如何将自己的循环添加到 Qt？

Question

我不知道该怎么做。当我的 Qt 应用程序不在焦点时，我有一个 while 循环供 xlib 读取按键。这是 ubuntu 16.04 python3-xlib 包 /usr/share/doc/python3-xlib/examples/record_demo.py 的复制粘贴。但这破坏了 Qt 应用程序的功能，因为它只读取按键而不处理 Qt 的事件循环。我应该让我的 Qt 应用程序为此设置第二个线程吗？或者我可以将 xlib 的循环挂接到 Qt 的循环上吗？

我正在使用 python3、pyqt5 和 python3-xlib。

下面是文件/usr/share/doc/python3-xlib/examples/record_demo.py

#!/usr/bin/python3
#
# examples/record_demo.py -- demonstrate record extension
#
#    Copyright (C) 2006 Alex Badea <vamposdecampos@gmail.com>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

# Simple demo for the RECORD extension
# Not very much unlike the xmacrorec2 program in the xmacro package.

import sys
import os

# Change path so we find Xlib
sys.path.insert(1, os.path.join(sys.path[0], '..'))

from Xlib import X, XK, display
from Xlib.ext import record
from Xlib.protocol import rq

local_dpy = display.Display()
record_dpy = display.Display()

def lookup_keysym(keysym):
    for name in dir(XK):
        if name[:3] == "XK_" and getattr(XK, name) == keysym:
            return name[3:]
    return "[%d]" % keysym

def record_callback(reply):
    if reply.category != record.FromServer:
        return
    if reply.client_swapped:
        print("* received swapped protocol data, cowardly ignored")
        return
    if not len(reply.data) or reply.data[0] < 2:
        # not an event
        return

    data = reply.data
    while len(data):
        event, data = rq.EventField(None).parse_binary_value(data, record_dpy.display, None, None)

        if event.type in [X.KeyPress, X.KeyRelease]:
            pr = event.type == X.KeyPress and "Press" or "Release"

            keysym = local_dpy.keycode_to_keysym(event.detail, 0)
            if not keysym:
                print("KeyCode%s %s" % (pr, event.detail))
            else:
                print("KeyStr%s %s" % (pr, lookup_keysym(keysym)))

            if event.type == X.KeyPress and keysym == XK.XK_Escape:
                local_dpy.record_disable_context(ctx)
                local_dpy.flush()
                return
        elif event.type == X.ButtonPress:
            print("ButtonPress %s" % event.detail)
        elif event.type == X.ButtonRelease:
            print("ButtonRelease %s" % event.detail)
        elif event.type == X.MotionNotify:
            print("MotionNotify %i %i" % (event.root_x, event.root_y))


# Check if the extension is present
if not record_dpy.has_extension("RECORD"):
    print("RECORD extension not found")
    sys.exit(1)
r = record_dpy.record_get_version(0, 0)
print("RECORD extension version %d.%d" % (r.major_version, r.minor_version))

# Create a recording context; we only want key and mouse events
ctx = record_dpy.record_create_context(
        0,
        [record.AllClients],
        [{
                'core_requests': (0, 0),
                'core_replies': (0, 0),
                'ext_requests': (0, 0, 0, 0),
                'ext_replies': (0, 0, 0, 0),
                'delivered_events': (0, 0),
                'device_events': (X.KeyPress, X.MotionNotify),
                'errors': (0, 0),
                'client_started': False,
                'client_died': False,
        }])

# Enable the context; this only returns after a call to record_disable_context,
# while calling the callback function in the meantime
record_dpy.record_enable_context(ctx, record_callback)

# Finally free the context
record_dpy.record_free_context(ctx)

Answer 1

Qt 的事件循环是一个 X 事件循环。你不需要另一个。

由于您从事件循环中以回调的形式获取信息，这将“正常工作”：只要您使用与 Qt 相同的 xcb 库，并在那里注册回调，您的回调就会被调用.

如果您以事件的形式获取信息，您可以过滤所有到达您的应用程序的本机 X 事件：使用 QCoreApplication::installNativeEventFilter。您对QAbstractNativeEventFilter 的具体实现将接收本地事件作为指向xcb_generic_event_t 的指针，请参阅the documentation。

不过，如果发生事件，与 Python 的互操作会有点复杂。您可能需要在 C++ 中实现事件过滤器并将其公开给 Python。