How to get color data of a pixel when DPI is

So I have a program with 2 forms. The first form opens a small dialog in which the user can select a color from anywhere on the screen when a key is pressed. The code for this is below and it works perfectly, WHEN DPI IS SET TO 100%.

My issue is that I have a QHD screen on my laptop. If I set my DPI to 100%, everything becomes microscopic. So, since I am primarily developing this program for myself, I would like it to work with different DPIs. Ideally it would work with any DPI, that way the program is portable and I can distribute it.

The code is below. On a keypress, a bitmap of the desktop is created, and the color or the pixel under the cursor's current location is stored into a color variable. Again it works very well with 100% dpi, but gives only black/white colors when dpi is different. I've tried setting AutoScale mode to DPI, Font, and None, but the results did not change.

I've been researching this issue for 3 days but I cannot find a solution.

Thanks for your time!

private void PixelColor_KeyDown(object sender, KeyEventArgs e)
{
Point cursor = new Point();
cursor.X = Cursor.Position.X;
cursor.Y = Cursor.Position.Y;
Color c = GetColorAt(cursor);
this.BackColor = c;
}
Bitmap screenPixel = new Bitmap(1, 1, PixelFormat.Format32bppArgb);
public Color GetColorAt(Point location)
{
using (Graphics gdest = Graphics.FromImage(screenPixel))
{
using (Graphics gsrc = Graphics.FromHwnd(IntPtr.Zero))
{
IntPtr hSrcDC = gsrc.GetHdc();
IntPtr hDC = gdest.GetHdc();
int retval = BitBlt(hDC, 0, 0, 1, 1, hSrcDC, location.X, location.Y, (int)CopyPixelOperation.SourceCopy);
gdest.ReleaseHdc();
gsrc.ReleaseHdc();
}
}
return screenPixel.GetPixel(0, 0);
}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Laxmidhar Sahoo8y ago
sir I am working with the color picker may help you
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
    {
        Point cursor = new Point();
        cursor.X = Cursor.Position.X;
        cursor.Y = Cursor.Position.Y;
        Color c = GetColorAt(cursor);
        this.BackColor = c;
    }
public Color GetColorAt(Point location)
      {

          int xp = location.X;
          int yp = location.Y;
          Bitmap b = new Bitmap(pictureBox1.Image);
          Color colour = b.GetPixel(xp, yp);

          return colour;
      }
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How to get color data of a pixel when DPI is > 100%