android viewpager实现竖屏滑动效果

public class VerticalViewPager extends ViewPager {  private OnItemClickListener mOnItemClickListener;  public VerticalViewPager(Context context) {    super(context);    init();  }  public VerticalViewPager(Context context, AttributeSet attrs) {    super(context, attrs);    init();    setup();  }  private void init() {    // The majority of the magic happens here    setPageTransformer(true, new VerticalPageTransformer());    // The easiest way to get rid of the overscroll drawing that happens on the left and right    setOverScrollMode(OVER_SCROLL_NEVER);  }   private MotionEvent swapXY(MotionEvent ev) {    float width = getWidth();    float height = getHeight();    float newX = (ev.getY() / height) * width;    float newY = (ev.getX() / width) * height;    ev.setLocation(newX, newY);    return ev;  }  @Override  public boolean onInterceptTouchEvent(MotionEvent ev){    boolean intercepted = super.onInterceptTouchEvent(swapXY(ev));    swapXY(ev); // return touch coordinates to original reference frame for any child views    return intercepted;  }  private float scaleY ;  @Override  public boolean onTouchEvent(MotionEvent ev) {    System.out.println("----------getY" + ev.getY());    System.out.println("----------scaleY" + scaleY);    if (ev.getAction()==MotionEvent.ACTION_MOVE){    }    if (ev.getAction()==MotionEvent.ACTION_DOWN){      scaleY = ev.getY();    }    if (ev.getAction()==MotionEvent.ACTION_UP){      if (scaleY == ev.getY()){        System.out.println("------------------======");        scaleY= 0;        return false;      }    }    try {      return super.onTouchEvent(swapXY(ev));    }catch (Exception e){    }    return true;  }  public void setOnItemClickListener(OnItemClickListener onItemClickListener) {    mOnItemClickListener = onItemClickListener;  }  public interface OnItemClickListener {    void onItemClick(int position);  }  private void setup() {    final GestureDetector tapGestureDetector = new  GestureDetector(getContext(), new TapGestureListener());    setOnTouchListener(new OnTouchListener() {      @Override      public boolean onTouch(View v, MotionEvent event) {        tapGestureDetector.onTouchEvent(event);        return false;      }    });  }  private class TapGestureListener extends GestureDetector.SimpleOnGestureListener {    @Override    public boolean onSingleTapConfirmed(MotionEvent e) {      if(mOnItemClickListener != null) {        mOnItemClickListener.onItemClick(getCurrentItem());      }      return true;    }  }}

private class VerticalPageTransformer implements ViewPager.PageTransformer {    private float MIN_SCALE = 0.5f;    @Override    public void transformPage(View view, float position) {      if (position < -1) { // [-Infinity,-1)        // This page is way off-screen to the left.        view.setAlpha(0);      }else if (position <= 0) { // [-1,1]        view.setAlpha(1 + position);        view.setTranslationX(-view.getWidth() * position);        view.setPivotY( view.getMeasuredHeight());        view.setPivotX( view.getMeasuredWidth()/2);        view.setTranslationY( position * view.getHeight());        float scaleFactor = MIN_SCALE + (1 - MIN_SCALE)            * (1 - Math.abs(position));        view.setScaleX(scaleFactor);        view.setScaleY(scaleFactor);      }      else if (position <= 1) { // [-1,1]        view.setAlpha(1);        view.setTranslationX(-view.getWidth() * position);        view.setTranslationY( position * view.getHeight());        float scaleFactor = MIN_SCALE + (1 - MIN_SCALE)            * (1 - Math.abs(position));      } else { // (1,+Infinity]        view.setAlpha(0);        view.setTranslationY( position * view.getHeight());      }    }  }