手动调用ItemTouchHelper.OnChildDraw（）在RecyclerView上滑动项

Question

问题是ItemTouchHelper.onChildDraw()将canvas作为参数，根据文档，该参数是“RecyclerView正在绘制其子级的画布”。有没有办法从recyclerview中获取画布？如果执行ItemTouchHelper.onChildDraw（new Canvas（）...),则会执行代码,但在ViewWholder后面没有绘制任何内容,因为它显然不是recyclerview使用的画布...也许有办法设置一个canvas供recyclerview使用吗？

谢谢你的正手点子。

Answer 1

我解决这一问题的方法是创建一个自定义视图，扩展RecyclerView，并保存android onDraw（）生成的canvas对象。然后我可以获取相同的画布，只要我想通过代码手动触发滑动。

public class CanvasRecyclerView extends RecyclerView {
    private Canvas mCanvas;

    public CanvasRecyclerView(final Context context) { super(context); }

    public CanvasRecyclerView(final Context context, @Nullable final AttributeSet attrs) { super(context, attrs); }

    @Override public void onDraw(final Canvas c) {
        mCanvas = c;
        super.onDraw(c);
    }

    public Canvas getCanvas() {
        return mCanvas;
    }
}

希望有帮助！

更新

private fun swipeCard(direction: Int) {
    val visibleChild = (recyclerView?.layoutManager as LinearLayoutManager).findFirstVisibleItemPosition()
    val holder = recyclerView?.findViewHolderForAdapterPosition(visibleChild) ?: return

    val dX = if (direction == LEFT) -holder.itemView.width else holder.itemView.width

    val translation = SwipeAnimation(dX.toFloat()) //your translation here
    translation.setSwipingElements(recyclerView, touchHelper, holder)
    emptyView.startAnimation(translation)
}