[英]SnapHelper Item Position
I'm using vertical RecyclerView
to list my items and SnapHelper
to snap center item.我正在使用垂直
RecyclerView
列出我的项目并SnapHelper
来捕捉中心项目。 The idea is to randomize selection, so user swipe screen or shake the device and it is scrolling to random position.这个想法是随机选择,所以用户滑动屏幕或摇动设备,它就会滚动到随机位置。
Number of items is 20, however I use Integer.MAX_VALUE
for the number of elements in RecyclerView
and initialize RecyclerView with position Integer.MAX_VALUE / 2
to create some kind of endless list.项目数为 20,但是我使用
Integer.MAX_VALUE
作为RecyclerView
中的元素数,并使用位置Integer.MAX_VALUE / 2
初始化 RecyclerView 以创建某种无限列表。
To scroll to random position on device shake I need to know current snapped item position.要滚动到设备抖动的随机位置,我需要知道当前捕捉的项目位置。
Is there any way to do it?有什么办法吗?
Here is my Fragment code:这是我的片段代码:
public class PlaceListFragment extends Fragment {公共类 PlaceListFragment 扩展片段 {
private static final String TAG = "PlaceListFragment";
public static final String ARG_KEY1 = "key1";
private ArrayList<PlaceItem> places;
private RecyclerView recyclerView;
private SensorManager sensorManager;
private float accelValue;
private float accelLast;
private float shake;
SnapHelper snapHelper;
Vibrator vibe;
public static PlaceListFragment newInstance() {
Bundle args = new Bundle();
PlaceListFragment fragment = new PlaceListFragment();
fragment.setArguments(args);
return fragment;
}
public static PlaceListFragment newInstance(ArrayList<PlaceItem> places) {
Bundle args = new Bundle();
args.putParcelableArrayList(PlaceListActivity.KEY_PLACES, places);
PlaceListFragment fragment = new PlaceListFragment();
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
Log.d(TAG, "onCreate()");
super.onCreate(savedInstanceState);
places = getArguments().getParcelableArrayList(PlaceListActivity.KEY_PLACES);
accelValue = SensorManager.GRAVITY_EARTH;
accelLast = SensorManager.GRAVITY_EARTH;
shake = 0.00f;
vibe = (Vibrator) getActivity().getSystemService(Context.VIBRATOR_SERVICE);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_place_list, container, false);
recyclerView = (RecyclerView) v.findViewById(R.id.place_list);
snapHelper = new LinearSnapHelper();
snapHelper.attachToRecyclerView(recyclerView);
recyclerView.setOnFlingListener(snapHelper);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerView.setAdapter(new PlaceListAdapter(getActivity(), places));
recyclerView.scrollToPosition(PlaceListAdapter.MIDDLE);
sensorManager = (SensorManager) getActivity().getSystemService(Context.SENSOR_SERVICE);
sensorManager.registerListener(sensorListener, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),SensorManager.SENSOR_DELAY_NORMAL);
return v;
}
@Override
public void onResume() {
super.onResume();
}
@Override
public void onPause() {
super.onPause();
}
private final SensorEventListener sensorListener = new SensorEventListener() {
@Override
public void onSensorChanged(SensorEvent event) {
float x = event.values[0];
float y = event.values[1];
float z = event.values[2];
accelLast = accelValue;
accelValue = (float) Math.sqrt((double) (x*x + y*y + z*z));
float delta = accelValue - accelLast;
shake = shake * 0.9f + delta;
if (shake > 12) {
vibe.vibrate(200);
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
};
}
And here is adapter:这是适配器:
public class PlaceListAdapter extends RecyclerView.Adapter<PlaceListAdapter.PlaceAdapterHolder> {
private final FragmentActivity context;
public static final int HALF_MAX_VALUE = Integer.MAX_VALUE/2;
public static int MIDDLE;
private List<PlaceItem> placeItems;
public static class PlaceAdapterHolder extends RecyclerView.ViewHolder {
private ImageView image;
private TextView textMain;
private TextView textRating;
public PlaceAdapterHolder(View itemView) {
super(itemView);
image = (ImageView) itemView.findViewById(R.id.icon);
textMain = (TextView) itemView.findViewById(R.id.txt_main_line);
textRating = (TextView) itemView.findViewById(R.id.txt_right_field);
