Flash winForm on update

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I'm working on C# winForm project where I need to "flash/blink" the form when the form receives an update. Here's the code I got from a VB example that I tried to convert to C# but I'm missing something because it's not flashing when i click the buttion. Can someone please tell/show me what I'm doing wrong here?

Thanks in advance,
-DA

public class Form1 : Form
{
   public Form1()
   {
      Initialize();
   }


   public void button1_Click(object sender, EventArgs e)
   {
      FlashForm.FlashWindow(this, FlashForm.FlashOptions.ALL, true, 5);
   }
}


public struct FlashWindowInfo
{
   public int cbSize;
   public IntPtr hwnd;
   public uint dwFlags;
   public uint uCount;
   public uint dwTimeout;
}

public static class FlashForm
{
   [DllImport("user32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]

   public static extern bool FlashWindowEx(ref FlashWindowInfo pInfo);

   public enum FlashOptions : uint
   {
      ALL = 0x3,
      CAPTION = 0x1,
      STOP = 0,
      TIMER = 0x4,
      TIMERNOFG = 0xc,
      TRAY = 0x2
   }

   public struct FlashWindowInfo
   {
      public int cbSize;
      public IntPtr hwnd;
      public uint dwFlags;
      public uint uCount;
      public uint dwTimeout;
   }

   public static void FlashWindow(Form FormToFlash, FlashOptions Options, bool FlashIfFocused, uint FlashTimes = 5)
   {
      if (!FlashIfFocused && FormToFlash.ContainsFocus)
          return;

      FlashWindowInfo info = default(FlashWindowInfo);
      var _with1 = info;
      _with1.cbSize = Marshal.SizeOf(info);
      _with1.dwFlags = Convert.ToUInt32(Options);
      _with1.dwTimeout = 0;
      _with1.hwnd = FormToFlash.Handle;
      _with1.uCount = FlashTimes;
      FlashWindowEx(ref info);
   }
}

Posted 25-Sep-13 14:10pm

d.allen101

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Matt T Heffron · Accepted Answer · 2013-09-25T14:20:00

The struct FlashWindowInfo has value semantics, which means using _with is the problem, because it makes a copy of info. Simplify to:

C#

public static void FlashWindow(Form FormToFlash, FlashOptions Options, bool FlashIfFocused, uint FlashTimes = 5)
{
   if (!FlashIfFocused && FormToFlash.ContainsFocus)
       return;

   FlashWindowInfo info = default(FlashWindowInfo);
   info.cbSize = Marshal.SizeOf(info);
   info.dwFlags = Convert.ToUInt32(Options);
   info.dwTimeout = 0;
   info.hwnd = FormToFlash.Handle;
   info.uCount = FlashTimes;
   FlashWindowEx(ref info);
}

You probably want to add

C#

[StructLayout(LayoutKind.Sequential)]

to the struct FlashWindowInfo declaration.