Question

I’m receiving from socket communication an image as byte[] and then I try to show it in a pictureBox. When I run the code it shows a message error only saying: "NullReferenceException"

The catch handling the exception is ex1 and I checked and the pic isn’t null so I can’t figure it out why this exception is happening.

This is my code:

try
{
    if (pictureBox1.InvokeRequired)
    {
        try
        {
            pic = imageEmp;
            addControlHandler c = new addControlHandler(addPic);
            this.Invoke(c);
        }
        catch (Exception exc) { MessageBox.Show(exc.Message); }
    }
    else
    {
        pictureBox1.Image = ByteToImage(imageEmp);
    }
}
catch (Exception ex1) 
{
    MessageBox.Show(ex1.Message);                
}

public void addPic()  //when invokeRequired == true
{
    pictureBox1.Image = ByteToImage(pic); 
}

Here is the code to convert byte[] to Image:

public Image ByteToImage(byte[] imageBytes)  //convert byte[] to image
{
    MemoryStream ms = new MemoryStream(imageBytes, 0, imageBytes.Length);
    ms.Write(imageBytes, 0, imageBytes.Length);
    Image image = new Bitmap(ms); 
    return image;
}

UPDATE 1: Regarding Hans answer, I make he following changes:

Change my ByteToImage to Hans’s answer and to check where the error is I added this lines in the place where this.Invoke(c) was:

if (c != null)
{
    try
    {
        this.Invoke(c);
    }
    catch (Exception e_c)
    {
        MessageBox.Show(e_c.Message, "exc from e_c");
    }
}

This give me an exception : NullReferenceException

Thanks for any help!

UPDATE 2: Now it’s working, I send JPEG images instead of JPG and it show it now. Don’t know why this happens but now it’s working ok.

Answer 1

Here is an example that you can try I have tested this just now using my own method this works so replace your code with the lines of code in my btnStudentPic_Click let me know if this works for you..

For Compact Framework try this instead

public static byte[] ReadAllBytes(string path)
{
byte[] buffer;

using (FileStream fs = new FileStream(path, FileMode.Open,
FileAccess.Read, FileShare.Read))
{
int offset = 0;
int count = (int)fs.Length;
buffer = new byte[count];
while (count > 0)
{
int bytesRead = fs.Read(buffer, offset, count);
offset += bytesRead;
count -= bytesRead;
}
}

return buffer;
}

//Windows example below don’t use for CF

    private void btnStudentPic_Click(object sender, EventArgs e)
    {
        Image picture = (Image)BrowseForPicture();
        this.picStudent.Image = picture;
        this.picStudent.SizeMode = PictureBoxSizeMode.StretchImage;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <returns></returns>
    private Bitmap BrowseForPicture()
    {
       // Bitmap picture = null;

        try
        {
            if (this.fdlgStudentPic.ShowDialog() == DialogResult.OK)
            {
                byte[] imageBytes = File.ReadAllBytes(this.fdlgStudentPic.FileName);
                StudentPic = new Bitmap( this.fdlgStudentPic.FileName);
                StuInfo.StudentPic = imageBytes;
            }
            else
            {
                StudentPic = Properties.Resources.NoPhotoAvailable;
            }
        }
        catch (Exception)
        {
            MessageBox.Show("That was not a picture.", "Browse for picture");
            StudentPic = this.BrowseForPicture();
        }

        return StudentPic;
    }