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

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