PySide & QWT object disable/destroy

DarB

I am just learning OOP and PySide. I have created a code as below. The application doesn't do anything much (it's a development project in learning stages).

import numpy as np
import sys

from qtpy.QtWidgets import (
    QWidget,
    QMainWindow,
    QVBoxLayout,
    QAction,
    QMenu,
    QLabel,
    QApplication,
    QMessageBox,
    QDesktopWidget,
)
from qtpy.QtCore import Qt, Slot, QPoint, QObject
from qwt import (
    QwtPlot,
    QwtPlotMarker,
    QwtPlotGrid,
    QwtLegend,
    QwtPlotCurve,
    QwtLegendData,
)


class contexMenuHelper(QObject):
    def __init__(self, plot, legend, legendItem):
        super(contexMenuHelper, self).__init__()
        self.plot = plot
        self.legend = legend
        self.legendItem = legendItem
        

    @Slot(QPoint)
    def contextMenuSlot(self, pos):       
        context = QMenu(self.legendItem)
        context.addAction(QAction("Delete", self))
        context.exec_(self.legendItem.mapToGlobal(pos))


class Plot(QwtPlot, QMainWindow):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.setAxisTitle(QwtPlot.xBottom, "X-axis")
        self.setAxisTitle(QwtPlot.yLeft, "Y-axis")
        self.setCanvasBackground(Qt.white)
        self.setAxisScale(QwtPlot.yLeft, -2, 2)
        QwtPlotGrid.make(self, color=Qt.lightGray, width=0, style=Qt.DotLine)

        legend = QwtLegend()
        legend.setDefaultItemMode(QwtLegendData.Checkable)
        self.insertLegend(legend, QwtPlot.RightLegend)

        x = np.arange(-5.0, 5.0, 0.1)
        curves = []
        curves.append(
            QwtPlotCurve.make(
                x, np.cos(x), "Cosinus", self, linecolor="red", antialiased=True
            )
        )
        curves.append(
            QwtPlotCurve.make(
                x, np.sin(x), "Sinus", self, linecolor="blue", antialiased=True
            )
        )
        self.helpers = dict()
        for a in curves:
            legend.legendWidget(a).setContextMenuPolicy(Qt.CustomContextMenu)
            h = contexMenuHelper(self, legend, legend.legendWidget(a))
            self.helpers[a]  = h
            legend.legendWidget(a).customContextMenuRequested.connect(h.contextMenuSlot)

        QwtPlotMarker.make(
            align=Qt.AlignRight | Qt.AlignTop,
            linestyle=QwtPlotMarker.HLine,
            color="black",
            plot=self,
        )
        for keys, value in self.helpers.items():
            print(keys)
            print(value)    
        # insert a vertical marker at x = 0
        QwtPlotMarker.make(
            align=Qt.AlignRight | Qt.AlignTop,
            linestyle=QwtPlotMarker.VLine,
            color="black",
            plot=self,
        )

        legend.checked.connect(self.showCurve)
        self.replot()

    @Slot(object, bool, int)
    def showCurve(self, obj, condition, num):
        obj.setVisible(not condition)
        self.replot()

    @Slot(object, bool, int)
    def __del__(self,  obj, condition):
        print('Destructor called, vehicle deleted.')


class SimplePlot(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        layout = QVBoxLayout()
        self.setLayout(layout)
        plot = Plot()
        plot.setTitle("Trigonometric")
        self.setWindowTitle("Trigonometric")
        layout.addWidget(plot)
        label = QLabel("Press the legend to en/disable a curve")
        layout.addWidget(label)
        self.center()

    def center(self):
        qr = self.frameGeometry()
        cp = QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())

    def closeEvent(self, event):
        reply = QMessageBox.question(
            self,
            "Message",
            "Are you sure to quit?",
            QMessageBox.Yes | QMessageBox.No,
            QMessageBox.No,
        )

        if reply == QMessageBox.Yes:
            event.accept()
        else:
            event.ignore()


if __name__ == "__main__":

    app = QApplication(sys.argv)
    window = SimplePlot()
    window.show()
    window.resize(800, 600)
    sys.exit(app.exec_())

I made the active legend and the context menu.
ContextMenu
I want to make it so that when I select "Delete" from the context menu, the corresponding function waveform in the graph and the corresponding object in the legend will be deleted.

SGaist

Hi and welcome to devnet,

One way is to keep a map of legend and curve and in the slot connected to your delete action you remove both from the plot.

DarB

Hello .
Thank you for saying hello. :)

Using : QwtPlotCurve.detach(curves[1])

I am able to get what I need.

