今天小编给大家分享一下Python怎么用cv2动态绘制圆和矩形的相关知识点，内容详细，逻辑清晰，相信大部分人都还太了解这方面的知识，所以分享这篇文章给大家参考一下，希望大家阅读完这篇文章后有所收获，下面我们一起来了解一下吧。
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()