How to increase and decrease opacity of a form?

Kanhialal,

Try this source code:
using System.Drawing;
using System.Windows.Forms;

namespace ConsoleApplication
{

    class MyForm : Form
    {
        public MyForm()
        {
            _progressBar = new ProgressBar();
            _progressBar.Minimum = 0;
            _progressBar.Maximum = 100;
            _progressBar.Value = 0;

            _progressBar.Location = new Point(10, 10);
            _progressBar.Width = ClientSize.Width - 20;

            Controls.Add(_progressBar);

            _timer = new System.Threading.Timer(new System.Threading.TimerCallback(TimerCallback), this, 200, 200);

            IncreaseProgress(0);    // Forces opacity to be recalculated

        }

        private delegate void IncreaseProgressDelegate(int change);

        private void IncreaseProgress(int change)
        {
           
            int newValue = _progressBar.Value + change;
           
            if (newValue > _progressBar.Maximum)
                newValue = _progressBar.Maximum;
            else if (newValue < _progressBar.Minimum)
                newValue = _progressBar.Minimum;
           
            _progressBar.Value = newValue;

            this.Opacity = (double)_progressBar.Value / ((double)(_progressBar.Maximum - _progressBar.Minimum));

        }

        private void TimerCallback(object state)
        {
            MyForm form = (MyForm)state;
            form.BeginInvoke(new IncreaseProgressDelegate(IncreaseProgress), 5);
        }

        private ProgressBar _progressBar;

        private System.Threading.Timer _timer;

    }

    class Program
    {

        static void Main(string[] args)
        {
            MyForm form = new MyForm();
            form.ShowDialog();
        }

    }
}

It is a console application but you have to add System.Windows.Forms reference to work.

It creates a form with a progress bar and sets opacity equal to percentual value of the progress. So when progress is 0, opacity is 0 (i.e. form is completely invisible). Progress bar moves on timer and as soon as it reaches its maximum value 100, opacity of the form reaches value 1.0, which means that it is completely visible.

Zoran