OSX Lion AppleScript : How to get current space # from mission control?

I'm trying to figure out how to get the current space # from mission control. Source would be helpful, but more helpful would be info on how to figure this out myself. I've written a few applescripts, but more often than not it seems like any time I need to do something new (that I can't find dictionary documentation for) it falls under the category of "tell this specific app (e.g. "System Events") this very specific thing" and I've no clue how I would actually figure that out.

Specifically what I am trying to do:

I hate the new mission control in OSX 10.7. I want my spaces "grid" back since I used it all the time. I used to navigate between spaces using arrow keys (e.g. ALT+↑) every few seconds. Now I'm stuck with this clunky 1x9 array of spaces instead of an elegant 3x3 grid. I've re-mapped all my spaces to use the number pad, which partially takes care of the problem (since it is a 3x3 grid), but only when I have an external keyboard attached.

Basically, I want to be able to use ALT+↑ and ↓ again, but to do so I need to detect the current space # so that I can switch from space 5-->2, for example.

Dave's answer below, although far more detailed than I expected, requires writing an app to do this (plus it still doesn't fully answer the question). If it's at all possible, I'd rather just bind a few keys to an applescript.

Solution 1:

I'm trying to figure this out myself. Not there yet, but in the right direction:

• Each Mission Control "space" gets a uuid assigned to it...
• ...except for the very first one (AFAIK), and the Dashboard one.

You can read them here:

$ defaults read com.apple.spaces
$ defaults read com.apple.desktop

File locations:

~/Library/Preferences/com.apple.spaces.plist
~/Library/Preferences/com.apple.desktop.plist

Here's mine. I have four spaces enabled, and three entries show up:

$ defaults read com.apple.spaces
{
    spaces =     (
                {
            type = 0; 
            uuid = "9F552977-3DB0-43E5-8753-E45AC4C61973";
        },
                {
            type = 0;
            uuid = "44C8072A-7DC9-4E83-94DD-BDEAF333C924";
        },
                {
            type = 0;
            uuid = "6FADBDFE-4CE8-4FC9-B535-40D7CC3C4C58";
        }
    );
}

If you delete a space, that entry will get removed from the file. If you add a space, an entry will be added. Again, there's never an entry for Desktop 1 or Dashboard.

I'm not sure if there's a public API to figure out what space uuid is being displayed on a display. I'd assume that no uuid means Display 1, and the others' mean Display 1+n.

I took a quick glance through the AppleScript Editor Library (Window ---> Library) and didn't see any entries under System Events for spaces. This is probably something that can be done with Cocoa, perhaps via private API, but I'm not sure about AppleScript.

UPDATE - July 23, 2011

It looks like Dock controls Mission Control. You can grab its header files like so:

1. Go to: /System/Library/CoreServices/Dock
2. Right-Click and Show Package Contents
3. Navigate: /Contents/MacOS/
4. Copy and paste the Dock binary to your desktop.
5. Run: $class-dump ~/Desktop/Dock

That'll spit out all of its header files (it's long; almost 7,500 lines). You can see the spaceUUID strings appearing in there. There's a class called WVSpace which appears to represent a single Space in Mission Control, and a lot of other WV* classes.

I'll keep looking at it tomorrow; too tired now. :)

UPDATE - July 24, 2011

Inside Dock there's a class called WVSpaces. It has a number of attributes including:

WVSpace *currentSpace;
unsigned int currentWorkspace;
WVSpace *nextSpace;                     // Space on the right???
WVSpace *previousSpace;                 // Space on the left???
BOOL currentSpaceIsDashboard;
BOOL dashboardIsCurrent;
...lots more...

Each WVSpace class has an NSString *_uuid; attribute, which is likely its SpaceUUID. So theoretically you can get the current space number like so:

WVSpace *currentSpace = [[WVSpaces sharedInstance] currentSpace];
NSString *currentSpaceUUID = [currentSpace _uuid];     // Empty string if main space???

The trick is, how to get access to the private WVSpaces class buried inside of Dock? I'm assuming it's Singleton as it has an NSMutableArray *_spaces; attribute, probably with every space listed in it. Only one space gets displayed at a time (this holds true if you're using multiple monitors; the space spans across both of them), so it makes sense to only have one WVSpaces instance.

So it looks like it'll require some SIMBL hacking of Dock to gain access to WVSpaces.

Solution 2:

I've been poking around, and I came up with this: https://gist.github.com/1129406

Spaces have a nonsequential ID and a sequential index (0-based). You can get the ID in two ways:

• from public APIs (see get_space_id)
• from the private CGS API CGSGetWorkspace

You can set the current space by index using public APIs (though the notifications themselves are not publicly documented): see set_space_by_index

You can set the current space by ID using private the CGS API CGSSetWorkspace.

You cannot get the current space index directly. However, if you're always using the same set of nine spaces, you can rotate through them once using set_space_by_index, collect their IDs, and build a mapping. Then you will be able to get the current index from the ID.

Solution 3:

... also been working on this :)

You say that you "need to to detect the current space #". This is not strictly true: To move down one row, you just move 3 spaces right, so in principle you could just bind something like

tell application "System Events" to tell process "WindowServer"
    key code {124, 124, 124} using control down
end tell

to Alt-down (with FastScripts, Alfred or some other fast method that avoids the overhead of Automator). This approach will fail if you ever hit down in the bottom row, of course -- but if you are truly hard-wired, you never do :)
You have to "Enable access for assistive devices" in the Universal Access preference pane for the key code approach to work.

Caveat: This doesn't work. When I launch the script above, I nicely jump three spaces. The problem is that afterwards my keyboard goes unresponsive: It seems that only the window manager is receiving events: I can close windows and switch space, but I cannot interact with any applications.
My theory is that this happens when the jump causes the current application to change during the execution of the script -- but I have no idea how to fix this.

A related observation: The Mission Control (i.e. /Applications/Mission Control.app/Contents/MacOS/Mission\ Control) seems to react to some command line arguments:

• Mission\ Control: show mission control
• Mission\ Control 1: show desktop
• Mission\ Control 2: show current application windows

I tried putting in some of the UUID's from defaults read com.apple.spaces, but that didn't do much. So much for fumbling in the dark.

Solution 4:

I wrote an app - does it work for you?

Change Space.app

The keys to make it work are control-shift and the arrow keys, although this may be fixable if you are stuck on ALT.

Make sure you have 9 spaces (desktops) set up before you start, and you'll need to change the default ctrl-up and ctrl-down key bindings in System Preferences to something else (in Keyboard -> Keyboard Shortcuts -> Mission Control : Mission Control and Show Desktop).

On the first run it it will cycle through your desktops to enumerate them when you first change space.

Then you should be able to change between desktops like in a 3x3 grid.

There may be a few wrinkles, but it's basically functional, at least for me.

Solution 5:

http://switchstep.com/ReSpaceApp

This works, is free (right now) and is awesome.

Just be sure to manually create as many spaces as your layout (in preferences) is expecting.