用RecyclerView实现“反弹”ItemTouchHelper.Callback动画
用RecyclerView实现“反弹”ItemTouchHelper.Callback动画
提问于 2015-09-25 14:45:19
我正在尝试使用扩展RecyclerView的Helper类在我的ItemTouchHelper.Callback行中创建一个动画。
ItemTouchHelper默认的“滑动”行为是，如果以足够的速度滑动一行，它就会从视图中消失(即滑动到错误)。在我的例子中，我想要创建一个动画，如果发生这样的事件，将使行直接反弹。
我已经能够创建一个ValueAnimator，如果它是从屏幕上滑动的话，就可以将该行动画回视图。但是，问题是，我无法让父ItemTouchHelper类认识到它存储的x值已经从行的宽度(因此它完全脱离屏幕)更改为0 (以便它回到屏幕上)。
这意味着，每当我在行完成自定义动画之后与它交互时，它的行为就好像该行仍然处于脱离屏幕的状态，即使它是完全可见的。这通常意味着按下它意味着行从X的0位置跳转到行宽的X位置，然后从屏幕的边缘再次显示动画。在完全重置并再次正常运行之前，它会做几次这样的操作。
这段视频将有助于显示问题。由于前两次滑动不是抛出屏幕，默认行为有效。然而，当行被从屏幕上划掉并反弹回来后，点击行显示它从右边的边缘向后回击：
下面是我用来执行动画的代码：
public class CustomItemTouchHelper extends ItemTouchHelper.Callback {
private RecoverAnimation ra;
private boolean animatorRunning;
//...
@Override
public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
final float per = (dX/viewHolder.itemView.getWidth());
if (per > 0.8F && !animatorRunning && !isCurrentlyActive) {
ra = new RecoverAnimation(c, recyclerView, viewHolder, ItemTouchHelper.ANIMATION_TYPE_SWIPE_CANCEL, actionState, dX, dY, 0, 0);
ra.start();
} else {
getDefaultUIUtil().onDraw(c, recyclerView, viewHolder.itemView, dX, dY, actionState, isCurrentlyActive);
}
}
//...注意，这个内部类RecoverAnimation是从ItemTouchHelper源代码中提取的：
private class RecoverAnimation implements AnimatorListenerCompat {
final float mStartDx;
final float mStartDy;
final float mTargetX;
final float mTargetY;
final Canvas mCanvas;
final RecyclerView mRecyclerView;
final RecyclerView.ViewHolder mViewHolder;
final int mActionState;
private final ValueAnimatorCompat mValueAnimator;
float mX;
float mY;
// if user starts touching a recovering view, we put it into interaction mode again,
// instantly.
boolean mOverridden = false;
private boolean mEnded = false;
private float mFraction;
public RecoverAnimation(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
int actionState, float startDx, float startDy, float targetX, float targetY) {
mRecyclerView = recyclerView;
mCanvas = c;
mActionState = actionState;
mViewHolder = viewHolder;
mStartDx = startDx;
mStartDy = startDy;
mTargetX = targetX;
mTargetY = targetY;
mValueAnimator = AnimatorCompatHelper.emptyValueAnimator();
mValueAnimator.addUpdateListener(
new AnimatorUpdateListenerCompat() {
@Override
public void onAnimationUpdate(ValueAnimatorCompat animation) {
setFraction(animation.getAnimatedFraction());
update();
}
});
mValueAnimator.setTarget(viewHolder.itemView);
mValueAnimator.addListener(this);
setFraction(0f);
}
public void setDuration(long duration) {
mValueAnimator.setDuration(duration);
}
public void start() {
animatorRunning = true;
mViewHolder.setIsRecyclable(false);
mValueAnimator.start();
}
public void cancel() {
mValueAnimator.cancel();
}
public void setFraction(float fraction) {
mFraction = fraction;
}
/**
* We run updates on onDraw method but use the fraction from animator callback.
* This way, we can sync translate x/y values w/ the animators to avoid one-off frames.
*/
public void update() {
if (mStartDx == mTargetX) {
mX = ViewCompat.getTranslationX(mViewHolder.itemView);
} else {
mX = mStartDx + mFraction * (mTargetX - mStartDx);
}
if (mStartDy == mTargetY) {
mY = ViewCompat.getTranslationY(mViewHolder.itemView);
} else {
mY = mStartDy + mFraction * (mTargetY - mStartDy);
}
getDefaultUIUtil().onDraw(mCanvas, mRecyclerView, mViewHolder.itemView, mX, mY, mActionState, false);
}
@Override
public void onAnimationStart(ValueAnimatorCompat animation) {
}
@Override
public void onAnimationEnd(ValueAnimatorCompat animation) {
animatorRunning = false;
mEnded = true;
getDefaultUIUtil().onDraw(mCanvas, mRecyclerView, mViewHolder.itemView, 0, 0, ItemTouchHelper.ACTION_STATE_IDLE, false);
getDefaultUIUtil().clearView(mViewHolder.itemView);
}
@Override
public void onAnimationCancel(ValueAnimatorCompat animation) {
setFraction(1f); //make sure we recover the view's state.
}
@Override
public void onAnimationRepeat(ValueAnimatorCompat animation) {
}
}我能做些什么来解决这个问题，还是根本不可能(现在)？
回答 1
Stack Overflow用户
回答已采纳
发布于 2016-07-07 11:37:05
以下解决方案将反弹回收查看项目，而不实现您的自定义RecoverAnimation类。
public class CustomItemTouchHelper extends ItemTouchHelper.Callback {
private RecoverAnimation ra;
private boolean animatorRunning;
private boolean swipeBack = false;
//...
@Override
public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
recyclerView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event)
{
if(event.getAction() == MotionEvent.ACTION_UP || event.getAction() == MotionEvent.ACTION_CANCEL)
{
swipeBack = true;
}
else
{
swipeBack = false;
}
return false;
}
});
}
@Override
public int convertToAbsoluteDirection(int flags, int layoutDirection) {
return swipeBack ? 0 : super.convertToAbsoluteDirection(flags, layoutDirection);
}
//...页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/32784798
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