RotateDownPageTransformer.java

package com.mgw.member.ui.widget.transformer;

import com.nineoldandroids.view.ViewHelper;

import android.annotation.SuppressLint;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.View;
/**
 * http://blog.csdn.net/lmj623565791/article/details/40411921
 * @author zhy
 *
 */
public class RotateDownPageTransformer implements ViewPager.PageTransformer
{
	private static final float MIN_SCALE = 0.85f;
	private static final float MIN_ALPHA = 0.5f;
	private static final float ROT_MAX = 20.0f;
	private float mRot;
	private float mTrans;

	@SuppressLint("NewApi")
	public void transformPage(View view, float position)
	{

		Log.e("TAG", view + " , " + position + "");

		if (position < -1)
		{ // [-Infinity,-1)
			// This page is way off-screen to the left.
			ViewHelper.setRotation(view, 0);

		} else if (position <= 1) // a页滑动至b页 ； a页从 0.0 ~ -1 ；b页从1 ~ 0.0
		{ // [-1,1]
			// Modify the default slide transition to shrink the page as well
			if (position < 0)
			{

				mRot = (ROT_MAX * position);
				ViewHelper.setPivotX(view, view.getMeasuredWidth() * 0.5f);
				ViewHelper.setPivotY(view, view.getMeasuredHeight());
				ViewHelper.setRotation(view, mRot);
			} else
			{

				mRot = (ROT_MAX * position);
				ViewHelper.setPivotX(view, view.getMeasuredWidth() * 0.5f);
				ViewHelper.setPivotY(view, view.getMeasuredHeight());
				ViewHelper.setRotation(view, mRot);
			}

			// Scale the page down (between MIN_SCALE and 1)

			// Fade the page relative to its size.

		} else
		{ // (1,+Infinity]
			// This page is way off-screen to the right.
			ViewHelper.setRotation(view, 0);
		}
	}
}