我有一个RecycleView，其中显示项目列表。我像这样为RecyclerView指定默认的动画器：
recyclerView.setItemAnimator( new DefaultItemAnimator() );
一切正常，但是我想使用自己的自定义动画来添加/删除/更新列表中的元素。
我定义了一个自定义动画类，如下所示：
public class MyAnimator extends RecyclerView.ItemAnimator {
@Override
public boolean animateDisappearance(@NonNull RecyclerView.ViewHolder viewHolder, @NonNull ItemHolderInfo preLayoutInfo, @Nullable ItemHolderInfo postLayoutInfo) {
return false;
}
@Override
public boolean animateAppearance(@NonNull RecyclerView.ViewHolder viewHolder, @Nullable ItemHolderInfo preLayoutInfo, @NonNull ItemHolderInfo postLayoutInfo) {
return false;
}
@Override
public boolean animatePersistence(@NonNull RecyclerView.ViewHolder viewHolder, @NonNull ItemHolderInfo preLayoutInfo, @NonNull ItemHolderInfo postLayoutInfo) {
return false;
}
@Override
public boolean animateChange(@NonNull RecyclerView.ViewHolder oldHolder, @NonNull RecyclerView.ViewHolder newHolder, @NonNull ItemHolderInfo preLayoutInfo, @NonNull ItemHolderInfo postLayoutInfo) {
return false;
}
@Override
public void runPendingAnimations() {
}
@Override
public void endAnimation(RecyclerView.ViewHolder item) {
}
@Override
public void endAnimations() {
}
@Override
public boolean isRunning() {
return false;
}
}
并以与对DefaultItemAnimator相同的方式进行设置。动画不再播放了，所以我想它起作用了，但是问题是项目有时会相互堆叠，而当我删除所有项目时，仍然剩下一些，所以我想我丢失了一些东西。
据我了解，animateDisappearance是一种从列表中删除该项目时调用的方法。如果我返回false，就应该跳过动画，据我理解，对吗？
我是否在正确的轨道上？当我在github上查找此示例时，结果很少，总的来说，我似乎找不到如何执行此操作的基本代码示例，而我发现的全部都是数千行代码。
如何在不使用任何外部库的情况下简单地用自己的默认覆盖添加/删除动画？谢谢！
编辑：
我能够通过以下方式覆盖默认动画：
recyclerView.setItemAnimator(new DefaultItemAnimator() {
@Override
public boolean animateRemove(RecyclerView.ViewHolder holder) {
holder.itemView.clearAnimation();
final RecyclerView.ViewHolder h = holder;
holder.itemView.animate()
.alpha(0)
.setInterpolator(new AccelerateInterpolator(2.f))
.setDuration(1350)
.setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
dispatchRemoveFinished(h);
}
})
.start();
//
return false;
}
} );
动画效果很好，但是由于某种原因，似乎立即触发了“ dispatchRemoveFinished”，因此，在移除视图之后，它们会立即执行此操作，而不是在动画之后调整其余元素。有什么办法可以解决这个问题？
答案 0 :(得分：2)
实施data.table时，您必须遵循一些规则，否则RecyclerView状态会变得混乱：
所有返回false的空方法也必须至少调用library(data.table)
setDT(dat)
reward <- dat[!is.na(X.targetResp), .(reward)]
reward
# reward
# 1: 1
# 2: 2
# 3: 5
才能清除动画状态。
如果这些方法是开始动画的，则应该RecyclerView.ItemAnimator，存储动画请求并返回true，以调用实际上应该开始动画的dispatchAnimationFinished(viewHolder)。
您需要跟踪正在进行的动画才能正确取消它们。您还将收到对已经进行动画处理的项目的请求。
这是一个示例dispatchAnimationStarted(viewHolder)，仅对移除和移动进行动画处理。请注意充当动画数据持有者和动画状态侦听器的内部类：
runPendingAnimations()您还可以重写SimpleItemAnimator类，该类将ItemAnimator方法解析为public class RecAnimator extends RecyclerView.ItemAnimator {
private final static String TAG = "RecAnimator";
private final static int ANIMATION_TYPE_DISAPPEAR = 1;
private final static int ANIMATION_TYPE_MOVE = 2;
// must keep track of all pending/ongoing animations.