However, I really don't know how to hook this up to "Deleate" in the context menu.

Please help me with the code .

SGaist

Did you build the map I suggested ?

DarB

Hi.
@SGaist
Unfortunately I don't understand what you are writing about, I am new to PySide :( . Please provide clear translations.

I made it this way.
Please write if it is correct ?
And how else can it be done ?

import numpy as np
import sys

from qtpy.QtWidgets import (
    QWidget,
    QMainWindow,
    QVBoxLayout,
    QAction,
    QMenu,
    QLabel,
    QApplication,
    QMessageBox,
    QDesktopWidget,
)
from qtpy.QtCore import Qt, Slot, QPoint, QObject
from qwt import (
    QwtPlot,
    QwtPlotMarker,
    QwtPlotGrid,
    QwtLegend,
    QwtPlotCurve,
    QwtLegendData,
)


class contexMenuHelper(QObject):
    def __init__(self, plot, legend, legendItem):
        super(contexMenuHelper, self).__init__()
        self.plot = plot
        self.legend = legend
        self.legendItem = legendItem
        self.emlSel = QAction("Delete")


    @Slot(QPoint)
    def contextMenuSlot(self, pos):       
        context = QMenu(self.legendItem)
        context.addAction(self.emlSel)        
        context.exec_(self.legendItem.mapToGlobal(pos))
        self.emlSel.triggered.connect(self.destroy())
    
    @Slot()
    def destroy(self):
        QwtPlotCurve.detach(self.legend)

     
        

class Plot(QwtPlot, QMainWindow):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.setAxisTitle(QwtPlot.xBottom, "X-axis")
        self.setAxisTitle(QwtPlot.yLeft, "Y-axis")
        self.setCanvasBackground(Qt.white)
        self.setAxisScale(QwtPlot.yLeft, -2, 2)
        QwtPlotGrid.make(self, color=Qt.lightGray, width=0, style=Qt.DotLine)

        legend = QwtLegend()
        legend.setDefaultItemMode(QwtLegendData.Checkable)
        legend.resize(100,100)
        self.insertLegend(legend, QwtPlot.RightLegend)
        
        x = np.arange(-5.0, 5.0, 0.1)
        curves = []
        curves.append(
            QwtPlotCurve.make(
                x, np.cos(x), "Cosinus", self, linecolor="red", antialiased=True
            )
        )
        curves.append(
            QwtPlotCurve.make(
                x, np.sin(x), "Sinus", self, linecolor="blue", antialiased=True
            )
        )

        self.helpers = dict()
        for a in curves:
            legend.legendWidget(a).setContextMenuPolicy(Qt.CustomContextMenu)
            h = contexMenuHelper(self, a, legend.legendWidget(a))
            self.helpers[a]  = h
            legend.legendWidget(a).customContextMenuRequested.connect(h.contextMenuSlot)


        QwtPlotMarker.make(
            align=Qt.AlignRight | Qt.AlignTop,
            linestyle=QwtPlotMarker.HLine,
            color="black",
            plot=self,
        )

        QwtPlotMarker.make(
            align=Qt.AlignRight | Qt.AlignTop,
            linestyle=QwtPlotMarker.VLine,
            color="black",
            plot=self,
        )

        legend.checked.connect(self.showCurve)
        self.replot()

    @Slot(object, bool, int)
    def showCurve(self, obj, condition, num):
        obj.setVisible(not condition)
        self.replot()


class SimplePlot(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        layout = QVBoxLayout()
        self.setLayout(layout)
        plot = Plot()
        plot.setTitle("Trigonometric")
        self.setWindowTitle("Trigonometric")
        layout.addWidget(plot)
        label = QLabel("Press the legend to en/disable a curve")
        layout.addWidget(label)
        self.center()

    def center(self):
        qr = self.frameGeometry()
        cp = QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())

    def closeEvent(self, event):
        reply = QMessageBox.question(
            self,
            "Message",
            "Are you sure to quit?",
            QMessageBox.Yes | QMessageBox.No,
            QMessageBox.No,
        )

        if reply == QMessageBox.Yes:
            event.accept()
        else:
            event.ignore()


if __name__ == "__main__":

    app = QApplication(sys.argv)
    window = SimplePlot()
    window.show()
    window.resize(850, 600)
    sys.exit(app.exec_())

SGaist

Sorry, I think I have misunderstood your answer. You have it working so I am unsure what you were asking.

DarB

It works like this. It's only working now. Compare the two codes for yourself. However, thank you very much for your support. Thanks to you, it dazzled my brain :)

Please also note the error I made :(