DataGridView won't repaint itself when updated from another thread

Question

I have a problem updating DataGridView from another thread. Let me explain. When user clicks a button on a form I need to populate the grid with some rows. This process takes some time, so I'm doing it in a separate thread. Before starting the thread I set DataGridView.Enabled property to false, to prevent user from editing items while they are being added, and just before the working thread ends I set Enabled back to true.

The problem is DataGridView won't update its contents correctly if scrollbars need to be shown. I'll illustrate this with a screenshot:

As you can see, the last visible row is partially drawn and the DataGridView won't scroll down. If I resize the grid, making it to repaint itself, all rows appear normally.

Here is some code:

    private void button1_Click(object sender, EventArgs e)
    {
        string[] fileNames = new string[] { "file1", "file2", "file3" };
        Thread AddFilesToListThread = new Thread(ThreadProcAddRowsToGrid);
        dataGridView1.Enabled = false;
        AddFilesToListThread.Start(fileNames);
    }

    delegate void EmptyDelegate();

    private void ThreadProcAddRowsToGrid(object fileNames)
    {
        string[] files = (string[])fileNames;
        foreach (string file in files)
        {
            EmptyDelegate func = delegate
            {
                dataGridView1.Rows.Add(file);
            };
            this.Invoke(func);
        }

        EmptyDelegate func1 = delegate
        {
            dataGridView1.Enabled = true;
        };
        this.BeginInvoke(func1);
    }

I've also notices that only Enabled property causes this strange behaviour. Changing, for example, BackgroundColor works fine.

Could you help me see where the problem is?

Answer 1

Have you tried DataGridView.Refresh()

Maybe setting the readonly property instead of dataGridView1.Enabled = true;?

Alternatively, I think this may be solved by separating your data from the UI.

It looks to me like this is a simplified example for SO here but if you can I would suggest replacing the equivalent line;

dataGridView1.Rows.Add(file);

with

DataTable table = getData(); //In your snippet (file)
BindingSource source = new BindingSource();
source.DataSource = table
dataGridView1.Datasource = source;

Then you can also refresh the data using ResetBindings on the BindingSource;

table = getData();; //Update your data object
source.ResetBindings(false);