Sample Apps to Control Screen Brightness

This will help us to create a brightness controller in andriod.

1. Create a Layout with seekbar
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">


    <Button android:text="Show Brightness Panel" android:id="@+id/Button01"
        android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>


    <LinearLayout android:id="@+id/panel" android:orientation="vertical"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:layout_alignParentBottom="true" android:paddingTop="10dip"
        android:paddingBottom="30dip" android:paddingLeft="20dip"
        android:paddingRight="20dip" android:gravity="center_horizontal"
        android:visibility="gone">

        <TextView android:text="Brightness Level"
            android:layout_width="fill_parent" android:layout_height="wrap_content"
            android:gravity="center" android:textAppearance="?android:attr/textAppearanceLarge" />

        <SeekBar android:id="@+id/seek" android:layout_width="fill_parent"
            android:layout_height="wrap_content" android:max="100"
            android:progress="100" />

    </LinearLayout>

</LinearLayout>

2. Create an activity to control the brightness
public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    private static final String BRIGHTNESS_PREFERENCE_KEY = "brightness";
    private View brightnessPanel;
    private SeekBar brightnessControl;
    private int brightness = 50;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        brightnessPanel = findViewById(R.id.panel);
        brightnessControl = (SeekBar) findViewById(R.id.seek);

        Button btn = (Button) findViewById(R.id.Button01);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showBrightnessPanel();

            }
        });

        brightnessControl
                .setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
                    public void onProgressChanged(SeekBar seekBar,
                            int progress, boolean fromUser) {
                        setBrightness(progress);
                    }

                    public void onStartTrackingTouch(SeekBar seekBar) {
                    }

                    public void onStopTrackingTouch(SeekBar seekBar) {
                        hideBrightnessPanel();
                    }
                });
    }

    private void showBrightnessPanel() {
        Animation animation = AnimationUtils.loadAnimation(this,
                android.R.anim.slide_in_left);
        brightnessControl.setProgress(this.brightness);
        brightnessPanel.setVisibility(View.VISIBLE);
        brightnessPanel.startAnimation(animation);
    }

    private void setBrightness(int value) {
        if (value < 10) {
            value = 10;
        } else if (value > 100) {
            value = 100;
        }
        brightness = value;
        WindowManager.LayoutParams lp = getWindow().getAttributes();
        lp.screenBrightness = (float) value / 100;       
        lp.flags |= WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
        getWindow().setAttributes(lp);
    }

    private void hideBrightnessPanel() {
        Animation animation = AnimationUtils.loadAnimation(MainActivity.this,
                android.R.anim.slide_out_right);
        brightnessPanel.startAnimation(animation);
        brightnessPanel.setVisibility(View.GONE);
        PreferenceManager.getDefaultSharedPreferences(this).edit().putInt(
                BRIGHTNESS_PREFERENCE_KEY, brightnessControl.getProgress())
                .commit();
    }

}