CODEWITHSUNDEEP
c#datagridview
mj82
mj82

Reputation: 5263

Changing row color in not-active DataGridView

What's the best way of changing some rows back color in DataGridView, when it's not active??

In "real" world I would like to use it for formatting all DataGridView rows after button click, depending on some criterias.

To reproduce behaviour, please try:
1. In WinForms application put TabControl with two tab pages. On the first tab put button, on second - DataGridView.
2. Use following code:

using System;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {

        public int counter = 0;

        public Form1()
        {
            InitializeComponent();

            DataTable dt = new DataTable();

            dt.Columns.Add("Name", typeof(string));
            dt.Columns.Add("Surname", typeof(string));
            dt.Rows.Add("Mark", "Spencer");
            dt.Rows.Add("Mike", "Burke");
            dt.Rows.Add("Louis", "Amstrong");

            dataGridView1.DataSource = dt;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            counter++;
            this.Text = "Event counter: " + counter.ToString();

            dataGridView1.Rows[1].DefaultCellStyle.BackColor = System.Drawing.Color.Red;
        }
    }
}

I put the counter variable for testing different options to see, how many times the event of color changing is fired (less is better ;) - ideally only once).

Now, when you first click the button WITHOUT going on tabPage2, and then you switch to tabPage2 - the color of row will not change. This is the problem I have.

It will work when you first activate tabPage2, and then press the button, or when you programatically set tabControl1.SelectedIndex = 1;, then color row and then switch back to tabControl1.SelectedIndex = 0; - but in this situation it "blinks".

I also tried to put code of color changing to cell_painting event, but for me it's overkill - it's fired couple hundred times in short time, even when you move mouse over datagridview, while I need to do it only once.

Do you have any advice how to solve that issue?

Best regards,
Marcin

Upvotes: 3

Views: 1940

Answers (1)

David Hall
David Hall

Reputation: 33163

One possibility is to the colour within the datagridview paint event (which gets fired when the tabpage changes). 

private void dataGridView1_Paint(object sender, PaintEventArgs e)
{
    dataGridView1.Rows[0].DefaultCellStyle.BackColor = Color.Red;
}

This works nicely for me - the paint event does get called several times when you change the tab, so if you want to only set the DefaultCellStyle once you could do something like:

public partial class Form1 : Form
{

    private bool setcol;
    private bool painted;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        setcol = true;
        painted = false;
    }

    private void dataGridView1_Paint(object sender, PaintEventArgs e)
    {
        if (setcol && !painted)
        {
            painted = true;
            dataGridView1.Rows[0].DefaultCellStyle.BackColor = Color.Red;
        }
    }
}

Upvotes: 1

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