Question

I have a Windows Form with a label and a picture box. To retreive an image from a web service I use a thread.

The user click on a button and first the label must be displayed and then new thread is started to retrieve the image. This is the code:

private void menuItem1_Click(object sender, EventArgs e)  {  etiquetaCargando.Visible = true;  this.Invoke(new System.Threading.ThreadStart(RequestImage));  } 

The problem is this: label etiquetaCargando doesn’t appear.

I’m programming on Compact Framework.

What it’s happening?

Thanks!

Answer 1

The question is unclear, but by using Invoke, you are defeating the purpose of having the image request on a separate thread. (You might notice that your interface becomes unresponsive while the request is happening)

Instead, it is better to create a new thread object, start it, and then use the Invoke to set the image (after it has been retrieved), something along the lines of

private void menuItem1_Click(object sender, EventArgs e) {         etiquetaCargando.Visible = true;     Thread reqThread =         new Thread(new ThreadStart(RequestImage));     reqThread.Start(); }  private void RequestImage() {     /* Get the image     ...     */     Invoke(SetTheImage, new object[] { theImage }); } 

this assumes that you have a method SetTheImage which will actually do the job of displaying the image on your form.