Center text on a OpenCV frame in Python

center_text_on_cv2_frame.py

#!/usr/bin/env python

import cv2
import numpy as np
from enum import IntEnum

class Position(IntEnum):
    """
    Where on frame do we want to print text.
    """
    TopLeft = 0
    MidLeft = 1
    BottomLeft = 2
    TopMid = 10
    Mid = 11
    BottomMid = 12
    TopRight = 20
    MidRight = 21
    BottomRight = 22

def framePrint(frame, text: str, position: Position = Position.BottomLeft, padPx=10):
    """
    Prints text on the frame.
    @param frame: Frame
    @param text: Text to be printed
    @param position: Where on frame we want to print the text
    @param padPx: Padding (in pixels)
    """
    font = cv2.FONT_HERSHEY_SIMPLEX
    textSize = cv2.getTextSize(text, font, fontScale=1.0, thickness=1)[0]
    frameW = frame.shape[1]
    frameH = frame.shape[0]

    yPos = int(position) % 10
    if yPos == 0: # Y Top
        y = textSize[1] + padPx
    elif yPos == 1: # Y Mid
        y = int(frameH / 2) + int(textSize[1] / 2)
    else:  # yPos == 2. Y Bottom
        y = frameH - padPx

    xPos = int(position) // 10
    if xPos == 0: # X Left
        x = padPx
    elif xPos == 1:  # X Mid
        x = int(frameW / 2) - int(textSize[0] / 2)
    else:  # xPos == 2  # X Right
        x = frameW - textSize[0] - padPx

    cv2.putText(frame, text, (x, y), font, fontScale=1.0, color=(255,255,255))

frame = np.zeros((600, 900, 3), np.uint8)
txt = "Hello World!"

framePrint(frame, 'TopLeft!', Position.TopLeft)
framePrint(frame, 'TopMid!', Position.TopMid)
framePrint(frame, 'TopRight!', Position.TopRight)
framePrint(frame, 'MidLeft!', Position.MidLeft)
framePrint(frame, 'Middle!', Position.Mid)
framePrint(frame, 'MidRight!', Position.MidRight)
framePrint(frame, 'BottomLeft!', Position.BottomLeft)
framePrint(frame, 'BottomMid!', Position.BottomMid)
framePrint(frame, 'BottomRight!', Position.BottomRight)

cv2.imshow('Frame', frame)
cv2.waitKey()

you could just have a vertical align parameter and a horizontal align one