Python. Determining the area of ​​a figure found using OpenCV?

Question

Python

A document is given (let's say that it is printed, and not drawn as I have here)
The code is written in such a way that it finds the contour of the object's border, but I cannot take the area or points.
Here is the result of what I managed to do.
I need to calculate the area of ​​\u200b\u200bthis figure ... The first thing that came to my mind was the Peak formula, but in order to do it, you need to build a cell with a size of 1 cm on an A4 sheet (accuracy is not as important as the result) . Further, using the formula S = L + (B / 2) -1, it will be possible to calculate the area of ​​\u200b\u200bthe figure, where L are points inside the figure, and B are points on the contour of the figure.
As I understand it, you can somehow calculate the points inside the object through the cv.floodfill function, but I could not master it. Who can write this code for me? I already have no idea, I just started to study OpenCV (3.7), but there are very few such instructions, I only find a theory that does not relate to my task in any way

#мой код
import numpy as np
import cv2 as cv
import imutils
import cv2

# параметры цветового фильтра
hsv_min = np.array((0, 54, 5), np.uint8)
hsv_max = np.array((187, 255, 253), np.uint8)
img = cv.imread("C:\\45\\000.jpg")
hsv = cv.cvtColor(img, cv.COLOR_BGR2HSV )
# меняем цветовую модель с BGR на HSV
thresh = cv.inRange(hsv, hsv_min, hsv_max )
# применяем цветовой фильтр
# ищем контуры и складируем их в переменную contours
contours, hierarchy = cv.findContours(thresh.copy(), cv.RETR_EXTERNAL, cv.CHAIN_APPROX_NONE)
#попытка нарисовать хотябы линию на картинке (не работает)
c = max(contours, key = cv.contourArea)
M = cv2.moments(c)
if M["m00"] != 0:
    cX = int(M["m10"] / M["m00"])
    cY = int(M["m01"] / M["m00"])
    print (cX,cY)
else:
    cX, cY = 0,0
    print (cX,cY)

# отображаем контуры поверх изображения
cv.drawContours(img, contours, -1, (255, 0, 0), 2, cv.LINE_AA, hierarchy, 0)
cv.imshow('contours', img)
cv.drawContours(img, contours, -1, (255, 0, 0), 2, cv.LINE_AA, hierarchy, 2)
# выводим итоговое изображение в окно
cv.imshow('All_con', img)
cv.imshow('thresh', thresh)
cv.waitKey()
cv.destroyAllWindows()

Answer 1

It's already calculated, it's M["m00"].

Answer 2

There are many ways.
If the polygon is vectorized, i.e., the coordinates of the ends of all its edges are known, then the polygon is triangulated into a set of triangles (it is first divided into a set of convex polygons) and its area is calculated for each.
If it is a raster, then yes, it is necessary to calculate the area of ​​the filled figure. Here the main problem is in determining the starting point, which will definitely lie inside the polygon.