I'm creating a form with a few buttons and a combobox at runtime.
dim f as new form
(blah blah)
then the buttons acceptDescription and rejectDescription are set up...
then the combobox descriptionCombo is set up...
then...
AddHandler acceptDescription.Click, AddressOf handleAcceptedDescription
AddHandler rejectDescription.Click, AddressOf handleRejectedDescription
then I have these two methods to catch the click events... but can't figure out how to reference the other runtime generated controls. (combobox if accepted, form if rejected)
Private Sub handleAcceptedDescription(ByVal sender As System.Object, ByVal e As System.EventArgs)
'stub
'will need to reference the chosen combobox value here
dim acceptedDescription as string = descriptionCombo.selectedValue .tostring
End Sub
Private Sub handleRejectedDescription(ByVal sender As System.Object, ByVal e As System.EventArgs)
'I want to close the runtime created form here, but can't reference it
f.close()
'and return user to main form
Me.Focus()
End Sub
If the code for generating the form is in your main form, then declare the Form variable at the class level of the main form class so you can access it from the event handlers. Same goes for your combobox and text field- you need to make sure the variables are declared outside the scope of the handlers so you can reference them within the handlers.
Why can't you reference it? Just save it as a module/form-level variable and you're set.
In order to avoid global definitions, the best answer is
Private Sub handleRejectedDescription(ByVal sender As System.Object, ByVal e As System.EventArgs)
'sender is a button in this case.
'get the button
dim b as new button
b = ctype(sender,button)
'now get the button's parent form
dim f as new form
f = ctype(b.parent, form)
'now close the form
f.close()
End Sub
Related
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 help to call a function in a usercontrol that is shown in a panel within the form, so far this is i tried, but no luck, i can't still get the text inputted on the textbox
Public Class Form1
Private Sub LinkLabel1_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
Dim ustudent As New StudentAdd
ustudent.Dock = DockStyle.Fill
SplitContainer1.Panel2.Controls.Add(ustudent)
End Sub
Private Sub ToolStripButton1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ToolStripButton1.Click
ustudent.SaveData()
End If
End Sub
End Class
in user control have some textbox
textbox1 and textbox2
Public Class StudentAdd
Public Sub SaveData() As Boolean
'just testing whether it could work well
' getting textbox value
MsgBox(TextBox1.Text)
End Sub
End Class
But ustudent is a local var, try to declare it outside link_clicked event. Do you want to create multiple user controls in the win or just one?
For one you could add it at design time by dragging from the your project components panel
For more, you should implement some logic to identify the selected component and make it available for save data. If you want to save all just enumerate components in Panel2 (of type StudentAdd) and call the method
I do know how to handle event of textboxes in my form. But want to make this code shorter because I will 30 textboxes. It's inefficient to use this:
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged, TextBox2.TextChanged, TextBox3.TextChanged, TextBox4.TextChanged, TextBox5.TextChanged, TextBox6.TextChanged, TextBox7.TextChanged, TextBox8.TextChanged, TextBox9.TextChanged, TextBox10.TextChanged
Dim tb As TextBox = CType(sender, TextBox)
Select Case tb.Name
Case "TextBox1"
MsgBox(tb.Text)
Case "TextBox2"
MsgBox(tb.Text)
End Select
End Sub
Is there a way to shorten the handler?
You can use Controls.OfType + AddHandler programmatically. For example:
Dim textBoxes = Me.Controls.OfType(Of TextBox)()
For Each txt In textBoxes
AddHandler txt.TextChanged, AddressOf txtTextChanged
Next
one handler for all:
Private Sub txtTextChanged(sender As Object, e As EventArgs)
Dim txt = DirectCast(sender, TextBox)
Select Case txt.Name
Case "TextBox1"
MsgBox(txt.Text)
Case "TextBox2"
MsgBox(txt.Text)
End Select
End Sub
If you have created very Textbox with the Designer, I don't think there is a better method.
But, if you have created the Textboxes dynamically, you should AddHandler in this way:
For i = 0 to 30
Dim TB as New Texbox
AddHandler TB.TextChanged, TextBox1_TextChanged
'Set every Property that you need
Me.Controls.Add(TB)
Next
Say If you are having that 30 textboxes inside a panel(PnlTextBoxes), Now you can create handler for your textboxes dynamically like this below
For each ctrl in PnlTextBoxes.controls
If TypeOf ctrl is TextBox then
AddHandler ctrl.TextChanged, AddressOf CommonClickHandler
end if
Next
Private Sub CommonHandler(ByVal sender As System.Object, _
ByVal e As System.EventArgs)
MsgBox(ctype(sender,TextBox).Text)
End Sub
The best way would be to inherit from TextBox, override its OnTextChanged method to add your custom handling code, and then use that on your form(s) instead of the built-in TextBox control.
