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POC# How do I call methods on objects created by the main thread from a worker thread?
 

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  1. POC# How do I call methods on objects created by the main thread from a worker thread?
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    <blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="https://stackoverflow.com/questions/974317/cross-thread-operation-not-valid-exception-on-inner-controls">&ldquo;Cross-thread operation not valid&rdquo; exception on inner controls</a> </p> </blockquote> <p>I am a beginner in C# and lately I run over a cross thread ex. Now I searched high and low to find an answer to my problem however, none seem to be same as mine so hopefully some could help. Here is mine problem explained. </p> <p>1) I extend a Microsoft.VisualBasic.PowerPacks.OvalShape to add some more functionality to it so it meets my needs and here is what I extend to the class:</p> <pre><code>public class MyShape: Microsoft.VisualBasic.PowerPacks.OvalShape { int imageNumber; public MyShape() { imageNumber = 0; this.BackgroundImage = global::_4InARow.Properties.Resources.grey; } public int getImageNumber() { return imageNumber; } public bool setImage(int imgNo) { imageNumber = imgNo; if (imgNo == 0) { this.BackgroundImage = global::_4InARow.Properties.Resources.grey; return true; } else if (imgNo == 1) { this.BackgroundImage = global::_4InARow.Properties.Resources.blue; return true; } else if (imgNo == 2) { this.BackgroundImage = global::_4InARow.Properties.Resources.red; return true; } else { return false; } } } </code></pre> <p>2) In designer class I create several objects fom the <code>class MyShape</code> and later add them to a ShapeContainer, using <code>main thread</code> or <code>UI thread.(highlight ShapeContainer)</code></p> <p>3) in the main class called <code>(FourInARow_Server)</code> I add all the objects created in a jagged Array using <code>arrayLoad()</code> method. (class is listed below)</p> <p>The Exception occurs when I asynchronously access the method <code>changeColor(int x, int y, int color)</code> using the worker thread(not the thread in which the objects were created). However I can access the objects if for instance I say</p> <pre><code> if(circles[1][1].getImageNumber() == 0) {//do something}; </code></pre> <p>(this using worker thread and main thread works OK) </p> <p>One other thing about the exception is that, when complaining that a worker thread called an an object created in the main thread, it is the ShapeContainer object that throws the exception rather than the MyShape object. </p> <p>I am now looking for a solution to safely acces the changeColor method to change the color of each object using both threads.<br> Like I said I did look on-line for an answer but none were like what I am facing and I hope some one could help. Thanks!</p> <pre><code>public partial class FourInARow_Server : Form { private MyShape[][] circles = new MyShape[7][]; private Socket newConnection; private Thread newThread; private int player; private bool flag_MyTurn; private bool flag_ConnectionAlive; private bool flag_MoveAllowed; private bool flag_EventBlocker; public FourInARow_Server() { InitializeComponent(); arrayLoad(); player = 1; flag_MyTurn = true; flag_ConnectionAlive = false; flag_MoveAllowed = false;//variable needed to prevent user from loosing its turn if it clicks on a colomn that hasn,t got any more available moves. flag_EventBlocker = true; this.labelSystemMessage.Text = "To begin play, please press \"Launch Server\" \n and wait for opponent to connect "; } private void arrayLoad()//Load all ovall shapes into an array { MyShape[] colOne = { x1y1, x1y2, x1y3, x1y4, x1y5, x1y6}; MyShape[] colTwo = { x2y1, x2y2, x2y3, x2y4, x2y5, x2y6}; MyShape[] colThree = { x3y1, x3y2, x3y3, x3y4, x3y5, x3y6}; MyShape[] colFour = { x4y1, x4y2, x4y3, x4y4, x4y5, x4y6 }; MyShape[] colFive = { x5y1, x5y2, x5y3, x5y4, x5y5, x5y6 }; MyShape[] colSix = { x6y1, x6y2, x6y3, x6y4, x6y5, x6y6}; MyShape[] colSeven = {x7y1, x7y2, x7y3, x7y4, x7y5, x7y6 }; circles[0] = colOne; circles[1] = colTwo; circles[2] = colThree; circles[3] = colFour; circles[4] = colFive; circles[5] = colSix; circles[6] = colSeven; } private void changeColor(int x, int y, int color) { if (color == 0) { circles[x][y].setImage(0); } else if (color == 1) { circles[x][y].setImage(1); } else if (color == 2) { circles[x][y].setImage(2); } Application.DoEvents(); } } </code></pre>
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