How to read the screen pixels?

Question

I want to read a rectangular area, or whole screen pixels. As if screenshot button was pressed.

How i do this?

Edit: Working code:

Answer 1

You can use the code below to read the screen pixels:

HWND desktop = GetDesktopWindow();
HDC desktopHdc = GetDC(desktop);
COLORREF color = GetPixel(desktopHdc, x, y);