使用 python 在打开的 cv 中使用鼠标事件绘制矩形或线条

Posted 2023-03-16

【中文标题】使用 python 在打开的 cv 中使用鼠标事件绘制矩形或线条

【英文标题】：Drawing rectangle or line using mouse events in open cv using python

【发布时间】：2014-04-04 03:41:36

【问题描述】：

我试图在两个坐标之间画一条直线，这将通过单击图像或鼠标事件获得。我可以在单击鼠标时绘制单个圆圈，但无法弄清楚如何在这些点之间画线。当我使用这段代码时，我只能打印开始和结束坐标，不能在它们之间画线。

import numpy as np
import cv2
import cv2.cv as cv

boxes = []

def on_mouse(event, x, y, flags, params):
    if event == cv.CV_EVENT_LBUTTONDOWN:
         print 'Start Mouse Position: '+str(x)+', '+str(y)
         sbox = [x, y]
         boxes.append(sbox)

    elif event == cv.CV_EVENT_LBUTTONUP:
        print 'End Mouse Position: '+str(x)+', '+str(y)
        ebox = [x, y]
        boxes.append(ebox)


count = 0
while(1):
    count += 1
    img = cv2.imread('img.jpg',0)
    img = cv2.blur(img, (3,3))

    cv2.namedWindow('real image')
    cv.SetMouseCallback('real image', on_mouse, 0)
    cv2.imshow('real image', img)
    if count < 50:
        if cv2.waitKey(33) == 27:
            cv2.destroyAllWindows()
            break
    elif count >= 50:
        if cv2.waitKey(0) == 27:
            cv2.destroyAllWindows()
            break
        count = 0

不知何故，我无法提取循环外的坐标。有人可以建议如何在我点击图像的点之间画线或矩形吗？

【问题讨论】：

此链接可能有帮助：docs.opencv.org/doc/tutorials/core/basic_geometric_drawing/…

【参考方案1】：

你可以参考下面我用来裁剪图像的 C++ 代码

#include <iostream>
#include "opencv2/opencv.hpp"
#include <stdio.h>

using namespace std;
using namespace cv;


Mat src,img,ROI;
Rect cropRect(0,0,0,0);
 Point P1(0,0);
 Point P2(0,0);

const char* winName="Crop Image";
bool clicked=false;
int i=0;
char imgName[15];


void checkBoundary()
       //check croping rectangle exceed image boundary
       if(cropRect.width>img.cols-cropRect.x)
         cropRect.width=img.cols-cropRect.x;

       if(cropRect.height>img.rows-cropRect.y)
         cropRect.height=img.rows-cropRect.y;

        if(cropRect.x<0)
         cropRect.x=0;

       if(cropRect.y<0)
         cropRect.height=0;


void showImage()
    img=src.clone();
    checkBoundary();
    if(cropRect.width>0&&cropRect.height>0)
        ROI=src(cropRect);
        imshow("cropped",ROI);
    

    rectangle(img, cropRect, Scalar(0,255,0), 1, 8, 0 );
    imshow(winName,img);



void onMouse( int event, int x, int y, int f, void* )


    switch(event)

        case  CV_EVENT_LBUTTONDOWN  :
                                        clicked=true;

                                        P1.x=x;
                                        P1.y=y;
                                        P2.x=x;
                                        P2.y=y;
                                        break;

        case  CV_EVENT_LBUTTONUP    :
                                        P2.x=x;
                                        P2.y=y;
                                        clicked=false;
                                        break;

        case  CV_EVENT_MOUSEMOVE    :
                                        if(clicked)
                                        P2.x=x;
                                        P2.y=y;
                                        
                                        break;

        default                     :   break;


    


    if(clicked)
     if(P1.x>P2.x) cropRect.x=P2.x;
                       cropRect.width=P1.x-P2.x; 
        else          cropRect.x=P1.x;
                       cropRect.width=P2.x-P1.x; 

        if(P1.y>P2.y) cropRect.y=P2.y;
                       cropRect.height=P1.y-P2.y; 
        else          cropRect.y=P1.y;
                       cropRect.height=P2.y-P1.y; 

