import cv2
import math
 
path ='test.jpg'
img = cv2.imread(path)
pointsList = []

#鼠标点 
def mousePoints(event,x,y,flags,params):
    if event == cv2.EVENT_LBUTTONDOWN:
        size = len(pointsList)
        if size != 0 and size % 3 != 0:
            cv2.line(img,tuple(pointsList[round((size-1)/3)*3]),(x,y),(0,0,255),2)
        cv2.circle(img,(x,y),5,(0,0,255),cv2.FILLED)
        pointsList.append([x,y])
        print(x,y)#打印坐标点
 
#梯度 
def gradient(pt1,pt2):
    return (pt2[1]-pt1[1])/(pt2[0]-pt1[0])
#获得角度 
def getAngle(pointsList):
    pt1, pt2, pt3 = pointsList[-3:]
    m1 = gradient(pt1,pt2)
    m2 = gradient(pt1,pt3)
    angR = math.atan((m2-m1)/(1+(m2*m1)))
    angD = round(math.degrees(angR))
 
    cv2.putText(img,str(angD),(pt1[0]-40,pt1[1]-20),cv2.FONT_HERSHEY_COMPLEX,
                1.5,(0,0,255),2)
                
while True:
    if len(pointsList) % 3 == 0 and len(pointsList) !=0:
        getAngle(pointsList)
    cv2.imshow('Image',img)
    cv2.imwrite('img.jpg',img)  
    cv2.setMouseCallback('Image',mousePoints)
    if cv2.waitKey(1) and 0xFF == ord('q'):
        pointsList = []
        img = cv2.imread(path)