Python cv2 图片中鼠标画框如何在下次画框时自动删除上一次框

问题遇到的现象和发生背景

使用cv2库来在图片上画框，如何在下一次画框时，自动删除上一次的框

问题相关代码，请勿粘贴截图

import cv2

global img
global point1, point2
global g_rect
drawing = False  # 鼠标按下为真
ix, iy = -1, -1
px, py = -1, -1


def draw_circle(event, x, y, flags, param):
    global ix, iy, drawing, px, py, img, point1, point2
    img2 = img.copy()
    if event == cv2.EVENT_LBUTTONDOWN:  # 左键点击,则在原图打点
        drawing = True
        ix, iy = x, y
        xy = "%d,%d" % (x, y)
        point1 = (ix, iy)
        cv2.circle(img2, point1, 2, (0, 255, 0), thickness=0)
        cv2.putText(img, xy, (x, y), cv2.FONT_HERSHEY_PLAIN, 1.5, (0, 255, 0), thickness=1)
        cv2.imshow('image', img2)

    elif event == cv2.EVENT_MOUSEMOVE and (flags & cv2.EVENT_FLAG_LBUTTON):  # 按住左键拖曳，画框
        if drawing == True:
            cv2.rectangle(img2, point1, (x, y), (0, 255, 0), thickness=0)
            cv2.imshow('image', img2)
            cv2.waitKey(16)

    elif event == cv2.EVENT_LBUTTONUP:  # 左键释放，显示
        drawing = False
        point2 = (x, y)
        xy = "%d,%d" % (x, y)
        cv2.rectangle(img, (ix, iy), (x, y), (0, 255, 0), thickness=0)
        cv2.putText(img, xy, (x, y), cv2.FONT_HERSHEY_PLAIN, 1.5, (0, 255, 0), thickness=1)
        cv2.imshow('image', img2)
        px, py = -1, -1


def get_coordinate_by_frame(img_path):
    global img
    img = cv2.imread(img_path)  # 图片路径
    cv2.namedWindow('image', cv2.WINDOW_AUTOSIZE)
    cv2.setMouseCallback('image', draw_circle)
    while True:
        cv2.imshow('image', img)
        cv2.waitKey(1)
        # 点击窗口X按钮关闭窗口
        if cv2.getWindowProperty('image', cv2.WND_PROP_VISIBLE) < 1:
            break


if __name__ == '__main__':
    pass
    img_path = "E:\import\\1.png"
    get_coordinate_by_frame(img_path)

运行结果及报错内容

我的解答思路和尝试过的方法

我想要达到的结果

下次画框时，上次的框自动删除

建议每次画框都在原图的基础上拷贝一份，在拷贝上画框，这样就不会一直在一个地方画框