C＃Picturebox.Image必须先加载两次，然后才能在代码中使用

Question

I have a picturebox on a windows form that gets filled with this command:

pBProcess.ImageLocation = Path.GetDirectoryName(processFile) + "\\" + processes[processStep2Nr] + ".png";

After the images is loaded I'm trying to do two things that both only work after I loaded that image twice.

First thing:

Positioning.CenterHorizontally(pBProcess, pBProcess.Image.Width);

Which does this:

public static void CenterHorizontally(this Control control, int Width)
{
    Rectangle parentRect = control.Parent.ClientRectangle;
    control.Left = (parentRect.Width - Width) / 2;
}

and the second thing I'm trying to do is to save the image to a SQLDatabase.

cmdLine = "INSERT INTO " + processToSave + " (Picture) VALUES  (@Image);";
MemoryStream stream = new MemoryStream();
pBProcess.Image.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
byte[] pic = stream.ToArray();
using (SqlCommand sqlCmd = new SqlCommand(cmdLine, connection))
{
//Parameter definieren
   sqlCmd.Parameters.Add("@Image", SqlDbType.Image);
   sqlCmd.Parameters["@Image"].Value = pic;
   sqlCmd.ExecuteNonQuery();
 }

Boths actions are executed correctly after I load the picturebox.image a second time.

What causes this and how can I fix it?

Edit:

This is how I create the table I want to save the picture to:

//Tabelle wird erstellt und anschließend gefüllt
strInsert = "CREATE TABLE " + processToSave + "(Attributes NVARCHAR(50), Value TINYINT, Picture IMAGE);";
using (SqlCommand sqlCmd = new SqlCommand(strInsert, connection))
{
    sqlCmd.ExecuteNonQuery();
}
strInsert = "INSERT INTO " + processToSave + " (Attributes, Value) VALUES (@Attributes, @Value);";
foreach (ListViewItem item in checkedItems)
{
    using (SqlCommand sqlCmd = new SqlCommand(strInsert, connection))
    {
        //Parameter definieren
        sqlCmd.Parameters.Add("@Attributes", SqlDbType.NVarChar);
        sqlCmd.Parameters["@Attributes"].Value = item.Text;
        sqlCmd.Parameters.Add("@Value", SqlDbType.Int);
        sqlCmd.Parameters["@Value"].Value = Convert.ToInt32(item.SubItems[1].Text);
        sqlCmd.ExecuteNonQuery();
    }
}
strInsert = "INSERT INTO " + processToSave + " (Picture) VALUES  (@Image);";
MemoryStream stream = new MemoryStream();
pBProcess.Image.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
byte[] pic = stream.ToArray();
using (SqlCommand sqlCmd = new SqlCommand(strInsert, connection))
{
    //Parameter definieren
    sqlCmd.Parameters.Add("@Image", SqlDbType.Image);
    sqlCmd.Parameters["@Image"].Value = pic;
    sqlCmd.ExecuteNonQuery();
}

And this is how I read the picture from the DB:

MemoryStream stream = new MemoryStream();
strInsert = "SELECT [Picture] FROM " + processToLoad;
SqlCommand sqlCmd2 = new SqlCommand(strInsert, connection);
byte[] image = (byte[])sqlCmd2.ExecuteScalar();
stream.Write(image, 0, image.Length);
Bitmap bitmap = new Bitmap(stream);
pBProcess.Image = bitmap;

this is NOT working. But when I create a table in the DB called "Bilder" which has only "Picture" with DBType Image and change the code to this:

strInsert = "INSERT INTO Bilder (Picture) VALUES  (@Image);";
MemoryStream stream = new MemoryStream();
pBProcess.Image.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
byte[] pic = stream.ToArray();
using (SqlCommand sqlCmd = new SqlCommand(strInsert, connection))
{
    //Parameter definieren
    sqlCmd.Parameters.Add("@Image", SqlDbType.Image);
    sqlCmd.Parameters["@Image"].Value = pic;
    sqlCmd.ExecuteNonQuery();
}

...

MemoryStream stream = new MemoryStream();
strInsert = "SELECT [Picture] FROM Bilder";
SqlCommand sqlCmd2 = new SqlCommand(strInsert, connection);
byte[] image = (byte[])sqlCmd2.ExecuteScalar();
stream.Write(image, 0, image.Length);
Bitmap bitmap = new Bitmap(stream);
pBProcess.Image = bitmap;

It actually works. What's wrong in my original code?

Answer 1

I was mixing up two problems here.

The problem with

Positioning.CenterHorizontally(pBProcess, pBProcess.Image.Width);

was fixed by putting this statement into the LoadCompleted Event of the picturebox.

The second problem was that I actually inserted a lot of rows into my table (attributes + value) and at the end I inserted another row, consisting only of the image. When I read the table looking for the image, I only read the first row (I think) but there was no image to be found. So I changed the code, putting the image into the first row and then changing the commandline:

bool first = true;
foreach (ListViewItem item in checkedItems)
{
   if (first)
     cmdLine = "INSERT INTO " + processToSave + " (Attributes, Value, Picture) VALUES (@Attributes, @Value, @Image);";
   else
     cmdLine = "INSERT INTO " + processToSave + " (Attributes, Value) VALUES (@Attributes, @Value);";
   using (SqlCommand sqlCmd = new SqlCommand(cmdLine, connection))
   {
     //Parameter definieren
     sqlCmd.Parameters.Add("@Attributes", SqlDbType.NVarChar);
     sqlCmd.Parameters["@Attributes"].Value = item.Text;
     sqlCmd.Parameters.Add("@Value", SqlDbType.Int);
     sqlCmd.Parameters["@Value"].Value = Convert.ToInt32(item.SubItems[1].Text);
     if (first)
     {
        sqlCmd.Parameters.Add("@Image", SqlDbType.Image);
        sqlCmd.Parameters["@Image"].Value = pic;
        first = false;
     }
     sqlCmd.ExecuteNonQuery();
  }
}