How to increase and decrease opacity of a form?

Question

Hi I am want to (--) decrease the opacity of a form on timer just like... if(progressbar.value=30) { this.opacity-=10; } But this is not working .. Please help..

Zoran Horvat · Answer

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 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

Zoran Horvat · Answer

Kanhialal Please don't forget to tick This is correct answer for the post which has solved the problem. Thanks Zoran

Kanhialal kk · Answer

yes sir( Zoran ) it meats my requirement thanks

Zoran Horvat · Answer

Kanhialal Did this code solve your problem? Zoran

Zoran Horvat · Answer

It is OK if you have means to access the invisible form. And it is certainly allowed by the Opacity property. In my example I have closed the form as soon as it hits opacity 0 but if that form is accessed programmatically from another form then it can be closed on some other condition (or made visible again by setting positive opacity). It would only be stupid to set opacity to 0 if that form's controls are the only mean of controling it - then user can't see the close button or something similar. Zoran

robert alis · Answer

But is it ok to set opacity to 0 if (_progressBar.Value == _progressBar.Maximum && this.Opacity == 0) Close(); // Close the form as it becomes invisible

Zoran Horvat · Answer

To reverse the opacity direction i.e. to make it reduce as progress bar continues you should change the IncreaseProgress function: private void IncreaseProgress(int change) { int newValue = _progressBar.Value + change; if (newValue > _progressBar.Maximum) newValue = _progressBar.Maximum; else if (newValue newValue = _progressBar.Minimum; _progressBar.Value = newValue; this.Opacity = (double)(_progressBar.Maximum - _progressBar.Value) / ((double)(_progressBar.Maximum - _progressBar.Minimum)); if (_progressBar.Value == _progressBar.Maximum && this.Opacity == 0) Close(); // Close the form as it becomes invisible }

Dorababu Meka · Answer

If you write as per your code the form is not getting visible Opacity applying but unable to see that form so try in between 0.1 to 0.80 . Even if you apply 0.80 you can see the opacity set to Low

Dorababu Meka · Answer

See we already said that if you take value above or equal to 1 will remain the form as it is so try as per suggested

Kanhialal kk · Answer

but sir i want that opacity continue -- as we use in loop.. with progress value/..

Zoran Horvat · Answer

Opacity is the double property which receives values in range 0.00 to 1.00. If you want to reduce it by 10% then your code should look like this: if (progressbar.value == 30) this.opacity -= 0.1; This should work. Zoran

Dorababu Meka · Answer

I think greater than 1 will show normal form I just created a sample one and code as follows ot works fine for me private void Form2_Load(object sender EventArgs e) { progressbar.Minimum = 0; progressbar.Maximum = 100; progressbar.Value = 30; if (progressbar.Value == 30) { this.Opacity = .75; } }