
Return True
End If
i = 2
Return MyBase.ProcessTabKey(forward)
End Function
You need to override ProcessCmdKey function
Private isTab As Boolean = False
Private isShiftTab As Boolean = False
Protected Overrides Function ProcessCmdKey(ByRef msg As Message, ByVal keyData As Keys) As Boolean
If keyData = Keys.Tab Then
isTab = True
'Do something with it.
Else
isTab = False
End If
Return MyBase.ProcessCmdKey(msg, keyData)
End Function
Situation:
I have a context menu in a VB.NET form with fires an event handler on ItemClicked. The auto-generated subroutine receives sender and e as parameters. As I don't reinvent the wheel multiple times, I linked this context menu to three text boxes. Let's name them Textbox1, Textbox2 and Textbox3.
Problem: How can I figure out in which textbox the menu was opened?
Okay, what did I already try?
sender contains the menu itself,
e.ClickedItem just returns the single menu item that was selected.
sender.Parent is always nothing
sender.OwnerItem is also always Nothing`
Me.Textbox1.Focused is always False, even if its the "parent" control of the menu.
Okay, I found a solution that works fine, and here's the code for all VB.NET coders that have the same problem.
The context menu is linked in TextBox1, so we need to add another event handler that saves the sending control into the menu:
Private Sub TextBox1_MouseUp(sender As Windows.Forms.Control, e As System.Windows.Forms.MouseEventArgs) Handles TextBox1.MouseUp
If e.Button = Windows.Forms.MouseButtons.Right Then
ContextMenu.Tag = sender
End If
End Sub
And this is the code of the event handler when clicking a menu item:
Private Sub ContextMenu_ItemClicked(sender As System.Object, e As System.Windows.Forms.ToolStripItemClickedEventArgs) Handles ContextMenu.ItemClicked
ContextMenu.Close()
If ContextMenu.Tag Is Nothing Then
Debug.Print("debug info: forgot to set sender? well ... KABOOM!")
Exit Sub
End If
Dim oParent As Windows.Forms.Control
Try
oParent = ContextMenu.Tag
Catch ex As Exception
Debug.Print("debug info: tag contains data other than sender control. well ... KABOOM!")
Exit Sub
End Try
' Do fancy stuff here.
' Release sender
ContextMenu.Tag = Nothing
End Sub
The ContextMenuStrip has a SourceControl property which contains a reference to the control which opened the menu. The event fires from one of the ToolStripMenuItems in the ContextMenuStrip, so you have to get the "parent" first:
' cast sender to menuitem
Dim mi = CType(sender, ToolStripMenuItem)
' cast mi.Owner to CMS
Dim cms = CType(mi.Owner, ContextMenuStrip)
' the control which opened the menu:
Console.WriteLine(cms.SourceControl.Name)
Under certain conditions the SourceControl can get lost but you can track it yourself with a variable and the parent ContextMenuStrip Opening event:
' tracking var:
Private MenuSourceControl As Control
Private Sub cms_Opening(sender As Object, e As CancelEventArgs) Handles cms.Opening
' set reference in case/before it is lost
MenuSourceControl = CType(sender, ContextMenuStrip).SourceControl
End Sub
Private Sub CutToolStripMenuItem_Click(sender...
If MenuSourceControl IsNot Nothing Then
' do your stuff
' optionally clear the tracking var
MenuSourceControl = Nothing
End If
End Sub
It should be also easier to get the SourceControl when dealing with sub items
You can also capture the related control in the MouseDown event of the related Control in cases where the same menu is used with different controls:
Private Sub lv2_MouseDown(sender As Object,
e As MouseEventArgs) Handles lv2.MouseDown,
myLV.MouseDown, lv1.MouseDown ...
If e.Button = Windows.Forms.MouseButtons.Right Then
MenuSourceControl = DirectCast(sender, Control)
End If
End Sub
I need to set the text value of a DataGridView.EditingControl. I've tried
myDGV.EditingControl.Text() = "1/1/2001"
and
myDGV.EditingControl.Text = "1/1/2001"
and
myDGV.EditingControl.Text("1/1/2001")
which causes an InvalidCastException (didn't check that could only be an integer).
There is no Value() property for the control, so how do I set the the value?
(Yes, I've verified that the cell is in edit mode)
You need to handle the EditingControlShowing event.
Private Sub HandleDgvEditingControlShowing(sender As Object, e As DataGridViewEditingControlShowingEventArgs) Handles Dgv.EditingControlShowing
If (TypeOf e.Control Is DataGridViewTextBoxEditingControl) Then
With DirectCast(e.Control, DataGridViewTextBoxEditingControl)
.Text = "1/1/2001"
End With
End If
End Sub
Note that this event will be fired for all editable cells. If you only want to manipulate the edit control for a given column you need to add another condition. Something like this:
If (Me.Dgv.CurrentCell.OwningColumn is Me.DgvFooColumn) Then
If you need to revert the edit from the CellValidating event then store the original value when the edit control is shown.
