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# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
import math
import sys
from PySide6.QtWidgets import QWidget, QApplication
from PySide6.QtCore import QPoint, QRect, QTimer, Qt
from PySide6.QtGui import QPainter, QPointList
WIDTH = 680
HEIGHT = 480
class PlotWidget(QWidget):
"""Illustrates the use of opaque containers. QPointList
wraps a C++ QList<QPoint> directly, removing the need to convert
a Python list in each call to QPainter.drawPolyline()."""
def __init__(self, parent=None):
super().__init__(parent)
self._timer = QTimer(self)
self._timer.setInterval(20)
self._timer.timeout.connect(self.shift)
self._points = QPointList()
self._points.reserve(WIDTH)
self._x = 0
self._delta_x = 0.05
self._half_height = HEIGHT / 2
self._factor = 0.8 * self._half_height
for i in range(WIDTH):
self._points.append(QPoint(i, self.next_point()))
self.setFixedSize(WIDTH, HEIGHT)
self._timer.start()
def next_point(self):
result = self._half_height - self._factor * math.sin(self._x)
self._x += self._delta_x
return result
def shift(self):
last_x = self._points[WIDTH - 1].x()
self._points.pop_front()
self._points.append(QPoint(last_x + 1, self.next_point()))
self.update()
def paintEvent(self, event):
with QPainter(self) as painter:
rect = QRect(QPoint(0, 0), self.size())
painter.fillRect(rect, Qt.white)
painter.translate(-self._points[0].x(), 0)
painter.drawPolyline(self._points)
if __name__ == "__main__":
app = QApplication(sys.argv)
w = PlotWidget()
w.show()
sys.exit(app.exec())
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