JPeroutek JPeroutek - 5 months ago 207
Vb.net Question

How to add a UserControl to a DataGridView in VB.net, and have the control always showing?

I made a usercontrol that is basically a panel with a bunch of labels, buttons, and Event Handlers on it. I want to be able to populate a DataGridView with these controls.

I have followed the instructions in this MSDN article, and have created a DataGridViewColumn and a DataGridViewCell class to associate with my Control.

The issue I am having is that the control is not rendering. When I run the code at the link above, It shows the date in the cell, and the user control only shows when the cell is being edited. What I'd like to have happen is that the control is always visible in the cell, similar to the behavior in a DataGridViewImageColumn.

How can I force the DataGridView to always show the control?

Answer

The main idea:

  1. Create a user control
  2. In form load event, for each record, create an instance of user control, set values to its properties, add event handlers, set its visiblity to false and then add it to your grid Controls collection, and set the tag of your wanted cell or that row to this control.
  3. Handle CellPainting event of your grid and for each row of grid, retrieve tag of your wanted cell and convert it to your control and position it in cell bounds and make it visible. To get the position that control should be shown use GetCellDisplayRectangle method of DataGridView

Screenshot:

My sample control with name of SomeControl, contains a label and a text box and a property SomeProperty and an event SomePropertyChanges. I show cell value in TextBox of my custom control.

You can do anything with your custom control containing any control and any type of properties and events.

enter image description here

Code:

Here is vb-like pseudo code.

'This is not VB, this is vb-like pseudo code 
Private Sub Form_Load(sender as object , e as EventArgs)
    'Get data
    'Show data in grid

    'For each row
    For Each row as DataGridViewRow in this.categoryDataGridView.Rows
        'Create an instance of control
        Dim myControl as New SomeControl()

        'Set properties and register event handlers
        myControl.SomeProperty = row.Cells[2].Value
        myControl.SomePropertyChanged += myControl_SomePropertyChanged

        'Make it invisible
        myControl.Visible = False

        'Set tag of your wanted cell to control
        row.Cells[2].Tag = myControl

        'Add control to Controls collection of grid
        this.categoryDataGridView.Controls.Add(myControl)
    Next
End Sub

Private Sub myControl_SomePropertyChanged(sender as object, e as EventArgs)

    'event handler of SomePropertyChanged for custom control
    'do stuff here
End Sub

Private Sub dataGridView_CellPainting(sender as object, e as DataGridViewCellPaintingEventArgs )
    'for each row
    For i as Integer=0 To dataGridView.RowCount- 1
        'Extract control from tag of your wanted cell
        var myControl= this.dataGridView.Rows[i].Cells[2].Tag as SomeControl

        'Get cell rectangle
        Dim cellRectangle As Rectangle= dataGridView.GetCellDisplayRectangle(2, i, True)

        'Set location
        myControl.Location = New Point(cellRectangle.X, cellRectangle.Y )

        'Set size
        myControl.Size = New Size(cellRectangle.Width - 1, cellRectangle.Height - 1)

        'Make visible
        myControl.Visible = True
    Next
}