# Copyright (C) 2022 The Qt Company Ltd. # SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause from PySide6.QtCore import (Qt, QEvent, QObject, QTimer, Signal, Slot) from PySide6.QtGui import (QColor, QFont, QPalette) from PySide6.QtWidgets import (QApplication, QGridLayout, QLabel, QMainWindow, QVBoxLayout, QWidget) import asyncio import signal import sys from random import randint class MainWindow(QMainWindow): set_num = Signal(int, QColor) def __init__(self, rows, cols): super().__init__() self.rows = rows self.cols = cols widget_central = QWidget() self.setCentralWidget(widget_central) layout_outer = QVBoxLayout(widget_central) self.widget_outer_text = QLabel() font = QFont() font.setPointSize(14) self.widget_outer_text.setFont(font) layout_outer.addWidget(self.widget_outer_text, alignment=Qt.AlignmentFlag.AlignCenter) widget_inner_grid = QWidget() layout_outer.addWidget(widget_inner_grid, alignment=Qt.AlignmentFlag.AlignCenter) self.layout_inner_grid = QGridLayout(widget_inner_grid) k = 1 for i in range(self.rows): for j in range(self.cols): box = QLabel(f"{k}") self.layout_inner_grid.addWidget(box, i, j, Qt.AlignmentFlag.AlignCenter) k += 1 self.set_num.connect(self.set_num_handler) @Slot(int, QColor) def set_num_handler(self, i, color): row = int((i - 1) / self.cols) col = (i - 1) - (row * self.cols) widget = self.layout_inner_grid.itemAtPosition(row, col).widget() font = QFont() font.setWeight(QFont.Bold) palette = QPalette() palette.setColor(QPalette.WindowText, color) widget.setFont(font) widget.setPalette(palette) class Eratosthenes(QObject): done_signal = Signal() """ This Sieve of Eratosthenes runs on a configurable tick (default 0.1 seconds). At each tick, a new subroutine will be created that will check multiples of the next prime number. Each of these subroutines also operates on the same tick. """ def __init__(self, num, window, tick=0.1): super().__init__() self.num = num self.sieve = [True] * self.num self.base = 0 self.window = window self.tick = tick self.coroutines = [] self.done = False self.loop = None def get_tick(self): return self.loop.time() + self.tick async def start(self): self.loop = asyncio.get_event_loop() asyncio.create_task(self.update_text()) while self.base <= self.num / 2: await asyncio.sleep(self.tick) for i in range(self.base + 1, self.num): if self.sieve[i]: self.base = i break asyncio.create_task(self.mark_number(self.base + 1)) while sum(self.coroutines) > 0: await asyncio.sleep(self.tick) self.done = True async def mark_number(self, base): id = len(self.coroutines) self.coroutines.append(1) color = QColor(randint(64, 192), randint(64, 192), randint(64, 192)) for i in range(2 * base, self.num + 1, base): if self.sieve[i - 1]: self.sieve[i - 1] = False self.window.set_num.emit(i, color) await asyncio.sleep(self.tick) self.coroutines[id] = 0 async def update_text(self): while not self.done: await asyncio.sleep(self.tick) if int(self.loop.time() + self.tick) % 2: text = "⚙️ ...Calculating prime numbers... ⚙️" else: text = "👩‍💻 ...Hacking the universe... 👩‍💻" self.window.widget_outer_text.setText(text) self.window.widget_outer_text.setText( "🥳 Congratulations! You found all the prime numbers and solved mathematics. 🥳" ) # This signals to the guest run when there are no more asyncio tasks # left so its event loop can finish. self.done_signal.emit() class AsyncHelper(QObject): class ReenterQtObject(QObject): """ This is a QObject to which an event will be posted, allowing asyncio to resume when the event is handled. event.fn() is the next entry point of the asyncio event loop. """ def event(self, event): if event.type() == QEvent.Type.User + 1: event.fn() return True return False class ReenterQtEvent(QEvent): """ This is the QEvent that will be handled by the ReenterQtObject. self.fn is the next entry point of the asyncio event loop. """ def __init__(self, fn): super().__init__(QEvent.Type(QEvent.Type.User + 1)) self.fn = fn def __init__(self, worker, entry): super().__init__() self.reenter_qt = self.ReenterQtObject() self.entry = entry self.loop = asyncio.new_event_loop() self.done = False self.worker = worker if hasattr(self.worker, "start_signal") and isinstance(self.worker.start_signal, Signal): self.worker.start_signal.connect(self.on_worker_started) if hasattr(self.worker, "done_signal") and isinstance(self.worker.done_signal, Signal): self.worker.done_signal.connect(self.on_worker_done) @Slot() def on_worker_started(self): """ To use asyncio and Qt together, one must run the asyncio event loop as a "guest" inside the Qt "host" event loop. """ if not self.entry: raise Exception("No entry point for the asyncio event loop was set.") asyncio.set_event_loop(self.loop) self.loop.create_task(self.entry()) self.loop.call_soon(self.next_guest_run_schedule) self.done = False # Set this explicitly as we might want to restart the guest run. self.loop.run_forever() @Slot() def on_worker_done(self): """ When all our current asyncio tasks are finished, we must end the "guest run" lest we enter a quasi idle loop of switching back and forth between the asyncio and Qt loops. We can launch a new guest run by calling launch_guest_run() again. """ self.done = True def continue_loop(self): """ This function is called by an event posted to the Qt event loop to continue the asyncio event loop. """ if not self.done: self.loop.call_soon(self.next_guest_run_schedule) self.loop.run_forever() def next_guest_run_schedule(self): """ This function serves to pause and re-schedule the guest (asyncio) event loop inside the host (Qt) event loop. It is registered in asyncio as a callback to be called at the next iteration of the event loop. When this function runs, it first stops the asyncio event loop, then by posting an event on the Qt event loop, it both relinquishes to Qt's event loop and also schedules the asyncio event loop to run again. Upon handling this event, a function will be called that resumes the asyncio event loop. """ self.loop.stop() QApplication.postEvent(self.reenter_qt, self.ReenterQtEvent(self.continue_loop)) if __name__ == "__main__": rows = 40 cols = 40 num = rows * cols app = QApplication(sys.argv) main_window = MainWindow(rows, cols) eratosthenes = Eratosthenes(num, main_window) async_helper = AsyncHelper(eratosthenes, eratosthenes.start) # This establishes the entry point for the asyncio guest run. It # varies depending on how and when its event loop is to be # triggered, e.g., from the beginning (as here) or rather at a # specific moment like a button press. QTimer.singleShot(0, async_helper.on_worker_started) main_window.show() signal.signal(signal.SIGINT, signal.SIG_DFL) app.exec()