modify a an existing Android ROM to control user actions

Question

I am creating an Android application for a customer which will be pre-installed and distributed together with the handsets. Now the customer asked me to lock down the ROM to

Answer 1

There's not really a whole lot you need to do to make a single-purpose device. If you play your cards right, it should be something you can do without having to tinker with the ROM.

The quick-and-easy route would be to deploy your application as a replacement for the stock launcher, just like any of the other home replacements that are available. Setting that as the default would cover most of the opportunities for casual tampering, since it would leave no other way to launch or install anything else. The only other things I can think of off the top of my head that you'd need to do are snag the search button so it doesn't bring up the default Android search box atop your app and the green key so the phone app won't come up.

You would, of course, need a way to get to the original launcher to maintain the device and install new versions of your app. I'd accomplish that using a "Maintenance" menu item somewhere that asks for some form of authentication (e.g., a password), changes the home app back to the original and launches it. When you're done doing what you need to do, set your app as the default launcher and you're back in business.

Edit to address MAINERROR (now Octavian Damiean)'s comment:

Any activity in any application can register itself as a home application by adding an intent filter on the android.intent.category.HOME category. It's literally four lines in the manifest, and you don't have to write any code to support it. Take a look at lines 77-82 in the stock launcher's manifest for an example of how this is done. (Ignore the filters on DEFAULT and MONKEY; they're not necessary.) Once the activity is selected as the default handler for the category, it becomes the first thing launched at boot and what comes up when the Home key is pressed. HTC Sense, aHome, Panda Home, etc. all use this mechanism.

Launching the stock home (or any other application) explicitly is about five lines of code.

Side note: There's a application on the Market called Home Switcher that lets you launch any of the activities filtering on the HOME category or set one as the default.

Unless the handset manufacturer adds a lot of shovelware, the stuff that runs in the background should be inconsequential and won't get in the way.

Answer 2

Blrfl's answer is great, but it still has a problem: if the user long presses the HOME button, the recent applications popup will appear an the user will be able to launch another app.

Answer 3

There was a similar question already somewhere. You can indeed limit the functionality of your device by the amount you want or have to. In order to achieve this you will definitely have to build your own modified ROM.

You will have to touch the ROM because you will have to get rid of several applications running in the background. One you won't need them anyway and two as you don't need them they would only consume resources.

You might want to take a look at http://source.android.com there you will find more information about the sources which will hopefully direct you where you need.