private final ArrayList<AnimInfo> pending = new ArrayList<>();
private final HashMap<RecyclerView.ViewHolder, AnimInfo> disappearances = new HashMap<>();
private final HashMap<RecyclerView.ViewHolder, AnimInfo> persistences = new HashMap<>();
@Override
public boolean animateDisappearance(@NonNull RecyclerView.ViewHolder viewHolder, @NonNull ItemHolderInfo preLayoutInfo, @Nullable ItemHolderInfo postLayoutInfo) {
pending.add(new AnimInfo(viewHolder, ANIMATION_TYPE_DISAPPEAR, 0));
dispatchAnimationStarted(viewHolder);
// new pending animation added, return true to indicate we want a call to runPendingAnimations()
return true;
}
@Override
public boolean animateAppearance(@NonNull RecyclerView.ViewHolder viewHolder, @Nullable ItemHolderInfo preLayoutInfo, @NonNull ItemHolderInfo postLayoutInfo) {
dispatchAnimationFinished(viewHolder);
return false;
}
@Override
public boolean animatePersistence(@NonNull RecyclerView.ViewHolder viewHolder, @NonNull ItemHolderInfo preLayoutInfo, @NonNull ItemHolderInfo postLayoutInfo) {
if (preLayoutInfo.top != postLayoutInfo.top) {
// required movement
int topDiff = preLayoutInfo.top - postLayoutInfo.top;
AnimInfo per = persistences.get(viewHolder);
if(per != null && per.isRunning) {
// there is already an ongoing animation - update it instead
per.top = per.holder.itemView.getTranslationY() + topDiff;
per.start();
// discard this animatePersistence call
dispatchAnimationFinished(viewHolder);
return false;
}
pending.add(new AnimInfo(viewHolder, ANIMATION_TYPE_MOVE, topDiff));
dispatchAnimationStarted(viewHolder);
// new pending animation added, return true to indicate we want a call to runPendingAnimations()
return true;
}
dispatchAnimationFinished(viewHolder);
return false;
}
@Override
public boolean animateChange(@NonNull RecyclerView.ViewHolder oldHolder, @NonNull RecyclerView.ViewHolder newHolder, @NonNull ItemHolderInfo preLayoutInfo, @NonNull ItemHolderInfo postLayoutInfo) {
dispatchAnimationFinished(oldHolder);
dispatchAnimationFinished(newHolder);
return false;
}
@Override
public void runPendingAnimations() {
for (AnimInfo ai: pending) {
ai.start();
}
pending.clear();
}
@Override
public void endAnimation(RecyclerView.ViewHolder item) {
AnimInfo ai = disappearances.get(item);
if (ai != null && ai.isRunning) {
ai.holder.itemView.animate().cancel();
}
ai = persistences.get(item);
if (ai != null && ai.isRunning) {
ai.holder.itemView.animate().cancel();
}
}
@Override
public void endAnimations() {
for (AnimInfo ai: disappearances.values())
if (ai.isRunning)
ai.holder.itemView.animate().cancel();
for (AnimInfo ai: persistences.values())
if (ai.isRunning)
ai.holder.itemView.animate().cancel();
}
@Override
public boolean isRunning() {
return !pending.isEmpty() &&
!disappearances.isEmpty() &&
!persistences.isEmpty();
}
/**
* This is container for each animation. It's also cancel/end listener for them.
* */
private final class AnimInfo implements Animator.AnimatorListener {
private final RecyclerView.ViewHolder holder;
private final int animationType;
private float top;
private boolean isRunning = false;
private AnimInfo(RecyclerView.ViewHolder holder, int animationType, float top) {
this.holder = holder;
this.animationType = animationType;
this.top = top;
}
void start(){
View itemView = holder.itemView;
itemView.animate().setListener(this);
switch (animationType) {
case ANIMATION_TYPE_DISAPPEAR:
itemView.setPivotY(0f);
itemView.animate().scaleX(0f).scaleY(0f).setDuration(getRemoveDuration());
disappearances.put(holder, this); // must keep track of all animations
break;
case ANIMATION_TYPE_MOVE:
itemView.setTranslationY(top);
itemView.animate().translationY(0f).setDuration(getMoveDuration());
persistences.put(holder, this); // must keep track of all animations
break;
}
isRunning = true;
}
private void resetViewHolderState(){
// reset state as if no animation was ran
switch (animationType) {
case ANIMATION_TYPE_DISAPPEAR:
holder.itemView.setScaleX(1f);
holder.itemView.setScaleY(1f);
break;
case ANIMATION_TYPE_MOVE:
holder.itemView.setTranslationY(0f);
break;
}
}
@Override
public void onAnimationEnd(Animator animation) {
switch (animationType) {
case ANIMATION_TYPE_DISAPPEAR:
disappearances.remove(holder);
break;
case ANIMATION_TYPE_MOVE:
persistences.remove(holder);
break;
}
resetViewHolderState();
holder.itemView.animate().setListener(null); // clear listener
dispatchAnimationFinished(holder);
if (!isRunning())
dispatchAnimationsFinished();
isRunning = false;
}
@Override
public void onAnimationCancel(Animator animation) {
// jump to end state
switch (animationType) {
case ANIMATION_TYPE_DISAPPEAR:
holder.itemView.setScaleX(0f);
holder.itemView.setScaleY(0f);
break;
case ANIMATION_TYPE_MOVE:
holder.itemView.setTranslationY(0f);
break;
}
}
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
}
}
，animate...等。