Develop Reference

Android device wont switch on programatically

We have written a test app to try and debug a issue with a 3rd party by reproducing the issues with our own source code.
The app has a feature to allow us to set times for when the devices switches off then on. This is to comply with green power saving policies.
The app switches the device off fine, but on switch on, we hear a 'click' at the expected time, but the display remains off. We wrote a test app and found this works well on other Android devices, but on the problem device we get the same - just the sound of the power relay clicking on, but nothing else.
We are wondering if this is something to do with a system setting on the devices that controls this behaviour.
The code to switch on is as follows:
public void wakeupTimer(){
new CountDownTimer(wakeupTime * 1000, 1000) {
public void onTick(long millisUntilFinished) {
textTimer.setText("0:"+checkDigit(wakeupTime));
wakeupTime--;
}
public void onFinish() {
PowerManager pm = (PowerManager) getApplicationContext().getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wakeLock = pm.newWakeLock(( PowerManager.FULL_WAKE_LOCK
| PowerManager.ON_AFTER_RELEASE
| PowerManager.ACQUIRE_CAUSES_WAKEUP), "commandandcontrol:TAG");
wakeLock.acquire();
finish();
}
}.start();
}

AMOLED display does not save power with full black display. Why is it so? [duplicate]

Before marking this post as a "duplicate", I am writing this post because no other post holds the solution to the problem.
I am trying to turn off the device, then after a few minutes or sensor change, turn it back on.
Turn Off Display Tests
I am able to turn off the screen using:
params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = 0;
getWindow().setAttributes(params);
I have been unable to turn off the screen using the wl.release() method.
Turn On Display Test
My first guess, as follows, does not work. Nothing happens, screen remains off.
params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = -1f;
getWindow().setAttributes(params);
I also then tried to use wakelocks, with no success.
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK, "tag");
wl.acquire();
Finally I have tried the following, with no result.
getWindow().addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
All in all, I don't get any kind of error in the console for any of these methods. My test text "Screen should be on", is on the the screen when I turn on the device using the power button. This shows that the code should have ran. Please only answer if you have tested the code, it seems like many of the functions such as params.screenBrightness = -1, do not work as they should according to the sdk.

I am going to assume you only want this to be in effect while your application is in the foreground.
This code:
params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = 0;
getWindow().setAttributes(params);
Does not turn the screen off in the traditional sense. It makes the screen as dim as possible. In the standard platform there is a limit to how dim it can be; if your device is actually allowing the screen to turn completely off, then it is some peculiarity of the implementation of that device and not a behavior you can count on across devices.
In fact using this in conjunction with FLAG_KEEP_SCREEN_ON means that you will never allow the screen to go off (and thus the device to go into low-power mode) even if the particular device is allowing you to set the screen brightness to full-off. Keep this very strongly in mind. You will be using much more power than you would if the screen was really off.
Now for turning the screen back to regular brightness, just setting the brightness value should do it:
WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = -1;
getWindow().setAttributes(params);
I can't explain why this wouldn't replace the 0 value you had previously set. As a test, you could try putting a forced full brightness in there to force to that specific brightness:
WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = 1;
getWindow().setAttributes(params);
This definitely works. For example, Google's Books apps uses this to allow you to set the screen brightness to dim while using a book and then return to regular brightness when turning that off.
To help debug, you can use "adb shell dumpsys window" to see the current state of your window. In the data for your window, it will tell you the current LayoutParams that have been set for it. Ensure the value you think is actually there.
And again, FLAG_KEEP_SCREEN_ON is a separate concept; it and the brightness have no direct impact on each other. (And there would be no reason to set the flag again when undoing the brightness, if you had already set it when putting the brightness to 0. The flag will stay set until you change it.)

I had written this method to turn on the screen after screen lock. It works perfectly for me. Try it-
private void unlockScreen() {
Window window = this.getWindow();
window.addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
window.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED);
window.addFlags(WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
}
And call this method from onResume().

