ViewPager

效果：

image.png

布局中viewPager必须设置android:clipChildren="false",同时它的父控件也必须设置，且viewpager需要设置与左边及右边的间隔:android:layout_marginLeft、android:layout_marginRight
·布局如下：

java中
设置缩放及透明效果主要在ScaleTransformer中，其中Viewpager需要设置page的间隔及预加载页数

@Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.ui_pager);        ViewPager pager = (ViewPager) findViewById(R.id.viewpager);        pager.setPageMargin(8);        pager.setOffscreenPageLimit(5);        pager.setPageTransformer(false,new ScaleTransformer());        pager.setAdapter(new MyAdapter(pager));    }     class MyAdapter extends PagerAdapter{         ViewPager mViewPager;         public MyAdapter(ViewPager viewPager){            mViewPager = viewPager;         }        @Override        public int getCount() {            return 5;        }        @Override        public boolean isViewFromObject(View view, Object object) {            return view==object;        }        @Override        public Object instantiateItem(ViewGroup container, final int position) {            ImageView imageView = new ImageView(PagerActivity.this);            imageView.setImageResource(R.drawable.a);            imageView.setOnClickListener(new View.OnClickListener() {                @Override                public void onClick(View view) {                    mViewPager.setCurrentItem(position);                    Toast.makeText(PagerActivity.this,"position:"+position,Toast.LENGTH_SHORT).show();                }            });            container.addView(imageView);            return imageView;        }         @Override         public void destroyItem(ViewGroup container, int position, Object object) {             container.removeView((View) object);         }     }

public class ScaleTransformer extends AlphaTransformer{    private float MIN_ALPHA = 0.5f;    private float MIN_SCALE = 0.70f;    /**     * position取值特点：     * 假设页面从0～1，则：     * 第一个页面position变化为[0,-1]     * 第二个页面position变化为[1,0]     */    @Override    public void transformPage(View page, float position) {        //缩放效果        if (position < -1 || position > 1) {            page.setAlpha(MIN_ALPHA);            page.setScaleX(MIN_SCALE);            page.setScaleY(MIN_SCALE);        } else if (position <= 1) { // [-1,1]            float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));            if (position < 0) {                float scaleX = 1 + 0.3f * position;                page.setScaleX(scaleX);                page.setScaleY(scaleX);            } else {                float scaleX = 1 - 0.3f * position;                page.setScaleX(scaleX);                page.setScaleY(scaleX);            }            page.setAlpha(MIN_ALPHA + (scaleFactor - MIN_SCALE) / (1 - MIN_SCALE) * (1 - MIN_ALPHA));        }    }}

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