Search for Pixel on screen

Question

I want to find a specific pixel coordinates from screen. Here's my code (I'm mega-super-newbie, I just started today with C#: ``` static string GetPixel(int X, int Y) { Point position = new Point(X, Y); var bitmap = new Bitmap(1, 1); var graphics = Graphics.FromImage(bitmap); graphics.CopyFromScreen(position, new Point(0, 0), new Size(1, 1)); var _Pixel = bitmap.GetPixel(0, 0); return "0x" + _Pixel.ToArgb().ToString("x").ToUpper().Remove(0, 2); //it returns a pixel color in a form of "0xFFFFFF" hex code //I had NO idea how to convert it to hex code so I did that :P } static void Main() { // for x = 1 to screen width... for (int x = 1; x <= Screen.PrimaryScreen.Bounds.Bottom; x++) { // for x = 1 and y = 1 to screen height... for (int y = 1; y <= Screen.PrimaryScreen.Bounds.Height; y++) { string pixel = GetPixel(x, y); if (pixel == "0x007ACC") //blue color { MessageBox.Show("Found 0x007ACC at: (" + x + "," + y + ")"); break; //exit loop } } } } ``` edit: Here's an error which appears wh…

Accepted Answer

Welcome to SO.

Most coordinates and other things are 0-based, just as in arrays.

That being said, it would be best to use the Bounds' X/Y/Width and Height properties for the loops:

```
var bounds = Screen.PrimaryScreen.Bounds;
for (int x = bounds.X; x < bounds.Width; x++) {
  for(int y = bounds.Y; y < bounds.Height; y++) {
    ..
```

And the proper way to convert the ARGB value to hex is to use the string.Format() method:

`string hex = string.Format("0x{0:8x}", argb);`

EDIT: Apparently `Graphics.CopyFromScreen` leaks handles like there's no tomorrow, which causes strange exceptions to be thrown when no more handles are available (source)

A quick workaround for your scenario could be to capture the whole screen once and then search in the bitmap, i.e. `Graphics.CopyFromScreen(new Position(0, 0), new Position(0, 0), new Size(bounds.Width, bounds.Height));`

Unfortunately this didn't get fixed in .Net 4.0 (don't know about 4.5), so the only proper solution seems to be to P/Invoke the native GDI functions, as described here.

Search for Pixel on screen

Solution

Problem