    


showImage();



int main()


    cout<<"Click and drag for Selection"<<endl<<endl;
    cout<<"------> Press 's' to save"<<endl<<endl;

    cout<<"------> Press '8' to move up"<<endl;
    cout<<"------> Press '2' to move down"<<endl;
    cout<<"------> Press '6' to move right"<<endl;
    cout<<"------> Press '4' to move left"<<endl<<endl;

    cout<<"------> Press 'w' increas top"<<endl;
    cout<<"------> Press 'x' increas bottom"<<endl;
    cout<<"------> Press 'd' increas right"<<endl;
    cout<<"------> Press 'a' increas left"<<endl<<endl;

    cout<<"------> Press 't' decrease top"<<endl;
    cout<<"------> Press 'b' decrease bottom"<<endl;
    cout<<"------> Press 'h' decrease right"<<endl;
    cout<<"------> Press 'f' decrease left"<<endl<<endl;

    cout<<"------> Press 'r' to reset"<<endl;
    cout<<"------> Press 'Esc' to quit"<<endl<<endl;


    src=imread("src.png",1);

    namedWindow(winName,WINDOW_NORMAL);
    setMouseCallback(winName,onMouse,NULL );
    imshow(winName,src);

    while(1)
    char c=waitKey();
    if(c=='s'&&ROI.data)
     sprintf(imgName,"%d.jpg",i++);
     imwrite(imgName,ROI);
     cout<<"  Saved "<<imgName<<endl;
    
    if(c=='6') cropRect.x++;
    if(c=='4') cropRect.x--;
    if(c=='8') cropRect.y--;
    if(c=='2') cropRect.y++;

    if(c=='w')  cropRect.y--; cropRect.height++;
    if(c=='d') cropRect.width++;
    if(c=='x') cropRect.height++;
    if(c=='a')  cropRect.x--; cropRect.width++;

    if(c=='t')  cropRect.y++; cropRect.height--;
    if(c=='h') cropRect.width--;
    if(c=='b') cropRect.height--;
    if(c=='f')  cropRect.x++; cropRect.width--;

    if(c==27) break;
    if(c=='r') cropRect.x=0;cropRect.y=0;cropRect.width=0;cropRect.height=0;
    showImage();

    


    return 0;

【参考方案2】：

这是一个python实现

import cv2
import cv2.cv as cv
from time import time
boxes = []
def on_mouse(event, x, y, flags, params):
   # global img
   t = time()

   if event == cv.CV_EVENT_LBUTTONDOWN:
      print 'Start Mouse Position: '+str(x)+', '+str(y)
      sbox = [x, y]
      boxes.append(sbox)
      # print count
      # print sbox

   elif event == cv.CV_EVENT_LBUTTONUP:
      print 'End Mouse Position: '+str(x)+', '+str(y)
      ebox = [x, y]
      boxes.append(ebox)
      print boxes
      crop = img[boxes[-2][1]:boxes[-1][1],boxes[-2][0]:boxes[-1][0]]

      cv2.imshow('crop',crop)
      k =  cv2.waitKey(0)
      if ord('r')== k:
         cv2.imwrite('Crop'+str(t)+'.jpg',crop)
         print "Written to file"

count = 0
while(1):
   count += 1
   img = cv2.imread('path.img',0)
   # img = cv2.blur(img, (3,3))
   img = cv2.resize(img, None, fx = 0.25,fy = 0.25)

   cv2.namedWindow('real image')
   cv.SetMouseCallback('real image', on_mouse, 0)
   cv2.imshow('real image', img)
   if count < 50:
       if cv2.waitKey(33) == 27:
           cv2.destroyAllWindows()
           break
       elif count >= 50:
          if cv2.waitKey(0) == 27:
             cv2.destroyAllWindows()
             break
          count = 0

【讨论】：

对于 python3 使用 EVENT_LBUTTONDOWN 和 EVENT_LBUTTONUP 而不是 CV_EVENT_LBUTTONDOWN 和 CV_EVENT_LBUTTONUP

对于python3 使用cv2.setMouseCallback('real image', on_mouse, 0) ;)

【参考方案3】：

这是您在图像上绘制线条和矩形的完整答案

import numpy as np
import cv2 

# Making The Blank Image
image = np.zeros((512,512,3))
drawing = False
ix = 0
iy = 0
# Adding Function Attached To Mouse Callback
def draw(event,x,y,flags,params):
    global ix,iy,drawing
    # Left Mouse Button Down Pressed
    if(event==1):
        drawing = True
        ix = x
        iy = y
    if(event==0):
        if(drawing==True):
            #For Drawing Line
            cv2.line(image,pt1=(ix,iy),pt2=(x,y),color=(255,255,255),thickness=3)
            ix = x
            iy = y
            # For Drawing Rectangle
            # cv2.rectangle(image,pt1=(ix,iy),pt2=(x,y),color=(255,255,255),thickness=3)
    if(event==4):
        drawing = False



# Making Window For The Image
cv2.namedWindow("Window")

# Adding Mouse CallBack Event
cv2.setMouseCallback("Window",draw)

# Starting The Loop So Image Can Be Shown
while(True):

    cv2.imshow("Window",image)

    if cv2.waitKey(20) & 0xFF == ord('q'):
        break

cv2.destroyAllWindows()

【讨论】：

也许你可以添加一些关于你的代码的解释，这样从长远来看它可能会有用。