Get "Position" (Not Resolution) of macOS Extended Display

Question

I have an extended display set up like this: In the extended display, I have a Finder window positioned on the left half of the extended screen:

When I call this AppleScript:

tell application "System Events"
    tell process "Finder"
            {position of window 1, size of window 1}
    end tell
end tell

I can get the position of the Finder window:

224, 1331, 881, 1075

However, if I move the bottom screen to the left: The same AppleScript call now provides a different window position:

10, 1331, 881, 1075

How can I get the "position" of the extended screen?

I know I can get the bounds of the desktop using:

tell application "Finder" to get bounds of window of desktop

But that returns the exact same result for both extended display positions:

0, 0, 2304, 2416

I also know I can get the display resolution using

system_profiler SPDisplaysDataType

But that doesn't seem to tell me anything about the extended display's "position", just its resolution.

That same link suggests the command

defaults read /Library/Preferences/com.apple.windowserver.plist

Which looks promising because it has UnmirroredOriginX and UnmirroredOriginY listed for displays. The problem with that file is that I don't see a way to figure out which one of the 17 (in my case) settings is currently active.

For background, my motivation for this question is to derive window positions like left, right, and center 1/3rds and comparable 1/4ths and half positions for windows in an extended display no matter where the extended display is "positioned" relative to the main display. I am trying to replicate the behavior of a program like Rectangle except programmatically. That way windows can automatically be opened and sent to certain positions when certain scripts are run.

I would just send keystrokes to Rectangle itself but it has no way of specifying main or extended display (only "Next" and "Previous" display), so there is no deterministic way to guarantee which display the window will go to as far as I know.

I would also be happy to hear about any other CLI accessible program that can position any window to any 1/2, 1/3, or 1/4 positions in a specific (main or extended) display.

score 1 · Accepted Answer · answered Dec 20 '22 at 00:22

The solution I came up with was to get the resolution using a regex on the output of

system_profiler SPDisplaysDataType

for lines matching

Resolution: (\d+) x (\d+)

I divide both of those numbers by 2 because I always use retina / 4K monitors. This calculation seems to exactly match the AppleScript position values for the 4K displays but not retina. Luckily for me, the 4K display is the only one I need to be completely accurate.

Because I always scale my main monitor to higher resolution than my laptop screen, I can infer that the larger number is the monitor and thus the main display and the smaller is the extended display.

I then call

tell application "System Events"
    tell process "%s"
            {position of window 1, size of window 1}
    end tell
end tell

On whatever target application's window needs to be positioned, which for me is always the frontmost (usually newly opened) window.

Because I always have the main monitor positioned on top of the extended display (laptop), if the returned Y position for the window is higher than the resolution height (divided by 2) of the main monitor, I assume it is in the extended display.

From there, I can keystroke the "Next Display" hotkey in Rectangle if it is in the wrong display. Then I can keystroke the appropriate 1/2, 1/3, 1/4 hotkey in Rectangle.

Get "Position" (Not Resolution) of macOS Extended Display

1 Answers1