使用ObjectAnimator开发打开、关闭书本动画

动画效果

动画效果-分享链接
（想做成gif图的，尝试各种工具无果）

ObjectAnimator简介及实现思路

　ObjectAnimator是从api level 11 （Android3.0x）增加的类。在11已下版本使用，你可以在工程中引入nineoldandroids包。
　这里直接翻译android文档的内容。
　This subclass of ValueAnimator provides support for animating properties on target objects. The constructors of this class take parameters to define the target object that will be animated as well as the name of the property that will be animated. Appropriate set/get functions are then determined internally and the animation will call these functions as necessary to animate the property.
　它是ValueAnimator的子类，提供对目标对象属性动画的支持。它的构造方法的参数包括要进行动画的目标对象以及进行动画的属性名。相应的set/get方法将在内部确定，必要时将调用它们进行动画。

　比如打开第一张图粉红色位置的书，第二张图是中间过程。
　动画分为三部分，褐色部分为背景（可以为背景设置不同的纯色），黄色部分为封面，灰色部分为加载图标。
　这三部分分别要新建一个ImageView，加入到FrameLayout中，使用WindowManager显示在屏幕上。

背景动画：从A移动到B(translationX, translationY属性)，同时放大（scaleX，scaleY属性）；
封面动画：从A移动到B，同时放大，旋转（rotationY）；
加载图标：在屏幕居中，从0放大到1；

关闭动画属性值与打开动画真好相反。

遇到的问题：

动画轴点（pivotX, pivotY）使用默认的(0, 0)即可；
y方向放大比例大时，x方向需要做平移，使view居中；
背景控件的布局参数不能为wrap_content, 否则，因其使用ColorDrawable作为背景，它将不可见；也不能是match_parent, 否则，它将填充屏幕。所以要为它指定宽、高。