That way, all of the event handling code is in one single place and you increase abstraction. The behavior follows and is defined within the control class itself, not the form that contains the control. And of course, it frees you from having a bunch of ugly, hard-to-maintain Handles statements, or worse, slow and even uglier For loops.
For example, add this code defining a new custom text box control to a new file in your project:
Public Class CustomTextBox : Inherits TextBox
Protected Overridable Sub OnTextChanged(e As EventArgs)
' Do whatever you want to do here...
MsgBox(Me.Text)
' Call the base class implementation for default behavior.
' (If you don't call this, the TextChanged event will never be raised!)
MyBase.OnTextChanged(e)
End Sub
End Class
Then, after you recompile, you should be able to replace your existing TextBox controls with the newly-defined CustomTextBox control that has all of your behavior built in.
When using flash, I was able to get to the focus of an event by accessing the event's "target" attribute.
so if I remember, it was something similar to.
button1.addEventListener(mouse_click, doSomething);
doSomething(e: Event){
e.target.size = 50000;
}
And I'm looking for the equivalent in VB.
If you can give me it's common name across all languages, I'd be doubly grateful. I don't quite know what to search for aside from "event.target VB.net equivalent, and that's not returning anything.
Thanks in advance.
edit: for those new to flash. By focus, I mean the physical object that was clicked on. So the example given would be accessing the clicked button's size.
In VB you can wire up event handlers declaratively using the WithEvents keyword or imperatively using AddHandler.
Private WithEvents myButton
' OR
Public Sub New
Dim newButton = New Button()
AddHandler newButton.Click, AddressOf MyClickHandler
End New
'To consume it you declare a method as follows:
' The Handles clause is used when declaring WithEvents
Private Sub MyClickHandler(sender As Object, e As EventArgs) Handles myButton.Click
' The sender has a handle on the object that raised the event (aka the button)
Dim btn = DirectCast(sender, Button)
btn.Size = New Size(500, 500)
End Sub
Got it!
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.button.onclick.aspx#Y0
Sub GreetingBtn_Click(ByVal sender As Object, ByVal e As EventArgs)
'When the button is clicked,
'change the button text, and disable it.
Dim clickedButton As Button = sender
clickedButton.Text = "...button clicked..."
clickedButton.Enabled = False
End Sub
The first parameter (sender by default) references the focused object. You can access it as you would any other normal variable, but it's information won't appear in the auto complete list unless you set it "As" that specific data type.
So I ended up with this
Private Sub nw_btn_Click(ByVal sender As System.Windows.Forms.Button, ByVal e AsSystem.EventArgs) Handles nw_btn.Click
sender.Hide()
End Sub
I have a windows form project with a main form. There is a textbox leave event that opens a new form. In that new forms load event i have a combobox item loop that populates the combobox items. It works perfectly fine if run on the main form but doesnt work on the second form. Why doesn't the comboboxes on the secondary form populate when that form is opened via a textbox_leave event from the main form?
this is the leave event
Private Sub tbChartTitle_Leave(sender As Object, e As System.EventArgs) Handles tbChartTitle.Leave
If Not tbChartTitle.Text = Nothing Then
frmTitleAttributes.Show()
End If
End Sub
This is the code that populates one of the comboboxes on the second form (it works if run on a combobox on the main form)
Private Sub frmTitleAttributes_Load(sender As Object, e As System.EventArgs) Handles Me.Load
InitializeComponent()
AddFonts()
End Sub
Private Sub AddFonts()
' Get the installed fonts collection.
Dim allFonts As New Drawing.Text.InstalledFontCollection
' Get an array of the system's font familiies.
Dim fontFamilies() As FontFamily = allFonts.Families
' Display the font families.
For i As Integer = 0 To fontFamilies.Length - 1
cbxTitleFonts.Items.Add(fontFamilies(i).Name)
Next
End Sub
make sure that the Load handler is hit after you show your form (use break point)
also you can try to call it in the Shown event
Private Sub frmTitleAttributes_Shown(sender as Object, e as EventArgs) _
Handles frmTitleAttributes.Shown
AddFonts()
End Sub