滑动时的 RecyclerView ItemTouchHelper

Question

我正在尝试在回收站视图中实现滑动删除。我有这个代码。

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;
    }
}

但是，问题在于该行在滑动时被删除。我想将它保留在那里，即当滑动该行时，显示删除按钮，然后用户可以单击它，而不是完全滑动删除它，而是在滑动后显示删除按钮。另外，我也在尝试添加编辑按钮，但在左侧，删除，有什么想法吗？

Answer 1

我发现这种实现滑动删除的新方法非常友好，即在 oncreate 方法中实现 new ItemTouchHelper()。您所要做的就是在回收站中传递您要删除的项目的位置。请参阅下面的示例代码。这里我实现了新的 ItemTouchHelper() 以删除我在屏幕上向右或向左滑动的任何笔记。

代码如下：

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 是我的 recyclerview 的实例

要了解如何清楚地实现它，请按照我的 github 中的代码进行操作。这里是链接。 https://github.com/sammymutahigicheru/NoteApp

Answer 2

创建 ItemTouchHelper 并将其附加到 recyclerview。

将帮助程序附加到 RecyclerView 的代码

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

ItemTouchHelper 类的代码

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
            }
        }
    };