There are few steps to generate gradient color for form in c#

Step 1- Take a form and drag – drop textbox and button

Step 2 – chose first color via button ‘color 1’

Step 3 – chose second color via button ‘color 2’

Step 4- selected color fill into textbox

 Step 5 – Then click on Apply button for generate gradient color for Form1

Step 6 – you can select custom color also

Code:

using System.Drawing.Drawing2D;
using System.Windows.Forms;
using System;
using System.Collections.Generic;
using System.Linq;
 
namespace GradientColor
{
 
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();       
        }
 
        ColorDialog cd = new ColorDialog();
        System.Drawing.Color strcolor1;
        System.Drawing.Color strcolor2;
 
        public void draw(object sender, PaintEventArgs e)
        {
            try
            {
                using (LinearGradientBrush brush = new LinearGradientBrush(ClientRectangle, strcolor1, strcolor2, LinearGradientMode.Vertical))
                {
                    e.Graphics.FillRectangle(brush, ClientRectangle);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
 
         public void Form1_Resize(object sender, System.EventArgs e)
        {
            Invalidate();
        }
 
         private void button1_Click(object sender, EventArgs e)
         {
             cd.ShowDialog();
             txtColor1.BackColor = cd.Color;
             strcolor1 = cd.Color;
         }
 
        private void button2_Click(object sender, EventArgs e)
        {
            cd.ShowDialog();
            txtcolor2.BackColor = cd.Color;
            strcolor2 = cd.Color;
        }
 
        private void btnApply_Click(object sender, EventArgs e)
        {
            Paint += draw;
            Invalidate();
        }
    }
}