Add Checkbox to Header Cell in Datagridview

Question

I have a form with a datagridview on it. In the first column of this datagridview is a CheckBoxColumn. I am trying to add a checkbox to the header of the first column to act as a select all for the checkboxes below it. I can't understand the C# examples I've found online and I haven't found any PowerShell examples. Can someone point me in the right direction of how to do this?

[void] [System.Reflection.Assembly]::LoadWithPartialName(“System.Windows.Forms”)
[void] [System.Reflection.Assembly]::LoadWithPartialName(“System.Drawing”)
$form = New-Object System.Windows.Forms.Form
$form.Size = New-Object System.Drawing.Size(400, 400)
$form.KeyPreview = $true

$CheckBoxColumn1 = New-object System.Windows.Forms.DataGridViewCheckBoxColumn
$CheckBoxColumn1.Width = 30
$CheckBoxColumn1.ReadOnly = $false

$DataGrid1 = New-Object System.Windows.Forms.DataGridView
$DataGrid1.Dock = "Fill"
$DataGrid1.BorderStyle = 'FixedSingle'
$DataGrid1.AlternatingRowsDefaultCellStyle.BackColor = 'LightGray'
$DataGrid1.AllowUserToAddRows = $false
$DataGrid1.RowHeadersVisible = $false
$DataGrid1.BackgroundColor = "White"
$DataGrid1.Columns.Add($CheckBoxColumn1) | Out-Null
$DataGrid1.ColumnCount = 3
$DataGrid1.Columns[1].name = 'col1'
$DataGrid1.Columns[2].name = 'col2'
$DataGrid1.Rows.add($false,'one','two')
$DataGrid1.Rows.add($false,'three','four')

##Add checkbox to header row column 0

$form.Controls.Add($DataGrid1)
$form.ShowDialog()

Answer 1

I couldn't find a way to add a checkbox to the column header cell itself, so I developed a work around. I ended up adding a checkbox to the form and strategically placed it where the header cell would be. I then handled various events to make it work correctly with the datagridview.

Notice that for the checkbox, I used the Click event instead of the CheckStateChanged event. This is because I don't want all the cell checkboxes to uncheck everytime I click a checkbox, but only the specific box I changed and the header checkbox.

$checkbox1 = New-Object System.Windows.Forms.CheckBox
$checkbox1.Location = New-Object System.Drawing.Size(10,5)
$checkbox1.Size = New-Object System.Drawing.Size(13,13)
$checkbox1.Visible = $true
$checkbox1.add_Click({
    if($checkbox1.Checked){
        for($i = 0; $i -lt $datagrid1.RowCount;$i++){
            $datagrid1.Rows[$i].Cells[0].Value = $true
        }
    }
    else{
        for($i = 0; $i -lt $datagrid1.RowCount;$i++){
            $datagrid1.Rows[$i].Cells[0].Value = $false
        }
    }
})
$form.Controls.Add($checkbox1)

#Handle Events:
$DataGrid1.add_CellContentClick({
    $datagrid1.EndEdit() #otherwise the cell value won't have changed yet
    [System.Windows.Forms.DataGridViewCellEventArgs]$e = $args[1]
    if($e.columnIndex -eq 0){
        if($datagrid1.rows[$e.RowIndex].Cells[$e.ColumnIndex].value -eq $false){
            $checkbox1.CheckState = 'unchecked'
        }
    }
})

If you want your checkbox to only appear when the datagrid populates, look into the Visible property. It can be set to $true or $false like this: $datagrid1.Visible = $false