C#

George_George wrote:

I am designing an application which could be treated as a framework application to host other components

led mike wrote:

Get real.

Mark Salsbery
Microsoft MVP - Visual C++

bool oldVal = ListBox1.Scrollable;
ListBox1.Scrollable = true;
ListBox1.EnsureVisible(index);
ListBox1.Scrollable = oldVal;

public partial class Form1 : Form
{
    private System.Windows.Forms.Panel panel1;
    private System.Windows.Forms.Label label1;
    private System.Windows.Forms.Button button1;
    private System.Windows.Forms.Button button2;

    public Form1()
    {
        InitializeComponent();

        // Create the controls.
        this.panel1 = new System.Windows.Forms.Panel();
        this.button1 = new System.Windows.Forms.Button();
        this.button2 = new System.Windows.Forms.Button();
        this.label1 = new System.Windows.Forms.Label();

        //
        // panel1
        //
        this.panel1.Controls.Add(this.label1);
        this.panel1.Location = new System.Drawing.Point(93, 12);
        this.panel1.Size = new System.Drawing.Size(60, 50);
        this.panel1.TabIndex = 0;
        //
        // button1
        //
        this.button1.Location = new System.Drawing.Point(12, 12);
        this.button1.Size = new System.Drawing.Size(75, 23);
        this.button1.TabIndex = 0;
        this.button1.Text = "Up";
        this.button1.UseVisualStyleBackColor = true;
        this.button1.Click += new System.EventHandler(this.scrollUp);
        //
        // button2
        //
        this.button2.Location = new System.Drawing.Point(12, 41);
        this.button2.Size = new System.Drawing.Size(75, 23);
        this.button2.TabIndex = 0;
        this.button2.Text = "Down";
        this.button2.UseVisualStyleBackColor = true;
        this.button2.Click += new System.EventHandler(this.scrollDown);
        //
        // label1
        //
        this.label1.Location = new System.Drawing.Point(0, 0);
        this.label1.Name = "label1";
        this.label1.Size = new System.Drawing.Size(60, 186);
        this.label1.TabIndex = 1;
        this.label1.Text = "This is a label with some text that goes on for ages and ages to " +
            "demonstrate how it is possible to manually scroll a control using a panel.";


        // Add the controls to the form.
        this.Controls.Add(this.button2);
        this.Controls.Add(this.button1);
        this.Controls.Add(this.panel1);

        this.ClientSize = new System.Drawing.Size(169, 75);
    }

    private void scrollUp(object sender, EventArgs e)
    {
        label1.Top += 10;
        if (label1.Top > 0)
        {
            label1.Top = 0;
        }
    }

    private void scrollDown(object sender, EventArgs e)
    {
        label1.Top -= 10;
        if (label1.Top < panel1.Height-label1.Height)
        {
            label1.Top = panel1.Height - label1.Height;
        }
    }
}

public void UpdateTextBox(String data)
{
    if (this.InvokeRequired)
    {
        this.Invoke(new Action<string>(UpdateTextBox), data);
        return;
    }

    txtData.Text = data;
}

Kurt wrote:

Isn't it possible to place an Invoke in the function that fires the event?

Kurt wrote:

Hmm, I thought of making a DLL, so the users can double click the event in the property window and fill in individual code. But the user would be forced to use invoke.

Kurt wrote:

We can use so many different controls in our projects and use their events without invoke. Do all those controls doesn't use asynchronous processes?

using System;
using System.ComponentModel;
using System.Threading;

namespace WorkerThreadEvent {
  class EventThread {
    private AsyncOperation operation;

    // Raised by the thread to report progress
    public event EventHandler<ProgressChangedEventArgs> ProgressChanged;

    private void OnProgress(Object progress) {
      EventHandler<ProgressChangedEventArgs> handler = ProgressChanged;
      if (handler != null) {
        ProgressChangedEventArgs args = new ProgressChangedEventArgs((int)progress, null);
        handler(this, args);
      }
    }

    // Start the worker thread by calling Run from the GUI thread
    public void Run() {
      operation = AsyncOperationManager.CreateOperation(null);
      ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc), null);
    }

    private void ThreadProc(Object state) {
      try {
        for (int i = 1; i <= 100; i++) {
          // simulate work
          Thread.Sleep(100);
          // raise an event on the GUI thread
          operation.Post(new SendOrPostCallback(OnProgress), i);
        }
      } finally {
        // end the asynchronous operation
        operation.OperationCompleted();
      }
    }

  }
}

public static class ThreadSafe
{
    public static void Invoke(Delegate method, object[] args)
    {
        if (method != null)
        {
            foreach (Delegate handler in method.GetInvocationList())
            {
                if (handler.Target is Control)
                {
                    Control target = handler.Target as Control;
                    if (target.IsHandleCreated)
                    {
                        target.BeginInvoke(handler, args);
                    }
                }
                else if (handler.Target is ISynchronizeInvoke)
                {
                    ISynchronizeInvoke target = handler.Target as ISynchronizeInvoke;
                    target.BeginInvoke(handler, args);
                }
                else
                {
                    handler.DynamicInvoke(args);
                }
            }
        }
    }
}


// example how to use it with events

public void OnDataReceived(object sender, DataReveivedEventArgs e)
{
    if (DataReceived != null) { ThreadSafe.Invoke(this.DataReceived, new object[] { this, e });
}