Toggling Picture Box visibility C#

Question

Why is the picture box control's visibility property not working here. I have initially set them to false, so that when the screen loads they are not visible. But then I wish to toggle this. I have done the following but does not seem to work. This is a windows forms application.

private void Action()
    {
        while (true)
        {

            Random r1 = new Random();
            int num = r1.Next(1,3);

            switch (num)
            {
                case 1:
                    pictureBoxLeft.Visible = true;
                    pictureBoxRight.Visible = true;
                    break;
                case 2:
                    pictureBoxLeft.Visible = true;
                    pictureBoxRight.Visible = false;
                    break;
                case 3:
                    pictureBoxLeft.Visible = false;
                    pictureBoxRight.Visible = true;
                    break;

            }

            Thread.Sleep(200);
            pictureBoxLeft.Visible = false;
            pictureBoxRight.Visible = false;
            Thread.Sleep(500);
        }
    }

Also to add, this is working properly with a text box!!! Any Ideas???

Many thanks in advance

Is this your code behind file? – Haris Hasan May 21 '11 at 20:59 — Haris Hasan, May 21 '11 at 20:59
Yes. this is my code behind file – Nishant May 21 '11 at 21:01 — Nishant, May 21 '11 at 21:01

score 5 · Answer 1 · answered May 21 '11 at 21:19

Setting the Visible property to true doesn't show the control, it only creates a message that will show it. As long as you are keeping the main thread busy with a Sleep, it will not process any messages, and the controls won't be shown.

You should show the picture boxes and then set up a timer with code that will hide the picture boxes when the timer's tick event is triggered. Then you exit your method so that the main thread can handle the messages that will show the picture boxes.

Haris Hasan · Answer 2 · 2011-05-21T21:01:37.547

1

This is your UI thread. UI thread is so busy that it is not getting time to refresh the display. UI thread is busy in endless while loop, so how can it update UI?

edited May 21 '11 at 21:01

answered May 21 '11 at 20:55

Haris Hasan

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Even textbox won't be enabled in this case. Can you edit text in textbox? – Haris Hasan May 21 '11 at 21:11
It is. If I replace the picture box with a text box the visibility toggles for it. I just need to toggle visibility here. Any ideas how to get around this? – Nishant May 21 '11 at 21:16
I know textbox appears in that case. I am not sure why it does. It shouldn't. What you are trying to achieve is incorrect. You won't be able to enter text in text box in this case. Am I right? – Haris Hasan May 21 '11 at 21:19
The UI won't respond/update to any input (not mouse nor keyboard) while stuck in the sleep. – Mario May 21 '11 at 21:22

score 0 · Answer 3 · answered May 20 '15 at 09:37

0

Whenever the UI changes does not apear after you did some changes, always do Refres(). e.g. pictureBoxLeft.Refresh();. This will always make UI changes appear. Please let me know if it works for you.

answered May 20 '15 at 09:37

Daya Paari

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1
1

score 0 · Answer 4 · answered May 21 '11 at 21:21

In addition to Thread.Sleep(); call Application.DoEvents() to trigger event handling/ui updating. However ensure you're not calling Action() again somehow. A simple Thread.Sleep() won't allow the UI to update as you're still in the handler and the framework won't be able fire any new events on its own as it won't know if you're finished when waiting (due to the thread still being busy).

Overall your approach might be a bad idea (depending on other code etc.). Consider using timers or a background worker instead.

Toggling Picture Box visibility C#

4 Answers4

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