主要代码

BookView.java

package com.example.openbookanimationproj;import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;import com.example.openbookanimationproj.R;
import com.nineoldandroids.animation.Animator;
import com.nineoldandroids.animation.Animator.AnimatorListener;
import com.nineoldandroids.animation.ObjectAnimator;
import com.nineoldandroids.view.ViewHelper;import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.WindowManager;
import android.widget.FrameLayout;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
import android.widget.ListView;
import android.widget.RelativeLayout;/*** A view to show the cover of a book. With method* {@link BookView#startOpenBookAnimation(OpenBookAnimEndListener, ViewParent)} and method* {@link BookView#startCloseBookAnimation()} to play opening and closing book animations.* * @author wenping0820@163.com* @date 2015-07-13*/
public class BookView extends RelativeLayout implements AnimatorListener {public static BookView sOpenedBookView;// Opening book animation durationprivate static final int OPEN_ANIMATION_DURATION = 500;// Closing book animation durationpublic static final int CLOSE_ANIMATION_DURATION = 500;// Animation background scalesprivate float mBgScaleX;private float mBgScaleY;// Animation cover scalesprivate float mCoverScaleX;private float mCoverScaleY;// BookView's location in the screenprivate int[] mLocation = new int[2];private WindowManager mWindowManager;// Parent of animation views(cover, background and loading icon)private FrameLayout mWmRootView;// coverprivate ImageView mCover = null;// Animation coverprivate ImageView mAnimCover;// Animation backgroundprivate ImageView mAnimBackground;// Animation loading iconprivate ImageView mLoadingIcon;// If opening animation has played.private AtomicBoolean mIsOpen = new AtomicBoolean(false);// Listener of opening book animation endingprivate OpenBookAnimEndListener mOpenBookAnimEndListener;// Total animations playedprivate AtomicInteger mAnimationCount = new AtomicInteger(0);// Total opening animations scheduledprivate int mTotalOpenBookAnim;// The parent of BookView(maybe a GridView or ListView or others)private static GridView mGridParent = null;private static ListView mListParent = null;// The opening book animation's end x value.private float mOpenBookEndBgX = 0;// The opening book animation's end x value. It will always be zero.private float mOpenBookEndBgY = 0;private Context mContext;public interface OpenBookAnimEndListener {public void onOpenBookAnimEnd();}public BookView(Context context) {this(context, null);mContext = context;initListener();}public BookView(Context context, AttributeSet attrs) {this(context, attrs, 0);mContext = context;initListener();}public BookView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);mContext = context;mWindowManager = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);initListener();}private void initListener() {setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View arg0) {if (!mIsOpen.get()) {sOpenedBookView = BookView.this;startOpenBookAnimation();}}});}public synchronized void startOpenBookAnimation() {startOpenBookAnimation(null, getParent());}/*** Start opening book animation.* * @param l Listener of opening book animation ending* @param parent*/@SuppressLint("NewApi")public synchronized void startOpenBookAnimation(OpenBookAnimEndListener l, ViewParent parent) {mOpenBookAnimEndListener = l;try {mGridParent = parent != null ? (GridView) parent : null;} catch (ClassCastException e) {mListParent = parent != null ? (ListView) parent : null;}if (!mIsOpen.get()) {mCover = (ImageView) findViewById(R.id.iv_book_cover);if (mCover == null/* || mBackground == null */) {return;}mWmRootView = new FrameLayout(mContext);getLocationInWindow(mLocation);mWindowManager.addView(mWmRootView, getDefaultWindowParams());// new animation viewsmAnimCover = new ImageView(mContext);mAnimCover.setScaleType(mCover.getScaleType());mAnimCover.setImageDrawable(mCover.getDrawable());mAnimBackground = new ImageView(mContext);mAnimBackground.setScaleType(mCover.getScaleType());// backgroundDrawable readPageBgDrawable = new ColorDrawable(mContext.getResources().getColor(R.color.loading_book_bg_color));mAnimBackground.setBackgroundDrawable(readPageBgDrawable);// loading iconmLoadingIcon = new ImageView(mContext);mLoadingIcon.setBackgroundResource(R.drawable.ic_book_loading);mLoadingIcon.setScaleType(ScaleType.CENTER_CROP);FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);lp.gravity = Gravity.CENTER;ViewGroup.LayoutParams params = mCover.getLayoutParams();// Add view to root. Be careful that the height and width of 'params' should be// specified values. WRAP_CONTENT or MATCH_PARENT will lead to wrong effect.mWmRootView.addView(mAnimBackground, params);mWmRootView.addView(mAnimCover, params);mWmRootView.addView(mLoadingIcon, lp);// view scaleDisplayMetrics dm = mContext.getResources().getDisplayMetrics();int screenWidth = dm.widthPixels;int screenHeight = dm.heightPixels;float scaleW = screenWidth / (float) mCover.getWidth();float