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Make a pictureBox public

Posted on 2006-07-15
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Last Modified: 2008-03-17
Hi, I got "The name 'pictureBox1' does not exist in the current context".
Should I make the pictureBox public? or does there have a simplier way?

using System;
...
namespace StartThreading
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            Thread Receiver = new Thread(new ThreadStart(StartThreading.Receiver.receiverStart));
            Receiver.Start();
        }

    }
    public class Receiver
    {
        public static void receiverStart()
        {
             //The name 'pictureBox1' does not exist in the current context
             pictureBox1.Image = (Bitmap)converter.ConvertFrom(receiveBytes);
        }
    }
}
0
Comment
Question by:ddlam
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6 Comments
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 17116116
It cannot access the PictureBox because it does not have a reference to either the PictureBox or the Form containing the PictureBox.  Either pass in one of those references to the class, or get rid of the class altogether:

        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            Thread Receiver = new Thread(new ThreadStart(receiverStart));
            Receiver.Start();
        }

        private void receiverStart()
        {
             pictureBox1.Image = (Bitmap)converter.ConvertFrom(receiveBytes);
        }

At any rate, you should be using Delegates and Invoke() to update the PictureBox from a Thread.

To pass in the references, don't use a static method.  Instead, create an instance of your class and pass in the reference to be stored in local variables.  Then create a Start() method that creates the thread internally and starts it.
0
 
LVL 9

Author Comment

by:ddlam
ID: 17116798
Could you show more code for my reference?
0
 
LVL 85

Assisted Solution

by:Mike Tomlinson
Mike Tomlinson earned 50 total points
ID: 17118944
I'm not at my computer (am inbetween houses at the moment)...

    public class Receiver
    {
        public PictureBox pb;

        public void receiverStart()
        {
             //The name 'pictureBox1' does not exist in the current context
             pictureBox1.Image = (Bitmap)converter.ConvertFrom(receiveBytes);
        }
    }

Then declare an instance and pass in the reference:

        private Receiver myReceiver;

        private void Form1_Load(object sender, EventArgs e)
        {
            myReceiver = new Receiver();
            myReceiver.pb = this.PictureBox1;
            Thread Receiver = new Thread(new ThreadStart(myReceiver.receiverStart));
            Receiver.Start();
        }
0
 
LVL 5

Accepted Solution

by:
paulb1989 earned 50 total points
ID: 17119227
I think you meant:

pb.Image = (Bitmap)converter.ConvertFrom(receiveBytes);

In any case, I'd do it like this:

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Receiver myReceiver = new Receiver();
            myReceiver.form = this;
            Thread Receiver = new Thread(new ThreadStart(myReceiver.receiverStart));
            Receiver.Start();
        }

        public void UpdatePictureBox(Image image)
        {
            pictureBox1.Image = image;
        }
    }

    public class Receiver
    {
        public Form1 form;

        public static void receiverStart()
        {
            typeof(Form1).GetMethod("UpdatePictureBox").Invoke(form, new object[] {(Bitmap)converter.ConvertFrom(receiveBytes)})
        }
    }

That way, you're not going to have issues with accessing the picturebox from another thread.
0
 
LVL 9

Author Comment

by:ddlam
ID: 17347159
Sorry for late replying ;)
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