Thread.Sleep() in C#

Question

I want to make an image viewer in C# Visual Studio 2010 which displays images one by one after seconds:

i = 0;

if (image1.Length > 0) //image1 is an array string containing the images directory
{
    while (i < image1.Length)
    {
        pictureBox1.Image = System.Drawing.Image.FromFile(image1[i]);
        i++;
        System.Threading.Thread.Sleep(2000);
    }

When the program starts, it stops and just shows me the first and last image.

i guess it's sleeping inbetween ;) - Thread.Sleep(123) stops the whole thread which in this case includes the image display i guess without knowing your surrounding code - however, using a Timer might bring you more luck — ChriPf, Aug 20 '12 at 14:39
Not sure why you were downvoted? Seemed like a good question to me. — CaffGeek, Aug 20 '12 at 14:41

score 17 · Accepted Answer · answered Aug 20 '12 at 14:38

17

Thread.Sleep blocks your UI thread use System.Windows.Forms.Timer instead.

answered Aug 20 '12 at 14:38

L.B

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1

any special reason to use System.Windows.Forms.Timer? – ChriPf Aug 20 '12 at 14:46
5

@ChriPf because the Windows Forms timer tick events automatically runs on the UI thread. No need to Invoke. – Chris Shain Aug 20 '12 at 14:50
TO explain: The windows shows the picture when it redraws. THe redraw is a UI thread event. You block the thread, no UI updates - and no other UI interaction either, so no button clicks etc. – TomTom Apr 13 '14 at 19:10

score 14 · Answer 2 · answered Aug 20 '12 at 14:49

Use a Timer.

First declare your Timer and set it to tick every second, calling TimerEventProcessor when it ticks.

static System.Windows.Forms.Timer myTimer = new System.Windows.Forms.Timer();
myTimer.Tick += new EventHandler(TimerEventProcessor);
myTimer.Interval = 1000;
myTimer.Start();

Your class will need the image1 array and an int variable imageCounter to keep track of the current image accessible to the TimerEventProcessor function.

var image1[] = ...;
var imageCounter = 0;

Then write what you want to happen on each tick

private static void TimerEventProcessor(Object myObject, EventArgs myEventArgs) {
    if (image1 == null || imageCounter >= image1.Length)
        return;

    pictureBox1.Image = Image.FromFile(image1[imageCounter++]);
}

Something like this should work.

I do not see System.Windows.Form.Timer on Visual Studio Mac classes. There is System.Threading.Timer but the syntax is different. — 1.21 gigawatts, May 15 '21 at 11:16

score 0 · Answer 3 · answered Aug 20 '12 at 14:38

0

Yes, because Thread.Sleep blocks the UI thread during the 2s.

Use a timer instead.

answered Aug 20 '12 at 14:38

ken2k

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score 0 · Answer 4 · answered Apr 13 '14 at 19:43

If you want to avoid using Timer and defining an event handler you can do this:

DateTime t = DateTime.Now;
while (i < image1.Length) {
    DateTime now = DateTime.Now;
    if ((now - t).TotalSeconds >= 2) {
        pictureBox1.Image = Image.FromFile(image1[i]);
        i++;
        t = now;
    }
    Application.DoEvents();
}

Thread.Sleep() in C#

4 Answers4

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