背景：如何在跨越兩個或兩個以上的item繪制一個view，該view需要跟隨recyclerView的滑動而整體移動。

 @Overridepublic void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {super.onDrawOver(c, parent, state);final View child = parent.getChildAt(1);if (child != null) {final int left = child.getLeft();final int right = child.getRight();final int top = child.getTop();final int bottom = child.getBottom();int rightV = (right - left) / 6;int leftV = (right - rightV) - VAUtils.dip2px(mContext, 225);int topV = bottom - VAUtils.dip2px(mContext, 16);int bottomV = topV + VAUtils.dip2px(mContext, 82);ViewGroup.MarginLayoutParams margin = new ViewGroup.MarginLayoutParams(mImageView.getLayoutParams());margin.setMargins(leftV, topV, rightV, bottomV);RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(margin);mImageView.setLayoutParams(layoutParams);if (!imageClicked) {mImageView.setVisibility(View.VISIBLE);}//畫筆final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);//圓心 x 坐標final float x = parent.getWidth() / 2 + left;圓心 y 坐標final float y = 100 + top;//半徑final float radius = 100;//漸變著色器 坐標隨意設置的final LinearGradient shader = new LinearGradient(x-50, 0, x+100, 200, Color.RED, Color.YELLOW, Shader.TileMode.REPEAT);paint.setShader(shader);//繪制圓c.drawCircle(x, y, radius, paint);}}

@Override
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {super.onDrawOver(c, parent, state);//畫筆final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);//圓心 x 坐標final float x = parent.getWidth() / 2;圓心 y 坐標final float y = 100;//半徑final float radius = 100;//漸變著色器 坐標隨意設置的final LinearGradient shader = new LinearGradient(x-50, 0, x+100, 200, Color.RED, Color.YELLOW, Shader.TileMode.REPEAT);paint.setShader(shader);//繪制圓c.drawCircle(x, y, radius, paint);
}