In my form I have MenuStrip, ContextMenuStrip and DataGridView.
This same ContextMenuStrip is attachetd to one MenuStripItem as "DropDown" and to DataGridView as "ContextMenuStrip". That works good.
Problem is that I have to know what is opening that ContextMenuStrip (MeuStripItem or DataGridView) so I can hide some Items depending on that.
This is my approach where I try to determine if caller is MenuStrip1 which don't work.
Private Sub mycontextmenu_Opening(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles mycontextmenu.Opening
If CType(sender, MenuStrip) Is MenuStrip1 Then
ExitToolStripMenuItem.Visible = False
Else
ExitToolStripMenuItem.Visible = True
End If
End Sub
Here error message appears: Unable to cast object of type 'System.Windows.Forms.ContextMenuStrip' to type 'System.Windows.Forms.MenuStrip'.
Please help to solve described problem.
sender is going to be the context menu strip
the source control property will retrieve the owner instance
Private Sub mycontextmenu_Opening(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles mycontextmenu.Opening
If mycontextmenu.SourceControl is MenuStrip1 Then
ExitToolStripMenuItem.Visible = False
Else
ExitToolStripMenuItem.Visible = True
End If
End Sub
Related
I created a registration form and added a form with features "Update, Delete, Refresh," along with a DataGridView to show data from the registration form.
Here's my form:
Since I inserted a TreeView, when I click the Update button as in the picture, I get the error:
Object Reference Not set to an instance of an object
I think my code in the TreeView form is wrong.
This is what I entered:
Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect
If e.Node.Text = "Update/Delete Student" Then
Dim regstu As New Registered_Students
regstu.MdiParent = Me
regstu.Show()
End If
End Sub
Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect
If e.Node.Text = "Update/Delete Student" Then
Dim regstu As New Registered_Students
Form_father.IsMdiContainer = True
Form_father.TopLevel = False
regstu.MdiParent = New Form_father
Form_father.Panel1_Container.Controls.Add(regstu)
regstu.Show()
End If
End Sub
I'm currently using a "Settings" form to set various settings for my application. What I'm trying to do is to revert settings back to before any changes the user has made before opening and changing a field. I have a text box with a data binding to a setting and when I make a change and click okay it gets saved the next time I open it. When I hit cancel it also gets saved. Not quite sure if I'm approaching this correctly.
Public Class frmSettings
Private _mysettings As Configuration.SettingsBase
Private Sub frmSettings_Load(...) Handles Me.Load
_mysettings = My.Settings
End Sub
Private Sub btnCancel_Click(...) Handles btnCancel.Click
For Each p As Configuration.SettingsPropertyValue In _mysettings.PropertyValues
My.Settings(p.Name) = p.PropertyValue
Next
Me.Close()
End Sub
Private Sub btnOkay_Click(...) Handles btnOkay.Click
My.Settings.Save()
Me.Close()
End Sub
End Class
Rather than using databound control you can simply load the value of the setting when the settings form loads. It is simple doing it that way, and it works. Otherwise you would have to make a clone of My.Settings: doing _mysettings = My.Settings is only creating a pointer to My.Settings, not a copy of it.
For example, I have a Form named ChangeConnectionString which has OK/Cancel buttons and a TextBox control named connString:
Public Class ChangeConnectionString
Private Sub bnOK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bnOK.Click
My.Settings.connectionString = connString.Text
My.Settings.Save()
Me.Close()
End Sub
Private Sub bnCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bnCancel.Click
Me.Close()
End Sub
Private Sub ChangeConnectionString_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
connString.Text = My.Settings.connectionString
End Sub
End Class
I have DataGridView with some data with it and I have a Button with Enabled property setting to (False), I want to do that: when I select row from DataGridView, the Button Enabled property change to (True).
I try this code but it don't work, so when I select row from DataGridView the Button Enabled property still (False). Help please.
Private Sub Form5_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If (Me.DataGridView1.SelectedRows.Count <> 0) Then
Button1.Enabled = True
End If
End Sub
Use CellClick Event. Like this.
Private Sub DataGridView1_CellClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellClick
If DataGridView1.SelectedRows.Count = 0 Then
Else
Button1.Enabled = True
Button2.Enabled = True
End If
End Sub
Don't copy/paste, I just typed it. Check first.
