Proper way to call AnimateWindow with a .NET WinForms Form?

Question

i'm trying to call AnimateWindow to animate the show and hide of a WinForms window.

Here's a copy of the win32 translation:

private static class NativeMethods
{
   public const int AW_ACTIVATE = 0x20000;
   public const int AW_HIDE = 0x10000;
   public const int AW_BLEND = 0x80000;
   public const int AW_CENTER = 0x00000010;
   public const int AW_SLIDE = 0X40000;
   public const int AW_HOR_POSITIVE = 0x1;
   public const int AW_HOR_NEGATIVE = 0X2;

   [DllImport("user32.dll", CharSet = CharSet.Auto)]
   public static extern int AnimateWindow(IntPtr hwand, int dwTime, int dwFlags);
}

But the problem is how to fit a call to AnimateWindow into the) WinForms scheme. One person suggests OnLoad:

protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);
    AnimateWindow(this.Handle, 200, AW_ACTIVATE | AW_HOR_NEGATIVE | AW_SLIDE);
}

and OnClosing:

protected override void OnClosing(System.ComponentModel.CancelEventArgs e)
{
    base.OnClosing(e);
    if (e.Cancel == false)
    {
        AnimateWindow(this.Handle, 200, AW_HIDE | AW_HOR_POSITIVE | AW_SLIDE);
    }
}

Except that it doesn't work.

• the form doesn't use any animation while appearing
• during hide the form animates its horizontal slide off the screen, then reappears, before hiding the normal way

What is the correct way to mix AnimateWindow with WinForms?

---

See also

• .NET AnimateWindow: this guy asked the same question. But since it was trying to achieve something else, people solved his problem rather than answering his question.
• C# WinForms AnimateWindow issue: This guy was interested in using AnimateWindow with child controls, rather than a top-level window.

---

Bonus Chatter

i was perusing through the Form -> Show -> Visible -> SetVisibleCore, when i discovered this bug:

protected virtual void SetVisibleCore(bool value)
{
   try
   {
      HandleCollector.SuspendCollect();
      //...snip...
   }  
   finally
   {
      HandleCollector.ResumeCollect();
   }
}

Nice to know that everyone can introduce these subtle errors.

Answer 1

I think AnimateWindow has it's limitations to work properly. For example, it doesn't play well with Aero, so to animate a sliding form, you would need to set the BorderStyle to None. Also, make sure the StartPosition is set to Manual.

Simple example:

public partial class Form1 : Form {

  public const int AW_ACTIVATE = 0x20000;
  public const int AW_HIDE = 0x10000;
  public const int AW_BLEND = 0x80000;
  public const int AW_CENTER = 0x00000010;
  public const int AW_SLIDE = 0X40000;
  public const int AW_HOR_POSITIVE = 0x1;
  public const int AW_HOR_NEGATIVE = 0X2;

  [DllImport("user32.dll", CharSet = CharSet.Auto)]
  public static extern int AnimateWindow(IntPtr hwand, int dwTime, int dwFlags);

  public Form1() {
    InitializeComponent();
  }

  private void button1_Click(object sender, EventArgs e) {
    Form toastForm = new Form();
    toastForm.ShowInTaskbar = false;
    toastForm.StartPosition = FormStartPosition.Manual;
    toastForm.FormBorderStyle = FormBorderStyle.None;
    toastForm.Size = new Size(256, 64);
    toastForm.Location = new Point(Screen.PrimaryScreen.WorkingArea.Right - toastForm.Width, 
                                   Screen.PrimaryScreen.WorkingArea.Bottom - toastForm.Height);

    Button closeButton = new Button();
    closeButton.Text = "Close";
    toastForm.Controls.Add(closeButton);
    closeButton.Click += delegate { toastForm.Close(); };

    AnimateWindow(toastForm.Handle, 200, AW_ACTIVATE | AW_HOR_NEGATIVE | AW_SLIDE);
    toastForm.Show();
  }
}

Answer 2

I'm not sure what your AnimateWindow call does, but when you need to change underlying native 'stuff' to do with windows forms, I've always used the CreateParams() override. You may find a similar function for what you are trying to achieve.

Here's an example of a transparent tool window, that doesn't activate when it is shown.

Protected Overrides ReadOnly Property CreateParams() As System.Windows.Forms.CreateParams
        Get
            Dim baseParams As Windows.Forms.CreateParams = MyBase.CreateParams

            baseParams.ExStyle = baseParams.ExStyle Or NativeMethods.ExtendedWindowsStyles.WS_EX_LAYERED Or NativeMethods.ExtendedWindowsStyles.WS_EX_TRANSPARENT Or NativeMethods.ExtendedWindowsStyles.WS_EX_NOACTIVATE Or NativeMethods.ExtendedWindowsStyles.WS_EX_TOOLWINDOW

            Return baseParams
        End Get
    End Property