C#

class LoadPicture : IDisposable
{
    public delegate void FinishedDelegate(Image img);
    public delegate void ProgressDelegate(int current, int max, string c, string t);
    public event FinishedDelegate Finished;
    public event ProgressDelegate ProgressChanged;

    string Tag;
    bool stop;

    public LoadPicture(string Tag)
    {
        this.Tag = Tag;
        stop = false;
    }

    ~LoadPicture()
    {
        ProgressChanged = null;
        Finished = null;
    }

    public void Load()
    {
        SqlConnection conn = new SqlConnection(AssetConfig.ConnectionString);
        SqlCommand cmd = new SqlCommand("SELECT Picture FROM Inventory_Pictures WHERE PictureID=@Tag", conn);
        cmd.Parameters.AddWithValue("@Tag", Tag);

        try
        {
            conn.Open();

            // HERE I AM WORKING ON A BETTER WAY OF TELLING IF IDataReader DOES NOT CONTAIN DATA...
            // HAVEN'T FIGURED IT OUT YET BUT THIS IS JUST TEMP
            SqlDataReader tmp = cmd.ExecuteReader();
            if (tmp.HasRows)
            {
                tmp.Close();

                IDataReader r = cmd.ExecuteReader(CommandBehavior.SequentialAccess);
                if (r != null)
                {
                    r.Read();

                    long size = r.GetBytes(0, 0, null, 0, 0);
                    byte[] buffer = new byte[size];
                    int bufferSize = 1024;
                    int dataIndex = 0;
                    long bytesRead = 0;

                    while ((bytesRead < size) && ((size - bytesRead) > 1024))
                    {
                        if (stop)
                            break;

                        bytesRead += r.GetBytes(0, dataIndex, buffer, dataIndex, bufferSize);
                        dataIndex += 1024;

                        decimal FileSize = (Convert.ToDecimal(size) / 1024) / 1024;
                        decimal CurrentSize = (Convert.ToDecimal(bytesRead) / 1024) / 1024;

                        // YOU NOTICE HERE I CHECK FOR IT BEING NULL BEFORE CALLING IT (So why is it trying to call it
                        // after the frmViewAsset is disposed since frmViewAsset should be disposing of it before closing?
                        if (ProgressChanged != null)
                            ProgressChanged(dataIndex, Convert.ToInt32(size), Math.Round(CurrentSize, 2).ToString(), Math.Round(FileSize, 2).ToString());
                    }

                    if (!stop)
                    {
                        bytesRead += r.GetBytes(0, dataIndex, buffer, dataIndex, Convert.ToInt32((size - bytesRead)));

                        MemoryStream ms = new MemoryStream(buffer);
                        if (Finished != null)
                            Finished(Image.FromStream(ms));

                        ms.Close();
                    }
                }
                r.Close();
            }
        }
        catch (Exception ex)
        {
            Error.WriteError(ErrorType.SQL, "LoadPicture", ex.ToString());
        }
        finally
        {
            if (conn != null)
            {
                conn.Close();
                conn.Dispose();
            }

            if (cmd != null)
                cmd.Dispose();
        }
    }

    public void Stop()
    {
        stop = true;
    }

    public void Dispose()
    {
        System.GC.SuppressFinalize(true);
    }
}

LoadPicture lp;
Thread t4;
private void frmViewAsset_Load(object sender, EventArgs e)
{
    lp = new LoadPicture(AssetID);
    lp.ProgressChanged += new LoadPicture.ProgressDelegate(p_ProgressChanged);
    lp.Finished += new LoadPicture.FinishedDelegate(p_Finished);

    t4 = new Thread(new ThreadStart(PopulatePicture));
    t4.Start();
}
private void PopulatePicture()
{
    lp.Load();
}
private void p_ProgressChanged(int current, int max, string c, string t)
{
    if (!this.IsDisposed)
    {
        Invoke((Action)(() => // <-- THIS IS LINE 388
        {
            pbPicture.Maximum = max;
            pbPicture.Value = current;

            lbPicProgress.Text = string.Format("{0}MB / {1}MB", c, t);
        }));
    }
}
private void p_Finished(Image img)
{
    Invoke((Action)(() =>
    {
        picAsset.Image = img;
    }));
}
private void frmViewAsset_FormClosing(object sender, FormClosingEventArgs e)
{
    lp.Stop();
    lp.Dispose();
}

lp.ProgressChanged -= new LoadPicture.ProgressDelegate(p_ProgressChanged);
lp.Finished -= new LoadPicture.FinishedDelegate(p_Finished);

public void Stop() {
    stop = true;
    ProgressChanged = null;
    Finished = null;
}

if (ProgressChanged != null && !stop) ProgressChanged(dataIndex, ...)

bytesRead += r.GetBytes(0, dataIndex, buffer, dataIndex, bufferSize);
dataIndex += bytesRead;

int newAmount = r.GetBytes(0, dataIndex, buffer, dataIndex, bufferSize);
bytesRead += newAmount;
dataIndex += newAmount;

public void Load()
{
    SqlConnection conn = new SqlConnection(AssetConfig.ConnectionString);
    SqlCommand cmd = new SqlCommand("SELECT Picture FROM Inventory_Pictures WHERE PictureID=@Tag", conn);
    cmd.Parameters.AddWithValue("@Tag", Tag);

    try
    {
        conn.Open();

