Get Screen Size on C#

The process is running under DPI virtualization. So we should apply the DPI aware manifest option to stop DPI virtualization

[DllImport("user32.dll", SetLastError=true)]
static extern bool SetProcessDPIAware();

Then

public enum SystemMetric
{
    VirtualScreenWidth = 78, // CXVIRTUALSCREEN 0x0000004E 
    VirtualScreenHeight = 79, // CYVIRTUALSCREEN 0x0000004F 
}

[DllImport("user32.dll")]
public static extern int GetSystemMetrics(SystemMetric metric);

public static Size GetVirtualDisplaySize()
{
    var width = GetSystemMetrics(SystemMetric.VirtualScreenWidth);
    var height = GetSystemMetrics(SystemMetric.VirtualScreenHeight);

    return new Size(width, height);
}

References
https://stackoverflow.com/questions/28339257/getsystemmetrics-and-tscreen-returns-wrong-value
https://www.pinvoke.net/default.aspx/user32/SetProcessDPIAware.html
https://stackoverflow.com/questions/1317235/c-get-complete-desktop-size
https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setprocessdpiaware

Take Screenshot on Windows Using Python

from PIL import ImageGrab
im = ImageGrab.grab()
im.save('screenshot.png')

Or

import win32gui, win32ui, win32con, win32api
hwin = win32gui.GetDesktopWindow()
width = win32api.GetSystemMetrics(win32con.SM_CXVIRTUALSCREEN)
height = win32api.GetSystemMetrics(win32con.SM_CYVIRTUALSCREEN)
left = win32api.GetSystemMetrics(win32con.SM_XVIRTUALSCREEN)
top = win32api.GetSystemMetrics(win32con.SM_YVIRTUALSCREEN)
hwindc = win32gui.GetWindowDC(hwin)
srcdc = win32ui.CreateDCFromHandle(hwindc)
memdc = srcdc.CreateCompatibleDC()
bmp = win32ui.CreateBitmap()
bmp.CreateCompatibleBitmap(srcdc, width, height)
memdc.SelectObject(bmp)
memdc.BitBlt((0, 0), (width, height), srcdc, (left, top), win32con.SRCCOPY)
bmp.SaveBitmapFile(memdc, 'screenshot.bmp')

Don’t forget to SetProcessDPIAware if necessary

import ctypes

user32 = ctypes.windll.user32
user32.SetProcessDPIAware()

References
https://stackoverflow.com/questions/4589206/python-windows-7-screenshot-without-pil