How do you highlight the row and/or column labels of a datagridview on mouseover of any cell (in c#)?

Question

With a DataGridView control on a Windows form, when you move the mouse over a row label (or column label) it's (the label cell) background changes to a shade of blue (or other colour depending on your Windows colour scheme no doubt).

I would like to produce that effect when moving the mouse over any cell in the grid - ie highlight the row label for the row the mouse is currently hovering over.

The logic for changing the style of the current row is simple enough using mouseover event. I can change other attributes of the row (like say the backcolor) but I would really like something more subtle than that and I think highlighting of the row label would be very effective.

Can it be done - if so how? (C# preferably)

Answer 1

You could override the OnCellPainting event to do what you want. Depending on the size of your DataGridView , you might see flickering, but this should do what you want.

    class MyDataGridView : DataGridView
    {
        private int mMousedOverColumnIndex = int.MinValue;
        private int mMousedOverRowIndex = int.MinValue;

        protected override void OnCellMouseEnter(DataGridViewCellEventArgs e)
        {
            mMousedOverColumnIndex = e.ColumnIndex;
            mMousedOverRowIndex = e.RowIndex;
            base.OnCellMouseEnter(e);
            base.Refresh();
        }

        protected override void OnCellPainting(DataGridViewCellPaintingEventArgs e)
        {
            if (((e.ColumnIndex == mMousedOverColumnIndex) && (e.RowIndex == -1)) ||
                ((e.ColumnIndex == -1) && (e.RowIndex == mMousedOverRowIndex)))
            {
                PaintColumnHeader(e, System.Drawing.Color.Red);
            }
            base.OnCellPainting(e);
        }

        private void PaintColumnHeader(System.Windows.Forms.DataGridViewCellPaintingEventArgs e, System.Drawing.Color color)
        {
            LinearGradientBrush backBrush = new LinearGradientBrush(new System.Drawing.Point(0, 0), new System.Drawing.Point(100, 100), color, color);
            e.Graphics.FillRectangle(backBrush, e.CellBounds);
            DataGridViewPaintParts parts = (DataGridViewPaintParts.All & ~DataGridViewPaintParts.Background);
            e.AdvancedBorderStyle.Right = DataGridViewAdvancedCellBorderStyle.None;
            e.AdvancedBorderStyle.Left = DataGridViewAdvancedCellBorderStyle.None;
            e.Paint(e.ClipBounds, parts);
            e.Handled = true;
        }
    }

Answer 2

You can hook into the DataGridView's CellMouseEnter and CellMouseLeave events and then change the backcolor accordingly. Something like this:

    private void dataGridView1_CellMouseEnter(object sender, DataGridViewCellEventArgs e)
    {
        if (e.RowIndex < 0 || e.ColumnIndex < 0) //column header / row headers
        {
            return;
        } 

        this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].Style.BackColor = Color.LightBlue;
    }

    private void dataGridView1_CellMouseLeave(object sender, DataGridViewCellEventArgs e)
    {
        if (e.RowIndex < 0 || e.ColumnIndex < 0) //column header / row headers
        {
            return;
        }

        this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].Style.BackColor = Color.White;
    }

Answer 3

I know you already have the response for this, but I will share something different.

This way, the whole row is painted . I just modified @BFree comments a little bit.

        private void dataGridView1_CellMouseEnter(object sender, DataGridViewCellEventArgs e)
    {
        if (e.RowIndex < 0 || e.ColumnIndex < 0) //column header / row headers
        {
            return;
        }
        foreach (DataGridViewCell cell in this.dataGridView1.Rows[e.RowIndex].Cells)
        {
           cell.Style.BackColor = Color.LightBlue;
        }
    }

    private void dataGridView1_CellMouseLeave(object sender, DataGridViewCellEventArgs e)
    {
        if (e.RowIndex < 0 || e.ColumnIndex < 0) //column header / row headers
        {
            return;
        }
        foreach (DataGridViewCell cell in this.dataGridView1.Rows[e.RowIndex].Cells)
        {
            cell.Style.BackColor = Color.White;
        }
    }