macOS/Python: Get dimension info about active screens

screen_info.py

from AppKit import NSScreen, NSDeviceSize, NSDeviceResolution
from Quartz import CGDisplayScreenSize

for i, screen in enumerate(NSScreen.screens(), 1):
    description = screen.deviceDescription()
    pw, ph = description[NSDeviceSize].sizeValue()
    rx, ry = description[NSDeviceResolution].sizeValue()
    mmw, mmh = CGDisplayScreenSize(description["NSScreenNumber"])
    scaleFactor = screen.backingScaleFactor()
    pw *= scaleFactor
    ph *= scaleFactor
    print(f"Display #{i}: {mmw:.1f} × {mmh:.1f} mm; {pw:.0f} × {ph:.0f} pixels; reported virtual resolution = {rx:.0f} × {ry:.0f} ppi; actual physical pixel density = {pw/mmw*25.4} × {ph/mmh*25.4} ppi")

Example output:

Display #1: 643.8 × 402.4 mm; 2560 × 1600 pixels; reported virtual resolution = 72 × 72 ppi; actual physical pixel density = 101.00000151686781 × 101.00000151686783 ppi
Display #2: 331.0 × 206.9 mm; 2880 × 1800 pixels; reported virtual resolution = 144 × 144 ppi; actual physical pixel density = 221.00000331908706 × 221.00000331908706 ppi

Thanks for this.