I am trying to implement a swipe feature for recyclerview. I found this tutorial for that:
Swipe ⇆ Drag ⇅ Bind RecyclerView
The code is available here:
First of all I don't understand why is there an interface SwipeHandler which is implemented by MainActivity and another one within the SwipeItemTouchHelperCallback class? SwipeHandler is never used!? Is that a mistake?
Why am I asking this question? Because for my own project I have some trouble to connect the swipe off event with the appropriate callback within my fragment. The onItemSwiped method within the fragment is never called. So I changed the code a bit (I don't have a SwipeHandler...just use the interface within SwipeItemTouchHelper):
public class FragmentFlightRecords extends Fragment implements SwipeToDeleteCallback.OnItemSwipeListener {
@Override
public void onItemSwiped(int position) {
saveAndRemoveItem(position);
showSnackbar("Swiped Left " + position);
}
}
layout.xml:
<variable
name="handler"
type="de.flightlogger.view.adapter.SwipeToDeleteCallback.OnItemSwipeListener" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/rv_flight_records"
android:layout_width="match_parent"
android:layout_height="0dp"
android:adapter="@{adapter}"
android:visibility="@{viewmodel.flightRecords.size() != 0}"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="@id/cl_total_flight_time"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
bind:bgColorSwipe="@{@color/primaryDarkColor}"
bind:drawableSwipe="@{@drawable/ic_add_black_24dp}"
bind:onItemSwipe="@{(position) -> handler.onItemSwiped(position)}"
bind:swipeEnabled="@{true}"
tools:listitem="@layout/rv_item_flight_records"/>
SwipeToDeleteCallback:
public class SwipeToDeleteCallback extends ItemTouchHelper.SimpleCallback {
private Drawable icon;
private ColorDrawable background;
private OnItemSwipeListener onItemSwipeListener;
private boolean swipeEnabled;
private SwipeToDeleteCallback(int dragDirs, int swipeDirs) {
super(dragDirs, swipeDirs);
}
private SwipeToDeleteCallback(Builder builder) {
this(builder.dragDirs, builder.swipeDirs);
background = builder.bgColorSwipe;
icon = builder.drawableSwipe;
swipeEnabled = builder.swipeEnabled;
onItemSwipeListener = builder.onItemSwipeListener;
}
@Override public boolean isItemViewSwipeEnabled() {
return swipeEnabled;
}
@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
return false;
}
@Override public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
int position = viewHolder.getAdapterPosition();
onItemSwipeListener.onItemSwiped(position);
}
@Override
public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
View itemView = viewHolder.itemView;
int backgroundCornerOffset = 20; //so background is behind the rounded corners of itemView
int iconMargin = (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
int iconTop = itemView.getTop() + (itemView.getHeight() - icon.getIntrinsicHeight()) / 2;
int iconBottom = iconTop + icon.getIntrinsicHeight();
if (dX > 0) { // Swiping to the right
int iconLeft = itemView.getLeft() + iconMargin;
int iconRight = itemView.getLeft() + icon.getIntrinsicWidth() + iconMargin;
icon.setBounds(iconLeft, iconTop, iconRight, iconBottom);
background.setBounds(itemView.getLeft(), itemView.getTop(),
itemView.getLeft() + ((int) dX) + backgroundCornerOffset, itemView.getBottom());
} else if (dX < 0) { // Swiping to the left
int iconLeft = itemView.getRight() - iconMargin - icon.getIntrinsicWidth();
int iconRight = itemView.getRight() - iconMargin;
icon.setBounds(iconLeft, iconTop, iconRight, iconBottom);
background.setBounds(itemView.getRight() + ((int) dX) - backgroundCornerOffset,
itemView.getTop(), itemView.getRight(), itemView.getBottom());
} else { // view is unSwiped
background.setBounds(0, 0, 0, 0);
}
background.draw(c);
icon.draw(c);
}
public interface OnItemSwipeListener {
void onItemSwiped(int position);
}
public static final class Builder {
private int dragDirs, swipeDirs;
private Drawable drawableSwipe;
private ColorDrawable bgColorSwipe;
private OnItemSwipeListener onItemSwipeListener;
private boolean swipeEnabled;
public Builder(int dragDirs, int swipeDirs) {
this.dragDirs = dragDirs;
this.swipeDirs = swipeDirs;
}
public Builder drawableSwipe(Drawable val) {
drawableSwipe = val;
return this;
}
public Builder bgColorSwipe(ColorDrawable val) {
bgColorSwipe = val;
return this;
}
public Builder onItemSwipeListener(OnItemSwipeListener val) {
onItemSwipeListener = val;
return this;
}
public Builder setSwipeEnabled(boolean val) {
swipeEnabled = val;
return this;
}
public SwipeToDeleteCallback build() {
return new SwipeToDeleteCallback(this);
}
}
}
Binding Adapter:
@BindingAdapter(value = {"swipeEnabled", "drawableSwipe", "bgColorSwipe", "onItemSwipe"}, requireAll = false)
public static void setItemSwipeToRecyclerView(RecyclerView recyclerView, boolean swipeEnabled, Drawable drawableSwipe, ColorDrawable bgColorSwipe,
SwipeToDeleteCallback.OnItemSwipeListener onItemSwipe) {
ItemTouchHelper.Callback swipeCallback = new SwipeToDeleteCallback
.Builder(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT)
.bgColorSwipe(bgColorSwipe)
.drawableSwipe(drawableSwipe)
.setSwipeEnabled(swipeEnabled)
.onItemSwipeListener(onItemSwipe)
.build();
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(swipeCallback);
itemTouchHelper.attachToRecyclerView(recyclerView);
}
The swiping itself works but it doesn't have a functionallity. The item of the recyclerview is not deleted and debuging tells me that the callback onItemSwiped within the fragment is never called. So what am I missing to hook up the swipe off event to the onItemSwiped callback within the fragment?
