How to get pixel color in graphics?

Question

1.00/5 (2 votes)

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I made

C#

private void FormMario_Shown(object sender, EventArgs e)
        {
            g = CreateGraphics();
        }

and then I want:

g.getPixel(x,y);

how to do that?

Posted 31-May-15 0:06am

john1990_1

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2 solutions

Solution 1

This isn't possible from the Graphics object itself. However, if the Graphics is bound to a Bitmap, you can use the GetPixel method of the Bitmap:

C#

Color c = bmp.GetPixel(x, y);

Posted 31-May-15 0:18am

Thomas Daniels

Comments

Sergey Alexandrovich Kryukov 31-May-15 14:36pm

You see, we don't know if the inquirer use any bitmap. What if there is no any bitmaps? I would approach it in a different way, by asking about the purpose of all this activity. I suspect the whole thing makes no sense.
—SA

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john1990_1 · Accepted Answer · 2015-05-31T00:21:00

I found this somewhere so I used the object of the form as control

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;


namespace OSOL_NAMESPACE
{
    class ClassSetGetPixel
    {


        [DllImport("user32.dll")]
        static extern IntPtr GetDC(IntPtr hWnd);
        [DllImport("user32.dll")]
        static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);
        [DllImport("gdi32.dll")]
        static extern int GetPixel(IntPtr hDC, int x, int y);
        [DllImport("gdi32.dll")]
        static extern int SetPixel(IntPtr hDC, int x, int y, int color);

        static public Color GetPixel(Control control, int x, int y)
        {
            Color color = Color.Empty;
            if (control != null)
            {
                IntPtr hDC = GetDC(control.Handle);
                int colorRef = GetPixel(hDC, x, y);
                color = Color.FromArgb(
                    (int)(colorRef & 0x000000FF),
                    (int)(colorRef & 0x0000FF00) >> 8,
                    (int)(colorRef & 0x00FF0000) >> 16);
                ReleaseDC(control.Handle, hDC);
            }
            return color;
        }
        static public void SetPixel(Control control, int x, int y, Color color)
        {
            if (control != null)
            {
                IntPtr hDC = GetDC(control.Handle);
                int argb = color.ToArgb();
                int colorRef =
                    (int)((argb & 0x00FF0000) >> 16) |
                    (int)(argb & 0x0000FF00) |
                    (int)((argb & 0x000000FF) << 16);
                SetPixel(hDC, x, y, colorRef);
                ReleaseDC(control.Handle, hDC);
            }
        }


    }
}

This is better for GetPixel:

static Color GetPixel(Point p)
      {
          using (var bitmap = new Bitmap(1, 1))
          {
              using (var graphics = Graphics.FromImage(bitmap))
              {
                  graphics.CopyFromScreen(p, new Point(0, 0), new Size(1, 1));
              }
              return bitmap.GetPixel(0, 0);
          }
      }