Voice Access, modified: technical notes.

The problem

In Voice Access settings, Configure activation key opens a popup. It records every key you press, then waits for you to tap OK. On a keypad-only phone, that fails two separate ways.

A USB mouse doesn't help either. The phone turns clicks into key presses too.

What the patch changes

One small part of the app, the key popup. Nothing else.

• Press a key: the popup records it, same as before.
• Let go of that same key: the popup saves your choice and closes. No OK button needed.
• Holding a key does nothing until you let go. Auto-repeat is ignored.
• Back cancels without saving. In the original app, Back got recorded as a key too.
• Clear still clears the key.

The key that opens the popup can't save itself by accident. The popup only saves on a release when the press also started inside it.

The bug hiding in the firmware

The first version of this patch was correct and still didn't save. Logging showed the key was captured and the save ran every time. The phone threw the value away at the last step.

Android settings popups remember which button you clicked, then check it when the popup closes. OK sets the value to -1. Stock Android checks for -1. This phone's firmware checks for -3, the "neutral" button:

# android.preference.DialogPreference.onDismiss, pulled from the phone
iget p1, p0, ...DialogPreference;->mWhichButtonClicked:I
const/4 v0, -0x3        # stock Android uses -0x1 here
if-ne p1, v0, :cancelled

So OK sets -1, the check looks for -3, and every save gets treated as a cancel. The popup closes and looks like it worked. This hits every settings popup of this type on the phone, not only Voice Access.

Install

You need a computer with Android platform-tools (adb) and USB debugging turned on in the phone's developer options.

1. Remove the original Voice Access

The modified app is signed with a different key than the original, so the original has to come off first. Its settings go with it.

Copyadb uninstall com.android.cts.apps.accessibility.voiceaccess

2. Install the modified app

Copyadb install voiceaccess-autosave.apk

3. Set it up on the phone

1. Settings, Accessibility, Voice Access: turn it on.
2. Allow the microphone and finish setup.
3. In Voice Access settings: Configure activation key, then Activation key.
4. Press and release the key you want. The popup closes by itself.

Turn Voice Access on from the phone itself. Don't flip accessibility settings over adb.

Check that it saved

The line under "Activation key" should now show your key, for example KEYCODE_SPEAKER. "No key assigned" means nothing saved.

If the key saves but holding it doesn't start Voice Access, the phone is using that key for something else first. Pick a different key. That's not a problem with the patch.

Will it work on my phone?

Check the app, not the phone model.

• Same Voice Access build. The patch is for version 4.0.304676510 only. Other builds rename their internals, so the patch would have to be redone for them. To check your version:

  Copyadb shell dumpsys package com.android.cts.apps.accessibility.voiceaccess | grep versionName

• Any firmware. The patch doesn't rely on the firmware bug, so it works whether your phone has it or not.

Going back

Keep your original APK. To undo, uninstall the modified app and install the original. The two are signed with different keys, so one can't install over the other. You'll set up Voice Access again either way.