单击时在图像中绘制一个固定大小的矩形，并通过移动鼠标更改其位置

Question

我需要在点击鼠标左键时在图像中绘制一个固定大小的矩形，并通过移动鼠标来改变它在图像中的位置。我想出了这段代码，它基本上是在图像中绘制矩形，其中鼠标指针是矩形对角线的交点。

import cv2 as cv
import numpy as np

#flags
move_rectangle = False

#color for rectangle
BLUE = [255,0,0]

def mouse(event,x,y,flags,params):
    global move_rectangle, BLUE

    #draw rectangle where x,y is rectangle center
    if event == cv.EVENT_LBUTTONDOWN:
        move_rectangle = True

    elif event == cv.EVENT_MOUSEMOVE:
        if move_rectangle:
            cv.rectangle(bg,(x-int(0.5*cols),y-int(0.5*rows)),
            (x+int(0.5*cols),y+int(0.5*rows)),BLUE, -1)

    elif event == cv.EVENT_LBUTTONUP:
        move_rectangle = False
        cv.rectangle(bg,(x-int(0.5*cols),y-int(0.5*rows)),
        (x+int(0.5*cols),y+int(0.5*rows)),BLUE, -1)


if __name__ == '__main__':

    #loading images
    fg = cv.imread('sample.jpg')
    bg = cv.imread('beach.jpg')
    #grabing height and width of foreground image
    rows, cols = fg.shape[:2]

    cv.namedWindow('draw')
    cv.setMouseCallback('draw', mouse)

    while True:

        cv.imshow('draw', bg)
        k = cv.waitKey(1)

        #waiting for esc to exit
        if k == 27 & 0xFF:
            break

    cv.destroyAllWindows()

但是，我不知道如何让它只在鼠标指针的位置绘制矩形。我需要摆脱前面矩形后面的 "shadow"。

阴影

如何做到这一点？

Answer 1

我相信您需要做的只是在收到移动事件时重新初始化图像

import cv2 as cv

move_rectangle = False
BLUE = [255,0,0]

fg = cv.imread('sample.jpg')
bg = cv.imread('beach.jpg')
bgCopy = bg.copy()

def mouse(event,x,y,flags,params):
    global move_rectangle, BLUE, fg, bg, bgCopy
    #draw rectangle where x,y is rectangle center
    if event == cv.EVENT_LBUTTONDOWN:
        move_rectangle = True

    elif event == cv.EVENT_MOUSEMOVE:
        bg = bgCopy.copy() #!! your image is reinitialized with initial one
        if move_rectangle:
            cv.rectangle(bg,(x-int(0.5*cols),y-int(0.5*rows)),
            (x+int(0.5*cols),y+int(0.5*rows)),BLUE, -1)

    elif event == cv.EVENT_LBUTTONUP:
        move_rectangle = False
        cv.rectangle(bg,(x-int(0.5*cols),y-int(0.5*rows)),
        (x+int(0.5*cols),y+int(0.5*rows)),BLUE, -1)

if __name__ == '__main__':
    rows, cols = fg.shape[:2]

    cv.namedWindow('draw')
    cv.setMouseCallback('draw', mouse)

    while True:

        cv.imshow('draw', bg)
        k = cv.waitKey(1)

        #waiting for esc to exit
        if k == 27 & 0xFF:
            break

    cv.destroyAllWindows()

单击时在图像中绘制一个固定大小的矩形，并通过移动鼠标更改其位置

Draw a fixed sized rectangle in image on click and change its location by moving the mouse

python

opencv

mouseevent

python-3.x