Saving image in PictureBox, getting NullReferenceException

Question

Using Visual Studio C#. I want to save the image inside my PictureBox as a .png using SaveFileDialog, but whenever I try to, I keep getting NullReferenceException at the last line. I can't seem to figure out what's causing this and how to fix it.

private void button_Save_Click(object sender, EventArgs e)
    {
        SaveFileDialog sfd = new SaveFileDialog();
        sfd.Filter = "PNG(*.PNG)|*.png";

        if (sfd.ShowDialog() == DialogResult.OK)
            pictureBox.Image.Save(sfd.FileName, ImageFormat.Png);
    }

@VijunavVastivch Looks like pictureBox.Image has no value. I used Graphics.DrawImage to draw onto the picture box in another method. How should I go about fixing this? — Fudgenuggets, Feb 20 '18 at 00:48

Joseph · Answer 1 · 2018-02-20T20:24:41.307

The reason that you're getting a NullReferenceException is because pictureBox.Image.Save(...) is actually trying to use the image in the picture box to save to your computer, but there is no image in the picturebox to save, resulting in the error.

What I think you're trying to accomplish is putting the image inside the picturebox. And if that's the case, I'd recommend using the following:

private void button_Save_Click(object sender, EventArgs e)
{
    var fd = new OpenFileDialog { Filter = @"PNG(*.PNG)|*.png" };

    if (fd.ShowDialog() == DialogResult.OK)
        pictureBox.Image = Image.FromFile(fd.FileName);
}

An explanation of the downvote would be nice. – Joseph Mar 31 '18 at 03:16 — Joseph, Mar 31 '18 at 03:16

Saving image in PictureBox, getting NullReferenceException

1 Answers1