它画多个矩形，因为你画矩形的每一个鼠标移动后，用户按下按钮。相反，你应该画每当事件完成时，即当用户释放左键。我修正了你的代码，并添加了一个基本的参考图像，让你看到你的矩形时，你正在绘制。希望它有帮助!

import cv2
import numpy as np

drawing  = False
ix,iy = -1, -1
img = cv2.imread('drawing_over_image/dog.jpg')
refimg = img.copy()
def draw(event, x, y, flags, params):

    global ix, iy, drawing

    if event == cv2.EVENT_LBUTTONDOWN:
        ix,iy = x,y
        drawing = True
    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing:
            if ix < x and iy < y:
                cv2.rectangle(img=refimg, pt1=(ix,iy), pt2=(x,y), color=[255,0,0], thickness=1)
    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False
        if ix < x and iy < y:
            cv2.rectangle(img=img, pt1=(ix,iy), pt2=(x,y), color=[255,0,0], thickness=1)


if __name__ == "__main__":
    
    while True:
        cv2.imshow(winname='image', mat=refimg)
        cv2.setMouseCallback('image', draw)
        refimg = img.copy()
        if cv2.waitKey(1) & 0xFF == 27:
            cv2.destroyAllWindows()
            break

输出：

编辑：
第18行和第28行中存在拼写错误mat=refimg至img
修改代码：

import cv2
import numpy as np

drawing  = False
ix,iy = -1, -1
img = cv2.imread('drawing_over_image/dog.jpg')
)
def draw(event, x, y, flags, params):

    global ix, iy, drawing

    if event == cv2.EVENT_LBUTTONDOWN:
        ix,iy = x,y
        drawing = True
    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing:
            if ix < x and iy < y:
                cv2.rectangle(img, pt1=(ix,iy), pt2=(x,y), color=[255,0,0], thickness=1)
    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False
        if ix < x and iy < y:
            cv2.rectangle(img, pt1=(ix,iy), pt2=(x,y), color=[255,0,0], thickness=1)

cv2.setMouseCallback("Rectangle Window", draw_rectangle)
if __name__ == "__main__":
    while True:
        cv2.imshow(winname='image', img)        
        if cv2.waitKey(1) & 0xFF == 27:
            break

这是我如何使用树莓派4B在Linux上的

import cv2
import numpy as np

drawing = False # true if mouse is pressed
mode = True # if True, draw rectangle.
ix,iy = -1,-1

# mouse callback function
def draw_circle(event,x,y,flags,param):
  global ix,iy,drawing,mode

  if event == cv2.EVENT_LBUTTONDOWN:
      drawing = True
      ix,iy = x,y

  elif event == cv2.EVENT_MOUSEMOVE:
    if drawing == True:
        if mode == True:
            cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),3)
            a=x
            b=y
            if a != x | b != y:
                 cv2.rectangle(img,(ix,iy),(x,y),(0,0,0),-1)
        else:
            cv2.circle(img,(x,y),5,(0,0,255),-1)

  elif event == cv2.EVENT_LBUTTONUP:
    drawing = False
    if mode == True:
        cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),2)

    else:
        cv2.circle(img,(x,y),5,(0,0,255),-1)

img = np.zeros((512,512,3), np.uint8)
cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_circle)

while(1):
 cv2.imshow('image',img)
 k = cv2.waitKey(1) & 0xFF
 if k == ord('m'):
    mode = not mode
 elif k == 27:
    break

cv2.destroyAllWindows()