Python利用cv2动态绘制圆和矩形的示例详解

新手，参考了以下链接：

python opencv在图像上画矩形（已验证）

本文可以实现在指定图片上动态绘制圆和矩形。

import cv2
import numpy as np
import copy

class Rect(object):

#创建一个类用于接收鼠标点击产生的数据坐标点。

def __init__(self):

self.t1 = (0,0)

self.br = (0,0)

self.r = 0

def regularize(self):

pt1 = (min(self.t1[0],self.br[0]),min(self.t1[1],self.br[1]))

br1 = (max(self.t1[0],self.br[0]),max(self.t1[1],self.br[1]))

self.t1 = pt1

self.br = br1

class DrawRects(object):

def __init__(self,img,color = (0,255,0),thickness = 3):

self.img = img

self.image_for_show = img.copy()

'''
       用于覆盖之前的图片，然后在新的空白图片上将以前绘制的图片和目前最新的图片
       绘制的到新的图片上。
       '''

self.color = color

self.thickness = thickness

self.left_button_down = False #用于判断左键是否按下。

self.current_rect = Rect() #用于接收最新绘制的图形。

self.rects = [] #用于接收绘制的矩形数据。

self.circles = [] #用于接收绘制的圆数据

@staticmethod
   def __clip(value,low,high):

output = max(value,low)

output = min(output,high)

return output

def shrink_point(self,x,y):

height,width = self.image_for_show.shape[0:2]

x_shrink = self.__clip(x,0,width)

y_shrink = self.__clip(y,0,height)

return (x_shrink,y_shrink)

'''
   上述方法用于限制鼠标点击产生的数据在图片范围内。
   '''

def reset_image(self):

self.image_for_show = self.img.copy()

def append(self):

if draw_circle_now:

self.rects.append(['c',copy.deepcopy(self.current_rect)])

else:

self.rects.append(['r',copy.deepcopy(self.current_rect)])

def draw(self):

for rect in self.rects:

if rect[0] == 'r':

cv2.rectangle(self.image_for_show,rect[1].t1,rect[1].br,color = self.color,thickness=self.thickness)

elif rect[0] == 'c':

cv2.circle(self.image_for_show,rect[1].t1,rect[1].r,color = self.color,thickness = self.thickness)

def cal_R(self):

self.current_rect.r = int((abs(self.current_rect.br[0] - self.current_rect.t1[0])**2 + abs(self.current_rect.br[1] - self.current_rect.t1[1])**2)**0.5)

#print(self.current_circle.r)

return self.current_rect.r

def draw_current_rect(self):

if draw_circle_now:

self.current_rect.r = self.cal_R()

cv2.circle(self.image_for_show,self.current_rect.t1,self.current_rect.r,color = self.color,thickness=3)

else:

cv2.rectangle(self.image_for_show,self.current_rect.t1,self.current_rect.br,
                     color = self.color,thickness = self.thickness)

def pop(self):

rect = Rect()

if self.rects:

rect = self.rects.pop()

return rect

def onmouse_draw_rect(event,x,y,flags,draw_rects):

if event == cv2.EVENT_LBUTTONDOWN:

draw_rects.left_button_down = True

draw_rects.current_rect.t1 = (x,y)

if draw_rects.left_button_down  and event == cv2.EVENT_MOUSEMOVE:

draw_rects.current_rect.br = draw_rects.shrink_point(x,y)

draw_rects.reset_image()

draw_rects.draw()

draw_rects.draw_current_rect()

if event == cv2.EVENT_LBUTTONUP:

draw_rects.left_button_down = False

draw_rects.current_rect.br = draw_rects.shrink_point(x,y)

#draw_rects.current_rect.regularize()

draw_rects.append()

if (not draw_rects.left_button_down) and  event == cv2.EVENT_RBUTTONDOWN:

draw_rects.pop()

draw_rects.reset_image()

draw_rects.draw()

draw_circle_now = False

img = np.zeros((516,516,3),np.uint8)

draw_rects = DrawRects(img,(0,255,255))

cv2.namedWindow('image')

cv2.setMouseCallback('image',onmouse_draw_rect,draw_rects)

while True:

cv2.imshow('image',draw_rects.image_for_show)

key = cv2.waitKey(30)

if key == ord('c'):

draw_circle_now = not draw_circle_now

elif key == 27:

break

cv2.destroyAllWindows()

来源：https://blog.csdn.net/weixin_66412464/article/details/125356885