NickName:Nishant Ask DateTime:2011-05-22T04:47:10

Toggling Picture Box visibility C#

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

Copyright Notice：Content Author:「Nishant」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/6084367/toggling-picture-box-visibility-c-sharp

Answers

Guffa 2011-05-21T21:19:30

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.\n\nYou 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 2011-05-21T20:55:29

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?",

Mario 2011-05-21T21:21:11

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).\n\nOverall your approach might be a bad idea (depending on other code etc.). Consider using timers or a background worker instead.",