If this is WinForms, you want to handle the Grid's SelectionChanged event:
Private Sub DataGridView1_SelectionChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles DataGridView1.SelectionChanged
Button1.Enabled = ( DataGridView1.SelectedRows.Count > 0 )
End Sub
If this is WebForms, you want to re-think this. You should use javascript to control it, rather than causing a postback to change the button state. We can do a much better job help you with what javascript might look like if you can tell us a lot more about how the context for this page.
If I want to set the focus on a textbox when the form is first opened, then at design time, I can set it's tabOrder property to 0 and make sure no other form control has a tabOrder of 0.
If I want to achieve the same result at run-time, using code, how should I proceed?
Are there alternatives to using tabOrder?
I assume any run-time code will be in the form's constructor or its onload event handler?
EDIT
In other words I'd like to be able to type straight into the textbox as soon as the form appears without having to manually tab to it, or manually select it.
Because you want to set it when the form loads, you have to first .Show() the form before you can call the .Focus() method. The form cannot take focus in the Load event until you show the form
Private Sub RibbonForm1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Me.Show()
TextBox1.Select()
End Sub
I think what you're looking for is:
textBox1.Select();
in the constructor. (This is in C#. Maybe in VB that would be the same but without the semicolon.)
From http://msdn.microsoft.com/en-us/library/system.windows.forms.control.focus.aspx :
Focus is a low-level method intended primarily for custom control
authors. Instead, application programmers should use the Select method
or the ActiveControl property for child controls, or the Activate
method for forms.
Private Sub Form1_Shown(sender As Object, e As EventArgs) Handles Me.Shown
TextBox1.Select()
End Sub
Using Focus method
Private Sub frmTest_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
yourControl.Focus()
End Sub
To set focus,
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)
TextBox1.Focus()
End Sub
Set the TabIndex by
Me.TextBox1.TabIndex = 0
Quite simple :
For the tab control, you need to handle the _SelectedIndexChanged event:
Private Sub TabControl1_SelectedIndexChanged(sender As Object, e As System.EventArgs) _
Handles TabControl1.SelectedIndexChanged
If TabControl1.SelectedTab.Name = "TabPage1" Then
TextBox2.Focus()
End If
If TabControl1.SelectedTab.Name = "TabPage2" Then
TextBox4.Focus()
End If
I think the appropriate event handler to use is "Shown".
And you only need to focus the appropriate text box.
Private Sub Me_Shown(sender As Object, e As EventArgs) Handles MyBase.Shown
myTextbox.Focus()
End Sub
create a textbox:
<TextBox Name="tb">
..hello..
</TextBox>
focus() ---> it is used to set input focus to the textbox control
tb.focus()
I have multiple textbox in a form. How do I know what textbox the cursor currently is?
Trying to do something like this:
If TextBox2.Focus() = True Then
MessageBox.Show("its in two")
ElseIf TextBox3.Focus = True Then
MessageBox.Show("its in three")
End If
But I think its not working.
TextBox.Focus actually assigns the focus to the given textbox. What you're looking for is TextBox.Focused. :)
In fact, all form controls have the Focused property.
I know this already has an accepted answer but I just think this method is a bit easier and should be up here for people who find this through Google or whatever.
Public focussedTextBox As TextBox
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
For Each control As Control In Me.Controls
If control.GetType.Equals(GetType(TextBox)) Then
Dim textBox As TextBox = control
AddHandler textBox.Enter, Sub() focussedTextBox = textBox
End If
Next
End Sub
This way you can then just refer to the focussedTextBox at any time. You should make sure that you check that there is a focussedTextBox before you do however becuase when the application first loads there will not be. You can do this using:
If Not focussedTextBox Is Nothing Then
...
End If
Alternatively, you could set focussedTextBox to a TextBox of your choice on form load, either by setting its value or by focussing the TextBox.
Obviously, it will not work if you are calling your code in a Button_Click because when you click the Button then the focus is itself goes to the Button which you have clicked.
You can do two things:
Make a combined Focus event for all TextBoxes and check its Sender object.
Private Sub TextBox_Focus(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox2.Enter, TextBox3.Enter
Dim currTextBox As TextBox = sender
If currTextBox.Equals(TextBox2) Then
MessageBox.Show("it's in two")
ElseIf currTextBox.Equals(TextBox3) Then
MessageBox.Show("it's in three")
End If
End Sub
OR
Take a global string variable, and set its value at each TextBox_Focus event, then check string value in the button click event.
Dim str As String
Private Sub TextBox2_Focus(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox2.Enter
str = "two"
End Sub
Private Sub TextBox3_Focus(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox3.Enter
str = "three"
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
MessageBox.Show("it's in " & str)
End Sub