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package it.niedermann.android.crosstabdnd;
import android.content.res.Resources;
import android.util.Log;
import android.view.DragEvent;
import android.view.View;
import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.viewpager2.widget.ViewPager2;
import com.google.android.material.tabs.TabLayout;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
public class CrossTabDragAndDrop<
TabFragment extends Fragment & DragAndDropTab<ItemAdapter>,
ItemAdapter extends RecyclerView.Adapter<?> & DragAndDropAdapter<ItemModel>,
ItemModel extends DragAndDropModel
> {
private static final String TAG = CrossTabDragAndDrop.class.getCanonicalName();
private static final ScrollHelper SCROLL_HELPER = new ScrollHelper();
private final boolean isLayoutLtr;
private final float pxToReact;
private final float pxToReactTopBottom;
private final int dragAndDropMsToReact;
private final int dragAndDropMsToReactTopBottom;
private final int displayX;
private long lastSwap = 0;
private long lastMove = 0;
private final Set<ItemMovedByDragListener<ItemModel>> moveListenerList = new HashSet<>(1);
public CrossTabDragAndDrop(@NonNull Resources resources, boolean isLayoutLtr) {
this.displayX = resources.getDisplayMetrics().widthPixels;
final float density = resources.getDisplayMetrics().density;
this.pxToReact = resources.getInteger(R.integer.drag_n_drop_dp_to_react) * density;
this.dragAndDropMsToReactTopBottom = resources.getInteger(R.integer.drag_n_drop_dp_to_react_top_bottom);
this.pxToReactTopBottom = dragAndDropMsToReactTopBottom * density;
this.dragAndDropMsToReact = resources.getInteger(R.integer.drag_n_drop_ms_to_react);
this.isLayoutLtr = isLayoutLtr;
}
public void register(final ViewPager2 viewPager, TabLayout stackLayout, FragmentManager fm) {
viewPager.setOnDragListener((View v, DragEvent dragEvent) -> {
DraggedItemLocalState<TabFragment, ItemAdapter, ItemModel> draggedItemLocalState = (DraggedItemLocalState<TabFragment, ItemAdapter, ItemModel>) dragEvent.getLocalState();
View draggedView = draggedItemLocalState.getDraggedView();
switch (dragEvent.getAction()) {
case DragEvent.ACTION_DRAG_STARTED: {
draggedView.setVisibility(View.INVISIBLE);
draggedItemLocalState.onDragStart(viewPager, fm);
break;
}
case DragEvent.ACTION_DRAG_LOCATION: {
RecyclerView currentRecyclerView = draggedItemLocalState.getRecyclerView();
ItemAdapter itemAdapter = draggedItemLocalState.getItemAdapter();
long now = System.currentTimeMillis();
if (lastSwap + dragAndDropMsToReact < now) { // don't change Tabs so fast!
int oldTabPosition = viewPager.getCurrentItem();
boolean shouldSwitchTab = true;
int newTabPosition = -1;
// change tab? if yes, which direction?
if (dragEvent.getX() <= pxToReact) {
newTabPosition = isLayoutLtr ? oldTabPosition - 1 : oldTabPosition + 1;
} else if (dragEvent.getX() >= displayX - pxToReact) {
newTabPosition = isLayoutLtr ? oldTabPosition + 1 : oldTabPosition - 1;
} else {
shouldSwitchTab = false;
}
if (shouldSwitchTab && isMovePossible(viewPager, newTabPosition)) {
removeItem(currentRecyclerView, draggedView, itemAdapter);
detectAndKillDuplicatesInNeighbourTab(viewPager, draggedItemLocalState.getDraggedItemModel(), fm, oldTabPosition, newTabPosition);
switchTab(dragEvent, viewPager, stackLayout, fm, draggedItemLocalState, now, newTabPosition);
return true;
}
}
//scroll if needed
if (dragEvent.getY() <= pxToReactTopBottom) {
SCROLL_HELPER.startScroll(currentRecyclerView, ScrollHelper.ScrollDirection.UP);
} else if (dragEvent.getY() >= currentRecyclerView.getBottom() - pxToReactTopBottom) {
SCROLL_HELPER.startScroll(currentRecyclerView, ScrollHelper.ScrollDirection.DOWN);
} else {
SCROLL_HELPER.stopScroll();
}
if (lastMove + dragAndDropMsToReactTopBottom < now) {
//push around the other items
pushAroundItems(draggedView, currentRecyclerView, dragEvent, itemAdapter, draggedItemLocalState, now);
}
break;
}
case DragEvent.ACTION_DRAG_ENDED: {
draggedItemLocalState.getRecyclerView().removeOnChildAttachStateChangeListener(draggedItemLocalState.getInsertedListener());
SCROLL_HELPER.stopScroll();
draggedView.setVisibility(View.VISIBLE);
// Clean up the original dragged view, so the next onBindViewHolder() will not display the view at the position of the original dragged view as View.INVISIBLE
draggedItemLocalState.getOriginalDraggedView().setVisibility(View.VISIBLE);
notifyListeners(draggedItemLocalState);
break;
}
}
return true;
