How to set the back color of the row / column header cell in a datagridview - c# winform

Question

I want to set the back color of the row header and column header intersection cell of a datagridview. I tried the below code, but it throws an exception that the number should be non negative.

DataGridViewCell cell = dgview.Rows[-1].Cells[-1];
cell.Style.BackColor = Color.Red;

I want to set the color as shown in the image below

I also refered the below article, but it shows how to set the color of the whole column header. But my requirement is to set the color of a single cell - row-column header intersection cell.

how-to-change-the-color-of-winform-datagridview-header

Any help is much appreciated. Thank you.

Regards,

Vinay

Answer 1

Store the current ColumnHeadersDefaultCellStyle in a variable.

Set the ColumnHeadersDefaultCellStyle to how you want the corner to be.

Then change all of the columns headers to how you want columns 0 to ... back to the old style.

Below is an example where the form is called "MyForm". This example shows the default constructor of MyForm.

Example:

    public MyForm()
    {
        InitializeComponent();

        // insert code here to add columns  ...
        // ...
        // ...
        // ...

        DataGridViewCellStyle oldDefault = dgview.ColumnHeadersDefaultCellStyle.Clone();

        dgview.ColumnHeadersDefaultCellStyle.BackColor = Color.Red;

        foreach (DataGridViewColumn item in dgview.Columns)
        {
            item.HeaderCell.Style = oldDefault;
        }
    }

Answer 2

    private void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
    {
        if (e.RowIndex == -1 && e.ColumnIndex ==  -1)

        {
            using (Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor))
            {
                using (Brush backColorBrush = new SolidBrush(Color.Red))
                {
                    using (Pen gridLinePen = new Pen(gridBrush))
                    {
                        // Clear cell 
                        e.Graphics.FillRectangle(backColorBrush, e.CellBounds);
                        //Bottom line drawing
                        e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom-1 , e.CellBounds.Right, e.CellBounds.Bottom-1);
                        e.Handled = true;
                    }
                }
            }
        }

Answer 3

This is a bit of a hack, but add a PictureBox inside the DataGridView using the designer(if you're using VS) and initialize it's properties such as:

pictureBox1.BackColor = Color.Red;
pictureBox1.Width = dgView.RowHeadersWidth;
pictureBox1.Height = dgView.ColumnHeadersHeight;