How can I get the value of a QComboBox that is part of a custom QListWidgetItem using self.myQListWidget.itemSelectionChanged.connect()?

Question

I've got a QListWidget that I have populated with multiple instances of an item generated from a custom widget. This custom widget contains a QComboBox. I have it so the plot at the bottom updates when any of the QComboBoxes are changed, but how do I make the plot update when the user selects a particular row in my list? I can't figure out how to get the current value of the QComboBox for the selected item.

class MainWidget(QWidget):

    def showselection(self):

        # get current selection from QComboBox for selected item
        # run self.bias_graph.updateplot passing in current selection

    def __init__(self, parent):

        super().__init__(parent)

        grid = QGridLayout()

        self.bias_graph = BiasGraph(self, width=5, height=4)

        self.multiplexerList = QListWidget()

        for i in range(10):

            item = QListWidgetItem(self.multiplexerList)
            itemWidget = MultiplexerListItem(self.bias_graph, i)
            item.setSizeHint(itemWidget.sizeHint())
            self.multiplexerList.addItem(item)
            self.multiplexerList.setItemWidget(item, itemWidget)

        self.multiplexerList.itemSelectionChanged.connect(self.showselection)

        heading1 = QLabel('Multiplexer')
        heading2 = QLabel('Waveform')
        heading1.setFixedHeight(50)
        heading2.setFixedHeight(50)

        grid.addWidget(heading1, 0, 0)
        grid.addWidget(heading2, 0, 1)
        grid.addWidget(self.multiplexerList, 1, 0, 1, 2)

        bottomleft = self.bias_graph

        grid.addWidget(bottomleft, 11, 0)

        self.setLayout(grid)

        self.show()

class MultiplexerListItem(QWidget):

    def __init__(self, main_plot, i,  parent = None):

        super().__init__(parent)

        grid = QGridLayout()

        grid.addWidget(QLabel(str(i + 1)), 0, 0)

        waveselect = QComboBox()
        waveselect.addItem("A")
        waveselect.addItem("B")
        waveselect.activated[str].connect(main_plot.updateplot)
        grid.addWidget(waveselect, 0, 1)

        self.setLayout(grid)

class BiasGraph(FigureCanvas):

    def __init__(self, parent = None, width=5, height=4, dpi=100):

        fig = Figure(figsize = (width, height), dpi = dpi)
        self.axes = fig.add_subplot(111)

        FigureCanvas.__init__(self, fig)
        self.setParent(parent)

        FigureCanvas.setSizePolicy(self,
            QSizePolicy.Expanding,
            QSizePolicy.Expanding)
        FigureCanvas.updateGeometry(self)

        default = []
        A = [0, 0, -1, -2, -3, -2, -1, 0, 0]
        B = [0, 0, 1, 2, 3, 2, 1, 0, 0]
        self.data = {"A" : A, "B" : B}

        self.plot(default)

    def updateplot(self, text):

        self.plot(self.data[text])

    def plot(self, X):

        self.axes.clear()
        ax = self.figure.add_subplot(111)
        ax.plot(X, 'r-')
        ax.set_title('Bias Waveform')
        self.draw()

eyllanesc eyllanesc · Accepted Answer · 2018-07-18T14:04:01

First you must obtain the selected item using currentItem(), and then the widget using itemWidget(), this will return a MultiplexerListItem associated with the item, but currently it will be difficult to obtain the QComboBox, to facilitate this you must make the QComboBox member of the MultiplexerListItem class . then access the QComboBox and the corresponding text.

    def showselection(self):
        it = self.multiplexerList.currentItem()
        widget = self.multiplexerList.itemWidget(it)
        combo = widget.waveselect
        print(combo.currentText())

...

class MultiplexerListItem(QWidget):
    def __init__(self, main_plot, i,  parent = None):
        super().__init__(parent)
        grid = QGridLayout()
        grid.addWidget(QLabel(str(i + 1)), 0, 0)
        self.waveselect = QComboBox()
        self.waveselect.addItems(["A", "B"])
        self.waveselect.activated[str].connect(main_plot.updateplot)
        grid.addWidget(self.waveselect, 0, 1)
        self.setLayout(grid)

How can I get the value of a QComboBox that is part of a custom QListWidgetItem using self.myQListWidget.itemSelectionChanged.connect()?

1 Answers