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Calling method from a second class to update QListView data

I have two tabs, Tab1, and Tab2. On Tab2, there is a button that when clicked, calls a method that updates the QListView data in the same tab. This works successfully.
When trying to call the same method from another class, it will not work. Below is a minimum reproducible example.
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import (
QDesktopWidget,
QVBoxLayout,
QHBoxLayout,
QPushButton,
)
from PyQt5.QtCore import Qt
class App(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.init_ui()
def init_ui(self):
self.setWindowTitle('App')
self.resize(1200, 800)
self.center()
self.window = MainWindow(self)
self.setCentralWidget(self.window)
self.show()
def center(self):
qr = self.frameGeometry()
cp = QDesktopWidget().availableGeometry().center()
qr.moveCenter(cp)
self.move(qr.topLeft())
class MainWindow(QtWidgets.QWidget):
def __init__(self, parent):
super(MainWindow, self).__init__(parent)
layout = QVBoxLayout(self)
# Initialize Tabs
tab_holder = QtWidgets.QTabWidget()
tab1 = Home()
tab2 = SecondTab()
tab_holder.addTab(tab1, "Tab1")
tab_holder.addTab(tab2, 'Tab2')
layout.addWidget(tab_holder)
class Home(QtWidgets.QWidget):
def __init__(self, parent=None):
super(Home, self).__init__(parent)
lay = QVBoxLayout(self)
self.btn_login = QPushButton('Login')
self.btn_login.clicked.connect(self.login)
lay.addWidget(self.btn_login)
#QtCore.pyqtSlot()
def login(self):
print('Hello')
SecondTab.load_info()
class SecondTab(QtWidgets.QWidget):
def __init__(self, parent=None):
super(SecondTab, self).__init__(parent)
lay = QVBoxLayout(self)
# Choice Boxes
layout_choice_boxes = QHBoxLayout()
self.list_of_items = QtWidgets.QListView()
self.model_dist = QtGui.QStandardItemModel(self.list_of_items)
layout_choice_boxes.addWidget(self.list_of_items)
# Load data button.
self.loadData = QPushButton('Load Data')
self.loadData.clicked.connect(self.load_info)
# Add all components to main layout.
lay.addLayout(layout_choice_boxes)
lay.addWidget(self.loadData)
#QtCore.pyqtSlot()
def load_info(self):
for member in ['Item 1', 'Item 2', 'Item 3']:
item = QtGui.QStandardItem(member)
item.setCheckable(True)
item.setEditable(False)
check = Qt.Unchecked
item.setCheckState(check)
self.model_dist.appendRow(item)
self.list_of_items.setModel(self.model_dist)
# Press the green button in the gutter to run the script.
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
ex = App()
sys.exit(app.exec_())
The error is on the line in the class Home() where I try to call the method from the SecondTab() class: SecondTab.load_info()
The load_info() method uses self in the SecondTab class, so I tried passing in the class directly like this: SecondTab.load_info(SecondTab()), however, it did not work.

This is a problem about the basic OOP issues, you have to interact with the instances (the objects) and not the classes (the abstraction). So the solution is that the connection between the objects "tab1" and "tab2":
class MainWindow(QtWidgets.QWidget):
def __init__(self, parent):
super(MainWindow, self).__init__(parent)
layout = QVBoxLayout(self)
# Initialize Tabs
tab_holder = QtWidgets.QTabWidget()
tab1 = Home()
tab2 = SecondTab()
tab_holder.addTab(tab1, "Tab1")
tab_holder.addTab(tab2, 'Tab2')
layout.addWidget(tab_holder)
tab1.btn_login.clicked.connect(tab2.load_info)
class Home(QtWidgets.QWidget):
def __init__(self, parent=None):
super(Home, self).__init__(parent)
lay = QVBoxLayout(self)
self.btn_login = QPushButton('Login')
lay.addWidget(self.btn_login)

How to change PushButton border radius

I want to change border radius of my PushButton lesson1
Tried to create a class Button with setStyleSheet in __init__ and create an object.
import sys
from pyto import *
from PyQt5 import QtCore, QtGui, QtWidgets
class MyWin(QtWidgets.QMainWindow):
def __init__(self, parent=None):
QtWidgets.QWidget.__init__(self, parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
self.ui.lesson1 = Button()
class Button(QtWidgets.QPushButton):
def __init__(self, parent = None):
super(Button, self).__init__(parent)
self.setStyleSheet('border-radius: 15px;')
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
myapp = MyWin()
myapp.show()
sys.exit(app.exec_())
No errors, but setStyleSheet doesn't work.

The code self.ui.lesson1 = Button() does not replace the self.ui.lesson1 created by Qt Designer, it only causes the new Button() to be assigned to the name self.ui.lesson1. So if you want to set the stylesheet it is not necessary to create another class:
# ...
class MyWin(QtWidgets.QMainWindow):
def __init__(self, parent=None):
QtWidgets.QWidget.__init__(self, parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
# self.ui.lesson1 = Button()
self.ui.lesson1.setStyleSheet('border-radius: 15px; background-color: red;')
# ...
I have added the background color to make the radius visible.

How to draw on QGraphicsView from QMainWindow

Current design shown below of QgraphicsView and QMainWindow class is an example of the design I have in a different software.
I had to add scrollbars to the QGraphicsView.
The original software has all mouse events handled in QMainWindow.
Questions: What is the way to draw on QGraphicsView through QMainWindow?
import sys
from PyQt4 import QtGui
from PyQt4 import QtCore
class Window(QtGui.QGraphicsView):
def __init__(self, parent=None):
QtGui.QGraphicsView.__init__(self, parent)
self.scene = QtGui.QGraphicsScene(self)
self.scene.setBackgroundBrush(QtGui.QBrush(QtCore.Qt.darkGray, QtCore.Qt.SolidPattern))
self.setScene(self.scene)
#self.setDragMode(QtGui.QGraphicsView.ScrollHandDrag)
self.setTransformationAnchor(QtGui.QGraphicsView.AnchorUnderMouse)
#self.viewport().setCursor(QtCore.Qt.CrossCursor)
self.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
self.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
print "sdsads"
def mousePressEvent(self, ev):
item = QtGui.QGraphicsTextItem("")
item.setPos(ev.x(), ev.y())
self.scene.addItem(item)
print "ev.x() ", ev.x()
class CityscapesLabelTool(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QMainWindow.__init__(self, parent)
centralwidget = Window()
self.setCentralWidget(centralwidget)
centralwidget.scene.addPixmap(QtGui.QPixmap("exit.png"))
app = QtGui.QApplication(sys.argv)
GUI = CityscapesLabelTool()
GUI.show()
sys.exit(app.exec_())