I would suggest this one:
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "tag");
wl.acquire();
The flag ACQUIRE_CAUSES_WAKEUP is explained like that:
Normal wake locks don't actually turn on the illumination. Instead,
they cause the illumination to remain on once it turns on (e.g. from
user activity). This flag will force the screen and/or keyboard to
turn on immediately, when the WakeLock is acquired. A typical use
would be for notifications which are important for the user to see
immediately.
Also, make sure you have the following permission in the AndroidManifewst.xml file:
<uses-permission android:name="android.permission.WAKE_LOCK" />

Hi I hope this will help:
private PowerManager mPowerManager;
private PowerManager.WakeLock mWakeLock;
public void turnOnScreen(){
// turn on screen
Log.v("ProximityActivity", "ON!");
mWakeLock = mPowerManager.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "tag");
mWakeLock.acquire();
}
#TargetApi(21) //Suppress lint error for PROXIMITY_SCREEN_OFF_WAKE_LOCK
public void turnOffScreen(){
// turn off screen
Log.v("ProximityActivity", "OFF!");
mWakeLock = mPowerManager.newWakeLock(PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK, "tag");
mWakeLock.acquire();
}

WakeLock screenLock = ((PowerManager)getSystemService(POWER_SERVICE)).newWakeLock(
PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "TAG");
screenLock.acquire();
//later
screenLock.release();
//User Manifest file

Are you sure you requested the proper permission in your Manifest file?
<uses-permission android:name="android.permission.WAKE_LOCK" />
You can use the AlarmManager1 class to fire off an intent that starts your activity and acquires the wake lock. This will turn on the screen and keep it on. Releasing the wakelock will allow the device to go to sleep on its own.
You can also take a look at using the PowerManager to set the device to sleep: http://developer.android.com/reference/android/os/PowerManager.html#goToSleep(long)

Simply add
android:keepScreenOn="true"
or call
setKeepScreenOn(true)
on parent view.

The best way to do it ( using rooted devices) :
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
.
.
.
int flags = WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD | WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON;
getWindow().addFlags(flags); // this is how your app will wake up the screen
//you will call this activity later
.
.
.
}
Now we have this two functions:
private void turnOffScreen(){
try{
Class c = Class.forName("android.os.PowerManager");
PowerManager mPowerManager = (PowerManager) this.getSystemService(Context.POWER_SERVICE);
for(Method m : c.getDeclaredMethods()){
if(m.getName().equals("goToSleep")){
m.setAccessible(true);
if(m.getParameterTypes().length == 1){
m.invoke(mPowerManager,SystemClock.uptimeMillis()-2);
}
}
}
} catch (Exception e){
}
}
And this:
public void turnOnScreen(){
Intent i = new Intent(this,YOURACTIVITYWITHFLAGS.class);
startActivity(i);
}
Sorry for my bad english.

Here is a successful example of an implementation of the same thing, on a device which supported lower screen brightness values (I tested on an Allwinner Chinese 7" tablet running API15).
WindowManager.LayoutParams params = this.getWindow().getAttributes();
/** Turn off: */
params.flags = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
//TODO Store original brightness value
params.screenBrightness = 0.1f;
this.getWindow().setAttributes(params);
/** Turn on: */
params.flags = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
//TODO restoring from original value
params.screenBrightness = 0.9f;
this.getWindow().setAttributes(params);
If someone else tries this out, pls comment below if it worked/didn't work and the device, Android API.

To keep screen on:
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
Back to screen default mode:
just clear the flag FLAG_KEEP_SCREEN_ON
getWindow().clearFlags(android.view.WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

This is worked on Marshmallow
private final String TAG = "OnOffScreen";
private PowerManager _powerManager;
private PowerManager.WakeLock _screenOffWakeLock;
public void turnOnScreen() {
if (_screenOffWakeLock != null) {
_screenOffWakeLock.release();
}
}
public void turnOffScreen() {
try {
_powerManager = (PowerManager) this.getSystemService(POWER_SERVICE);
if (_powerManager != null) {
_screenOffWakeLock = _powerManager.newWakeLock(PROXIMITY_SCREEN_OFF_WAKE_LOCK, TAG);
if (_screenOffWakeLock != null) {
_screenOffWakeLock.acquire();
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
}

If your app is a system app,you can use PowerManager.goToSleep() to turn screen off,you requires a special permission
before you use goToSleep(), you need use reflection just like:
public static void goToSleep(Context context) {
PowerManager powerManager= (PowerManager)context.getSystemService(Context.POWER_SERVICE);
try {
powerManager.getClass().getMethod("goToSleep", new Class[]{long.class}).invoke(powerManager, SystemClock.uptimeMillis());
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
}
}
Now,you can use goToSleep() to turn screen off.
This is what happens when the power key is pressed to turn off the screen.

