Figure Canvas widget not showing up - python-3.x

Question

I'm trying to embed a matplotlib animation into my PyQt5-GUI. Here's my class of the animation:
class AnimationCanvas(FigureCanvas):
def __init__(self, parent=None, width=5, height=4, dpi=100):
self.fig = Figure(figsize=(width, height), dpi=dpi)
self.fig.set_facecolor('#1a1a1a')
self.ax = self.fig.add_subplot(111,polar=True)
self.ax.set_facecolor('#333333')
self.ax.set_ylim(0,1)
self.ax.tick_params(axis='x', labelsize=8,colors='#ffffff')
self.ax.set_yticks([]) # Shows no r values
self.ax.set_xticks(np.pi/180. * np.linspace(0, 360, 18, endpoint=False)) # A line every 20 degrees
self.ax.grid(color='#595959', linestyle='-.', linewidth=0.7)
self.ax.set_title("Position of the speakers", pad = 8,
fontdict= dict(
color = '#ffffff',
fontsize = 15,
fontweight = 0.9))
self.line, = self.ax.plot([], [], marker = 'X', color= '#ffffe6',markersize=15)
super(AnimationCanvas, self).__init__(self.fig)
When I use the following code in a MainWindow class (that handles the animation) to set it as a central widget it shows, no problem there. But I want to embed it into my existing GUI so that it's not the central widget. When I try to give it an absolute position by using setGeometry() or move(), it just doesn't show up anymore. I've also tried using QVBoxLayout and adding self.canvas to the layout, that works too, but I don't know how to stylize it properly so that it doesn't look like a huge mess with those unwanted whitespaces.
class MainWindow(QtWidgets.QMainWindow):
def __init__(self,xdata, *args, **kwargs,):
super(MainWindow, self).__init__(*args, **kwargs)
widget = QWidget()
vbox = QVBoxLayout(widget)
self.canvas = AnimationCanvas(self, width=5, height=4, dpi=100)
self.setCentralWidget(self.canvas)
vbox.addWidget(self.canvas)
self.angles = xdata*(3.14/180)
self.ydata = np.ones(len(self.angles))*0.96
self.index = 0
self.line = self.canvas.line
self.plot_button = QtWidgets.QPushButton(self.canvas)
self.plot_button.setGeometry(QtCore.QRect(5, 5, 50, 25))
self.plot_button.setText("plot")
self.plot_button.setObjectName("plot")
self.plot_button.clicked.connect(self.plot_animation)
vbox.addWidget(self.plot_button)
self.setCentralWidget(widget)
self.setGeometry(300, 300, 800, 600)
Questions:
Why doesn't setGeometry() work in this instance and how to fix it.
If I have to use QVBoxLayout, what's the best way to achieve a nice look? addSpacing() and addStretch() everywhere seems like a bit of an overkill to me.
Thanks in advance!

Answer 1

If you want to place your AnimationCanvas directly on the central widget then call setParent in the constructor.
class AnimationCanvas(FigureCanvas):
def __init__(self, parent=None, width=5, height=4, dpi=100):
...
super(AnimationCanvas, self).__init__(self.fig)
self.setParent(parent)
And construct the AnimationCanvas with parent widget, the central widget of the QMainWindow. The call to setGeometry on the QPushButton will now work, it will be placed on the AnimationCanvas at position (5, 5) with the size (50, 25).
class MainWindow(QtWidgets.QMainWindow):
def __init__(self,xdata=None, *args, **kwargs,):
super(MainWindow, self).__init__(*args, **kwargs)
widget = QWidget()
self.setCentralWidget(widget)
self.canvas = AnimationCanvas(parent=widget, width=5, height=4, dpi=100)
self.plot_button = QtWidgets.QPushButton(self.canvas)
self.plot_button.setGeometry(QtCore.QRect(5, 5, 50, 25))
self.setGeometry(300, 300, 800, 600)
If you use a layout then setGeometry will usually be ignored because the layout manages the position and size of all its widgets. However, you could add only the AnimationCanvas to the layout and not the QPushButton, allowing it to stay on the AnimationCanvas with the exact geometry you specify.
class MainWindow(QtWidgets.QMainWindow):
def __init__(self,xdata=None, *args, **kwargs,):
super(MainWindow, self).__init__(*args, **kwargs)
widget = QWidget()
self.setCentralWidget(widget)
vbox = QVBoxLayout(widget)
self.canvas = AnimationCanvas(width=5, height=4, dpi=100)
vbox.addWidget(self.canvas)
self.plot_button = QtWidgets.QPushButton(self.canvas)
self.plot_button.setGeometry(QtCore.QRect(5, 5, 50, 25))
self.setGeometry(300, 300, 800, 600)