Question

我需要在我的RecyclerView上执行一些拖动类似的操作，当我到达RecyclerView的顶端或底端时，我想要顺利滚动它...

我这样做如下：我发布此runnable进行滚动，直到用户不再接近RecyclerView的开头/结尾。

mScroll = new Runnable() {
        @Override
        public void run() {
            rvImages.smoothScrollBy(0, mScrollDist.get());
            mHandler.postDelayed(mScroll, 100);
        }
    };

我需要定义的问题是，滚动所需的距离应该在100毫秒内完成，这样整体滚动就会很平滑。

我怎样才能做到这一点？

Answer 1

使用自定义LinearLayoutManager

ClassBasedView

自定义Scrool速度

     public class MyCustomLayoutManager extends LinearLayoutManager {
            //We need mContext to create our LinearSmoothScroller
            private Context mContext;

            public MyCustomLayoutManager(Context context) {
                super(context);
                mContext = context;
            }

            //Override this method? Check.
            @Override
            public void smoothScrollToPosition(RecyclerView recyclerView,
                RecyclerView.State state, int position) {

                //Create your RecyclerView.SmoothScroller instance? Check.
                LinearSmoothScroller smoothScroller = 
                    new LinearSmoothScroller(mContext) {

                    //Automatically implements this method on instantiation.
                    @Override
    public PointF computeScrollVectorForPosition(int targetPosition) {
        //What is PointF? A class that just holds two float coordinates.
        //Accepts a (x , y)
        //for y: use -1 for up direction, 1 for down direction.
        //for x (did not test): use -1 for left direction, 1 for right
        //direction.
        //We let our custom LinearLayoutManager calculate PointF for us
        return MyCustomLayoutManager.this.computeScrollVectorForPosition
            (targetPosition);
    }
};

                //Docs do not tell us anything about this,
                //but we need to set the position we want to scroll to.
                smoothScroller.setTargetPosition(position);

                //Call startSmoothScroll(SmoothScroller)? Check.
                startSmoothScroll(smoothScroller);
            }
        }

活动：

//Make an instance variable at the top of you custom LayoutManager
private static final float MILLISECONDS_PER_INCH = 50f;
    .
    .
    .
    LinearSmoothScroller smoothScroller = 
        new LinearSmoothScroller(mContext) {
        .
        .
        .
        //The holy grail of smooth scrolling
        //returns the milliseconds it takes to scroll one pixel.
        @Override
        protected float calculateSpeedPerPixel
            (DisplayMetrics displayMetrics) {
            return MILLISECONDS_PER_INCH / displayMetrics.densityDpi;
        }
    };

source code

ReyclerView - 以预定义的时间以编程方式滚动

1 个答案: