如何全屏打开matplotlib图形？

Question

I am working on pyqt5 app and there is widget containing graph made with matplotlib. I want to add a function which allows user to click the graph and it will be open full screen. How can I do that?
The graph in the widget is built like that:

class CanvasUp(FigureCanvas):
    def __init__(self, parent=None, width=5, height=5, dpi=50):
        self.fig = Figure(figsize=(width, height), dpi=dpi)
        self.axes = self.fig.add_subplot(111)
        FigureCanvas.__init__(self, self.fig)
        self.setParent(parent)
        self.plot()

def plot(self):
            # obtaining data
            ...
            ax = self.figure.add_subplot(111)

            self.figure.text(0.5, 0.5, "TEST", transform=ax.transAxes,
                             fontsize=40, color='gray', alpha=0.5,
                             ha='center', va='center')
            ax.fill_between(x1, y1=y1, label='psavert', alpha=0.5, color='tab:green', linewidth=2)

            dt = ax.plot(x1, y1)
            ax.set_title(lab, loc='left')
            ax.grid()
            self.draw_idle()           

If I simplify my programe it looks like that:

from PyQt5.QtWidgets import QDialog, QVBoxLayout
from PyQt5.QtWidgets import QApplication
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure
import sys

class CanvasUp(FigureCanvas):
    def __init__(self, parent=None, width=5, height=5, dpi=50):
        self.fig = Figure(figsize=(width, height), dpi=dpi)
        self.axes = self.fig.add_subplot(111)
        FigureCanvas.__init__(self, self.fig)
        self.setParent(parent)
        self.plot()

    def plot(self):
        try:
            x1 = [1, 2, 3]
            y1 = [3, 2, 1]
            ax = self.figure.add_subplot(111)
            ax.set_ylim([0, max(y1)*1.15])

            self.figure.text(0.5, 0.5, "test", transform=ax.transAxes,
                             fontsize=40, color='gray', alpha=0.5,
                             ha='center', va='center')
            ax.fill_between(x1, y1=y1, label='psavert', alpha=0.5, color='tab:green', linewidth=2)
            dt = ax.plot(x1, y1)
            ax.grid()
            self.draw_idle()
        except:
            print("Bad graphs")


class MainWindow(QDialog):
    def __init__(self):
        super().__init__()
        self.setGeometry(50, 50, 700, 700)
        layout = QVBoxLayout(self)
        plot = CanvasUp()
        layout.addWidget(plot)
        self.show()

if __name__ == '__main__':
        App = QApplication(sys.argv)
        window = MainWindow()
        sys.exit(App.exec())

Answer 1

If you want to show a child widget in full screen, you'll need to set its parent to None .

Note that if you want to restore the previous state, you also need to keep track of the previous position within the layout. In your example is not really a requirement, but if there are more widgets you have to consider that.

class CanvasUp(FigureCanvas):
    toggle = pyqtSignal()
    def __init__(self, parent=None, width=5, height=5, dpi=50):
        self.fig = Figure(figsize=(width, height), dpi=dpi)
        self.axes = self.fig.add_subplot(111)
        FigureCanvas.__init__(self, self.fig)
        self.setParent(parent)
        self.plot()

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            # emit a signal to notify the parent that we want to toggle the mode
            self.toggle.emit()

    # ...

class MainWindow(QDialog):
    def __init__(self):
        super().__init__()
        self.setGeometry(50, 50, 700, 700)
        self.setWindowTitle('fig test')
        layout = QVBoxLayout(self)
        self.plot = CanvasUp()
        layout.addWidget(self.plot)
        self.show()
        self.plot.toggle.connect(self.toggleFigure)

    def toggleFigure(self):
        if self.plot.parent():
            # store the current index in the layout
            self.layoutIndex = self.layout().indexOf(self.plot)
            self.plot.setParent(None)
            # manually reparenting a widget requires to explicitly show it,
            # usually by calling show() or setVisible(True), but this is
            # automatically done when calling showFullScreen()
            self.plot.showFullScreen()
        else:
            self.layout().insertWidget(self.layoutIndex, self.plot)

If you're using a grid layout, though, the index is not enough, since insertWidget only exists for QBoxLayouts, so grid coordinates must be extracted before reparenting the widget.
Consider that, while you could store the coordinates in a variable while adding the widget to the layout, it's always better to get them only when required.

class MainWindow(QDialog):
    def __init__(self):
        super().__init__()
        self.setGeometry(50, 50, 700, 700)
        self.setWindowTitle('fig test')
        layout = QGridLayout(self)
        layout.addWidget(QPushButton(), 0, 0)
        layout.addWidget(QPushButton(), 0, 1)
        self.plot = CanvasUp()
        layout.addWidget(self.plot, 1, 0, 1, 2)
        self.show()
        self.plot.toggle.connect(self.toggleFigure)

    def toggleFigure(self):
        if self.plot.parent():
            layoutIndex = self.layout().indexOf(self.plot)
            # store the position in grid coordinates:
            # row, column, horizontal span and vertical span
            self.layoutPosition = self.layout().getItemPosition(layoutIndex)
            self.plot.setParent(None)
            self.plot.showFullScreen()
        else:
            self.layout().addWidget(self.plot, *self.layoutPosition)