RecyclerView ItemTouchHelper 滑动

Question

I'm trying to implement swipe to delete in a recycler view. I have this code.

public abstract class SwipeToDeleteCallback extends ItemTouchHelper.Callback {
    private Context context;
    private Paint clearPaint;
    private ColorDrawable background;
    private int backgroundColor;
    private Drawable deleteDrawable;
    private int intrinsicWidth;
    private int intrinsicHeight;

    public SwipeToDeleteCallback(Context context) {
        this.context = context;
        background = new ColorDrawable();
        backgroundColor = Color.parseColor("#DB3236");
        clearPaint = new Paint();
        clearPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
        deleteDrawable = ContextCompat.getDrawable(this.context, R.drawable.ic_delete_white_24dp);
        intrinsicWidth = deleteDrawable.getIntrinsicWidth();
        intrinsicHeight = deleteDrawable.getIntrinsicHeight();
    }

    @Override
    public int getMovementFlags(@NonNull RecyclerView recyclerView,
                                @NonNull RecyclerView.ViewHolder viewHolder) {
        return makeMovementFlags(0, ItemTouchHelper.LEFT);
    }

    @Override
    public boolean onMove(@NonNull RecyclerView recyclerView,
                          @NonNull RecyclerView.ViewHolder viewHolder,
                          @NonNull RecyclerView.ViewHolder viewHolder1) {
        return false;
    }

    @Override
    public void onChildDraw(@NonNull Canvas canvas, @NonNull RecyclerView recyclerView,
                            @NonNull RecyclerView.ViewHolder viewHolder, float dX, float dY,
                            int actionState, boolean isCurrentlyActive) {
        super.onChildDraw(canvas, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);

        View itemView = viewHolder.itemView;
        int itemHeight = itemView.getHeight();

        boolean isCancelled = dX == 0 && !isCurrentlyActive;

        if (isCancelled) {
            clearCanvas(canvas, itemView.getRight() + dX, (float) itemView.getTop(),
                    (float) itemView.getRight(), (float) itemView.getBottom());
            super.onChildDraw(canvas, recyclerView, viewHolder, dX, dY, actionState,
                    isCurrentlyActive);
            return;
        }

        background.setColor(backgroundColor);
        background.setBounds(itemView.getRight() + (int) dX, itemView.getTop(),
                itemView.getRight(), itemView.getBottom());
        background.draw(canvas);

        int deleteIconTop = itemView.getTop() + (itemHeight - intrinsicHeight) / 2;
        int deleteIconMargin = (itemHeight - intrinsicHeight) / 2;
        int deleteIconLeft = itemView.getRight() - deleteIconMargin - intrinsicWidth;
        int deleteIconRight = itemView.getRight() - deleteIconMargin;
        int deleteIconBottom = deleteIconTop + intrinsicHeight;

        deleteDrawable.setBounds(deleteIconLeft, deleteIconTop, deleteIconRight, deleteIconBottom);
        deleteDrawable.draw(canvas);

        super.onChildDraw(canvas, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
    }

    private void clearCanvas(Canvas canvas, Float left, Float top, Float right, Float bottom) {
        canvas.drawRect(left, top, right, bottom, clearPaint);
    }

    @Override
    public float getSwipeThreshold(@NonNull RecyclerView.ViewHolder viewHolder) {
        return 0.7f;
    }
}

However, the problem is that the row is deleted as it is swiped. I would like to maintain it there ie when the row is swiped, show the delete button and then the user can click on it, instead of swiping fully deletes it, instead show the delete button after the swipe. Also, am trying to add the edit button as well but on the left, with the delete, any ideas how?

Answer 1

Create ItemTouchHelper and attach it to recyclerview.

Code to attach helper to RecyclerView

itemTouchHelper = new ItemTouchHelper(simpleCallback);
itemTouchHelper.attachToRecyclerView(recyclerView);

Code of ItemTouchHelper class

ItemTouchHelper.SimpleCallback simpleCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {

        private void drawText(String text, Canvas c, RectF button, Paint p) {
            float textSize = 30;
            p.setColor(Color.WHITE);
            p.setAntiAlias(true);
            p.setTextSize(textSize);

            float textWidth = p.measureText(text);
            c.drawText(text, button.centerX() - (textWidth / 2), button.centerY() + (textSize / 2), p);
        }

        @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) {

                View itemView = viewHolder.itemView;
                Paint p = new Paint();

                if (dX > 0) {
                    c.drawRect((float) itemView.getLeft(), (float) itemView.getTop(), dX,
                            (float) itemView.getBottom(), p);
                } else {
                    RectF rightButton = new RectF(itemView.getRight() - 200, (itemView.getTop() + dpToPx(4)),
                            (itemView.getRight() - dpToPx(4)), (itemView.getBottom() - dpToPx(8)));
                    p.setColor(ContextCompat.getColor(MainActivity.this, R.color.colorAccent));
                    c.drawRoundRect(rightButton, 10, 10, p);
                    drawText("Del", c, rightButton, p);
                }

                // Fade out the view when it is swiped out of the parent
                final float alpha = 1 - Math.abs(dX) / (float) viewHolder.itemView.getWidth();
                viewHolder.itemView.setAlpha(alpha);
                viewHolder.itemView.setTranslationX(dX);
            } else {
                super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
            }
        }

        @Override
        public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
            return false;
        }

        @Override
        public void onSwiped(final RecyclerView.ViewHolder viewHolder, int direction) {
            final int position = viewHolder.getAdapterPosition();
            if (direction == ItemTouchHelper.LEFT) {
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setMessage("Are you sure to delete?");
                builder.setPositiveButton("REMOVE", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        adapter.notifyItemRemoved(position);
                        mProductViewModel.delete(adapter.getItem(position));
                        return;
                    }
                }).setNegativeButton("CANCEL", new DialogInterface.OnClickListener() {  //not removing items if cancel is done
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        adapter.notifyItemRemoved(position + 1);
                        adapter.notifyItemRangeChanged(position, adapter.getItemCount());
                        return;
                    }
                }).show();  //show alert dialog
            }
        }
    };

Answer 2

I find this new way of implementing swipe to delete quite friendly,that is implementing new ItemTouchHelper() in oncreate method.All you have to do is pass in the position of the item you want to delete in the recyclervew. See the the example code below.Here i implemented the new ItemTouchHelper() for it to delete any note i swipe right or left of my screen.

here is the code:

new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0,
            ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
        @Override
        public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder viewHolder1) {
            return false;
        }

        @Override
        public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int i) {
            noteViewModel.delete(noteAdapter.getNoteAt(viewHolder.getAdapterPosition()));
            Toast.makeText(MainActivity.this, "Note Deleted", Toast.LENGTH_SHORT).show();
        }
    }).attachToRecyclerView(rv_notes);

rv_notes is the instance of my recyclerview

To understand how you can implement it clearly ,follow the code in my github.Here is the link. https://github.com/sammymutahigicheru/NoteApp