DefaultItemAnimator是Android OS中一个默认的RecyclerView动画实现类,如果产品需求没有特别复杂的动画要求,可以使用DefaultItemAnimator实现简单的动画效果。DefaultItemAnimator动画的实现流程和原理已经在上两节中做过简单介绍,如果还没有看过的童鞋,最好先打眼扫一下之前两节的内容,有助于理解。附上链接地址:
1 RecyclerView.ItemAnimator终极解读(一)--RecyclerView源码解析
2 RecyclerView.ItemAnimator终极解读(二)--SimpleItemAnimator和DefaultItemAnimator源码解析
这一节,我们主要通过继承DefaultItemAnimator来实现稍微复杂一点的自定义动画。效果如下两张图所示:
如上两张图所示:每点击一个item时,更新所点击item的背景颜色和文本信息。 第一张图是没有添加动画效果, 第二张图是添加自定义动画之后的效果。
主要代码就是在自定义的动画类MyDefaultItemAnimator.java中, 如下所示:
package material.danny_jiang.com.mydefaultitemanimator; import android.animation.Animator; import android.animation.AnimatorListenerAdapter; import android.animation.AnimatorSet; import android.animation.ArgbEvaluator; import android.animation.ObjectAnimator; import android.graphics.Color; import android.graphics.drawable.ColorDrawable; import android.support.annotation.NonNull; import android.support.v4.util.ArrayMap; import android.support.v7.widget.DefaultItemAnimator; import android.support.v7.widget.RecyclerView; import android.util.Log; import android.view.View; import android.view.animation.AccelerateInterpolator; import android.view.animation.DecelerateInterpolator; import android.widget.LinearLayout; import android.widget.TextView; import java.util.List; /** * Created by axing on 16/5/25. */ public class MyDefaultItemAnimator extends DefaultItemAnimator { private static final String TAG = "MyDefaultItemAnimator"; // 定义动画执行时的加速度 private AccelerateInterpolator mAccelerateInterpolator = new AccelerateInterpolator(); private DecelerateInterpolator mDecelerateInterpolator = new DecelerateInterpolator(); ArgbEvaluator mColorEvaluator = new ArgbEvaluator(); /** * 定义正在执行Animator的ViewHolder的Map集合 * 此集合会保存用户点击的ViewHolder对象,目的在于当用户不停的点击某一item时 * 会先判断此ViewHolder种的itemView动画是否正在执行,如果正在执行则停止 */ private ArrayMap<RecyclerView.ViewHolder, AnimatorInfo> mAnimatorMap = new ArrayMap<>(); /** * 复写canReuseUpdatedViewHolder方法并返回true,通知RecyclerView在执行动画时可以复用ViewHolder对象 * @param viewHolder * @return */ @Override public boolean canReuseUpdatedViewHolder(RecyclerView.ViewHolder viewHolder) { return true; } /** * 自定义getItemHolderInfo方法,将ViewHolder中的背景颜色和TextView的文本信息传入ColorTextInfo中 * @param viewHolder * @param info * @return */ @NonNull private ItemHolderInfo getItemHolderInfo(MyViewHolder viewHolder, ColorTextInfo info) { //获取当前正在操作的ViewHolder对象 final MyViewHolder myHolder = viewHolder; //获取ViewHolder中itemView背景颜色 final int bgColor = ((ColorDrawable) myHolder.container.getBackground()).getColor(); //将背景颜色和TextView的文本信息赋值给ColorTextInfo对象的color和text变量 info.color = bgColor; info.text = (String) myHolder.textView.getText(); return info; } /** * 通过ViewHolder对象获取动画执行之前itemView中的背景颜色和文本信息 * 初始化ColorTextInfo对象,并将背景颜色和文本信息进行赋值 * @return */ @NonNull @Override public ItemHolderInfo recordPreLayoutInformation(RecyclerView.State state, RecyclerView.ViewHolder viewHolder, int changeFlags, List<Object> payloads) { Log.e(TAG, "recordPreLayoutInformation: " + viewHolder.toString()); ColorTextInfo info = (ColorTextInfo) super.recordPreLayoutInformation(state, viewHolder, changeFlags, payloads); return getItemHolderInfo((MyViewHolder) viewHolder, info); } /** * 通过ViewHolder对象获取动画执行之后itemView中的背景颜色和文本信息 * 初始化ColorTextInfo对象,并将背景颜色和文本信息进行赋值 * @return */ @NonNull @Override public ItemHolderInfo recordPostLayoutInformation(@NonNull RecyclerView.State state, @NonNull RecyclerView.ViewHolder viewHolder) { Log.e(TAG, "recordPostLayoutInformation: " + viewHolder.toString()); ColorTextInfo info = (ColorTextInfo) super.recordPostLayoutInformation(state, viewHolder); return getItemHolderInfo((MyViewHolder) viewHolder, info); } /** * 复写obtainHolderInfo,返回自定义的ItemHolderInfo对象 * @return */ @Override public ItemHolderInfo obtainHolderInfo() { Log.e(TAG, "obtainHolderInfo: "); return new ColorTextInfo(); } /** * 自定义ItemHolderInfo对象,持有两个变量,依次来表示每一个Item的背景颜色和文本信息 */ private class ColorTextInfo extends ItemHolderInfo { int color; String text; } /** * 创建执行animateChange的动画Info对象,内部封装了所需要执行一个动画类的相关信息 * 起始alpha属性动画,和起始旋转属性动画 */ private class AnimatorInfo { Animator overallAnim; ObjectAnimator fadeToBlackAnim, fadeFromBlackAnim, oldTextRotator, newTextRotator; public AnimatorInfo(Animator overallAnim, ObjectAnimator fadeToBlackAnim, ObjectAnimator fadeFromBlackAnim, ObjectAnimator oldTextRotator, ObjectAnimator newTextRotator) { this.overallAnim = overallAnim; this.fadeToBlackAnim = fadeToBlackAnim; this.fadeFromBlackAnim = fadeFromBlackAnim; this.oldTextRotator = oldTextRotator; this.newTextRotator = newTextRotator; } } /** * Custom change animation. Fade to black on the container background, then back * up to the new bg coolor. Meanwhile, the text rotates, switching along the way. * If a new change animation occurs on an item that is currently animating * a change, we stop the previous change and start the new one where the old * one left off. * 真正的执行change动画的方法: * 通过传入的preInfo和postInfo,分别将动画前后的背景色和文本信息设置到alpha属性动画和旋转属性动画中 */ @Override public boolean animateChange(@NonNull final RecyclerView.ViewHolder oldHolder, @NonNull final RecyclerView.ViewHolder newHolder, @NonNull ItemHolderInfo preInfo, @NonNull ItemHolderInfo postInfo) { Log.e(TAG, "animateChange: "); if (oldHolder != newHolder) { //第一次显示所有的RecyclerView时,新旧ViewHolder是不相等的 return super.animateChange(oldHolder, newHolder, preInfo, postInfo); } final MyViewHolder viewHolder = (MyViewHolder) newHolder; // 获取动画前后的背景色和文本信息 ColorTextInfo oldInfo = (ColorTextInfo) preInfo; ColorTextInfo newInfo = (ColorTextInfo) postInfo; int oldColor = oldInfo.color; int newColor = newInfo.color; final String oldText = oldInfo.text; final String newText = newInfo.text; // 获取需要被执行动画的View视图对象 LinearLayout newContainer = viewHolder.container; final TextView newTextView = viewHolder.textView; // 从mAnimatorMap缓存中查找当前newHolder对应的itemView动画是否在执行中,如果是则终止动画 AnimatorInfo runningInfo = mAnimatorMap.get(newHolder); long prevAnimPlayTime = 0; boolean firstHalf = false; if (runningInfo != null) { firstHalf = runningInfo.oldTextRotator != null && runningInfo.oldTextRotator.isRunning(); prevAnimPlayTime = firstHalf ? runningInfo.oldTextRotator.getCurrentPlayTime() : runningInfo.newTextRotator.getCurrentPlayTime(); runningInfo.overallAnim.cancel(); } // 初始化背景颜色渐变的属性动画 ObjectAnimator fadeToBlack = null, fadeFromBlack; if (runningInfo == null || firstHalf) { int startColor = oldColor; if (runningInfo != null) { startColor = (Integer) runningInfo.fadeToBlackAnim.getAnimatedValue(); } fadeToBlack = ObjectAnimator.ofInt(newContainer, "backgroundColor", startColor, Color.BLACK); fadeToBlack.setEvaluator(mColorEvaluator); if (runningInfo != null) { fadeToBlack.setCurrentPlayTime(prevAnimPlayTime); } } fadeFromBlack = ObjectAnimator.ofInt(newContainer, "backgroundColor", Color.BLACK, newColor); fadeFromBlack.setEvaluator(mColorEvaluator); if (runningInfo != null && !firstHalf) { fadeFromBlack.setCurrentPlayTime(prevAnimPlayTime); } AnimatorSet bgAnim = new AnimatorSet(); if (fadeToBlack != null) { bgAnim.playSequentially(fadeToBlack, fadeFromBlack); } else { bgAnim.play(fadeFromBlack); } // 初始化旋转的属性动画 ObjectAnimator oldTextRotate = null, newTextRotate; if (runningInfo == null || firstHalf) { oldTextRotate = ObjectAnimator.ofFloat(newTextView, View.ROTATION_X, 0, 90); oldTextRotate.setInterpolator(mAccelerateInterpolator); if (runningInfo != null) { oldTextRotate.setCurrentPlayTime(prevAnimPlayTime); } oldTextRotate.addListener(new AnimatorListenerAdapter() { boolean mCanceled = false; @Override public void onAnimationStart(Animator animation) { newTextView.setText(oldText); } @Override public void onAnimationCancel(Animator animation) { mCanceled = true; } @Override public void onAnimationEnd(Animator animation) { if (!mCanceled) { //old动画执行之后,需要重新设置文本信息 newTextView.setText(newText); } } }); } newTextRotate = ObjectAnimator.ofFloat(newTextView, View.ROTATION_X, -90, 0); newTextRotate.setInterpolator(mDecelerateInterpolator); if (runningInfo != null && !firstHalf) { newTextRotate.setCurrentPlayTime(prevAnimPlayTime); } AnimatorSet textAnim = new AnimatorSet(); if (oldTextRotate != null) { textAnim.playSequentially(oldTextRotate, newTextRotate); } else { textAnim.play(newTextRotate); } AnimatorSet changeAnim = new AnimatorSet(); changeAnim.playTogether(bgAnim, textAnim); changeAnim.addListener(new AnimatorListenerAdapter() { @Override public void onAnimationEnd(Animator animation) { dispatchAnimationFinished(newHolder); mAnimatorMap.remove(newHolder); } }); changeAnim.start(); AnimatorInfo runningAnimInfo = new AnimatorInfo(changeAnim, fadeToBlack, fadeFromBlack, oldTextRotate, newTextRotate); mAnimatorMap.put(newHolder, runningAnimInfo); return true; } @Override public void endAnimation(RecyclerView.ViewHolder item) { super.endAnimation(item); if (!mAnimatorMap.isEmpty()) { final int numRunning = mAnimatorMap.size(); for (int i = numRunning; i >= 0; i--) { if (item == mAnimatorMap.keyAt(i)) { mAnimatorMap.valueAt(i).overallAnim.cancel(); } } } } @Override public boolean isRunning() { return super.isRunning() || !mAnimatorMap.isEmpty(); } @Override public void endAnimations() { super.endAnimations(); if (!mAnimatorMap.isEmpty()) { final int numRunning = mAnimatorMap.size(); for (int i = numRunning; i >= 0; i--) { mAnimatorMap.valueAt(i).overallAnim.cancel(); } } } }
每段代码的含义的用途都已经在代码中添加了相应的注释,请耐得住寂寞,仔细查看^_^
自定义ItemAnimator实现好之后,剩下的就是初始化RecyclerView,并通过setItemAnimator方法将自定义ItemAnimator对象传递给RecyclerView。
MainActivity.java中的相关代码如下:
recyclerView = ((RecyclerView) findViewById(R.id.recyclerview)); recyclerView.setLayoutManager(new LinearLayoutManager(this)); recyclerView.setAdapter(new RecyclerAdapter(this, recyclerView)); recyclerView.setItemAnimator(new MyDefaultItemAnimator());
RecyclerAdapter.java代码如下:
@Override public void onBindViewHolder(MyViewHolder holder, int position) { final MyViewHolder myHolder = (MyViewHolder) holder; int color = mColors.get(position); myHolder.container.setBackgroundColor(color); myHolder.textView.setText("#" + Integer.toHexString(color)); } @Override public int getItemCount() { return mColors.size(); } private View.OnClickListener mItemAction = new View.OnClickListener() { @Override public void onClick(View v) { changeItem(v); } }; @Override public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View container = mainActivity.getLayoutInflater().inflate(R.layout.item_layout, parent, false); container.setOnClickListener(mItemAction); return new MyViewHolder(container); } private int generateColor() { int red = ((int) (Math.random() * 200)); int green = ((int) (Math.random() * 200)); int blue = ((int) (Math.random() * 200)); return Color.rgb(red, green, blue); } private void generateData() { for (int i = 0; i < 100; ++i) { mColors.add(generateColor()); } } private void changeItem(View view) { int position = mRecyclerView.getChildAdapterPosition(view); if (position != RecyclerView.NO_POSITION) { int color = generateColor(); mColors.set(position, color); notifyItemChanged(position); } }
MyViewHolder.java代码如下:
package material.danny_jiang.com.mydefaultitemanimator; import android.support.v7.widget.RecyclerView; import android.view.View; import android.widget.LinearLayout; import android.widget.TextView; /** * Created by axing on 16/5/25. */ class MyViewHolder extends RecyclerView.ViewHolder { public TextView textView; public LinearLayout container; public MyViewHolder(View v) { super(v); container = (LinearLayout) v; textView = (TextView) v.findViewById(R.id.textview); } @Override public String toString() { return super.toString() + " \"" + textView.getText() + "\""; } }
时间: 2024-11-08 23:33:52