android brightness control

package com.smarttpapers.reader.dialog;

import android.app.Activity;
import android.app.Dialog;
import android.content.ContentResolver;
import android.content.Context;
import android.net.Uri;
import android.provider.Settings;
import android.provider.Settings.SettingNotFoundException;
import android.view.WindowManager;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;

import com.smarttpapers.reader.R;

public class DialogBrightness extends Dialog{

    private int brightnessValue;
    private boolean isAuto;
    public DialogBrightness(final Context context, int theme) {
        super(context, theme);
        setContentView(R.layout.popup_brightness);
        setTitle("Brightness");
        setCanceledOnTouchOutside(true);
        final SeekBar brightness = (SeekBar)findViewById(R.id.page_bightness);
        int nowBrightnessValue = 0;
        final ContentResolver resolver = ((Activity)context).getContentResolver();
        try {
            nowBrightnessValue = android.provider.Settings.System.getInt(
                    resolver, Settings.System.SCREEN_BRIGHTNESS);
        } catch (Exception e) {
            e.printStackTrace();
        }
        brightness.setProgress(nowBrightnessValue);
        isAuto=isAutoBrightness(resolver);
        if(isAuto){
            stopAutoBrightness((Activity)context);
        }
        brightness.setOnSeekBarChangeListener(
                new OnSeekBarChangeListener() {
            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                saveBrightness(resolver, brightnessValue);
            }
            
            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {}
            
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress,
                    boolean fromUser) {
                brightnessValue=progress+10;
                setBrightness((Activity)context, brightnessValue);
            }
        });
    }
    public boolean isAutoBrightness(ContentResolver aContentResolver) {
        boolean automicBrightness = false;
        try {
            automicBrightness = Settings.System.getInt(aContentResolver,
                    Settings.System.SCREEN_BRIGHTNESS_MODE) == Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC;
        } catch (SettingNotFoundException e) {
            e.printStackTrace();
        }
        return automicBrightness;
    }
     public void setBrightness(Activity activity, int bright) {
            WindowManager.LayoutParams lp = activity.getWindow().getAttributes();
            lp.screenBrightness = Float.valueOf(bright) * (1f / 255f);
            activity.getWindow().setAttributes(lp);
        }
    public void startAutoBrightness(Activity activity) {
        Settings.System.putInt(activity.getContentResolver(),
                Settings.System.SCREEN_BRIGHTNESS_MODE,
                Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC);
    }
    public void stopAutoBrightness(Activity activity) {
        Settings.System.putInt(activity.getContentResolver(),
                Settings.System.SCREEN_BRIGHTNESS_MODE,
                Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);
    }
    public void saveBrightness(ContentResolver resolver, int bright) {
        Uri uri = android.provider.Settings.System
                .getUriFor("screen_brightness");
        android.provider.Settings.System.putInt(resolver, "screen_brightness",
                bright);
        resolver.notifyChange(uri, null);
    }
}