TAB带地线滑动效果(类似QQ)

主界面：

public class MainActivity extends FragmentActivity {
    private static final String TAG = "MainActivity";
    private ViewPager mPager;
    private ArrayList<Fragment> fragmentsList;
    private ImageView ivBottomLine;
    private TextView tvTabActivity, tvTabGroups, tvTabFriends, tvTabChat;

    private int currIndex = 0;
    private int bottomLineWidth;
    private int offset = 0;
    private int position_one;
    private int position_two;
    private int position_three;
    private Resources resources;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.main);
        resources = getResources();
        InitWidth();
        InitTextView();
        InitViewPager();
    }

    private void InitTextView() {
        tvTabActivity = (TextView) findViewById(R.id.tv_tab_activity);
        tvTabGroups = (TextView) findViewById(R.id.tv_tab_groups);
        tvTabFriends = (TextView) findViewById(R.id.tv_tab_friends);
        tvTabChat = (TextView) findViewById(R.id.tv_tab_chat);

        tvTabActivity.setOnClickListener(new MyOnClickListener(0));
        tvTabGroups.setOnClickListener(new MyOnClickListener(1));
        tvTabFriends.setOnClickListener(new MyOnClickListener(2));
        tvTabChat.setOnClickListener(new MyOnClickListener(3));
    }

    private void InitViewPager() {
        mPager = (ViewPager) findViewById(R.id.vPager);
        fragmentsList = new ArrayList<Fragment>();
        LayoutInflater mInflater = getLayoutInflater();
        View activityView = mInflater.inflate(R.layout.lay1, null);

        Fragment activityfragment = TestFragment.newInstance("Hello Activity.");
        Fragment groupFragment = TestFragment.newInstance("Hello Group.");
        Fragment friendsFragment=TestFragment.newInstance("Hello Friends.");
        Fragment chatFragment=TestFragment.newInstance("Hello Chat.");

        fragmentsList.add(activityfragment);
        fragmentsList.add(groupFragment);
        fragmentsList.add(friendsFragment);
        fragmentsList.add(chatFragment);
        
        mPager.setAdapter(new MyFragmentPagerAdapter(getSupportFragmentManager(), fragmentsList));
        mPager.setCurrentItem(0);
        mPager.setOnPageChangeListener(new MyOnPageChangeListener());
    }

    private void InitWidth() {
        ivBottomLine = (ImageView) findViewById(R.id.iv_bottom_line);
        bottomLineWidth = ivBottomLine.getLayoutParams().width;
        Log.d(TAG, "cursor imageview width=" + bottomLineWidth);
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        int screenW = dm.widthPixels;
        offset = (int) ((screenW / 4.0 - bottomLineWidth) / 2);
        Log.i("MainActivity", "offset=" + offset);

        position_one = (int) (screenW / 4.0);
        position_two = position_one * 2;
        position_three = position_one * 3;
    }

    public class MyOnClickListener implements View.OnClickListener {
        private int index = 0;

        public MyOnClickListener(int i) {
            index = i;
        }

        @Override
        public void onClick(View v) {
            mPager.setCurrentItem(index);
        }
    };

    public class MyOnPageChangeListener implements OnPageChangeListener {

        @Override
        public void onPageSelected(int arg0) {
            Animation animation = null;
            switch (arg0) {
            case 0:
                if (currIndex == 1) {
                    animation = new TranslateAnimation(position_one, 0, 0, 0);
                    tvTabGroups.setTextColor(resources.getColor(R.color.lightwhite));
                } else if (currIndex == 2) {
                    animation = new TranslateAnimation(position_two, 0, 0, 0);
                    tvTabFriends.setTextColor(resources.getColor(R.color.lightwhite));
                } else if (currIndex == 3) {
                    animation = new TranslateAnimation(position_three, 0, 0, 0);
                    tvTabChat.setTextColor(resources.getColor(R.color.lightwhite));
                }
                tvTabActivity.setTextColor(resources.getColor(R.color.white));
                break;
            case 1:
                if (currIndex == 0) {
                    animation = new TranslateAnimation(offset, position_one, 0, 0);
                    tvTabActivity.setTextColor(resources.getColor(R.color.lightwhite));
                } else if (currIndex == 2) {
                    animation = new TranslateAnimation(position_two, position_one, 0, 0);
                    tvTabFriends.setTextColor(resources.getColor(R.color.lightwhite));
                } else if (currIndex == 3) {
                    animation = new TranslateAnimation(position_three, position_one, 0, 0);
                    tvTabChat.setTextColor(resources.getColor(R.color.lightwhite));
                }
                tvTabGroups.setTextColor(resources.getColor(R.color.white));
                break;
            case 2:
                if (currIndex == 0) {
                    animation = new TranslateAnimation(offset, position_two, 0, 0);
                    tvTabActivity.setTextColor(resources.getColor(R.color.lightwhite));
                } else if (currIndex == 1) {
                    animation = new TranslateAnimation(position_one, position_two, 0, 0);
                    tvTabGroups.setTextColor(resources.getColor(R.color.lightwhite));
                } else if (currIndex == 3) {
                    animation = new TranslateAnimation(position_three, position_two, 0, 0);
                    tvTabChat.setTextColor(resources.getColor(R.color.lightwhite));
                }
                tvTabFriends.setTextColor(resources.getColor(R.color.white));
                break;
            case 3:
                if (currIndex == 0) {
                    animation = new TranslateAnimation(offset, position_three, 0, 0);
                    tvTabActivity.setTextColor(resources.getColor(R.color.lightwhite));
                } else if (currIndex == 1) {
                    animation = new TranslateAnimation(position_one, position_three, 0, 0);
                    tvTabGroups.setTextColor(resources.getColor(R.color.lightwhite));
                } else if (currIndex == 2) {
                    animation = new TranslateAnimation(position_two, position_three, 0, 0);
                    tvTabFriends.setTextColor(resources.getColor(R.color.lightwhite));
                }
                tvTabChat.setTextColor(resources.getColor(R.color.white));
                break;
            }
            currIndex = arg0;
            animation.setFillAfter(true);
            animation.setDuration(300);
            ivBottomLine.startAnimation(animation);
        }

        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {
        }

        @Override
        public void onPageScrollStateChanged(int arg0) {
        }
    }
}

FragmentPagerAdapter：

public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
    private ArrayList<Fragment> fragmentsList;

    public MyFragmentPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    public MyFragmentPagerAdapter(FragmentManager fm, ArrayList<Fragment> fragments) {
        super(fm);
        this.fragmentsList = fragments;
    }

    @Override
    public int getCount() {
        return fragmentsList.size();
    }

    @Override
    public Fragment getItem(int arg0) {
        return fragmentsList.get(arg0);
    }

    @Override
    public int getItemPosition(Object object) {
        return super.getItemPosition(object);
    }

}