        IDataReader r = cmd.ExecuteReader(CommandBehavior.SequentialAccess);
        if (r != null)
        {
            bool exist = r.Read();

            if (exist)
            {
                long size = r.GetBytes(0, 0, null, 0, 0);
                byte[] buffer = new byte[size];
                int bufferSize = 65536;
                long bytesRead = 0;
                decimal prevPercent = 0;

                while ((bytesRead < size) && ((size - bytesRead) > bufferSize))
                {
                    if (stop)
                        break;

                    long newAmount = r.GetBytes(0, (Int32)bytesRead, buffer, (Int32)bytesRead, bufferSize);
                    bytesRead += newAmount;

                    if (newAmount == 0)
                        break;

                    decimal FileSize = (size / 1024) / 1024;
                    decimal CurrentSize = (bytesRead / 1024) / 1024;

                    if (ProgressChanged != null && !stop)
                    {
                        decimal currentPercent = (CurrentSize / FileSize) * 100;
                        if (currentPercent != prevPercent)
                            ProgressChanged((int)CurrentSize, (int)FileSize, Math.Round(CurrentSize, 2).ToString(), Math.Round(FileSize, 2).ToString());

                        prevPercent = currentPercent;
                    }
                }

                if (!stop)
                {
                    MemoryStream ms = new MemoryStream(buffer);
                    if (Finished != null)
                        Finished(Image.FromStream(ms));

                    ms.Close();
                }
            }
            r.Close();
        }
    }
    catch (Exception ex)
    {
        Error.WriteError(ErrorType.SQL, "LoadPicture", ex.ToString());
    }
    finally
    {
        if (conn != null)
        {
            conn.Close();
            conn.Dispose();
        }

        if (cmd != null)
            cmd.Dispose();
    }
}

[5/24/2010 10:39:13 AM LoadPicture]: System.InvalidOperationException: Invoke or BeginInvoke cannot be called on a control until the window handle has been created.
   at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
   at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
   at System.Windows.Forms.Control.Invoke(Delegate method)
   at AssetMgmt.frmViewAsset.p_Finished(Image img) in C:\Applications\Windows Applications\AssetMgmt\AssetMgmt\frmViewAsset.cs:line 379
   at AssetMgmt.LoadPicture.Load() in C:\Applications\Windows Applications\AssetMgmt\AssetMgmt\Operations\LoadPicture.cs:line 81

It fails on the Finished.. I think only because I can't close the window quick enough during the Progress. Funny thing is I saw the image appear in the picturebox before it finally closed and it still showed this

if (!stop) {
    MemoryStream ms = new MemoryStream(buffer);   <<< long operation
    if (Finished != null) {
        Image img=Image.FromStream(ms);           <<< long operation
        Finished(img);
        ...
}

if (!stop) {
    MemoryStream ms = new MemoryStream(buffer);   <<< long operation
    if (Finished != null) {
        Image img=Image.FromStream(ms);           <<< long operation
        if (Finished != null && !stop) Finished(img);
    }
        ...
}

MemoryStream ms = new MemoryStream(buffer);   <<< long operation
Image img=Image.FromStream(ms);               <<< long operation
if (Finished != null && !stop) Finished(img);
...

change the variables
Thread.Sleep(100);

if (ProgressChanged != null && !stop)
                            {
                                decimal currentPercent = (CurrentSize / FileSize) * 100;
                                string CurrentMB = Math.Round(CurrentSize, 2).ToString();
                                string MaxMB = Math.Round(FileSize, 2).ToString();
                                int Current = (int)CurrentSize;
                                int Total = (int)FileSize;

                                if (currentPercent != prevPercent && ProgressChanged != null && !stop)
                                    ProgressChanged(Current, Total, CurrentMB, MaxMB);

                                prevPercent = currentPercent;
                            }

if (!stop)
                        {
                            MemoryStream ms = new MemoryStream(buffer);
                            Image img = Image.FromStream(ms);
                            if (Finished != null && !stop)
                                Finished(img);

                            ms.Close();
                        }

// this would be unacceptable most of the time, as it:
// 1. delays the execution of a handler on the GUI thread (handlers normally should be swift)
// 2. calls DoEvents (which is evil).
// We nevertheless do this so a background thread gets ample opportunity to terminate gracefully
for(int i=0; i<5; i++) {
    if (!t4.IsAlive) break;
    Application.DoEvents();
    Thread.Sleep(100);
}

public void Button_Click(...) {
    long-wielding calculation
    // Application.DoEvents();
    more long-wielding calculation
}

Jacob Dixon wrote:

you have to be trying to make it break for it to throw the error (which is what I'm doing

object o = 10;

if (o is int)
{
}

tan_chin wrote:

what I do not understand is it should generate an executable for a project

tan_chin wrote:

There are 2 errors, that is why build is not succeeded, I do not want to change anything right now since I am new at the company.

//This is the code from the second page that returns the array values back to the first
for (int iItem = 0; iItem <= checkedListBox1.CheckedItems.Count - 1; iItem++)
            {
                string s = (checkedListBox1.CheckedItems[iItem].ToString());
                checkedNames.Add(s);                
            }

            frmMain m = new frmMain(checkedNames);

            //I checked the array at this point just before the page closes and 
            //it comes up with the selected names.
            this.Close();