Manual Checkbox enable - winforms

Question

I have a ComboBox control on my form. What I want is when I change an item in the ComboBox from one to another, the event was handled. It is important that when changing and not when choosing the same element. All this time I used ComboBox.Add_SelectionChangeCommitted($function), but soon I realized that the block that is also executed by the handler when the same (selected) item is selected from the list. A little digging in ComboBox events I am completely confused. Having tried several events (SelectedItemChanged, SelectedIndexChanged) I could never able to achieve the desired result.
An example of what I want to do and what should not be done several times when choosing the same element. When the block of code for Manual is executed several times, the contents of all TextBox are cleared, but I don’t want to.
Add-Type -AssemblyName System.Windows.Forms
[System.Windows.Forms.Application]::EnableVisualStyles()
$Form = New-Object system.Windows.Forms.Form
$Form.ClientSize = '420,240'
$Form.TopMost = $false
$Form.FormBorderStyle = 'Fixed3D'
$Form.MaximizeBox = $false
$ComboBox = New-Object system.Windows.Forms.ComboBox
$ComboBox.width = 391
$ComboBox.height = 47
#('Automatic (DHCP)','Manual Input') | ForEach-Object {[void] $ComboBox.Items.Add($_)}
$ComboBox.location = New-Object System.Drawing.Point(13,57)
$ComboBox.DropDownStyle = 'DropDownList'
$ComboBox.DrawMode = 'OwnerDrawFixed'
$Button = New-Object system.Windows.Forms.Button
$Button.text = "Set"
$Button.width = 60
$Button.height = 30
$Button.visible = $false
$Button.enabled = $false
$Button.location = New-Object System.Drawing.Point(336,126)
$CheckBox = New-Object system.Windows.Forms.CheckBox
$CheckBox.width = 65
$CheckBox.height = 15
$CheckBox.visible = $false
$CheckBox.Checked = $false
$CheckBox.enabled = $true
$CheckBox.location = New-Object System.Drawing.Point(16,210)
$TextBox1 = New-Object system.Windows.Forms.TextBox
$TextBox1.Name = "TextBox1"
$TextBox1.multiline = $false
$TextBox1.width = 40
$TextBox1.height = 20
$TextBox1.visible = $false
$TextBox1.enabled = $true
$TextBox1.location = New-Object System.Drawing.Point(81,100)
$TextBox2 = New-Object system.Windows.Forms.TextBox
$TextBox2.Name = "TextBox2"
$TextBox2.multiline = $false
$TextBox2.width = 40
$TextBox2.height = 20
$TextBox2.visible = $false
$TextBox2.enabled = $false
$TextBox2.location = New-Object System.Drawing.Point(81,208)
$Form.controls.AddRange(#($TextBox1,$TextBox2,$Button,$ComboBox,$CheckBox))
$global:ManualChecked = $null
$global:AutomaticChecked = $null
$ComboBox.Add_SelectionChangeCommitted($methodSelection)
$netwValues = New-Object 'System.Collections.Hashtable'
$methodSelection =
{
switch($ComboBox.Text)
{
"Manual Input"
{
$CheckBox.Visible = $Button.Visible = $true
$Button.Enabled = $false
ForEach ($control in $Form.controls)
{
if ($control -is [System.Windows.Forms.TextBox] )
{
$control.Visible = $control.Enabled = $true
$control.Clear()
if($netwValues.Count -gt 0)
{
$control.Text = $netwValues.Item($control.Name)
$netwValues.Remove($control.Name)
}
}
}
if($global:ManualChecked -eq 1)
{
$CheckBox.Checked = $true
$TextBox2.Enabled = $true
}
else
{
$CheckBox.Checked = $false
$TextBox2.Enabled = $false
}
}
"Automatic (DHCP)"
{
ForEach($control in $Form.controls)
{
if($control -is [System.Windows.Forms.TextBox] -or $control -is [System.Windows.Forms.CheckBox] -or $control -is [System.Windows.Forms.Button])
{
$control.Visible = $control.Enabled = $true
if($control -is [System.Windows.Forms.Label] -or $control -is [System.Windows.Forms.TextBox])
{
$control.Enabled = $false
if($control -is [System.Windows.Forms.TextBox])
{
if($control.Text.Length)
{
$netwValues.Add($control.Name,$control.Text)
$control.Clear()
}
}
}
}
}
if($global:AutomaticChecked -eq 1)
{
$CheckBox.Checked = $true
}
else
{
$CheckBox.Checked = $false
}
}
}
}

Answer 1

You can implement this logic yourself.
# Simple class for using as item for combobox instead of just string.
class CbItem
{
CbItem([string] $value)
{
$this.Value = $value
}
[string] $Value
[string] ToString()
{
return $this.Value
}
}
# Add instances of this class into combobox.
$ComboBox.Items.Add([CbItem]::new('Automatic (DHCP)'))
$ComboBox.Items.Add([CbItem]::new('Manual Input'))
# Create a variable for storing current combobox's item.
$global:CurrentCbItem = $null
# Add logic at the begining of handler for exiting if selected item is the same as the last one.
$methodSelection =
{
if ([Object]::ReferenceEquals($global:CurrentCbItem, $ComboBox.SelectedItem))
{
return
}
$global:CurrentCbItem = $ComboBox.SelectedItem
...
}