安卓ItemTouchHelper:如何在滑动过程中画出越来越大的圆圈

public class CustomItemTouchHelperCallback extends ItemTouchHelper.Callback {
    private Paint circlePaint;
    private int maxCircleRadius;

    public CustomItemTouchHelperCallback() {
        circlePaint = new Paint();
        circlePaint.setColor(Color.RED);
        circlePaint.setStyle(Paint.Style.FILL);
        maxCircleRadius = 100; // 设置最大圆圈半径
    }

    @Override
    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN; // 允许上下拖拽
        int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END; // 允许左右滑动
        return makeMovementFlags(dragFlags, swipeFlags);
    }

    @Override
    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
        // 处理拖拽事件
        // 返回true表示已处理
        return true;
    }

    @Override
    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
        // 处理滑动事件
    }

    @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) {
            // 计算圆圈半径
            float radius = Math.min(Math.abs(dX), maxCircleRadius);
            // 计算圆圈中心坐标
            float centerX = viewHolder.itemView.getRight() - radius;
            float centerY = viewHolder.itemView.getTop() + viewHolder.itemView.getHeight() / 2;
            // 绘制圆圈
            c.drawCircle(centerX, centerY, radius, circlePaint);
        }
        super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
    }
}

ItemTouchHelper.Callback callback = new CustomItemTouchHelperCallback();
ItemTouchHelper itemTouchHelper = new ItemTouchHelper(callback);
itemTouchHelper.attachToRecyclerView(recyclerView);