据我所知,使用刷卡项目下方的背景(如许多谷歌应用程序)实现RecyclerView的刷卡到解除的一种可能性是实现ItemTouchHelper的简单回调并在方法中绘制背景onChildDraw。
这是我的实施:
ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.RIGHT) {
// create objects once and avoid allocating them in the onChildDraw method
Drawable background;
Drawable icon;
int iconMargin;
boolean initialized;
private void init() {
background = new ColorDrawable(Color.RED);
icon = ContextCompat.getDrawable(mAppContext, R.drawable.ic_delete_white_24dp);
iconMargin = (int) mAppContext.getResources().getDimension(R.dimen.fab_margin);
initialized = true;
}
@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
return false;
}
@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int swipeDir) {
// remove swiped item from the list and notify the adapter
int position = viewHolder.getAdapterPosition();
mItemList.remove(position);
mRecyclerViewAdapter.notifyDataSetChanged();
}
@Override
public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {
if (dX > 0) {
View itemView = viewHolder.itemView;
// if viewHolder has been swiped away, don't do anything
if (viewHolder.getAdapterPosition() == -1) {
return;
}
if (!initialized) {
init();
}
// draw background
int dXSwipe = (int) (dX * 1.05); // increase slightly dX to avoid view flickering, compensating loss of precision due to int conversion
background.setBounds(itemView.getLeft(), itemView.getTop(),
itemView.getLeft() + dXSwipe, itemView.getBottom());
background.draw(c);
// draw icon
int top = (itemView.getTop() + itemView.getBottom() - icon.getIntrinsicHeight()) / 2;
int left = itemView.getLeft() + iconMargin;
icon.setBounds(left, top, left + icon.getIntrinsicWidth(), top + icon.getIntrinsicHeight());
icon.draw(c);
}
}
super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
}
};
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(simpleItemTouchCallback);
itemTouchHelper.attachToRecyclerView(mRecyclerView);
现在,问题是如何在下面的背景中为视图设置动画。可以从Google日历中获取此动画的示例:当刷新事件或提醒时,左侧的图标会根据水平位移量进行放大。
有人知道如何实现这一目标吗?是否有必要采用不同的方法,可能在ViewHolder中有两个视图,如此处RecyclerView Swipe with a view below it所提出的那样?
答案 0 :(得分:3)
我发现了怎么做。
对于那些感兴趣的人,解决方案是使用两个视图(前景和背景)并在滑动过程中为背景设置动画。
布局:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/item_delete_background">
<ImageView
android:id="@+id/item_delete_icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginLeft="@dimen/fab_margin"
android:layout_marginStart="@dimen/fab_margin"
app:srcCompat="@drawable/ic_delete_white_24dp" />
<android.support.constraint.ConstraintLayout
android:id="@+id/item_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/gray_bg">
<!--recyclerview item layout-->
</android.support.constraint.ConstraintLayout>
</FrameLayout>
观点持有人:
class MyViewHolder extends RecyclerView.ViewHolder {
private ConstraintLayout mItemLayout;
private ImageView mItemDeleteIcon;
MyViewHolder(View v) {
super(v);
mItemLayout = (ConstraintLayout) v.findViewById(R.id.item_layout);
mEventDeleteIcon = (ImageView) v.findViewById(R.id.item_delete_icon);
}
View getViewToSwipe() {
return mItemLayout;
}
View getViewToAnimate() {
return mItemDeleteIcon;
}
}
和ItemTouchHelper回调:
ItemTouchHelper.SimpleCallback mItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.RIGHT) {
// override methods
public void onChildDrawOver(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
float dX, float dY,
int actionState, boolean isCurrentlyActive) {
// get the view which is currently swiped
ConstraintLayout itemLayout = (ConstraintLayout) ((MyViewHolder) viewHolder).getViewToSwipe();
// calculate relative horizontal displacement
// with proportion dXRelative : 1 = dX : (layoutWidth / 3)
float dXRelative = dX / itemLayout.getWidth() * 3;
// check size boundaries
if (dXRelative > 1) {
dXRelative = 1;
}
if (dXRelative < 0) {
dXRelative = 0;
}
// animate the icon with scaling on both dimensions
((MyViewHolder) viewHolder).getViewToAnimate().animate().scaleX(dXRelative).scaleY(dXRelative).setDuration(0).start();
// call draw over
getDefaultUIUtil().onDrawOver(c, recyclerView, ((MyViewHolder) viewHolder).getViewToSwipe(), dX, dY, actionState, isCurrentlyActive);
}
};
在此帖子之后完成了基本行为(视图持有者中的前景/背景)的实现:Use ItemTouchHelper for Swipe-To-Dismiss with another View displayed behind the swiped out。
希望这可能对某人有用。