Private Sub HandleDgvEditingControlShowing(sender As Object, e As DataGridViewEditingControlShowingEventArgs) Handles Dgv.EditingControlShowing
'Cache the edit control text
Me.cachedEditText = e.Control.Text
End Sub
Private Sub HandleDgvCellValidating(sender As Object, e As DataGridViewCellValidatingEventArgs) Handles Dgv.CellValidating
'Ensure that the edit control exists
If (Not Me.Dgv.EditingControl Is Nothing) Then
'Validate the edit
If (Not valid) Then
Me.Dgv.EditingControl.Text = Me.cachedEditText
End If
End If
End Sub
Private cachedEditText As String
My UserControl button disappears when I debug my program. I have checked the code including the designer.vb code countless times there's nothing that makes the button .enabled = false or .visible = false. Any ideas why this is happening?
On my UserControl:
Private Sub btn_Begin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn_Begin.Click
Start_Race()
End Sub
Public Sub Start_Race()
TimeNow(Past_Time)
TimeNow(Start_Time)
lbl_Start_Time_Driver.Text = Past_Time
btn_Begin.BackColor = Color.Green
btn_Begin.Text = "Started!"
End Sub
Public Property Active_bool As Boolean
Get
Return btn_Begin.Visible
End Get
Set(ByVal value As Boolean)
btn_Begin.Visible = value
End Set
End Property
On Form1:
Private Sub btn_Start_All_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn_Start_All.Click
Dim allActiveUserControls = From uc_Index In Controls.OfType(Of LapTimerGUI)()
Where uc_Index.Active_bool
For Each User_Control In allActiveUserControls
User_Control.Start_Race()
Next
End Sub
I do Google my head off before I post my ridiculous questions here btw :)
This is strange. Does any MsgBoxes pop up if you add this code to your UserControl:
Private Sub UserControl_ControlRemoved(sender As Object, e As System.Windows.Forms.ControlEventArgs) Handles Me.ControlRemoved
MsgBox("Control Removed!")
End Sub
Private Sub Button2_EnabledChanged(sender As Object, e As System.EventArgs) Handles Button2.EnabledChanged
MsgBox("EnabledChanged!")
End Sub
If so, then you can add a breakpoint to these MsgBoxes and lock at the CallStack (CTRL+L) from where it triggers.
Btw: If the control is removed somehow, .PerformClick() still triggers (for me). Thus I bet, that the control is somehow disabled (Enabled = False).
Lastly, if any container of the button (such as your UserControl) is disabled, the button will be disabled too,
After lots of playing around I finally found the problem!
The value was set to =False in my properties. I'm so blonde! Thanks guys for the help ^_^/
Public Property Active_bool As Boolean
Get
Return btn_Begin.Visible
End Get
Set(ByVal value As Boolean)
btn_Begin.Visible = value
End Set
End Property
Although, Something sets the values to =False ever now and then. Very annoying :3
And I can not set the value to =True in the properties... Only in the hidden designer code...
Is there any way to turn the damned error provider off when i try to close the form using the windows close button(X). It fires the validation and the user has to fill all the fields before he can close the form..this will be a usability issue because many tend to close the form using the (X) button.
i have placed a button for cancel with causes validation to false and it also fires a validation.
i found someone saying that if you use Form.Close() function validations are run...
how can i get past this annoying feature.
i have a MDI sturucture and show the form using
CreateExam.MdiParent = Me
CreateExam.Show()
on the mdi parent's menuitem click
and have this as set validation
Private Sub TextBox1_Validating(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox1.Validating
If String.IsNullOrEmpty(TextBox1.Text) Then
Err.SetError(TextBox1, "required")
e.Cancel = True
End If
If TextBox1.Text.Contains("'") Then
Err.SetError(TextBox1, "Invalid Char")
e.Cancel = True
End If
End Sub
Any help is much appreciated.
googling only showed results where users were having problem using a command button as close button and that too is causing problem in my case
The ValidateChildren() method prevents the form from closing. Paste this code in your form to fix that:
protected override void OnFormClosing(FormClosingEventArgs e) {
e.Cancel = false;
}
This is quite simple fix, in your Form's Closing Event, set a flag to indicate leaving the form, for example blnLeave, when the Form gets loaded, set the flag to False, when the Closing event gets triggered, set that to True within that event handler, then the change as follows would be
Private Sub TextBox1_Validating(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox1.Validating
If (blnLeave) Then
e.Cancel = False;
Return
End If
If String.IsNullOrEmpty(TextBox1.Text) Then
Err.SetError(TextBox1, "required")
e.Cancel = True
End If
If TextBox1.Text.Contains("'") Then
Err.SetError(TextBox1, "Invalid Char")
e.Cancel = True
End If
End Sub
Edit: Amended this answer for inclusion as per OP's comments. My suggestion is to handle the Form's Closed Event as shown
Private Sub Form1_FormClosed(ByVal sender As System.Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles MyBase.FormClosed
blnLeave = True
End Sub
And handle it here in the Form's window procedure override as shown here....
Private Const SC_CLOSE As Integer = &HF060
Private Const WM_MENUSELECT As Integer = &H11F
Private Function LoWord(ByVal Num As Integer) As Integer
LoWord = Num & &HFFFF
End Function
Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
If m.Msg = WM_MENUSELECT Then
If LoWord(m.WParam.ToInt32()) = SC_CLOSE Then
' Handle the closing via system Menu
blnLeave = True
End If
End If
MyBase.WndProc(m)
End Sub