Build and respond to events on multiple check boxes - winforms

Question

I am attempting to make a form with multiple check boxes, based on the array passed to the form creation function. I can calculate the correct location based on the count of what checkbox I am at is, but I am having trouble (I think) dealing with events. I have this for now (partial code, obviously)
$checkboxCount = 1
foreach ($year in $years) {
$checkbox = new-object System.Windows.Forms.checkbox
$checkbox.Size = new-object System.Drawing.Size(100,20)
$checkbox.Location = new-object System.Drawing.Size(10,($checkbox.Size.Height*$checkboxCount-10))
$checkbox.Text = "Revit $year"
$checkbox.Checked = $true
$Form.Controls.Add($checkbox)
$checkbox.Add_CheckStateChanged({
$results.$year = $checkbox.Checked
})
$checkboxCount ++
}
and the check boxes are created correctly, but when I return $results from the function they are all True. I am basing the code off of this, which works but with a static number of check boxes.
function checkbox_test{
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")
$results = #{
one = $true
two = $true
}
$optionCount = 2
# Set the size of your form
$Form = New-Object System.Windows.Forms.Form
$Form | Format-List *
$form.FormBorderStyle = 'FixedDialog'
$form.ShowInTaskbar = $false
$Form.width = 300
$Form.height = 150
$Form.Text = ”Px Tools Updater”
# Set the font of the text to be used within the form
$Font = New-Object System.Drawing.Font("Times New Roman",12)
$Form.Font = $Font
# create your checkbox
$checkbox1 = new-object System.Windows.Forms.checkbox
$checkbox1.Location = new-object System.Drawing.Size(10,7)
$checkbox1.Size = new-object System.Drawing.Size(100,20)
$checkbox1.Text = "One"
$checkbox1.Checked = $true
$Form.Controls.Add($checkbox1)
# create your checkbox
$checkbox2 = new-object System.Windows.Forms.checkbox
$checkbox2.Location = new-object System.Drawing.Size(10,27)
$checkbox2.Size = new-object System.Drawing.Size(100,20)
$checkbox2.Text = "Two"
$checkbox2.Checked = $true
$Form.Controls.Add($checkbox2)
# Add an OK button
$OKButton = new-object System.Windows.Forms.Button
$OKButton.Location = new-object System.Drawing.Size(10,70)
$OKButton.Size = new-object System.Drawing.Size(60,30)
$OKButton.Text = "OK"
$OKButton.Add_Click({$Form.Close()})
$form.Controls.Add($OKButton)
#Add a cancel button
$CancelButton = new-object System.Windows.Forms.Button
$CancelButton.Location = new-object System.Drawing.Size(225,100)
$CancelButton.Size = new-object System.Drawing.Size(60,30)
$CancelButton.Text = "Cancel"
$CancelButton.Margin = 0
$CancelButton.Add_Click({$Form.Close()})
$form.Controls.Add($CancelButton)
$checkbox1.Add_CheckStateChanged({
$results.one = $checkbox1.Checked
})
$checkbox2.Add_CheckStateChanged({
$results.two = $checkbox2.Checked
})
# Activate the form
$Form.Add_Shown({$Form.Activate()})
[void] $Form.ShowDialog()
$results
}
I am not sure if I am going wrong with the way I am referencing the results hash table, or maybe the entire approach is wrong?
Edit: I had a thought, that $year is meaningless in the event handler, so I added
$checkbox.Name = $year
and revised the event handler to
$results.($checkbox.Name) = $checkbox.Checked
and
$results.($Self.Name) = $checkbox.Checked
But no joy with either. But what is weird is that using $self results in an odd extra key being added to $return. It has no key name, but the value matches the last change made to any checkbox.
EDIT #2: In further testing, I changed the handler to
$results.2019 = $checkbox.Checked