}
public void bindPlace(PlaceItem placeItem) {
String placeName = placeItem.getName() == null? "?":placeItem.getName();
String firstLetter = placeName.substring(0, 1);
ColorGenerator generator = ColorGenerator.MATERIAL; // or use DEFAULT
int color = generator.getColor(placeName);
TextDrawable drawable = TextDrawable.builder()
.beginConfig()
.toUpperCase()
.endConfig()
.buildRect(firstLetter, color);
image.setImageDrawable(drawable);
textMain.setText(placeItem.getName());
textRating.setText(placeItem.getRating());
}
}
public PlaceListAdapter(FragmentActivity context, List<PlaceItem> placeItems) {
this.context = context;
this.placeItems = placeItems;
MIDDLE = HALF_MAX_VALUE - HALF_MAX_VALUE % placeItems.size();
}
@Override
public PlaceListAdapter.PlaceAdapterHolder onCreateViewHolder(ViewGroup parent, int viewType) {
final View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.place_list_one_line_item, parent, false);
return new PlaceAdapterHolder(view);
}
@Override
public int getItemCount() {
return Integer.MAX_VALUE;
}
@Override
public void onBindViewHolder(PlaceListAdapter.PlaceAdapterHolder holder, final int position) {
final PlaceItem placeItem = getItem(position);
holder.bindPlace(placeItem);
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
FragmentManager fm = context.getSupportFragmentManager();
PlaceDetailsFragment dialog = PlaceDetailsFragment.newInstance(getItem(position));
dialog.show(fm, "DETAILS_DIALOG");
}
});
}
private PlaceItem getItem(int position)
{
return placeItems.get(position % placeItems.size());
}
}
I used this on a project that had a RecyclerView
with SnapHelper
, not sure if it is what you want.我在一个有
RecyclerView
和SnapHelper
的项目上使用了它,不确定它是否是你想要的。
mRecyclerView.setHasFixedSize(true);
// use a linear layout manager
mLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
mRecyclerView.setLayoutManager(mLayoutManager);
// specify an adapter (see also next example)
mAdapter = new DemoSlidesAdapter(getApplicationContext());
mRecyclerView.setAdapter(mAdapter);
final SnapHelper snapHelper = new LinearSnapHelper();
snapHelper.attachToRecyclerView(mRecyclerView);
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
if(newState == RecyclerView.SCROLL_STATE_IDLE) {
View centerView = snapHelper.findSnapView(mLayoutManager);
int pos = mLayoutManager.getPosition(centerView);
Log.e("Snapped Item Position:",""+pos);
}
}
});
I try to use this code with a PagerSnapHelper to mimic the pager behaviour and it was useful but i found some corner cases to solve, if you move fast from the last page to the first one and keep swapping until see the boundarie then the IDLE state doesnt happen and you lose your index.我尝试将此代码与 PagerSnapHelper 一起使用来模拟寻呼机行为,它很有用,但我发现了一些需要解决的极端情况,如果您从最后一页快速移动到第一页并继续交换直到看到边界然后是空闲状态不会发生,您会丢失索引。 to solve that I move out the position from the IF and add a extra condition for this corner case.
为了解决这个问题,我从 IF 中移出位置,并为这个极端情况添加了一个额外的条件。
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)
val centerView = snapHelper.findSnapView(mLayoutManager)
val pos = mLayoutManager.getPosition(centerView!!)
if (newState == RecyclerView.SCROLL_STATE_IDLE || (pos == 0 && newState == RecyclerView.SCROLL_STATE_DRAGGING)) {
Log.d("BINDING", "positionView SCROLL_STATE_IDLE: $pos")
}
}
Code is in kotlin hope it helps代码在 kotlin 中,希望对您有所帮助
private fun recyclerViewScrollListener() = object: RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)
if (newState == RecyclerView.SCROLL_STATE_IDLE) {
// layoutManager is LinearLayoutManager
val pos = layoutManager.findFirstCompletelyVisibleItemPosition()
Log.e(TAG, "onScrollStateChanged: $pos")
}
}
}
recyclerView.setOnScrollListener(recyclerViewScrollListener())
recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener(){
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
....
}
})
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