Changing opacity in form with trackbar in C# don't works, why?

Question

I have (for fun) make a form in C#, with a trackbar. I want to change the Opacity of the form with it, so I wrote this:

private void trackBar1_Scroll(object sender, EventArgs e)
{
    progressBar1.Value = trackBar1.Value;
    System.Windows.Forms.Form.ActiveForm.Opacity = trackBar1.Value;
    label2.Text = trackBar1.Value.ToString();
}

When I start the program, the opacity will be 100% if the trackbar is in value 1 to 100, and if i drag the trackbar to 0, the form becomes fully transparant.

can you only get 100% Opacity or 0% Opacity when a form is started, or is what i want also possible?

Answer 1

Use this:

System.Windows.Forms.Form.ActiveForm.Opacity = ((double)(trackBar1.Value) /100.0)

You can have different degrees of opacity. For example 0.5 will give you 50% opacity.