android使用viewpager计算偏移量实现选项卡功能
这篇文章主要为大家详细介绍了android使用viewpager计算偏移量实现选项卡功能，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
本文实例为大家分享了android实现选项卡功能，通过计算偏移量，设置tetxview和imageView的对应值，一些color的值读者自己去补充
实现效果图：
（1）简单写一个主界面的布局activity_main.xml
（2）设置viewpager的适配器：FragmentAdapter
public class FragmentAdapter extends FragmentPagerAdapter { private ArrayList list; FragmentManager fm; public FragmentAdapter(FragmentManager fm, ArrayList list){ super(fm); this.fm = fm; this.list = list; } @Override public Fragment getItem(int position) { return list.get(position); } @Override public int getCount() { return list.size(); } } （3）然后设置三个fragment，因为有三个选项卡，所以我们新建三个fragment，分别是OneFragment、TwoFragment 、ThreeFragment ，布局的话也需要新建三个，跟fragment一一对应，因为布局过于简单，这里就不写了，简单写一点fragment的代码吧
public class OneFragment extends Fragment { @Nullable @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_one,null); return view; } }（4）在MainActivity中，设置fragment的适配器，设置显示内容，并且做viewpager的事件监听
public class MainActivity extends FragmentActivity implements ViewPager.OnPageChangeListener,View.OnClickListener{ private TextView tab1Tv; private TextView tab2Tv; private TextView tab3Tv; private View cursor; private ViewPager thirdVp; private ArrayList fragmentlist; private int offset = 0; private int screenWidth = 0; private int screenl_3; private LinearLayout.LayoutParams lp; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_product); //绑定控件 tab1Tv = (TextView)findViewById(R.id.tab1_tv); tab2Tv = (TextView)findViewById(R.id.tab2_tv); tab3Tv = (TextView)findViewById(R.id.tab3_tv); cursor = (View) findViewById(R.id.cursor); thirdVp = (ViewPager) findViewById(R.id.thire_vp); //获取屏幕宽度 DisplayMetrics dm = new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(dm); screenWidth = dm.widthPixels; screenl_3 = screenWidth/3; //裁剪3分之1 lp = (LinearLayout.LayoutParams)cursor.getLayoutParams(); fragmentlist = new ArrayList<>(); fragmentlist.add(new OneFragment()); fragmentlist.add(new TwoFragment()); fragmentlist.add(new ThreeFragment()); thirdVp.setAdapter(new FragmentAdapter(getSupportFragmentManager(),fragmentlist)); thirdVp.setCurrentItem(0); thirdVp.setOffscreenPageLimit(2); thirdVp.setOnPageChangeListener(this); tab1Tv.setOnClickListener(this); tab2Tv.setOnClickListener(this); tab3Tv.setOnClickListener(this); } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { offset = (screenl_3-cursor.getLayoutParams().width)/2; Log.d("TAG", "111----"+position + "--" + positionOffset + "--" + positionOffsetPixels); final float scale = getResources().getDisplayMetrics().density; if (position == 0){ lp.leftMargin = (int)(positionOffsetPixels/3)+offset; }else if(position ==1){ lp.leftMargin = (int)(positionOffsetPixels/3)+screenl_3+offset; } cursor.setLayoutParams(lp); upTextcolor(position); } private void upTextcolor(int position){ if (position==0){ tab1Tv.setTextColor(getResources().getColor(R.color.title_bag)); tab2Tv.setTextColor(getResources().getColor(R.color.text_color_context)); tab3Tv.setTextColor(getResources().getColor(R.color.text_color_context)); }else if(position==1){ tab1Tv.setTextColor(getResources().getColor(R.color.text_color_context)); tab2Tv.setTextColor(getResources().getColor(R.color.title_bag)); tab3Tv.setTextColor(getResources().getColor(R.color.text_color_context)); }else if(position==2){ tab1Tv.setTextColor(getResources().getColor(R.color.text_color_context)); tab2Tv.setTextColor(getResources().getColor(R.color.text_color_context)); tab3Tv.setTextColor(getResources().getColor(R.color.title_bag)); } } @Override public void onPageSelected(int position) { } @Override public void onPageScrollStateChanged(int state) { } @Override public void onClick(View view) { switch (view.getId()) { case R.id.tab1_tv: thirdVp.setCurrentItem(0); break; case R.id.tab2_tv: thirdVp.setCurrentItem(1); break; case R.id.tab3_tv: thirdVp.setCurrentItem(2); break; } } }
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