scaleH = screenHeight / (float) mCover.getHeight();float baseScale = Math.max(scaleW, scaleH);mBgScaleX = baseScale;mBgScaleY = baseScale;mCoverScaleX = baseScale / 3;mCoverScaleY = baseScale;// If scaleH is larger than scaleW, the ending x should be smaller to show the loading icon in the middle of// the screen.if (scaleW < scaleH) {mOpenBookEndBgX = (screenWidth - mCover.getWidth() * scaleH) / 2;}// start animationstartFlipCoverAnimation();}}private void startFlipCoverAnimation() {ViewHelper.setPivotX(mAnimBackground, 0);ViewHelper.setPivotY(mAnimBackground, 0);ViewHelper.setPivotX(mAnimCover, 0);ViewHelper.setPivotY(mAnimCover, 0);// Reset total opening animations scheduled.mTotalOpenBookAnim = 0;// loading iconstartIndividualAnim(mLoadingIcon, "scaleX", 0.0f, 1, true);startIndividualAnim(mLoadingIcon, "scaleY", 0.0f, 1, true);// background animationstartIndividualAnim(mAnimBackground, "translationX", mLocation[0], mOpenBookEndBgX, true);startIndividualAnim(mAnimBackground, "translationY", mLocation[1], mOpenBookEndBgY, true);startIndividualAnim(mAnimBackground, "scaleX", 1.0f, mBgScaleX, true);startIndividualAnim(mAnimBackground, "scaleY", 1.0f, mBgScaleY, true);// cover animationstartIndividualAnim(mAnimCover, "translationX", mLocation[0], mOpenBookEndBgX, true);startIndividualAnim(mAnimCover, "translationY", mLocation[1], mOpenBookEndBgY, true);startIndividualAnim(mAnimCover, "scaleX", 1.0f, mCoverScaleX, true);startIndividualAnim(mAnimCover, "scaleY", 1.0f, mCoverScaleY, true);startIndividualAnim(mAnimCover, "rotationY", 0, -100, true);}private WindowManager.LayoutParams getDefaultWindowParams() {WindowManager.LayoutParams params = new WindowManager.LayoutParams(WindowManager.LayoutParams.MATCH_PARENT,WindowManager.LayoutParams.MATCH_PARENT, 0, 0, WindowManager.LayoutParams.TYPE_APPLICATION_PANEL,WindowManager.LayoutParams.FLAG_FULLSCREEN, PixelFormat.RGBA_8888);return params;}/*** Close book animation.* * @param gridview BookItemView's parent.*/public synchronized void startCloseBookAnimation() {if (mIsOpen.get()) {/** You can change mLocation here. */// if (mGridParent != null) {// View firstView = mGridParent.getChildAt(0);// firstView.getLocationInWindow(mLocation);// mGridParent = null;// } else if (mListParent != null) {// View firstView = mListParent.getChildAt(0);// firstView.getLocationInWindow(mLocation);// mListParent = null;// } else {// getLocationInWindow(mLocation);// }if (mLoadingIcon != null) {mLoadingIcon.setVisibility(View.GONE);}if (CLOSE_ANIMATION_DURATION > 0) {// Reset open animation count.mTotalOpenBookAnim = 0;// loading iconstartIndividualAnim(mLoadingIcon, "scaleX", 1, 0.0f, false);startIndividualAnim(mLoadingIcon, "scaleY", 1, 0.0f, false);// background animationstartIndividualAnim(mAnimBackground, "translationX", mOpenBookEndBgX, mLocation[0], false);startIndividualAnim(mAnimBackground, "translationY", mOpenBookEndBgY, mLocation[1], false);startIndividualAnim(mAnimBackground, "scaleX", mBgScaleX, 1.0f, false);startIndividualAnim(mAnimBackground, "scaleY", mBgScaleY, 1.0f, false);// cover animationstartIndividualAnim(mAnimCover, "translationX", mOpenBookEndBgX, mLocation[0], false);startIndividualAnim(mAnimCover, "translationY", mOpenBookEndBgY, mLocation[1], false);startIndividualAnim(mAnimCover, "scaleX", mCoverScaleX, 1.0f, false);startIndividualAnim(mAnimCover, "scaleY", mCoverScaleY, 1.0f, false);startIndividualAnim(mAnimCover, "rotationY", -100, 0, false);} else {removeWindowView();}}}/*** Play one individual animation.* * @param target* @param property* @param startValue* @param endValue*/private void startIndividualAnim(View target, String property, float startValue, float endValue, boolean isOpen) {// Increase total opening animations scheduled.mTotalOpenBookAnim++;ObjectAnimator animator = ObjectAnimator.ofFloat(target, property, startValue, endValue).setDuration(isOpen ? OPEN_ANIMATION_DURATION : CLOSE_ANIMATION_DURATION);animator.addListener(this);animator.start();}public AtomicBoolean isOpen() {return mIsOpen;}public void hideLoadingView() {if (mLoadingIcon != null) {mLoadingIcon.setVisibility(View.GONE);}}public void removeWindowView() {mIsOpen.set(false);if (mWmRootView != null) {mWindowManager.removeView(mWmRootView);mWmRootView = null;}}@Overridepublic void onAnimationEnd(Animator arg0) {if (!mIsOpen.get()) {if (mAnimationCount.incrementAndGet() >= mTotalOpenBookAnim) {mIsOpen.set(true);if (mOpenBookAnimEndListener != null) {mOpenBookAnimEndListener.onOpenBookAnimEnd();} else {startActivity();}}} else {if (mAnimationCount.decrementAndGet() <= 0) {removeWindowView();}}}@Overridepublic void onAnimationRepeat(Animator arg0) {}@Overridepublic void onAnimationStart(Animator arg0) {}@Overridepublic void onAnimationCancel(Animator arg0) {}private void startActivity() {mContext.startActivity(new Intent(mContext, BookActivity.class));// Go to BookActivity smoothly.((Activity) mContext).overridePendingTransition(R.anim.fade_in, R.anim.fade_out);}
}

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