As per Android API 28 and above you need to do the following to turn on the screen
setShowWhenLocked(true);
setTurnScreenOn(true);
KeyguardManager keyguardManager = (KeyguardManager)
getSystemService(Context.KEYGUARD_SERVICE);
keyguardManager.requestDismissKeyguard(this, null);

Regarding to Android documentation it can be achieve by using following code line:
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
I have added this in my onCreate method and it works fine.
On the link you will find different ways to achieve this and general explanation as well.
Link to the documenation: https://developer.android.com/training/scheduling/wakelock.html

I wouldn't have hope of "waking the screen" in the activity. If the screen is off the activity is probably in a paused state and shouldn't be running any code.
When waking up, there is the issue of the lockscreen. I don't know how any app can automatically bypass the lockscreen.
You should consider running your background tasks in a service, and then using the notification manager to send a notification when whatever is detected. The notification should provide some sort of device alert (screen wake up, notification icon, notification led, etc). When clicking the notification it can launch the intent to start your activity.
You could also attempt to start the activity direct from the service, but I really don't know if that will turn the screen on or bypass the lockscreen.

I have tried all above solution but none worked for me. so I googled and found below solutions. I tried and it worked.
https://www.tutorialspoint.com/how-to-turn-android-device-screen-on-and-off-programmatically
if there is any suggestion then please give

switch off/on screen on PARTIAL_WAKE_LOCK

I'm using this code to enter in PARTIAL_WAKE_LOCK mode:
PowerManager pm = PowerManager.getSystemService(Context.POWER_SERVICE);
screenWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK,
"screenWakeLock");
pm.acquire();
but I do not succeed to switch off the screen and switch on when I need it,I read tens of examples without succeed in it.
I can't use code that require the permission DEVICE_POWER like goToSleep() and wakeUp().
My goal is switch on the screen for 1 second and to switch off it for 10 seconds, and then start again.
Thanks all.

The use of PowerManager requires DEVICE_POWER permission that is only for applications that are signed by the same signature was used to sign the firmware. That is why you cannot use goToSleep() and wakeUp().
This code worked for me to turn on/off the screen:
//Turn off - brighness to 0;
WindowManager.LayoutParams params = getWindow().getAttributes();
params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = 0;
getWindow().setAttributes(params);
To turn on just change the brighness to >0;

HDMI out programming for dual screen

In my search I found that, the Android SDK provides no support for controlling HDMI port activities and handling HDMI output, as of now. Though certain device manufacturers like Motorola (don't know if any other does that too) provide API's for a little better control. Below are the links to two of them, out of which the dual screen one (which suits my requirement pretty close) is deprecated.
motorola hdmi status api
motorola hdmi dual screen api
Mirroring is the default behavior on connecting HDMI but, I want my app to run a binded service on HDMI out. This will allow the phone to perform any other tasks simultaneously, w/o disturbing my service running on the HDMI screen.
Can someone please suggest how can I go about it? Or if any other manufacturer provides similar flexibility as Motorola?

