opencv上的鼠标事件

Question

我正在尝试编写一个函数，该函数将打开一个图像并在单击鼠标左键的位置绘制一个圆圈。然后可以使用 mousewheel/keyboard 调整圆的大小。此外，每次点击都会按顺序打印标签，例如第一个圆圈放置标签“1”，绘制的第二个圆圈放置标签“2”，依此类推。我已经设法在图像上获得圆圈和标签，但我不确定如何增加半径 或通过不同的点击更改标签。

import cv2
import numpy as np

# Create a black image and a window
windowName = 'Drawing'
img = cv2.imread('000025.png',cv2.IMREAD_COLOR)
cv2.namedWindow(windowName)








# mouse callback function
def draw_circle(event, x, y, flags, param):
    if event == cv2.EVENT_LBUTTONDOWN:
        cv2.circle(img, (x,y), 30, (255, 0,), 1)
        font = cv2.FONT_HERSHEY_SIMPLEX
        cv2.putText(img,'label' , (x + 30, y + 30), font, 1, (200, 255, 155), 1, cv2.LINE_AA)




# bind the callback function to window
cv2.setMouseCallback(windowName, draw_circle)


def main():
    while (True):
        cv2.imshow(windowName, img)
        if cv2.waitKey(20) == 27:
            break

    cv2.destroyAllWindows()


if __name__ == "__main__":
    main()

Answer 1

首先，您必须将可绘制对象的所有坐标（或其他属性）保存在全局动态对象中。

如果您正在绘制圆圈、标签或其他可绘制对象，则必须对应用程序进行指导。这可以通过在 OpenCV window 中创建菜单项或通过按键来完成（我都做过）。您必须跟踪上下文（下一步是单击 x，圆心的 y 坐标，圆中的点（对于半径计算，除非您决定对其使用 mousewheel/kbd）矩形的左上角等.

您必须将创建的可绘制对象存储在所述全局对象中。

如果你想 edit/delete 现有的可绘制对象，你必须制作迭代器函数，它检测最近的可绘制对象（通过其中间点或其他点）以进行正确选择。

以上仅在 OpenCV 中就可以实现。

Answer 2

我认为这可能适合你：

import cv2
import numpy as np
import math


# mouse callback function
def draw_circle(event, x, y, flags, param):
    global x1, y1, radius, num
    if event == cv2.EVENT_LBUTTONDOWN:
        x1, y1 = x, y

    if event == cv2.EVENT_LBUTTONUP:
        num += 1
        radius = int(math.hypot(x - x1, y - y1))
        cv2.circle(img, (x1,y1), radius, (255, 0,), 1)

        font = cv2.FONT_HERSHEY_SIMPLEX
        cv2.putText(img, f'label: {num}', (x + 30, y + 30), font, 1, (200, 255, 155), 1, cv2.LINE_AA)


if __name__ == "__main__":
    num = 0
    # Create a black image and a window
    windowName = 'Drawing'
    img = cv2.imread('img.jpg', cv2.IMREAD_COLOR)
    cv2.namedWindow(windowName)
    # bind the callback function to window
    cv2.setMouseCallback(windowName, draw_circle)
    while (True):
        cv2.imshow(windowName, img)
        if cv2.waitKey(20) == 27:
            break

    cv2.destroyAllWindows()

结果：

这是一个简单的代码，您可以使用鼠标事件做很多事情。

Answer 3

使用以下代码，您也可以在移动鼠标的同时可视化圆圈。我通过添加另一个涉及 MOUSEMOVE 事件的条件来补充 Salman 提供的代码。

import cv2
import numpy as np
import math

drawing = False

def draw_circle(event, x, y, flags, param):
    global x1, y1, drawing, radius, num, img, img2
    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
        x1, y1 = x, y
        radius = int(math.hypot(x - x1, y - y1))
        cv2.circle(img, (x1,y1), radius, (255, 0, 0), 1)

    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing == True:
            a, b = x, y
            if a != x & b != y:
                img = img2.copy()
                radius = int(math.hypot(a - x1, b - y1))
                cv2.circle(img, (x1,y1), radius, (255, 0, 0), 1)

    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False
        num += 1
        radius = int(math.hypot(x - x1, y - y1))
        cv2.circle(img, (x1,y1), radius, (255, 0, 255), 1)
        font = cv2.FONT_HERSHEY_SIMPLEX
        cv2.putText(img, '_'.join(['label', str(num)]), (x + 20, y + 20), font, 1, (200, 255, 155), 1, cv2.LINE_AA)
        img2 = img.copy()


if __name__ == "__main__":
    num = 0
    windowName = 'Drawing'

    img = np.zeros((500, 500, 3), np.uint8)
    img2 = img.copy()
    cv2.namedWindow(windowName)
    cv2.setMouseCallback(windowName, draw_circle)
    while (True):
        cv2.imshow(windowName, img)
        if cv2.waitKey(20) == 27:
            break

    cv2.destroyAllWindows()

示例输出：

Answer 4

Python class 使用 OpenCV 鼠标点击回调在图像中获取鼠标点击点的实现。您可以创建此 class 的对象并使用 getpt(n, img) 方法使用鼠标单击图像中的 select n 个点。为您的目的编辑和使用。

import cv2
import numpy as np
#events = [i for i in dir(cv2) if 'EVENT' in i]
#print (events)

class MousePts:
    def __init__(self,windowname,img):
        self.windowname = windowname
        self.img1 = img.copy()
        self.img = self.img1.copy()
        cv2.namedWindow(windowname,cv2.WINDOW_NORMAL)
        cv2.imshow(windowname,img)
        self.curr_pt = []
        self.point   = []

    def select_point(self,event,x,y,flags,param):
        if event == cv2.EVENT_LBUTTONDOWN:
            self.point.append([x,y])
            #print(self.point)
            cv2.circle(self.img,(x,y),5,(0,255,0),-1)
        elif event == cv2.EVENT_MOUSEMOVE:
            self.curr_pt = [x,y]
            #print(self.point)
                   
    def getpt(self,count=1,img=None):
        if img is not None:
            self.img = img
        else:
            self.img = self.img1.copy()
        cv2.namedWindow(self.windowname,cv2.WINDOW_NORMAL)
        cv2.imshow(self.windowname,self.img)
        cv2.setMouseCallback(self.windowname,self.select_point)
        self.point = []
        while(1):
            cv2.imshow(self.windowname,self.img)
            k = cv2.waitKey(20) & 0xFF
            if k == 27 or len(self.point)>=count:
                break
            #print(self.point)
        cv2.setMouseCallback(self.windowname, lambda *args : None)
        #cv2.destroyAllWindows()
        return self.point, self.img
         
if __name__=='__main__':
    img = np.zeros((512,512,3), np.uint8)
    windowname = 'image'
    coordinateStore = MousePts(windowname,img)

    pts,img = coordinateStore.getpt(3)
    print(pts)
        
    pts,img = coordinateStore.getpt(3,img)
    print(pts)
    
    cv2.imshow(windowname,img)
    cv2.waitKey(0)

opencv上的鼠标事件

mouse events on opencv

python

opencv

mouseevent