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Fading Forms In and Out

, 13 Aug 2007 CPOL
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Add fade transitions to your applications
Screenshot - FadeForm.jpg


Disclaimer: I am not the first to make a form fader, but I couldn't find one that did exactly what I wanted and so I created this.

I have had need in the past to cause my forms to perform fade transitions from one opacity to another. It was usually on load, close and window state changes. I finally decided to bring it all together in a nice, extendable Form. The FadeForm...

  • fades in on open.
  • fades out on close.
  • partially fades out on focus lost.
  • fades in on focus.
  • fades out on minimize.
  • fades in on restore.
  • must not annoy the user. Smile | :) A form fader definitely has that potential.

Using the Code

To use FadeForm, just extend it instead of Form and you are ready to go.

public class Form1 : FadeForm

It is defaulted to use the fade-in from nothing on open and out to nothing on close. It will also fade to 85% opacity when not the active window. You can set it to whatever you want, however.

//This would set the form with its default values.

You may, from time to time, want to disable the fade effect.

this.DisableFade(); //Turn off fade effects
this.EnableFadeDefaults(); //Turns on fade effects

You can also change the transition time.

this.FadeTime=1; //1 sec transition

You can also do a one-time fade to any value.

this.TargetOpacity=.25; //Fades the form to 25% opacity

Points of Interest

The opening and focus change events were easy to deal with. It was appropriate to use the built-in event listeners.

public FadeForm()
    this.timer.Tick += new System.EventHandler(this.timer_Tick);
    this.Deactivate += new System.EventHandler(this.FadeForm_Deactivate);
    this.Activated += new System.EventHandler(this.FadeForm_Activated);
    this.Load += new System.EventHandler(this.FadeForm_Load);

private void FadeForm_Load(object sender, EventArgs e)
   this.Opacity = minimizedOpacity;
   this.TargetOpacity = activeOpacity;

private void FadeForm_Deactivate(object sender, EventArgs e)
    this.TargetOpacity = inactiveOpacity;

private void FadeForm_Activated(object sender, EventArgs e)
    this.TargetOpacity = activeOpacity;

The minimize and close events where a little trickier because the actions had to be postponed until the fade transition was complete. I had to override WndProc in order to catch the request for those actions and postpone the action until the transition was done.

private const int WM_SYSCOMMAND = 0x112;
private const int WM_COMMAND = 0x111;
private const int SC_MINIMIZE = 0xF020;
private const int SC_RESTORE = 0xF120;
private const int SC_CLOSE = 0xF060; 

// Intercepts WindowMessages before they are processed.
protected override void WndProc(ref Message m)
    if (m.Msg==WM_SYSCOMMAND||m.Msg == WM_COMMAND) 
        //Fade to zero on minimze
        if (m.WParam == (IntPtr)SC_MINIMIZE) 
            heldMessage = m;
            this.TargetOpacity = minimizedOpacity;

         //Fade in if the window is restored from the taskbar
         else if (m.WParam == (IntPtr)SC_RESTORE 
           && this.WindowState == FormWindowState.Minimized) 
             base.WndProc(ref m);  
             this.TargetOpacity = activeOpacity;

         //Fade out if the window is closed.
         else if (m.WParam == (IntPtr)SC_CLOSE) 
             heldMessage = m; 
             this.TargetOpacity = minimizedOpacity;
     base.WndProc(ref m);

Once that was done, all I had to do was perform the transitions.

//Performs fade increment.
private void timer_Tick(object sender, EventArgs e)
    double fadeChangePerTick = timer.Interval * 1.0 / 1000 / fadeTime;

    //Check to see if it is time to stop the timer
    if (Math.Abs(targetOpacity - this.Opacity) < fadeChangePerTick)
        //There is an ugly black flash if you set the Opacity to 1.0
        if (targetOpacity == 1) this.Opacity = .999;
        else this.Opacity = targetOpacity;
        //Process held Windows Message.
        base.WndProc(ref heldMessage);
        heldMessage = new Message();
        //Stop the timer to save processor.
    else if (targetOpacity > this.Opacity) this.Opacity += fadeChangePerTick;
    else if (targetOpacity < this.Opacity) this.Opacity -= fadeChangePerTick;

It is interesting to notice that the opacity is never actually 1. That was a hack on my part to keep the window from flashing black. I am not sure what the cause of this is, but the fix was easy, so I may never know.

