为什么使用 python curses 窗口后 Windows 提示无响应？

Question

首先，我是python的新手。不得不在大学里学习它并被它的效率所吸引。

我有一个棘手的问题，即在使用 curses 窗口后 Windows 7 提示变得无响应。在 Windows 10 中它运行良好。请注意，我使用的是带有默认设置的 Win7 终端。在我的代码中，我创建了一个 curses 窗口来同时显示 2 个进度条，每个进度条用于文件下载。我通过将 curses 窗口传递给 FileDownload 类（每次下载一个类实例）来实现这一点，该类在该窗口内处理其进度条。奇怪的是，在 Windows 7 中，当下载完成并且控件返回到提示时，它变得对键盘没有响应。我通过在使用窗口后调用 curses.endwin() 来解决这个问题，但这会导致提示一直显示在屏幕缓冲区下方，从而隐藏了 curses 窗口。

这是我的代码。任何想法都非常感谢。谢谢！

# Skeleton version for simulations.
# Downloads 2 files simultaneously and shows a progress bar for each.
# Each file download is a FileDownload object that interacts with a
# common curses window passed as an argument.

import requests, math, threading, curses, datetime


class FileDownload:

    def __init__(self, y_pos, window, url):
        # Y position of the progress bar in the download queue window.
        self.__bar_pos = int(y_pos)
        self.__progress_window = window
        self.__download_url = url
        # Status of the file download object.
        self.__status = "queued"
        t = threading.Thread(target=self.__file_downloader)
        t.start()

    # Downloads selected file and handles its progress bar.
    def __file_downloader(self):
        file = requests.get(self.__download_url, stream=True)
        self.__status = "downloading"
        self.__progress_window.addstr(self.__bar_pos + 1, 1, "0%" + " " * 60 + "100%")
        size = int(file.headers.get('content-length'))
        win_prompt = "Downloading " + format(size, ",d") + " Bytes:"
        self.__progress_window.addstr(self.__bar_pos, 1, win_prompt)

        file_name = str(datetime.datetime.now().strftime("%Y-%m-%d_%H.%M.%d"))
        dump = open(file_name, "wb")

        # Progress bar length.
        bar_space = 58
        # Same as an index.
        current_iteration = 0
        # Beginning position of the progress bar.
        progress_position = 4
        # How many iterations will be needed (in chunks of 1 MB).
        iterations = math.ceil(size / 1024 ** 2)

        # Downloads the file in 1MB chunks.
        for block in file.iter_content(1024 ** 2):
            dump.write(block)

            # Progress bar controller.
            current_iteration += 1
            step = math.floor(bar_space / iterations)
            if current_iteration > 1:
                progress_position += step
            if current_iteration == iterations:
                step = bar_space - step * (current_iteration - 1)
            # Updates the progress bar.
            self.__progress_window.addstr(self.__bar_pos + 1, progress_position,
                                          "#" * step)
        dump.close()
        self.__status = "downloaded"

    # Returns the current status of the file download ("queued", "downloading" or
    # "downloaded").
    def get_status(self):
        return self.__status


# Instantiates each file download.
def files_downloader():

    # Creates curses window.
    curses.initscr()
    win = curses.newwin(8, 70)
    win.border(0)
    win.immedok(True)

    # Download URLs.
    urls = ["http://ipv4.download.thinkbroadband.com/10MB.zip",
            "http://ipv4.download.thinkbroadband.com/5MB.zip"]

    downloads_dct = {}
    for n in range(len(urls)):
        # Progress bar position in the window for the file.
        y_pos = n * 4 + 1
        downloads_dct[n + 1] = FileDownload(y_pos, win, urls[n])

    # Waits for all files to be downloaded before passing control of the terminal
    # to the user.
    all_downloaded = False
    while not all_downloaded:
        all_downloaded = True
        for key, file_download in downloads_dct.items():
            if file_download.get_status() != "downloaded":
                all_downloaded = False

    # Prevents the prompt from returning inside the curses window.
    win.addstr(7, 1, "-")

    # This solves the unresponsive prompt issue but hides the curses window if the screen buffer
    # is higher than the window size.
    # curses.endwin()

while input("\nEnter to continue: ") == "":
    files_downloader()

Answer 1

也许您正在使用 cygwin（和 ncurses）：ncurses（与任何其他 curses 实现一样）在运行时更改终端 I/O 模式。您可能看到的变化是

• 输入字符不回显
• 您必须键入 controlJ 来结束输入行，而不仅仅是 Enter
• 输出不会在每行末尾自动刷新

它进行这些更改以使其能够读取单个字符并更有效地使用终端。

要将 back 更改为终端的正常 I/O 模式，您可以使用 endwin 函数。 reset_shell_mode 函数也很有用。

进一步阅读：

• endwin（ncurses 手册）
• reset_shell_mode（ncurses 手册）