Question

I am using C#, Winforms, and .Net 3.5

My form has a custom DataGridView (double-buffered to prevent flickering during my cellformatting events, as seen here). When I perform a database search, I bind the resulting dataset to the datagridview.

I handle the CellFormatting event to paint rows a certain color, depending on their data.

My DataGridView code:

resultsGridView.DataSource = results.DefaultViewManager.DataSet.Tables[0];
resultsGridView.AlternatingRowsDefaultCellStyle.BackColor = Color.AliceBlue;
resultsGridView.BorderStyle = BorderStyle.Fixed3D;
resultsGridView.CellFormatting += new DataGridViewCellFormattingEventHandler(resultsGridView_CellFormatting);

My CellFormatting code:

void resultsGridView_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
    int rowIndex = e.RowIndex;
    DataGridViewRow therow = resultsGridView.Rows[rowIndex];
    if ((bool)therow.Cells["Sealed"].Value == true)
    {
        therow.DefaultCellStyle.BackColor = Color.Pink;
    }
    if (therow.Cells["Database"].Value as string == "PNG")
    {
        therow.DefaultCellStyle.BackColor = Color.LightGreen;
    }
}

Everything works great except that, when I handle the CellFormatting, the whole form’s Paint event seems to be turned off. The cursor stops blinking in the textbox, and the form’s menustrip looks like this:

The top is before a search, the bottom after. The menubar won’t redraw until I mouse over where the menuitems are, and then the last item to be highlighted will stay that way when I move the mouse out of the menubar. Moving the form seems to cause it to repaint, but then the problem remains.

Commenting out the resultsGridView.CellFormatting line in the datagridview code completely fixes the problem.

Am I painting the cells wrong, or is there something else I need to handle?

Answer 1

You are probably causing an exception inside this event. I’m not sure how the handling is defined, but surrounding the code with a try catch would be a first step.

try 
{
   int rowIndex = e.RowIndex;
   ....   
}
catch(Exception ex)
{
    System.Diagnostics.Trace.Error(ex.message);
}

On a second look, I don’t think therow.Cells["Sealed"] will work. Try something like therow.Cells["dataGridViewTextBoxColumn2"]. Cells is indexed by Column Name, not DataPropertyName.