"""
===============
Embedding in Qt
===============

Simple Qt application embedding Matplotlib canvases.  This program will work
equally well using Qt4 and Qt5.  Either version of Qt can be selected (for
example) by setting the ``MPLBACKEND`` environment variable to "Qt4Agg" or
"Qt5Agg", or by first importing the desired version of PyQt.
"""

import sys
import time

import numpy as np

from matplotlib.backends.qt_compat import QtCore, QtWidgets, is_pyqt5
if is_pyqt5():
    from matplotlib.backends.backend_qt5agg import (
        FigureCanvas, NavigationToolbar2QT as NavigationToolbar)
else:
    from matplotlib.backends.backend_qt4agg import (
        FigureCanvas, NavigationToolbar2QT as NavigationToolbar)
from matplotlib.figure import Figure


class ApplicationWindow(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        self._main = QtWidgets.QWidget()
        self.setCentralWidget(self._main)
        layout = QtWidgets.QVBoxLayout(self._main)

        static_canvas = FigureCanvas(Figure(figsize=(5, 3)))
        layout.addWidget(static_canvas)
        self.addToolBar(NavigationToolbar(static_canvas, self))

        dynamic_canvas = FigureCanvas(Figure(figsize=(5, 3)))
        layout.addWidget(dynamic_canvas)
        self.addToolBar(QtCore.Qt.BottomToolBarArea,
                        NavigationToolbar(dynamic_canvas, self))

        self._static_ax = static_canvas.figure.subplots()
        t = np.linspace(0, 10, 501)
        self._static_ax.plot(t, np.tan(t), ".")

        self._dynamic_ax = dynamic_canvas.figure.subplots()
        self._timer = dynamic_canvas.new_timer(
            50, [(self._update_canvas, (), {})])
        self._timer.start()

    def _update_canvas(self):
        self._dynamic_ax.clear()
        t = np.linspace(0, 10, 101)
        # Use fixed vertical limits to prevent autoscaling changing the scale
        # of the axis.
        self._dynamic_ax.set_ylim(-1.1, 1.1)
        # Shift the sinusoid as a function of time.
        self._dynamic_ax.plot(t, np.sin(t + time.time()))
        self._dynamic_ax.figure.canvas.draw()


if __name__ == "__main__":
    # Check whether there is already a running QApplication (e.g., if running
    # from an IDE).
    qapp = QtWidgets.QApplication.instance()
    if not qapp:
        qapp = QtWidgets.QApplication(sys.argv)

    app = ApplicationWindow()
    app.show()
    app.activateWindow()
    app.raise_()
    qapp.exec_()
