ColorAnimationView 实现了滑动Viewpager 时背景色动态变化的过渡效果

用法在注释中：

import android.animation.Animator;import android.animation.ArgbEvaluator;import android.animation.ObjectAnimator;import android.animation.ValueAnimator;import android.content.Context;import android.support.v4.view.ViewPager;import android.util.AttributeSet;import android.view.View;/* * ColorAnimationView 实现了滑动 Viewpager 的时候背景色动态变化的过渡效果 *  * ColorAnimationView colorAnimationView = (ColorAnimationView) findViewById(R.id.ColorAnimationView);ViewPager viewPager = (ViewPager) findViewById(R.id.viewPager);viewPager.setAdapter(adpter);colorAnimationView.setmViewPager(viewPager, resource.length);        colorAnimationView.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {            @Override            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {                Log.e("TAG","onPageScrolled");            }            @Override            public void onPageSelected(int position) {                Log.e("TAG","onPageSelected");            }            @Override            public void onPageScrollStateChanged(int state) {                Log.e("TAG","onPageScrollStateChanged");            }        });                    <FrameLayout 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="cn.taurusxi.guidebackgroundcoloranimation.sample.SampleActivity">    <com.*.ColorAnimationView        android:id="@+id/ColorAnimationView"        android:layout_width="match_parent"        android:layout_height="match_parent"/>    <android.support.v4.view.ViewPager        android:id="@+id/viewPager"        android:padding="30dp"        android:layout_width="match_parent"        android:layout_height="match_parent"/></FrameLayout> * @author Administrator * */public class ColorAnimationView extends Viewimplements ValueAnimator.AnimatorUpdateListener, Animator.AnimatorListener {private static final int RED = 0xffFF8080;private static final int BLUE = 0xff8080FF;private static final int WHITE = 0xffffffff;private static final int GREEN = 0xff80ff80;private static final int DURATION = 3000;ValueAnimator colorAnim = null;private PageChangeListener mPageChangeListener;ViewPager.OnPageChangeListener onPageChangeListener;public void setOnPageChangeListener(ViewPager.OnPageChangeListener onPageChangeListener) {this.onPageChangeListener = onPageChangeListener;}/** * 这是你唯一需要关心的方法 * @param mViewPager  你必须在设置 Viewpager 的 Adapter 这后，才能调用这个方法。 * @param count   ,viewpager孩子的数量 * @param colors int... colors ，你需要设置的颜色变化值~~ 如何你传人 空，那么触发默认设置的颜色动画 * *//** * This is the only method you need care about. * @param mViewPager  ,you need set the adpater before you call this. * @param count   ,this param set the count of the viewpaper's child * @param colors ,this param set the change color use (int... colors), *               so,you could set any length if you want.And by default. *               if you set nothing , don't worry i have already creat *               a default good change color! * */public void setmViewPager(ViewPager mViewPager, int count, int... colors) {//this.mViewPager = mViewPager;if (mViewPager.getAdapter() == null) {throw new IllegalStateException("ViewPager does not have adapter instance.");}mPageChangeListener.setViewPagerChildCount(count);mViewPager.setOnPageChangeListener(mPageChangeListener);if (colors.length == 0) {createDefaultAnimation();} else {createAnimation(colors);}}public ColorAnimationView(Context context) {this(context, null, 0);}public ColorAnimationView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public ColorAnimationView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);mPageChangeListener = new PageChangeListener();}private void seek(long seekTime) {if (colorAnim == null) {createDefaultAnimation();}colorAnim.setCurrentPlayTime(seekTime);}private void createAnimation(int... colors) {if (colorAnim == null) {colorAnim = ObjectAnimator.ofInt(this,"backgroundColor", colors);colorAnim.setEvaluator(new ArgbEvaluator());colorAnim.setDuration(DURATION);colorAnim.addUpdateListener(this);}}private void createDefaultAnimation() {colorAnim = ObjectAnimator.ofInt(this,"backgroundColor", WHITE, RED, BLUE, GREEN, WHITE);colorAnim.setEvaluator(new ArgbEvaluator());colorAnim.setDuration(DURATION);colorAnim.addUpdateListener(this);}@Override public void onAnimationStart(Animator animation) {}@Override public void onAnimationEnd(Animator animation) {}@Override public void onAnimationCancel(Animator animation) {}@Override public void onAnimationRepeat(Animator animation) {}@Override public void onAnimationUpdate(ValueAnimator animation) {invalidate();//long playtime = colorAnim.getCurrentPlayTime();}private class PageChangeListenerimplements ViewPager.OnPageChangeListener {private int viewPagerChildCount;public void setViewPagerChildCount(int viewPagerChildCount) {this.viewPagerChildCount = viewPagerChildCount;}public int getViewPagerChildCount() {return viewPagerChildCount;}@Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {int count = getViewPagerChildCount() - 1;if (count != 0) {float length = (position + positionOffset) / count;int progress = (int) (length * DURATION);ColorAnimationView.this.seek(progress);}// call the method by default            if (onPageChangeListener!=null){                onPageChangeListener.onPageScrolled(position,positionOffset,positionOffsetPixels);            }}@Override public void onPageSelected(int position) {            if (onPageChangeListener!=null) {                onPageChangeListener.onPageSelected(position);            }}@Override public void onPageScrollStateChanged(int state) {            if (onPageChangeListener!=null) {                onPageChangeListener.onPageScrollStateChanged(state);            }}}}