How do you automatically resize columns in a DataGridView control AND allow the user to resize the columns on that same grid?

Question

I am populating a DataGridView control on a Windows Form (C# 2.0 not WPF).

My goal is to display a grid that neatly fills all available width with cells - i.e. no unused (dark grey) areas down the right and sizes each column appropriately according to the data it contains, but also allows the user to resize any of the columns to their liking.

I am attempting to achieve this by setting the AutoSizeMode of each column to be DataGridViewAutoSizeColumnMode.AllCells except for one of the columns which I set to DataGridViewAutoSizeColumnMode.Fill in order to ensure the entire area of the grid is neatly filled with data. (I don't mind that when the user attempt to resize this column it springs back to a size that ensures the horizontal space is always used.)

However, as I mentioned, once loaded I would like to allow the user to resize the columns to suit their own requirements - in setting these AutoSizeMode values for each column it appears the user is then unable to then resize those columns.

I've tried not setting the AutoSizeMode of all the columns which does allow resizing BUT doesn't set the initial size according to the data the cells contain. The same result occurs when changing the grid's AutoSizeMode back to "Not Set" after loading the data.

Is there a setting I'm missing here which allows automatic setting of default column widths AND user resizing or is there another technique I must use when populating the DataGridView control?

Answer 1

This trick works for me:

    grd.DataSource = DT;

    // Set your desired AutoSize Mode:
    grd.Columns[0].AutoSizeMode = DataGridViewAutoSizeColumnMode.AllCells;
    grd.Columns[1].AutoSizeMode = DataGridViewAutoSizeColumnMode.AllCells;
    grd.Columns[2].AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill;

    // Now that DataGridView has calculated it's Widths; we can now store each column Width values.
    for (int i = 0; i <= grd.Columns.Count - 1; i++)
    {
        // Store Auto Sized Widths:
        int colw = grd.Columns[i].Width;

        // Remove AutoSizing:
        grd.Columns[i].AutoSizeMode = DataGridViewAutoSizeColumnMode.None;

        // Set Width to calculated AutoSize value:
        grd.Columns[i].Width = colw;
    }

In the Code above: You set the Columns AutoSize Property to whathever AutoSizeMode you need. Then (Column by Column) you store each column Width value (from AutoSize value); Disable the AutoSize Property and finally, set the Column Width to the Width value you previously stored.

Answer 2

Maybe you could call

dataGridView1.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.Fill);

After setting datasource. It will set the width and allow resize.

More on MSDN DataGridView.AutoResizeColumns Method (DataGridViewAutoSizeColumnsMode).