Opacity of Forms in C# - CodeProject®

Introduction

In C#, we can access the opacity of a Windows Form using the Opacity property. This article shows you how we can change it, using a simple project.

Using the code

System.Windows.Forms.Timer

We'll try to implement a fade-in and fade-out effect on our WinForm. To do that, we use System.Windows.Forms.Timer.

We will use three Timers in our project:

TimerFadein: Shows the fade-in effect. TimerFadein runs the following method on its Tick event.

private void TimerFadein_Tick(object sender, EventArgs e)
{
    //Prevents Timers overlapping 
    if (timerHalfFadeOut.Enabled || TimerFadeout.Enabled)
    {
        TimerFadein.Enabled = false;
        return;
    }
    timerRunning = true;
    //\\
    this.Opacity += 0.05;
    if (this.Opacity >= 0.95)
    {
        this.Opacity = 1;
        timerRunning = TimerFadein.Enabled = false;
    }
    maskedTextBoxOpacity.Text = (this.Opacity * 100).ToString();
    hScrollBar1.Value = (int)(this.Opacity * 100);
}

TimerFadeout: Shows the fade-out effect. TimerFadeout runs the method below on its Tick event.

private void TimerFadeout_Tick(object sender, EventArgs e)
{
    //Prevents Timers overlapping
    if (timerHalfFadeOut.Enabled || TimerFadein.Enabled)
    {
        TimerFadeout.Enabled = false;
        return;
    }
    timerRunning = true;
    //\\
    this.Opacity -= 0.05;
    if (this.Opacity <= 0.05)
    {
        this.Opacity = 0;
        Application.ExitThread();
    }
    maskedTextBoxOpacity.Text = (this.Opacity * 100).ToString();
    hScrollBar1.Value = (int)(this.Opacity * 100);
}

timerHalfFadeOut: Shows a 0.5 opacity and a fade-out effect. timerHalfFadeOut runs the method below on its Tick event.

private void timerHalfFadeOut_Tick(object sender, EventArgs e)
{
    //Prevents Timers overlapping
    if (TimerFadeout.Enabled || TimerFadein.Enabled)
    {
        timerHalfFadeOut.Enabled = false;
        return;
    }
    timerRunning = true;
    //\\
    this.Opacity -= 0.05;
    if (this.Opacity <= 0.50)
    {
        this.Opacity = 0.5;
        timerRunning = timerHalfFadeOut.Enabled = false;
    }
    maskedTextBoxOpacity.Text = (this.Opacity * 100).ToString();
    hScrollBar1.Value = (int)(this.Opacity * 100);
}

Running the WinApp with a fade-in effect

To show our app with a fade-in effect, we must change the opacity of our Form to zero in the constructor. We must enable TimerFadein too, to show our WinApp with a fade-in effect.

public Form1()
{
    InitializeComponent();
    this.Opacity = 0;
    TimerFadein.Enabled = true;
}

Well, other things (like closing the WinApp and the fade-out effect) are very similar to the above method. We only need to enable or disable the timers. See the source code for more details.

Good luck!