How to keep the screen on in Qt for android?

问题

I found a couple of solutions how to do that in Java, but did not find how can I do it in QML or Qt. I know that first I should set the WAKE_LOCK permission in AndroidManifest.xml. What should I do to make it possible to turn on and off the screen locking from Qt in runtime?

回答1:

You can use the Qt Android Extras module and use JNI to call the relevant Java function from C++. Something like :

void keepScreenOn() 
{
    QAndroidJniObject activity = QtAndroid::androidActivity();
    if (activity.isValid()) {
        QAndroidJniObject window = activity.callObjectMethod("getWindow", "()Landroid/view/Window;");

        if (window.isValid()) {
            const int FLAG_KEEP_SCREEN_ON = 128;
            window.callObjectMethod("addFlags", "(I)V", FLAG_KEEP_SCREEN_ON);
        }
    }
}

回答2:

Use window.callMethod<void> instead of window.callObjectMethod
Run on GUI thread with QtAndroid::runOnAndroidThread
Clear exceptions afterwards
To disable always on behaviour, use clearFlags

This is tested Qt 5.7 code:

void keep_screen_on(bool on) {
  QtAndroid::runOnAndroidThread([on]{
    QAndroidJniObject activity = QtAndroid::androidActivity();
    if (activity.isValid()) {
      QAndroidJniObject window =
          activity.callObjectMethod("getWindow", "()Landroid/view/Window;");

      if (window.isValid()) {
        const int FLAG_KEEP_SCREEN_ON = 128;
        if (on) {
          window.callMethod<void>("addFlags", "(I)V", FLAG_KEEP_SCREEN_ON);
        } else {
          window.callMethod<void>("clearFlags", "(I)V", FLAG_KEEP_SCREEN_ON);
        }
      }
    }
    QAndroidJniEnvironment env;
    if (env->ExceptionCheck()) {
      env->ExceptionClear();
    }
  });
}

回答3:

You can achieve this by editing the java file used by qt itself. In installation path under src in android path you will find QtActivity.java file. In the onCreate function add the below line

getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON, WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

WAKE_LOCK permission in AndroidManifest.xml also should be added.

Build the project, it will work fine.

来源：https://stackoverflow.com/questions/27758499/how-to-keep-the-screen-on-in-qt-for-android

标签

java

android

c++

qtandroidextras