Why does it sometimes call a method twice in a row inside a timer mark event?

Question

I have a solution with two projects. In the library project, I added the public static variable bool and set it to true. Then in the windows forms project, I use the flag. In the window shape designer, I added a timer, setting its interval to 1000.

I start the timer in the constructor. And then even I tick in the timer:

private void timer1_Tick(object sender, EventArgs e)
{
    if (SDKHandler.Saved == true)
    {
        timer1.Stop();
        DisplayLastTakenPhoto();
        TakePhotoButton.Enabled = true;
        SDKHandler.Saved = false;
        timer1.Start();
    }
}

And the DisplayLastTakenPhoto () method

private void DisplayLastTakenPhoto()
{
    string mypath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyPictures), "RemotePhoto");
    var directory = new DirectoryInfo(mypath);
    var myFile = directory.EnumerateFiles()
        .Where(f => f.Extension.Equals(".jpg", StringComparison.CurrentCultureIgnoreCase) || f.Extension.Equals("raw", StringComparison.CurrentCultureIgnoreCase))
        .OrderByDescending(f => f.LastWriteTime)
        .First();

    if (WaitForFile(myFile.FullName) == true) LiveViewPicBox.Load(myFile.FullName);
}

And the WaitForFile method

bool WaitForFile(string fullPath)
{
    int numTries = 0;
    while (true)
    {
        ++numTries;
        try
        {
            using (FileStream fs = new FileStream(fullPath, FileMode.Open,  FileAccess.ReadWrite, FileShare.None, 100))
            {
                fs.ReadByte();
                break;
            }
        }
        catch (Exception ex)
        {
            if (numTries > 10)
            {
                return false;
            }
            System.Threading.Thread.Sleep(500);
        }
    }
    return true;
}

Sometimes not all the time, but in some cases when it calls the DisplayLastTakenPhoto () method; twice in a row. Even if I stopped the timer first, I do timer1.Stop (); but still in some cases I see a method that is called twice.

And the second time it makes the program freeze and freeze sometimes even for 1-3 seconds.

Answer 1

, , . , . . , WaitForFile() . , PictureBox.Load() . , Image, . , , :)

, . , , . - , 5 , , . , -. , .

, Bitmap (Image) , . .

, FileSystemWatcher . , , FSW, . , , .

Answer 2

MSDN. , , :

"" "" . 5000- , Stop 3000 , Start , 5000 , Tick.

Windows Forms , . , 700 , - 500 , Stop , .

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