How to autosize column width in datagridview with large amount of rows in c#

Question

I have created a Winform application. One of the forms has a datagridview component. It is bound to a binding source that contains a large amount of data. I need to autosize 2 columns to get the fit I need. When autosize for those columns is set to none, it renders the data in the datagridview relatively fast. If I set autosize for those columns to what I need, it takes forever.

How can I accomplish what I need?

Visual Studio 2019 Winform project c#

Answer 1

Here is something to try. Make sure AutoSizeColumnMode is set to None.

internal static class DataGridViewExtensions
{
    /// <summary>
    /// Provides very fast and basic column sizing for large data sets.
    /// </summary>
    public static void FastAutoSizeColumns(this DataGridView targetGrid, params string[] includeColumns)
    {
        // Cast out a DataTable from the target grid data source.
        // We need to iterate through all the data in the grid and a DataTable supports enumeration.
        var gridTable = (DataTable)targetGrid.DataSource;

        // Create a graphics object from the target grid. Used for measuring text size.
        using (var gfx = targetGrid.CreateGraphics())
        {
            // Iterate through the columns.
            for (int index = 0; index < gridTable.Columns.Count; index++)
            {
                var test = gridTable.Columns[index];
                if (includeColumns.Contains(gridTable.Columns[index].ColumnName))
                {
                    // Leverage Linq enumerator to rapidly collect all the rows into a string array, making sure to exclude null values.
                    string[] colStringCollection = gridTable.AsEnumerable().Where(r => r.Field<object>(index) != null).Select(r => r.Field<object>(index).ToString()).ToArray();

                    // Sort the string array by string lengths.
                    colStringCollection = colStringCollection.OrderBy((x) => x.Length).ToArray();

                    // Get the last and longest string in the array.
                    string longestColString = colStringCollection.Last();

                    // Use the graphics object to measure the string size.
                    var colWidth = gfx.MeasureString(longestColString, targetGrid.Font);

                    // If the calculated width is larger than the column header width, set the new column width.
                    if (colWidth.Width > targetGrid.Columns[index].HeaderCell.Size.Width)
                    {
                        targetGrid.Columns[index].Width = (int)colWidth.Width;
                    }
                    else // Otherwise, set the column width to the header width.
                    {
                        targetGrid.Columns[index].Width = targetGrid.Columns[index].HeaderCell.Size.Width;
                    }
                }
            }
        }
    }
}

Then after load data. In this case I want to manually size two columns.

dataGridView1.FastAutoSizeColumns("ProductName", "CompanyName");