将子视图对齐ViewPager android的中心

Question

我需要将子视图设置为ViewPager的中心,并且我还要向当前视图边显示下一个和上一个视图的某些部分(如1下的当前屏幕).但目前当前视图从ViewPager的左侧开始(如预期的屏幕低于2).我怎样才能做到这一点？

这是我的代码..

MyViewPagerAdapter

public class MyViewPagerAdapter extends PagerAdapter {
    private Activity mActivity;
    private int mPageCount;
    public MyViewPagerAdapter(Activity activity,int pageCount) {
        mActivity = activity;
        mPageCount = pageCount;
    }

    @Override
    public int getCount() {
        return mPageCount;
    }

    @Override
    public boolean isViewFromObject(View view, Object obj) {
        return (view ==(View)obj);
    }

    @Override
    public Object instantiateItem(ViewGroup container,final int position) {
        ViewGroup viewGroup = (ViewGroup)mActivity.getLayoutInflater().inflate(
                R.layout.item_view, null);

        viewGroup.setBackgroundColor(randomColor());

        TextView textView = (TextView)viewGroup.findViewById(R.id.textView1);
        textView.setText("Page: "+(position+1));
        Button button = (Button) viewGroup.findViewById(R.id.button1);
        button.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Toast.makeText(mActivity, "Hey, Its clicked!!! at page "+(position+1), Toast.LENGTH_LONG).show();
            }
        });
        container.addView(viewGroup);
        return viewGroup;
    }

    Random rnd = new Random();
    private int randomColor(){
        return Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
    }

    @Override
    public void destroyItem(ViewGroup collection, int position, Object view) {
        //must be overridden else throws exception as not overridden.
        Log.d("Tag", collection.getChildCount()+"");
        collection.removeView((View) view);
    }

    @Override
    public float getPageWidth(int position) {
        return 0.8f;
    }
}

主要活动

public class MainActivity extends Activity {
    private ViewPager viewPager;
    LinearLayout linearLayout;
    private int ID = 100; 

    private final int count = 8;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        viewPager = (ViewPager) findViewById(R.id.viewPager);
        linearLayout  = (LinearLayout) findViewById(R.id.indicator_layout);
        generateIndicators(count);


        MyViewPagerAdapter adapter = new MyViewPagerAdapter(this, count);
        viewPager.setAdapter(adapter);
        viewPager.setOnPageChangeListener(new OnPageChangeListener() {
            int oldPosition = 0;
            @Override
            public void onPageSelected(int position) {
                //this changes the old position's view state image
                ((TextView)linearLayout.getChildAt(oldPosition)).setText("");
                oldPosition = position;


                //this changes the current position's view state image
                ((TextView)linearLayout.getChildAt(position)).setText((position+1)+"");

            }
            //this method will be called repeatedly upto another item comes as front one(active one)
            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {


            }
            //this will be called as per scroll state
            @Override
            public void onPageScrollStateChanged(int arg0) {


            }
        });

        viewPager.setOffscreenPageLimit(4);

    }

    private void generateIndicators(int count) {
        /// Converts 14 dip into its equivalent px
        int padd = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 3, getResources().getDisplayMetrics());

        for(int i=0;i<count;i++){
            TextView textView = new TextView(this);
            textView.setId(ID+i);
            final int currentItem = i;
            textView.setBackgroundResource(R.drawable.white_cell);
            textView.setPadding(padd,padd,padd,padd);
            /// Converts 14 dip into its equivalent px
            int size = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 10, getResources().getDisplayMetrics());
            textView.setTextSize(size);
            textView.setGravity(Gravity.CENTER);
            /// Converts 14 dip into its equivalent px
            int px = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 30, getResources().getDisplayMetrics());

            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(px, px);
            linearLayout.addView(textView,params);
        }

        ((TextView)linearLayout.getChildAt(0)).setText("1");

    }





}

activity_main.xml中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >



   <android.support.v4.view.ViewPager
       android:id="@+id/viewPager"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent"
       android:layout_alignParentLeft="true"
       android:layout_alignParentTop="true" >
   </android.support.v4.view.ViewPager>


   <LinearLayout
       android:id="@+id/indicator_layout"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_alignParentBottom="true"
       android:layout_centerHorizontal="true"
       android:layout_marginBottom="19dp" >
   </LinearLayout>

</RelativeLayout>

item_view.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="100dp"
    android:layout_height="match_parent"
    android:id="@+id/root_view"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="Text"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="click me" />

</LinearLayout>

当前屏幕

预期的屏幕

Answer 1

对于一个应用程序,我使用以下方式实现类似,标准ViewPager:

• 使内部布局中的实际内容全屏显示页面.例如,将全屏布局设为RelativeLayout透明背景,将实际内容设为另一个RelativeLayout居中于父级.如果我没记错的话,原因就在于只有内部布局作为页面,在ViewPagerGalaxy Nexus等设备上不会占用所有屏幕宽度.

• 使用ViewPager.setPageMargin()设置你要多少下一/上一页的显示负页边距即.确保它仅与父全屏布局的透明区域重叠.

• 调用ViewPager.setOffscreenPageLimit()屏幕外页面计数至少2从默认值调整到通过在屏幕外1真正创建页面来确保平滑分页.否则,您将看到在屏幕上已部分显示的同时绘制的下一页/上一页.

Answer 2

对于任何不满意的人来说,OP没有用解决方案更新他的问题,这是一个链接,用最简单的努力解释如何在XML中解决这个问题:http://blog.neteril.org/blog/2013/10/ 14 /机器人尖-viewpager-与突出子女/

基本上当你用XML声明你的viewpager时,给它相同的左右填充并设置android:clipToPadding ="false".(他的xml示例中缺少clipToPadding,这是实现此效果所必需的)

Answer 3

最后,我在GitHub中添加了我的解决方案.我已经做了一些很好的技巧来获得解决方案.您可以从以下链接获取项目(实际上我已经计划创建一个带有解释的博客,但我有很多时间可以做).

这是链接(https://github.com/noundla/Sunny_Projects/tree/master/CenterLockViewPager)

您必须将文件从com.noundla.centerviewpagersample.comps包中复制到项目中.您可以在MainActivity课堂上看到该Viewpager的用法.

如果有人有问题,请告诉我.