android使用viewpager計算偏移量實現(xiàn)選項卡功能

更新時間：2018年12月21日 10:20:29 作者：cf8833

這篇文章主要為大家詳細介紹了android使用viewpager計算偏移量實現(xiàn)選項卡功能，具有一定的參考價值，感興趣的小伙伴們可以參考一下

本文實例為大家分享了android實現(xiàn)選項卡功能，通過計算偏移量，設置tetxview和imageView的對應值，一些color的值讀者自己去補充

實現(xiàn)效果圖：

（1）簡單寫一個主界面的布局activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:clipToPadding="true"
 android:fitsSystemWindows="true"
 android:background="@color/bg_color">

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:background="@color/bag_gray"
 android:orientation="vertical">

 <LinearLayout
  android:layout_width="match_parent"
  android:layout_height="36dp"
  android:background="@android:color/white"
  android:orientation="horizontal"
  android:weightSum="3">

  <TextView
  android:id="@+id/tab1_tv"
  android:layout_width="0dp"
  android:layout_height="wrap_content"
  android:layout_gravity="center"
  android:layout_weight="1"
  android:gravity="center"
  android:text="商品"
  android:textColor="@color/title_bag"
  android:textSize="18sp" />

  <TextView
  android:id="@+id/tab2_tv"
  android:layout_width="0dp"
  android:layout_height="wrap_content"
  android:layout_gravity="center"
  android:layout_weight="1"
  android:gravity="center"
  android:text="評價"
  android:textColor="@color/text_color_context"
  android:textSize="18sp" />
  <TextView
  android:id="@+id/tab3_tv"
  android:layout_width="0dp"
  android:layout_height="wrap_content"
  android:layout_gravity="center"
  android:layout_weight="1"
  android:gravity="center"
  android:text="詳情"
  android:textColor="@color/text_color_context"
  android:textSize="18sp" />

 </LinearLayout>

 <View
  android:layout_width="match_parent"
  android:layout_height="0.5dp"
  android:background="@color/text_color_context" />
 <View
  android:id="@+id/cursor"
  android:layout_width="50dp"
  android:layout_height="2dp"
  android:layout_marginLeft="40dp"
  android:layout_marginTop="0dip"
  android:background="@color/title_bag"
  />
 <android.support.v4.view.ViewPager
  android:id="@+id/thire_vp"
  android:layout_width="match_parent"
  android:layout_height="match_parent"/>
 </LinearLayout>

</LinearLayout>

（2）設置viewpager的適配器：FragmentAdapter

public class FragmentAdapter extends FragmentPagerAdapter {
 private ArrayList<Fragment> list;
 FragmentManager fm;

 public FragmentAdapter(FragmentManager fm, ArrayList<Fragment> 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）然后設置三個fragment，因為有三個選項卡，所以我們新建三個fragment，分別是OneFragment、TwoFragment 、ThreeFragment ，布局的話也需要新建三個，跟fragment一一對應，因為布局過于簡單，這里就不寫了，簡單寫一點fragment的代碼吧

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，設置fragment的適配器，設置顯示內(nèi)容，并且做viewpager的事件監(jiān)聽

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<Fragment> 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);

 //綁定控件
 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);

 //獲取屏幕寬度
 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;
 }
 }
}

以上就是本文的全部內(nèi)容，希望對大家的學習有所幫助，也希望大家多多支持腳本之家。

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