Programmatically enabling/disabling accessibility settings on Android device

Question

How can I programmatically enable/disable an android screen reader service such as TalkBack?

I am developing a kiosk type application that will be installed on an Android device that will be loaned to visitors while they visit a particular museum. (We are still in the process of determining what device we will use.) The plan is to only allow users to use our app and not have access to the android settings application. However, we'd like to allow users to configure some accessibility settings. When they are finished with the device, we need to restore all the settings to our defaults.

The discussion at the link below has many suggesting launching Android's Settings app. But we don't want users accessing many other settings.

How to Programmatically Enable/Disable Accessibility Service in Android

Answer 1

Only system apps can enable/disable accessibility service programatically. System apps can directly write in settings secure db to start accessibility service.

Settings.Secure.putString(getContentResolver(),Settings.Secure.ENABLED_ACCESSIBILITY_SERVICES, "com.packagename/com.packagename.componentname");

Following permission is required to write in settings secure db:

<uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS" />

For non system apps, only way to start accessibility service is direct them to accessibility settings screen via intent and let user manually start the service :

Intent intent = new Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS);

Answer 2

I think there might be a way to do that if you make your app an AccessibilityService (but you would have to enable it manually after install).

Then in your AccessibilityService class, inside onAccessibilityEventmethod you can explore views (recursively) and perform clicks - in the example below it will click on TalkBack item in settings - after that it should toggle the toggle button on next screen (the trick is that you can click on parent not the switch view itself) - I haven't tried this code :)

@Override
public void onAccessibilityEvent(AccessibilityEvent event) {
    AccessibilityNodeInfo source = event.getSource();        
    if(event.getEventType()==AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED) 
        explore(source);

}

private void explore(AccessibilityNodeInfo view){
    int count = view.getChildCount();
    for(int i=0; i<count; i++){
        AccessibilityNodeInfo child = view.getChild(i);
        if(!MODE_TALK_BACK_SCREEN){
            if(child.getText()!=null && child.getText().toString().toLowerCase().contains("TalkBack")){
                child.getParent().performAction(AccessibilityNodeInfo.ACTION_CLICK);
                MODE_TALK_BACK_SCREEN=true;
                return;
            }
        }else{
            if("ToggleButton".equals(child.getClassName().toString())){ //there ony one toggle button on the screen
                child.getParent().performAction(AccessibilityNodeInfo.ACTION_CLICK);
                performGlobalAction(GLOBAL_ACTION_BACK);
                performGlobalAction(GLOBAL_ACTION_BACK);//need to go back two time - i don't know if that will work :)
                return;
            }
        }
        explore(child);
        child.recycle();
    }

so now if you open accessibility settings with Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS); it will perform clicks for you - you would have to somehow cover it with full screen toast or service with view

I'm currently working on automatic airplane mode toggle and it works - so should do the job in your case

take a look on my serviceconfig.xml

<accessibility-service     xmlns:android="http://schemas.android.com/apk/res/android"
android:description="@string/accessibility_service_description"
android:packageNames="com.android.settings"
android:accessibilityEventTypes="typeWindowStateChanged"
android:accessibilityFlags="flagDefault"
android:accessibilityFeedbackType="feedbackSpoken"
android:notificationTimeout="100"
android:canRetrieveWindowContent="true"
android:settingsActivity="com.example.android.accessibility.ServiceSettingsActivity"
/>

Answer 3

From lollipop you can not change all settings that breaks the security policy. Some of them you may access but you have to take permission for that. So please don't waste time on that.