});
}
private void switchTab(DragEvent dragEvent, ViewPager2 viewPager, TabLayout stackLayout, FragmentManager fm, final DraggedItemLocalState<TabFragment, ItemAdapter, ItemModel> draggedItemLocalState, long now, int newPosition) {
viewPager.setCurrentItem(newPosition);
draggedItemLocalState.onTabChanged(viewPager, fm);
Objects.requireNonNull(stackLayout.getTabAt(newPosition)).select();
final RecyclerView recyclerView = draggedItemLocalState.getRecyclerView();
final ItemAdapter itemAdapter = draggedItemLocalState.getItemAdapter();
RecyclerView.OnChildAttachStateChangeListener onChildAttachStateChangeListener = new RecyclerView.OnChildAttachStateChangeListener() {
@Override
public void onChildViewAttachedToWindow(@NonNull View view) {
recyclerView.removeOnChildAttachStateChangeListener(this);
draggedItemLocalState.setInsertedListener(null);
view.setVisibility(View.INVISIBLE);
draggedItemLocalState.setDraggedView(view);
pushAroundItems(view, recyclerView, dragEvent, itemAdapter, (DraggedItemLocalState<TabFragment, ItemAdapter, ItemModel>) draggedItemLocalState, now);
}
@Override
public void onChildViewDetachedFromWindow(@NonNull View view) {/* do nothing */}
};
draggedItemLocalState.setInsertedListener(onChildAttachStateChangeListener);
recyclerView.addOnChildAttachStateChangeListener(onChildAttachStateChangeListener);
//insert item in new tab
View firstVisibleView = recyclerView.getChildAt(0);
int positionToInsert = firstVisibleView == null ? 0 : recyclerView.getChildAdapterPosition(firstVisibleView) + 1;
itemAdapter.insertItem(draggedItemLocalState.getDraggedItemModel(), positionToInsert);
lastSwap = now;
}
private void pushAroundItems(@NonNull View view, RecyclerView recyclerView, DragEvent dragEvent, ItemAdapter itemAdapter, DraggedItemLocalState<TabFragment, ItemAdapter, ItemModel> draggedItemLocalState, long now) {
View viewUnder = recyclerView.findChildViewUnder(dragEvent.getX(), dragEvent.getY());
if (viewUnder != null) {
int toPositon = recyclerView.getChildAdapterPosition(viewUnder);
if (toPositon != -1) {
int fromPosition = recyclerView.getChildAdapterPosition(view);
if (fromPosition != -1 && fromPosition != toPositon) {
recyclerView.post(() -> {
itemAdapter.moveItem(fromPosition, toPositon);
draggedItemLocalState.setPositionInItemAdapter(toPositon);
});
lastMove = now;
}
}
}
}
private static boolean isMovePossible(ViewPager2 viewPager, int newPosition) {
return newPosition < Objects.requireNonNull(viewPager.getAdapter()).getItemCount() && newPosition >= 0;
}
private void detectAndKillDuplicatesInNeighbourTab(ViewPager2 viewPager, ItemModel itemToFind, FragmentManager fm, int oldTabPosition, int newTabPosition) {
int tabPositionToCheck = newTabPosition > oldTabPosition ? newTabPosition + 1 : newTabPosition - 1;
if (isMovePossible(viewPager, tabPositionToCheck)) {
viewPager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
@Override
public void onPageSelected(int position) {
super.onPageSelected(position);
viewPager.unregisterOnPageChangeCallback(this);
ItemAdapter itemAdapter = DragAndDropUtil.<TabFragment>getTabFragment(fm, Objects.requireNonNull(viewPager.getAdapter()).getItemId(tabPositionToCheck)).getAdapter();
itemAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
@Override
public void onChanged() {
super.onChanged();
itemAdapter.unregisterAdapterDataObserver(this);
List<ItemModel> itemList = itemAdapter.getItemList();
for (int i = 0; i < itemList.size(); i++) {
ItemModel c = itemList.get(i);
if (itemToFind.getComparableId().equals(c.getComparableId())) {
itemAdapter.removeItem(i);
itemAdapter.notifyItemRemoved(i);
Log.v(TAG, "DnD removed dupe at tab " + tabPositionToCheck + ": " + c.toString());
break;
}
}
}
});
}
});
}
}
private void removeItem(RecyclerView currentRecyclerView, View view, ItemAdapter itemAdapter) {
int oldItemPosition = currentRecyclerView.getChildAdapterPosition(view);
if (oldItemPosition != -1) {
itemAdapter.removeItem(oldItemPosition);
}
}
private void notifyListeners(DraggedItemLocalState draggedItemLocalState) {
for (ItemMovedByDragListener listener : moveListenerList) {
listener.onItemMoved(draggedItemLocalState.getDraggedItemModel(), draggedItemLocalState.getCurrentTabId(), draggedItemLocalState.getPositionInItemAdapter());
}
}
public void addItemMovedByDragListener(ItemMovedByDragListener<ItemModel> listener) {
moveListenerList.add(listener);
}
}
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