expecting that to mean any change results in that change applied to the 2019 key. not so. So I am thinking it relates to the way hash tables are passed and referenced and likely I am doing this all wrong. Perhaps worrisome is the fact that I can find tons of information on making check boxes react to and change other parts of the form, but so far nothing on just getting results back.
EDIT #3: OK, seems the answer (of sorts) is there is no need for event handlers, because I only really care about end state anyway. So, with some extra cleanup to also handle Cancel I have this, and it works. Still curious how, or if, I could interact directly with $results from an event handler though.
function checkbox_test{
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")
$years = #('2016', '2017', '2018', '2019')
$optionCount = $years.Count
# Set the size of your form
$Form = New-Object System.Windows.Forms.Form
$form.FormBorderStyle = 'FixedDialog'
$form.ShowInTaskbar = $false
$Form.width = 300
$Form.height = ($years.Count * 30 + 50 + 40) #150
$Form.Text = ”Px Tools Updater”
# Set the font of the text to be used within the form
$Font = New-Object System.Drawing.Font("Times New Roman",12)
$Form.Font = $Font
# create Checkboxes
$checkboxCount = 1
foreach ($year in $years) {
$checkbox = new-object System.Windows.Forms.checkbox
$checkbox.Size = new-object System.Drawing.Size(100,20)
$checkbox.Location = new-object System.Drawing.Size(10,($checkbox.Size.Height*$checkboxCount-10))
$checkbox.Text = "Revit $year"
$checkbox.Name = $year
$checkbox.Checked = $true
$Form.Controls.Add($checkbox)
$checkboxCount ++
}
# Add an OK button
$OKButton = new-object System.Windows.Forms.Button
$OKButton.Size = new-object System.Drawing.Size(60,30)
$OKButton.Location = new-object System.Drawing.Size(10,($form.DisplayRectangle.Height - $OKButton.Size.Height - 10))
$OKButton.Text = "OK"
$OKButton.Add_Click({
$Form.DialogResult = [System.Windows.Forms.DialogResult]::OK
$Form.Close()
})
$form.Controls.Add($OKButton)
#Add a cancel button
$CancelButton = new-object System.Windows.Forms.Button
$CancelButton.Size = new-object System.Drawing.Size(60,30)
$CancelButton.Location = new-object System.Drawing.Size(($form.DisplayRectangle.Width - $CancelButton.Size.Width - 10),($form.DisplayRectangle.Height - $CancelButton.Size.Height - 10))
$CancelButton.Text = "Cancel"
$CancelButton.Add_Click({
$Form.Close()
})
$form.Controls.Add($CancelButton)
# Activate the form
$Form.Add_Shown({$Form.Activate()})
if ($Form.ShowDialog() -eq 'OK') {
$results = New-Object Collections.Specialized.OrderedDictionary
foreach ($control in $form.Controls) {
if ($years -contains $control.Name) {
$results.Add($control.Name, $control.Checked)
}
}
} else {
$results = $null
}
[void] $Form.Dispose
$results
}
#Call the function
$returned = checkbox_test
Foreach ($key in $returned.keys) {
Write-Host "[$key] $($returned.$key)!"
}

Answer 1

The foreach loop used to assign each checkbox event handler above effectively overwrites the previous one, and therefore you only capture the last one. (2019)
Instead, assign the event hander the way it's traditionally done in Windows Forms:
$results = New-Object Collections.Specialized.OrderedDictionary;
foreach ($year in $years) {
$checkbox = new-object System.Windows.Forms.checkbox
$Form.Controls.Add($checkbox);
$checkbox.Size = new-object System.Drawing.Size(100,20)
$checkbox.Location = new-object System.Drawing.Size(10,($checkbox.Size.Height*$checkboxCount-10))
$checkbox.Text = "Revit $year"
$checkbox.Name = $year
$checkbox.Checked = $true
$results.Add($year, $checkbox.Checked);
# HERE!
$checkbox.Add_CheckStateChanged({
# $this -eq sender, optionally $_ -eq EventArgs
$year = $this.name;
$results.$year = $this.Checked;
});
$checkboxCount++
}