how to resize physical android screen from terminal/shell

Question

A while ago, I was able to resize the screens on Android. For example, I had a Xoom, and was able to run a command from ADB which shrunk it down to a 7" screen (leaving a black border around it). Granted, it was a little buggy because the home/back/app-switch buttons disappeared, but I know it's possible. It's a 1 line command where I input the new screen resolution in X and Y pixels for the Xoom.

I was wondering if anyone was familiar with this, and knows how to do it.

(and if anyone says it's not possible, I can assure you it is)

(and I want to do this so I can test apps in various screen sizes on my Nexus 10, and I'd prefer not using an emulator)

Answer 1

An update to this answer for Jelly Bean 4.3 from Android dev Adam Powell on Google+ (link found via this SO answer):

In Android 4.3 these options moved from the "am" command (ActivityManager) to the "wm" command (WindowManager). Type "adb shell wm" for details.

So you can now run on 4.3 devices:

adb shell wm size 1280x800 or whatever size or reset

and

adb shell wm density 480 or whatever density or reset

Just make sure the screen is not currently displaying at the moment you run the command.