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Capture video data from screen in Python（11个答案）
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我正在学习Open CV的教程，并尝试重写以下代码：https://github.com/learncodebygaming/opencv_tutorials/tree/master/005_real_time
（具体来说，就是windowcapture.py文件）
该文件使用win32gui、win32ui、win32con按窗口名捕获给定的打开窗口，并对它进行屏幕截图，以便稍后进行cv2处理。
我曾尝试使用Quartz for macOS重新创建此功能，示例如下：https://stackoverflow.com/a/48030215/14649706
我自己的www.example.com版本windowcapture.py是这样的：

import numpy as np
from Quartz import CGWindowListCopyWindowInfo, kCGNullWindowID, kCGWindowListOptionAll, CGRectNull, CGWindowListCreateImage, kCGWindowImageBoundsIgnoreFraming, kCGWindowListExcludeDesktopElements, CGImageGetDataProvider, CGDataProviderCopyData, CFDataGetBytePtr, CFDataGetLength
import os
from PIL import Image
import cv2 as cv

class WindowCapture:

    # properties
    window_name = None
    window = None
    window_id = None
    window_width = 0
    window_height = 0

    # constructor
    def __init__(self, given_window_name=None):
        if given_window_name is not None:

            self.window_name = given_window_name
            self.window = self.get_window()

            if self.window is None:
                raise Exception('Unable to find window: {}'.format(given_window_name))

            self.window_id = self.get_window_id()

            self.window_width = self.get_window_width()
            self.window_height = self.get_window_height()

            self.window_x = self.get_window_pos_x()
            self.window_y = self.get_window_pos_y()

    # determine the window we want to capture
    def get_window(self):
        windows = CGWindowListCopyWindowInfo(kCGWindowListOptionAll, kCGNullWindowID)
        for window in windows:
            name = window.get('kCGWindowName', 'Unknown')
            if name and self.window_name in name:
                
                return window
        return None
    
    def get_window_id(self):
        return self.window['kCGWindowNumber']

    def get_window_width(self):
        return int(self.window['kCGWindowBounds']['Width'])
    
    def get_window_height(self):
        return int(self.window['kCGWindowBounds']['Height'])

    def get_window_pos_x(self):
        return int(self.window['kCGWindowBounds']['X'])

    def get_window_pos_y(self):
        return int(self.window['kCGWindowBounds']['Y'])
    
    def get_image_from_window(self):
        image_filename = 'test-img.png'
        # -x mutes sound and -l specifies windowId
        os.system('screencapture -x -l %s %s' % (self.window_id, image_filename))
        pil_image = Image.open(image_filename)
        image_as_numpy_array = np.array(pil_image)
        os.remove(image_filename)

        image = cv.cvtColor(image_as_numpy_array, cv.COLOR_BGR2RGB)
        return image

这里我的get_image_from_window方法工作正常，我可以使用cv.imshow('cv', screenshot)查看它：

import cv2 as cv
from time import time
from windowcapture import WindowCapture

# initialize the WindowCapture class
wincap = WindowCapture('Blue Box Clicker')

loop_time = time()

while(True):
    # get an updated image of the game
    screenshot = wincap.get_image_from_window()

    cv.imshow('cv', screenshot)

    # debug the loop rate
    print('FPS {}'.format(1 / (time() - loop_time)))
    loop_time = time()

    # press 'q' with the output window focused to exit.
    # waits 1 ms every loop to process key presses
    if cv.waitKey(1) == ord('q'):
        cv.destroyAllWindows()
        break

print('Done.')

但是我不想在本地保存图像然后再加载它，我认为这是非常低效的，我想实现同样的功能，而不是实际保存图像文件，然后打开它。
类似于这里的做法（在上面的GitHub链接中）：

def get_screenshot(self):

        # get the window image data
        wDC = win32gui.GetWindowDC(self.hwnd)
        dcObj = win32ui.CreateDCFromHandle(wDC)
        cDC = dcObj.CreateCompatibleDC()
        dataBitMap = win32ui.CreateBitmap()
        dataBitMap.CreateCompatibleBitmap(dcObj, self.w, self.h)
        cDC.SelectObject(dataBitMap)
        cDC.BitBlt((0, 0), (self.w, self.h), dcObj, (self.cropped_x, self.cropped_y), win32con.SRCCOPY)

        # convert the raw data into a format opencv can read
        #dataBitMap.SaveBitmapFile(cDC, 'debug.bmp')
        signedIntsArray = dataBitMap.GetBitmapBits(True)
        img = np.fromstring(signedIntsArray, dtype='uint8')
        img.shape = (self.h, self.w, 4)

        # free resources
        dcObj.DeleteDC()
        cDC.DeleteDC()
        win32gui.ReleaseDC(self.hwnd, wDC)
        win32gui.DeleteObject(dataBitMap.GetHandle())

        # drop the alpha channel, or cv.matchTemplate() will throw an error like:
        #   error: (-215:Assertion failed) (depth == CV_8U || depth == CV_32F) && type == _templ.type() 
        #   && _img.dims() <= 2 in function 'cv::matchTemplate'
        img = img[...,:3]

        # make image C_CONTIGUOUS to avoid errors that look like:
        #   File ... in draw_rectangles
        #   TypeError: an integer is required (got type tuple)
        # see the discussion here:
        # https://github.com/opencv/opencv/issues/14866#issuecomment-580207109
        img = np.ascontiguousarray(img)

        return img

如何使用Quartz实现这一点？
我在MacOS（M1 Pro）上，真的很想让这个工作。
目前，这个程序运行在12fps左右。
它试图捕获的程序是另一个python程序（一个简单的pygame）：

import pygame
import random

# Set up the game window
pygame.init()
window_width, window_height = 640, 480
window = pygame.display.set_mode((window_width, window_height))
pygame.display.set_caption("Blue Box Clicker")

# Set up the clock
clock = pygame.time.Clock()

# Set up the game variables
background_color = (0, 0, 0)
box_color = (0, 0, 255)
box_width, box_height = 50, 50
box_x, box_y = 0, 0

# Set up the game loop
running = True
while running:

    # Handle events
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            if box_x <= mouse_x <= box_x + box_width and box_y <= mouse_y <= box_y + box_height:
                # Correct click
                box_x, box_y = random.randint(
                    0, window_width - box_width), random.randint(0, window_height - box_height)
                # Incorrect click

    # Draw the background
    window.fill(background_color)

    # Draw the box
    pygame.draw.rect(window, box_color, (box_x, box_y, box_width, box_height))

    # Update the window
    pygame.display.update()

    # Limit the frame rate
    clock.tick(60)

# Clean up
pygame.quit()