千变万化的ViewPager切换动画（2）

（1）创建项目Viewpager_anim_myself 都采用默认的方式，添加三张图片资源文件，，src-包目录下创建MyViewPagerTransformerAnim.java类

布局文件activity_main.xml如下：

编辑MainActivity.java

package com.lc.viewpager_anim;import java.util.ArrayList;import java.util.List;import android.os.Bundle;import android.app.Activity;import android.support.v4.view.PagerAdapter;import android.view.View;import android.view.ViewGroup;import android.view.Window;import android.widget.ImageView;import android.widget.ImageView.ScaleType;public class MainActivity extends Activity {MyViewPagerTransformerAnim myViewPagerTransformerAnim;private int[] mImgIds = new int[] { R.drawable.guide_image1,R.drawable.guide_image2, R.drawable.guide_image3 };private List<ImageView> mImages = new ArrayList<ImageView>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);requestWindowFeature(Window.FEATURE_NO_TITLE);setContentView(R.layout.activity_main);myViewPagerTransformerAnim = (MyViewPagerTransformerAnim) findViewById(R.id.id_viewpager);// 添加适配器myViewPagerTransformerAnim.setAdapter(new PagerAdapter() {/*** 初始化代码*/@Overridepublic Object instantiateItem(ViewGroup container, int position) {ImageView imageView = new ImageView(MainActivity.this);imageView.setImageResource(mImgIds[position]);imageView.setScaleType(ScaleType.CENTER_CROP);// 设置图片的形状防止变形container.addView(imageView);mImages.add(imageView);// 初始化myViewPagerTransformerAnim.setViewForPosition(imageView,position);return imageView;}@Overridepublic void destroyItem(ViewGroup container, int position,Object object) {container.removeView(mImages.get(position));myViewPagerTransformerAnim.removeViewFromPosition(position); // remove}@Overridepublic boolean isViewFromObject(View view, Object object) {return view == object;}@Overridepublic int getCount() {return mImgIds.length;}});}}其中自定义的view如下所示：MyViewPagerTransformerAnim.java

package com.lc.viewpager_anim;import java.util.HashMap;import java.util.Map;import com.nineoldandroids.view.ViewHelper;import android.R.integer;import android.content.Context;import android.support.v4.view.ViewPager;import android.util.AttributeSet;import android.util.Log;import android.view.View;/* * 自定义viewpager实现动画切换效果： * * 1、需要拿到当前切换的两个view * * 2、一个动画的梯度值 */public class MyViewPagerTransformerAnim extends ViewPager {private View mLeft;private View mRight;private float mTrans;private float mScale;private static final float MIN_SCALE = 0.6f;private Map<Integer, View> mChildren = new HashMap<Integer, View>();/* * 要有两个构造方法 */public MyViewPagerTransformerAnim(Context context, AttributeSet attrs) {super(context, attrs);}public MyViewPagerTransformerAnim(Context context) {super(context);}/* * 设置put的方法 */public void setViewForPosition(View view, int position) {mChildren.put(position, view);}/* * remove的方法 */public void removeViewFromPosition(Integer position) {mChildren.remove(position);}/** * 重写的方法 */@Overrideprotected void onPageScrolled(int position, float offset, int offsetPixels) {// Log.e("TAG", "position =" + position + ",offset = " + offset);mLeft = mChildren.get(position);mRight = mChildren.get(position + 1);animStack(mLeft, mRight, offset, offsetPixels);// 创建动画效果super.onPageScrolled(position, offset, offsetPixels);}private void animStack(View left, View right, float offset, int offsetPixels) {if (right != null) {// 从0-1页，offset:0`1mScale = (1 – MIN_SCALE) * offset + MIN_SCALE;mTrans = -getWidth() – getPageMargin() + offsetPixels;ViewHelper.setScaleX(right, mScale);ViewHelper.setScaleY(right, mScale);ViewHelper.setTranslationX(right, mTrans);}if (left != null) {left.bringToFront();}}}完整项目代码如下：

最大的成功在于最大的付出。

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