C#•2y ago

❔ 2 Errors in image downloading

My code:

private void button11_Click(object sender, EventArgs e)
        {
            saveFileDialog1.Filter = "JPG(*.JPG)|*.jpg";
            if(saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                if(pictureBox1.Image == null)
                {
                    pictureBox1.Image.Save(saveFileDialog1.FileName);
                }
            }
        }

private void button11_Click(object sender, EventArgs e)
        {
            saveFileDialog1.Filter = "JPG(*.JPG)|*.jpg";
            if(saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                if(pictureBox1.Image == null)
                {
                    pictureBox1.Image.Save(saveFileDialog1.FileName);
                }
            }
        }

Error string is pictureBox1.Image.Save(saveFileDialog1.FileName);, Warning name: Dereferencing a likely null reference. And 1 more error - the non-nullable "graphics" field must contain a non-null value when the constructor exits. Might be worth declaring the field as nullable, the second warning code is on image

22 Replies

inexQOP•2y ago

and to be more precise, after clicking on the warning, you are transferred to this line (On form)

Angius•2y ago

The first error means something there might be null. See which of those values are nullable and guard against that properly

ero•2y ago

Where is the warning on that line? Either pictureBox1, or pictureBox1.Image, or saveFileDialog1 can be null

Angius•2y ago

The second, well, I'd need to see some more code But you have some graphics field that doesn't have a default value, and you never give it a value in the constructor

inexQOP•2y ago

ok What code do you need?

Angius•2y ago

Well, the field The class the field is inside of Although the error can really only mean one thing, so

inexQOP•2y ago

inexQOP•2y ago

waait namespace EvanPaint { public partial class Form1 : Form this is form1 file

Angius•2y ago

And the field it mentions?

inexQOP•2y ago

I don't understand you what field

Angius•2y ago

inexQOP•2y ago

graphics? wait

private class ArrayPoints
        {
            private int index = 0;
            private Point[] points;
            public ArrayPoints(int size)
            {
                if(size <= 0) { size = 2; }
                points = new Point[size];
            }
            public void SetPoint(int x, int y)
            {
                if(index >= points.Length)
                {
                    index = 0;
                }
                points[index] = new Point(x, y);
                index++;
            }
            public void ResetPoints()
            {
                index = 0;
            }
            public int GetCountPoints()
            {
                return index;
            }
            public Point[] GetPoints()
            {
                return points;
            }
        }
        private bool isMouse = false;
        private ArrayPoints arrayPoints = new ArrayPoints(2);
        Bitmap map = new Bitmap(100, 100);
        Graphics graphics;
        Pen pen = new Pen(Color.Black, 3f);

        private void SetSize()
        {
            Rectangle rectangle = Screen.PrimaryScreen.Bounds;
            map = new Bitmap(rectangle.Width, rectangle.Height);
            graphics = Graphics.FromImage(map);
            pen.StartCap = System.Drawing.Drawing2D.LineCap.Round;
            pen.EndCap = System.Drawing.Drawing2D.LineCap.Round;
        }

private class ArrayPoints
        {
            private int index = 0;
            private Point[] points;
            public ArrayPoints(int size)
            {
                if(size <= 0) { size = 2; }
                points = new Point[size];
            }
            public void SetPoint(int x, int y)
            {
                if(index >= points.Length)
                {
                    index = 0;
                }
                points[index] = new Point(x, y);
                index++;
            }
            public void ResetPoints()
            {
                index = 0;
            }
            public int GetCountPoints()
            {
                return index;
            }
            public Point[] GetPoints()
            {
                return points;
            }
        }
        private bool isMouse = false;
        private ArrayPoints arrayPoints = new ArrayPoints(2);
        Bitmap map = new Bitmap(100, 100);
        Graphics graphics;
        Pen pen = new Pen(Color.Black, 3f);

        private void SetSize()
        {
            Rectangle rectangle = Screen.PrimaryScreen.Bounds;
            map = new Bitmap(rectangle.Width, rectangle.Height);
            graphics = Graphics.FromImage(map);
            pen.StartCap = System.Drawing.Drawing2D.LineCap.Round;
            pen.EndCap = System.Drawing.Drawing2D.LineCap.Round;
        }

graphics = Graphics.FromImage(map);

Angius•2y ago

Yeah, so the field graphics has a value only after you call SetSize() Before you call this method, it'll be undefined

inexQOP•2y ago

oh wait What i need to do

Angius•2y ago

You could give it a default value, and/or shut up the compiler about this error. Since it's a private field, you don't really risk accessing it when uninitialized Graphics graphics = default; would be one way, to give it a default value Graphics graphics = new(); would be another Graphics graphics = default!; if it still complains

inexQOP•2y ago

Do I need to edit private class on public class?

Angius•2y ago

What? You need to edit this particular class to give this particular field a default value

inexQOP•2y ago

my error is that what i can't save image in imagebox with button. Program showing savedialog but without saving file, i think warnings are same with this error

Angius•2y ago

Well, then, the issue is probably about something being null So the first error Fire up the debugger and see what might be null that shouldn't be

inexQOP•2y ago

i launched file with debbuging, all is working, but not save button Maybe the error is that there are empty buttons without code, or buttons that have an action created and are not inside the code? i think itš null and here is this string:

if(pictureBox1.Image == null)

if(pictureBox1.Image == null)

null if pictureBox image == null - save this image Hey @Angius! Thank you! I deleted string with code if(pictureBox1.Image == null) {} and code now working!!!

Angius•2y ago

Nice

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ 2 Errors in image downloading