14 segment display font viewer(simulator)

# 14 segment display decoder and viewer (simulator)
# the segment image is taken from below link
# https://www.youtube.com/channel/UCXBrLU1A-J51eVtTOEsIbAw/community?lb=UgkxViWPs-1e6Ii89cxlRPN2EHmUE_I0ngLM

import cv2
import numpy as np
import ctypes
ctypes.windll.user32.SetProcessDPIAware()

# 14 segment chars image
img = cv2.imread('segment.png')
seg_area = [(90, 114), (774, 1935)] # first and last display center coords
h_count = 8
v_count = 12
# pixels lower than this grayscale value will be considered as "ON"
threshold = 100
inverse_threshold = True

# position of each segments (clockwise, from outer to inner, centered)
seg_coords = [(1, -67), (36, -37), (38, 32), (2, 71), (-33, 37), (-34, -35), (-15, 3), (20, 2), (-16, -33), (2, -33), (18, -32), (20, 37), (2, 36), (-15, 37)]
seg_datas = []

# preprocess the image
img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
threshold_type = cv2.THRESH_BINARY_INV if inverse_threshold else cv2.THRESH_BINARY
ret, img = cv2.threshold(img, threshold, 255, threshold_type)

# parse 14 segment data - detect segment by distance
seg_w = (seg_area[1][0] - seg_area[0][0]) / (h_count-1)
seg_h = (seg_area[1][1] - seg_area[0][1]) / (v_count-1)
for v in range(v_count):
    for h in range(h_count):
        # current char index
        index = v*h_count + h
        seg_data = 0 # 14-bit binary data

        # current display center coord
        cx = ((seg_area[1][0] - seg_area[0][0]) / (h_count-1)) * h + seg_area[0][0]
        cy = ((seg_area[1][1] - seg_area[0][1]) / (v_count-1)) * v + seg_area[0][1]

        # crop current display image
        x0, x1 = int(cx - seg_w/2), int(cx + seg_w/2)
        y0, y1 = int(cy - seg_h/2), int(cy + seg_h/2)
        segment_img = img[y0:y1, x0:x1]

        # find contours and measure each distance to the nearest segment center
        contours, _ = cv2.findContours(segment_img, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
        for contour in contours:
            dists = []
            for coord in seg_coords:
                x, y = coord
                x = int(x+seg_w/2)
                y = int(y+seg_h/2)
                dist = cv2.pointPolygonTest(contour, (x, y), True)
                dists.append(dist)

            # find the nearest segment index
            seg_index = np.argmax(np.array(dists))
            seg_data |= 1 << seg_index

        # append to the list
        seg_datas.append(seg_data)

# print char segment datas
for data in seg_datas:
    print(f'0x{data:04x}, ', end='')

# segment display simulator

# the last image is used as "full segment display" reference
x0, x1 = int(seg_area[1][0] - seg_w/2), int(seg_area[1][0] + seg_w/2)
y0, y1 = int(seg_area[1][1] - seg_h/2), int(seg_area[1][1] + seg_h/2)
segment_img = img[y0:y1, x0:x1]

# find each segment with segment coordinates
segment_contours = []
contours, _ = cv2.findContours(segment_img, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
for coord in seg_coords:
    x, y = coord
    x = int(x+seg_w/2)
    y = int(y+seg_h/2)
    for contour in contours:
        if cv2.pointPolygonTest(contour, (x, y), False) > 0:
            segment_contours.append(contour)
            break

def draw_segment(segment_img, char_index, offset):
    seg_data = seg_datas[char_index]
    for seg_index in range(14):
        if seg_data & (1 << seg_index):
            segment_img = cv2.drawContours(segment_img, [segment_contours[seg_index]], -1, 255, -1, offset=offset)
    return segment_img

# main view loop
window = '14 segment viewer'
char_count = 10
text_list = list(' '*char_count)
auto_text_list = list('')
while True:
    img = np.zeros((int(seg_h), int(seg_w*char_count)), 'uint8')
    for i, char in enumerate(text_list):
        x = int(i*seg_w)
        img = draw_segment(img, ord(char)-32, (x, 0))

    cv2.imshow(window, img)
    if len(auto_text_list) != 0:
        key = cv2.waitKey(500)
        print(key)
        if key > 0:
            auto_text_list = []
        else:
            key = ord(auto_text_list.pop(0))
    else:
        key = cv2.waitKey(0)

    if cv2.getWindowProperty(window, cv2.WND_PROP_VISIBLE) < 1:
        break

    if key == 8: # backspace
        text_list = text_list[:-1]
        text_list.insert(0, ' ')
    elif key == 13: # enter
        text_list = list(' '*char_count)
    elif(key & 0xFF): # other keys
        text_list.pop(0)
        text_list.append(chr(key))