多显示器电脑截图时出现异常

我这台电脑有两个显示器，日常使用的是主显示器。编写此程序是为了实时监控另一显示器的状况，但遇到了一些问题。

"""
此程序旨在将另一个显示器的内容以窗口的形式显示在主显示器（打开该窗口的屏幕）上。
@File  : monitor.py
@Author: syf
@CSDN  : 稻草的使命
@Time  : 2022/12
"""
import cv2 as cv
import pyautogui
from PIL import ImageGrab
import numpy


def grab():
    image = pyautogui.screenshot(region=[0, 0, 1920, 1080])
    return image

def show(im):
    # im = numpy.array(im.getdata(), numpy.uint8).reshape(im.size[1], im.size[0], 3)
    img = cv.cvtColor(numpy.asarray(im), cv.COLOR_RGB2BGR)
    cv.imshow("monitor", img)
    cv.waitKey(500)

def save(frame):
    pass


if __name__ == '__main__':
    while True:
        show(grab())

运行结果一切正常，但当我尝试image = pyautogui.screenshot(region=[-100, 0, 50, 50])时，我想要得到另一显示器上的内容，结果窗口内部一片漆黑，什么也没有。

我尝试了各种方法，试遍各个模块的截图功能，但都只能获取主显示器上的内容。请问该如何解决，谢谢！

使用mss完成多屏幕截图

可以通过pip install mss安装mss工具库。

第1块屏幕

import os
import os.path

import mss


def on_exists(fname):
    # type: (str) -> None
    """
    Callback example when we try to overwrite an existing screenshot.
    """

    if os.path.isfile(fname):
        newfile = fname + ".old"
        print("{} -> {}".format(fname, newfile))
        os.rename(fname, newfile)


with mss.mss() as sct:
    filename = sct.shot(output="mon-{mon}.png", callback=on_exists)
    print(filename)

第2块屏幕

import mss
import mss.tools


with mss.mss() as sct:
    # Get information of monitor 2
    monitor_number = 2
    mon = sct.monitors[monitor_number]

    # The screen part to capture
    monitor = {
        "top": mon["top"],
        "left": mon["left"],
        "width": mon["width"],
        "height": mon["height"],
        "mon": monitor_number,
    }
    output = "sct-mon{mon}_{top}x{left}_{width}x{height}.png".format(**monitor)

    # Grab the data
    sct_img = sct.grab(monitor)

    # Save to the picture file
    mss.tools.to_png(sct_img.rgb, sct_img.size, output=output)
    print(output)

配合opencv对第2块屏幕截图

import mss
import cv2
import numpy as np

with mss.mss() as sct:
    
    # Get information of monitor 2
    monitor_number = 2
    mon = sct.monitors[monitor_number]

    # The screen part to capture
    monitor = {
        "top": mon["top"],
        "left": mon["left"],
        "width": mon["width"],
        "height": mon["height"],
        "mon": monitor_number,
    }
    output = "sct-mon{mon}_{top}x{left}_{width}x{height}.png".format(**monitor)

    # Grab the data
    sct_img = sct.grab(monitor)
    img = np.array(sct.grab(monitor)) # BGR Image
    
    # Display the picture
    cv2.imshow("OpenCV", img)
    cv2.waitKey(0)

补充点

sct.monitors # 如果只有一块屏幕
[{'left': 0, 'top': 0, 'width': 1366, 'height': 768}, 
{'left': 0, 'top': 0, 'width': 1366, 'height': 768}]

sct.monitors # 如果有2块屏幕
[{'left': 0, 'top': 0, 'width': 3286, 'height': 1080}, 
{'left': 1920, 'top': 0, 'width': 1366, 'height': 768}, 
{'left': 0, 'top': 0, 'width': 1920, 'height': 1080}]