Question

In my DataGridView, there’s a small tick mark which helps the user visualize which row they’re in but there doesn’t seem to be the same kind of tick mark for the current column that they’re in.

Answer 1

If you want an actual tic mark, you will either need to do some custom drawing, or manipulate the sorting tic mark. I don;t recommend the latter, because it is by now a convention that the little arrow in a column header means “sort.”

You can, however, play with the formatting of the header cell. In this (semi-crude, but effective) example, a change the text in the header cell to bold to indicate the column in which the currently selected cell resides. When the user changes cells, either by tabbing or by simply clicking into a new cell, the correct column header text changes to bold.

Obviously, there are some other properties to mess with, although you may have to fiddle about for a while trying to find the proper ways to use the style property. I used the bold text because it was an easy demo (it is probably how I would approach it in a project, as well however).

Basically, it all comes down to the DataGridViewColumn.HeaderCell.Style property.

In the following, I inherit from the DataGridview class, and then use some event handling to manipulate the header cell during the CellEnter event sourced by the control:

class dgvControl : DataGridView
{
    // Keep track of the most recently selected column:
    private DataGridViewColumn _currentColumn;

    public dgvControl() : base()
    {
        // Add a handler for the cell enter event:
        this.CellEnter += new DataGridViewCellEventHandler(dgvControl_CellEnter);

        // When the Control is initialized, instantiate the placeholder
        // variable as a new object:
        _currentColumn = new DataGridViewColumn();

        // In case there are no columns added (for the designer):
        if (this.Columns.Count > 0)
        {
            this.OnColumnFocus(0);
        }
    }


    void dgvControl_CellEnter(object sender, DataGridViewCellEventArgs e)
    {
        this.OnColumnFocus(e.ColumnIndex);        
    }


    void OnColumnFocus(int ColumnIndex)
    {
        // If the new cell is in the same column, do nothing:
        if (ColumnIndex != _currentColumn.Index)
        {
            // Set up a custom font to represent the current column:
            Font selectedFont = new Font(this.Font, FontStyle.Bold);

            // Grab a reference to the current column:
            var newColumn = this.Columns[ColumnIndex];

            // Change the font to indicate status:
            newColumn.HeaderCell.Style.Font = selectedFont;

            // Set the font of the previous column back to normal:
            _currentColumn.HeaderCell.Style.Font = this.Font;

            // Set the current column placeholder to refer to the new column:
            _currentColumn = newColumn;
        }

    }
}

UPDATE:

If you want to take more control, and mess with the header cell back color or other style properties other than the font, you will need to set the EnableHeadersVisualStyles property to false. The code below has been modified such that the background color of the header can be manipulated. The price for the increased flexibility is that you no longer get the somewhat slicker visual appearance of the headers (they flatten out, and no longer have the slight gradient).

You can be really ambitious and override the OnPaint method to do your own draing, but that seems a bit extreme. Try this code, see if the appearance of the headers is simply inbearable. Anyway, it’s a start!

class dgvControl : DataGridView
{
    // Keep track of the most recently selected column:
    private DataGridViewColumn _currentColumn;

    public dgvControl() : base()
    {
        this.EnableHeadersVisualStyles = false;

        // Add a handler for the cell enter event:
        this.CellEnter += new DataGridViewCellEventHandler(dgvControl_CellEnter);

        // When the Control is initialized, instantiate the placeholder
        // variable as a new object:
        _currentColumn = new DataGridViewColumn();

        // In case there are no columns added (for the designer):
        if (this.Columns.Count > 0)
        {
            this.OnColumnFocus(0);
        }
    }


    void dgvControl_CellEnter(object sender, DataGridViewCellEventArgs e)
    {
        this.OnColumnFocus(e.ColumnIndex);        
    }


    void OnColumnFocus(int ColumnIndex)
    {
        // If the new cell is in the same column, do nothing:
        if (ColumnIndex != _currentColumn.Index)
        {
            // Set up a custom font to represent the current column:
            Font selectedFont = new Font(this.Font, FontStyle.Bold);

            // Grab a reference to the current column:
            var newColumn = this.Columns[ColumnIndex];

            // Change the font to indicate status:
            newColumn.HeaderCell.Style.Font = selectedFont;

            // Change the color to a slightly darker shade of gray:
            newColumn.HeaderCell.Style.BackColor = Color.LightGray;


            // Set the font of the previous column back to normal:
            _currentColumn.HeaderCell.Style.Font = this.Font;

            // Change the color of the previous column back to the default:
            _currentColumn.HeaderCell.Style.BackColor = Color.Empty;


            // Set the current column placeholder to refer to the new column:
            _currentColumn = newColumn;
        }

    }
}