Making UI Thread wait using Thread.sleep

Question

I have written this code in C# for WP7 :

public void btn_handler(object sender, EventArgs args)
    {
        Button btn_Pressed = (Button)sender;
        Image         


        

Answer 1

You current approach is incorrect. It is keeping the UI thready busy. It updates the UI when it gets free.

Here is what is happening

Button Gets click. UI thread change the button background to Images. Then it sleeps for 5 secs and then it changes the background to white. Note that UI thread is still busy. It will only update the actual UI when it will be free. Once it has changed back color to white it gets free and updates the UI and you see the change on screen.

You need to do this

 //inside the button click event create a background worker
 BackgroundWorker worker = new BackgroundWorker();
 worker.RunWorkerCompleted += new 

 RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
 worker.DoWork += new DoWorkEventHandler(worker_DoWork);
 worker.RunWorkerAsync();

 Button btn_Pressed = (Button)sender;
 ImageBrush br = new ImageBrush();
 br.ImageSource = new BitmapImage(new Uri("/images/cat.png", UriKind.Relative));

 btn_Pressed.Background = br;


 public static void worker_RunWorkerCompleted(object sender, 
                                              RunWorkerCompletedEventArgs e)
    {
    //once backgroudn work i.e. DoWork is complete this method will be 
    //called and code below will execute in UI thread
    SolidColorBrush sBrush = new SolidColorBrush(); 
    sBrush.Color = System.Windows.Media.Colors.White;
    btn_Pressed.Background = sBrush;  
    }

 public  static  void worker_DoWork(object sender, DoWorkEventArgs e)
    {
    //it will wait 5 secs in the background thread
    Thread.Sleep(5000);
    }