ItemTouchHelper获取滑动方向

Question

我需要改变基于滑动方向的行项的背景颜色，如果向右滑动，则将颜色更改为绿色，如果向左滑动，则将颜色更改为红色。

但我发现很难弄清楚刷卡的方向。

这是我的代码。

public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback 
{

private final ItemTouchHelperAdapter mAdapter;
public SimpleItemTouchHelperCallback(ItemTouchHelperAdapter mAdapter) {
    this.mAdapter = mAdapter;
}

@Override
public boolean isItemViewSwipeEnabled() {
    return true;
}

@Override
public boolean isLongPressDragEnabled() {
    return false;
}

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

@Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
    final int swipeFlags = ItemTouchHelper.START |  ItemTouchHelper.END;
    return makeMovementFlags(dragFlags,swipeFlags);
}

@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
    if(direction == ItemTouchHelper.LEFT){
        Log.i("Swipe direction : ","Left");
    }
    else if (direction == ItemTouchHelper.RIGHT){
        Log.i("Swipe direction : ","Right");
    }
    mAdapter.onItemDismiss(viewHolder.getAdapterPosition());
}
}

我在日志里没有得到任何价值。

请提个建议。

Answer 1

如拉米斯所示，您可以使用ItemTouchHelper.SimpleCallback的onChildDraw回调来检测swipe 的方向，同时swipe正在进行，然后您可以使用此回调根据swipe的方向显示不同的项目背景。完成后，onSwiped回调将检测滑动的方向，您可以在那里决定要采取的操作。

new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {

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

        // dX (float) is the amount of horizontal displacement caused by user's action.            
        // If the horizontal displacement is positive the item is being 
        // swiped to the RIGHT, if it is negative the item is being 
        // swiped to the LEFT.

        if(dX >0) {
            // RIGHT swipe   
            } else {
            // LEFT swipe
            }
    }

}).attachToRecyclerView(mRecyclerView);

Answer 2

您可以使用onChildDraw方法，有关完整的代码Swipable Recycler view，请参阅下面的教程