android - 明るさを変えるには？

Question

徐々に明るさが変わる Runnable を実行します

private Runnable runnable = new Runnable(){

        @Override
        public void run(){
            if(intensity < 1){ intensity += intensityGrow; }
            if(intensity > 1){ intensity = 1f; }
            Log.e("intensity", intensity + "/grow "+intensityGrow);

            android.provider.Settings.System.putInt(
                getContentResolver(),

                android.provider.Settings.System.SCREEN_BRIGHTNESS,(int)(255*intensity)
            );
            AudioManager am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);

            am.setStreamVolume(
                AudioManager.STREAM_ALARM, (int) (am.getStreamMaxVolume(AudioManager.STREAM_ALARM) * intensity), 0
            );
            if(intensity < 1){
                Log.e("intensity", "continue");

                handler.postDelayed(runnable, 1000);
            }

        }
    };

私も使ってみました

        WindowManager.LayoutParams lp = getWindow().getAttributes();
        lp.screenBrightness = intensity;
        getWindow().setAttributes(lp);

<uses-permission android:name="android.permission.WRITE_SETTINGS"/> マニフェストにもあります 結果なし。