android - 在水平回收器 View 中捕捉

Question

我有一个水平的 Recycler View，我想在其中启用捕捉。我阅读了一些关于 SO 的主题并找到了 this代码工作得很好。我不太了解 Recycler View 和 Layout Managers 的内部工作原理，所以想问一下是否可以将代码修改为:

1. 无论 throw 速度如何，我只想向前或向后移动一个项目。

2. 捕捉速度很慢。如果我将 View 移动到宽度的一半以上，下一个项目就会进入中心但速度非常慢。可以增加它以便即时捕捉吗？

关于如何实现上述行为的任何想法都将非常有帮助。

Answer 1

在其他代码的帮助下终于弄明白了:

public class FlingRecyclerView extends RecyclerView {

    int screenWidth;

    public FlingRecyclerView(Context context) {
        super(context);
        WindowManager windowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
        Display display = windowManager.getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        screenWidth = size.x;
    }

    public FlingRecyclerView(Context context, AttributeSet attrs) {
        super(context, attrs);
        WindowManager windowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
        Display display = windowManager.getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        screenWidth = size.x;
    }

    public FlingRecyclerView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        WindowManager windowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
        Display display = windowManager.getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        screenWidth = size.x;
    }

    @Override
    public boolean fling(int velocityX, int velocityY) {
        LinearLayoutManager linearLayoutManager = (LinearLayoutManager) getLayoutManager();

//these four variables identify the views you see on screen.
        int lastVisibleView = linearLayoutManager.findLastVisibleItemPosition();
        int firstVisibleView = linearLayoutManager.findFirstVisibleItemPosition();
        View firstView = linearLayoutManager.findViewByPosition(firstVisibleView);
        View lastView = linearLayoutManager.findViewByPosition(lastVisibleView);

//these variables get the distance you need to scroll in order to center your views.
//my views have variable sizes, so I need to calculate side margins separately.
//note the subtle difference in how right and left margins are calculated, as well as
//the resulting scroll distances.


        int leftMargin = (screenWidth - lastView.getWidth()) / 2;
        int rightMargin = (screenWidth - firstView.getWidth()) / 2 + firstView.getWidth();
        int leftEdge = lastView.getLeft();
        int rightEdge = firstView.getRight();
        int scrollDistanceLeft = leftEdge - leftMargin;
        int scrollDistanceRight = rightMargin - rightEdge;

//if(user swipes to the left)
        if (velocityX > 0) smoothScrollBy(scrollDistanceLeft, 0);
        else smoothScrollBy(-scrollDistanceRight, 0);

        return true;
    }
}

非常适合我的要求。希望它也能帮助其他人。