在一个线程中运行 function 并返回一个列表

Question

我的主循环从 WindowCapture class 返回一个屏幕截图。 然后我将此屏幕截图传递给 Vision class，它有一个 find() function 以在 haystack_img 中找到 needle_img。 两个类都在下面。

# main.py
from windowcapture import WindowCapture
from vision import Vision
import cv2 as cv
import numpy as np

# find the handle for the window we want to capture
# initialize the WindowCapture class. This works, runs in its own thread and returns a screenshot.
wincap = WindowCapture('Calculator')
# initialize the find_item class. Reads the image, saves dimenstions of passed image.
needle_img = Vision('number_1.jpg')
# WindowCapture class runs in its own thread
wincap.start()

while True:
    if wincap.screenshot is None:
        continue
    # get an updated image of 'Calculator'
    haystack_img = wincap.screenshot
    # do object detection
    # How do I run below code its own thread?
    rectangles = find_item.find(haystack_img)
    if cv.waitKey(1) == ord('q'):
        wincap.stop()
        cv.destroyAllWindows()
        break

这是视觉 class：

import cv2 as cv
import numpy as np


class Vision:

    def __init__(self, needle_img_path, method=cv.TM_CCOEFF_NORMED):
        # load the image we're trying to match
        self.needle_img = cv.imread(needle_img_path, cv.IMREAD_UNCHANGED)
        # save the dimensions of the needle image
        self.needle_w = self.needle_img.shape[1]
        self.needle_h = self.needle_img.shape[0]
        self.method = method

    def find(self, haystack_img, threshold=0.7, max_results=28):
        # run the OpenCV algorithm
        result = cv.matchTemplate(haystack_img, self.needle_img, self.method)
        # Get the all the positions from the match result that exceed our threshold
        locations = np.where(result >= threshold)
        locations = list(zip(*locations[::-1]))
        if not locations:
            return np.array([], dtype=np.int32).reshape(0, 4)
        rectangles = []
        for loc in locations:
            rect = [int(loc[0]), int(loc[1]), self.needle_w, self.needle_h]
            rectangles.append(rect)
            rectangles.append(rect)
        rectangles, weights = cv.groupRectangles(rectangles, groupThreshold=1,
                                                 eps=0.5)
        if len(rectangles) > max_results:
            print('Warning: too many results, raise the threshold.')
            rectangles = rectangles[:max_results]
        return rectangles

当我尝试在 Vision class 本身中创建线程时，它没有返回矩形列表。 我想在单独的线程中运行这个 find() function 以提高性能。 另外，我认为我需要在更新矩形时锁定线程。 有人可以指出正确的方向或最佳方法吗？

成功将是在 needle_img obj 上的自己的线程中运行调用 find() function 并返回一个矩形列表，这样我就可以在主 haystack_img 上绘制这些矩形。