C# how using graphics properly

[Allohen]

Hello!

I'm writing a graphic program in C# (at first time).
The pixel of the picture stored in array of varible.

    public partial class Form1 : Form
    {
        public Bitmap scrBitmap = new Bitmap(1280, 800, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
        public Graphics ScrGraph; 
 

(ScrGraph is a Graphics varible for graphics, scrBitmap
is for the picture.)

I tried using for drawing picture, but nothig happen.

ScrGraph.DrawImage(scrBitmap, 0, 0,1280,800);
 

I starting to debug the program, but stop that line. The error is "NullReferenceExeption was unhandled."

How use the graphics and the drawimage function properly to update the picture?

[GaryTexmo]

Your graphics object needs to be set to something. When you create a new variable it's typically initialized to null. Where are you calling the DrawImage method on your graphics object?

If it's in the OnPaint method for a form, there should be a PaintEventArgs parameter in the parameter list for that method. There is a graphics object inside that event args object. If you're just doing it somewhere on the form, initialize ScrGraph in your constructor with this.CreateGraphics().

You mentioned you were new, so if this confuses you please post your complete source so I can see what you're doing.

Thanks!