You can see that I stop the timer after I reach my target opacity. You may wonder how it gets started. Every time I set TargetOpacity, the set method starts the timer. There's no sense running the timer and wasting processor power when you don't need it.

private double TargetOpacity
        targetOpacity = value;
         if (!timer.Enabled) timer.Start();
        return targetOpacity; 

I think I made it about as easy as possible. I always like to adhere to the KISS principle: Keep it simple, stupid.


I plan to add a Notify(int n) method that will oscillate the opacity n times in order to get the user's attention. I also think it would be nice to give a choice between mouseover-based and focus-based transitions.


  • 13 August, 2007 -- Original version posted


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Nicholas Seward
Instructor / Trainer
United States United States
I am a mechanical engineer that works as a high school math teacher in Mulberry, Arkansas. I use programming as one way to keep my mind sharp.

Comments and Discussions

Generalblack flash Pinmemberroundy7215-Mar-09 10:23 
GeneralRe: black flash PinmemberNicholas Seward15-Mar-09 16:49 
GeneralRe: black flash PinmemberAtanas Palavrov1-Apr-09 17:37 
I found that flash happen because Form.Opacity set method changes form style, and Windows kernel erases background then repaints window. I found this with remote debugginng in virtual machine with breakpoints in overriden WndProc, OnPaint, OnPaintBackground - in call stack you can see what realy happen. Avoiding to set opacity to 1 solves this problem but resizing and overlaping window with other windows still repaints with flicks. This kernel behavior is completely confising for me, could anyone explain it?
GeneralRe: black flash PinmemberAtanas Palavrov12-May-09 10:14 
GeneralRe: black flash [modified] PinmemberNicholas Seward12-May-09 11:13 
GeneralRe: black flash PinmemberAtanas Palavrov14-May-09 4:54 
GeneralRe: black flash PinmemberNicholas Seward14-May-09 6:49 
GeneralSystem ERROR Occured in Application Pinmembercoolpul6-Sep-08 3:50 
General.999 opacity and layout execution time Pinmembernukefusion26-Nov-07 5:10 
GeneralGeneral Comments Pinmemberchris17522-Aug-07 3:25 
GeneralRe: General Comments PinmemberNicholas Seward26-Aug-07 8:05 
GeneralRe: General Comments Pinmemberchris17527-Aug-07 2:13 
GeneralRe: General Comments PinmemberNicholas Seward27-Aug-07 5:46 
GeneralRe: General Comments Pinmemberchris17527-Aug-07 9:44 
GeneralRe: General Comments PinmemberNicholas Seward27-Aug-07 11:25 
GeneralRe: General Comments Pinmemberchris17527-Aug-07 9:54 
QuestionDoes it work with VB .Net ? PinmemberPatrice Dargenton22-Aug-07 1:26 
AnswerRe: Does it work with VB .Net ? PinmemberNicholas Seward26-Aug-07 7:58 
GeneralRe: Does it work with VB .Net ? PinmemberPatrice Dargenton27-Aug-07 2:54 
GeneralMDI child PinmemberWindows M15-Aug-07 5:10 
GeneralRe: MDI child PinmemberNicholas Seward16-Aug-07 15:42 
GeneralRe: MDI child PinmemberWindows M16-Aug-07 22:56 
GeneralCool... Pinmemberdgauerke13-Aug-07 9:41 
GeneralRe: Cool... PinmemberNicholas Seward13-Aug-07 20:04 
GeneralRe: Cool... Pinmemberddmccrory16-Aug-07 2:26 

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