Create a Service class like so.
public class MultiDisplayService extends Service {
#Override
public void onCreate() {
super.onCreate();
DisplayManager dm = (DisplayManager)getApplicationContext().getSystemService(DISPLAY_SERVICE);
if (dm != null){
Display dispArray[] = dm.getDisplays(DisplayManager.DISPLAY_CATEGORY_PRESENTATION);
if (dispArray.length>0){
Display display = dispArray[0];
Log.e(TAG,"Service using display:"+display.getName());
Context displayContext = getApplicationContext().createDisplayContext(display);
WindowManager wm = (WindowManager)displayContext.getSystemService(WINDOW_SERVICE);
View view = LayoutInflater.from(displayContext).inflate(R.layout.fragment_main,null);
final WindowManager.LayoutParams params = new WindowManager.LayoutParams(
WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.TYPE_TOAST,
WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN,
PixelFormat.TRANSLUCENT);
wm.addView(view, params);
}
}
}
Start the service, perhaps in your Application class.
public class MultiDisplayApplication extends Application {
#Override
public void onCreate() {
super.onCreate();
startService(new Intent(this, MultiDisplayService.class));
}
}
You will probably need more complex display add/remove logic based on DisplayManager.DisplayListener
mDisplayManager = (DisplayManager) this.getSystemService(Context.DISPLAY_SERVICE);
mDisplayManager.registerDisplayListener(this, null);
Using WindowManager.LayoutParams.TYPE_TOAST requires no permissions but seems like a hack. WindowManager.LayoutParams.TYPE_SYSTEM_ALERT might be more reasonable, but requieres
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
in your AndroidManifest.

android: turn off screen when close to face

My app allows the user to access their corporate voice mail. Normally, durring a phone call when the user holds the device up to their ear, the screen shuts off so they wont accidentally push buttons with their face. I would like to make my app do the same thing when the user is listening to their voice mail.
anyone know how to do this?

If you are allowed to look at open source code without causing yourself problems, check the source of the Android Phone Application. Specifically src/com/android/phone/PhoneApp.java and src/com/android/phone/InCallScreen.java.
From src/com/android/phone/PhoneApp.java:
//Around line 519
// Wake lock used to control proximity sensor behavior.
if ((pm.getSupportedWakeLockFlags()
& PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK) != 0x0) {
mProximityWakeLock = pm.newWakeLock(
PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK,
LOG_TAG);
}
....
// Around line 1334
if (((state == Phone.State.OFFHOOK) || mBeginningCall)&& !screenOnImmediately) {
// Phone is in use! Arrange for the screen to turn off
// automatically when the sensor detects a close object.
if (!mProximityWakeLock.isHeld()) {
if (DBG) Log.d(LOG_TAG, "updateProximitySensorMode: acquiring...");
mProximityWakeLock.acquire();
} else {
if (VDBG) Log.d(LOG_TAG, "updateProximitySensorMode: lock already held.");
}
} else {
// Phone is either idle, or ringing. We don't want any
// special proximity sensor behavior in either case.
if (mProximityWakeLock.isHeld()) {
if (DBG) Log.d(LOG_TAG, "updateProximitySensorMode: releasing...");
// Wait until user has moved the phone away from his head if we are
// releasing due to the phone call ending.
// Qtherwise, turn screen on immediately
int flags =
(screenOnImmediately ? 0 : PowerManager.WAIT_FOR_PROXIMITY_NEGATIVE);
mProximityWakeLock.release(flags);
}
}
Additionally, if you look at the code for the PowerManager class, PROXIMITY_SCREEN_OFF_WAKE_LOCK is documented (but hidden) and should do what you want ( I am not sure which API level this works for, however ) -- but not in the table for some reason.
/**
* Wake lock that turns the screen off when the proximity sensor activates.
* Since not all devices have proximity sensors, use
* {#link #getSupportedWakeLockFlags() getSupportedWakeLockFlags()} to determine if
* this wake lock mode is supported.
*
* {#hide}
*/
public static final int PROXIMITY_SCREEN_OFF_WAKE_LOCK = WAKE_BIT_PROXIMITY_SCREEN_OFF;
If you aren't afraid of using a potential undocumented feature, it should do exactly what you need.

as of API level 21 (Lollipop) you can get proximity wake lock this just like that:
if(powerManager.isWakeLockLevelSupported(PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK)) {
PowerManager.WakeLock wakeLock = powerManager.newWakeLock(PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK, TAG);
wakeLock.setReferenceCounted(false);
return wakeLock;
} else {
return null;
}
}
then it is up to you to acquire and release the lock.
PS: PowerManager#getSupportedWakeLockFlags was hidden, but now exists nomore. They have invented isWakeLockLevelSupported instead.

Probably you don't need it anymore but for the ones that are interested in code you could have a look at my SpeakerProximity project at http://code.google.com/p/speakerproximity/

What you are seeing is the use of a proximity sensor. For devices that have one, you access it through SensorManager.