In a QGraphicsView it is normal to add items to the scene, for example in case you want to draw a polygon you must use QGraphicsPolygonItem, also if you want to get correct points you must use QGraphicsScene instead of QGraphicsView.
In the following example you can indicate the polygon points by left clicking and finish the drawing with the right click.
import sys
from PyQt4 import QtCore, QtGui
class GraphicsScene(QtGui.QGraphicsScene):
def __init__(self, *args, **kwargs):
QtGui.QGraphicsScene.__init__(self, *args, **kwargs)
self.polygon = None
def mousePressEvent(self, ev):
if ev.button() == QtCore.Qt.RightButton:
self.polygon << ev.scenePos()
item = QtGui.QGraphicsPolygonItem(self.polygon)
item.setPen(QtGui.QPen(QtCore.Qt.red))
item.setBrush(QtGui.QBrush(QtCore.Qt.red))
self.addItem(item)
# or
# self.addPolygon(self.polygon, QtGui.QPen(QtCore.Qt.red), QtGui.QBrush(QtCore.Qt.red))
self.polygon = None
else:
if self.polygon is None:
self.polygon = QtGui.QPolygonF()
self.polygon << ev.scenePos()
class Window(QtGui.QGraphicsView):
def __init__(self, parent=None):
QtGui.QGraphicsView.__init__(self, parent)
self.scene =GraphicsScene(QtCore.QRectF(0, 0, 640, 480), self)
self.scene.setBackgroundBrush(QtGui.QBrush(QtCore.Qt.darkGray, QtCore.Qt.SolidPattern))
self.setScene(self.scene)
#self.setDragMode(QtGui.QGraphicsView.ScrollHandDrag)
self.setTransformationAnchor(QtGui.QGraphicsView.AnchorUnderMouse)
#self.viewport().setCursor(QtCore.Qt.CrossCursor)
self.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
self.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
class CityscapesLabelTool(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QMainWindow.__init__(self, parent)
centralwidget = Window()
self.setCentralWidget(centralwidget)
centralwidget.scene.addPixmap(QtGui.QPixmap("exit.png"))
app = QtGui.QApplication(sys.argv)
GUI = CityscapesLabelTool()
GUI.show()
sys.exit(app.exec_())
Output:
You have an XY problem, where you are looking for the solution for a solution of the main problem without knowing that it is the correct one, according to what you comment your main problem is to add QScrollBar to the QMainWindow, and in that element you want to make drawings, so for that it is not necessary to use a QGraphicsView but a QScrollArea.
import sys
from PyQt4 import QtCore, QtGui
class Window(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.polygon = None
self.setFixedSize(640, 480)
self.pixmap = None
def mousePressEvent(self, ev):
if self.polygon is None:
self.polygon = QtGui.QPolygon()
self.polygon << ev.pos()
self.update()
def paintEvent(self, ev):
painter = QtGui.QPainter(self)
painter.fillRect(self.rect(), QtGui.QBrush(QtCore.Qt.darkGray, QtCore.Qt.SolidPattern))
painter.drawPixmap(QtCore.QPoint(0, 0), QtGui.QPixmap("exit.png"))
if self.polygon is not None:
painter.setPen(QtCore.Qt.blue)
painter.drawPolyline(self.polygon)
class CityscapesLabelTool(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QMainWindow.__init__(self, parent)
scroll = QtGui.QScrollArea()
scroll.setBackgroundRole(QtGui.QPalette.Dark)
scroll.setWidget(Window())
scroll.setWidgetResizable(True)
self.setCentralWidget(scroll)
app = QtGui.QApplication(sys.argv)
GUI = CityscapesLabelTool()
GUI.show()
sys.exit(app.exec_())

Live Plotting with PyQtGraph in PyQt4 #2

First of all sorry for the lenght. I want to explain my problem as good as possible. I am quite new to Python and trying to make a plotting app using PyQtGraph embedded in PyQt4. Some days ago I got a really nice answer to my plotting problem, and my next step is to have two PyQtGraphs plot Widgets simoultaneously plotting in the same PyQt4's CentralWidget. By the same approach as in the link described, both plots work fine, but the GUI gets unresponsive. For overcoming this, I am aiming to use QThread, and for that, I need to have my plotting functions in different classes. But I am messing with my variables, and can't see how:
from PyQt4 import QtCore, QtGui
import pyqtgraph as pg
import random
class MainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.central_widget = QtGui.QStackedWidget()
self.setCentralWidget(self.central_widget)
self.login_widget = LoginWidget(self)
self.login_widget.button.clicked.connect(Plots.plotter)
self.central_widget.addWidget(self.login_widget)
class LoginWidget(QtGui.QWidget):
def __init__(self, parent=None):
super(LoginWidget, self).__init__(parent)
layout = QtGui.QHBoxLayout()
self.button = QtGui.QPushButton('Start Plotting')
layout.addWidget(self.button)
self.plot = pg.PlotWidget()
layout.addWidget(self.plot)
self.setLayout(layout)
class Plots(MainWindow):
def print(self):
print('hello World')
def plotter(self):
self.data = [0]
self.curve = self.login_widget.plot.getPlotItem().plot()
self.timer = QtCore.QTimer()
self.timer.timeout.connect(self.updater)
self.timer.start(0)
def updater(self):
self.data.append(self.data[-1]+0.2*(0.5-random.random()))
self.curve.setData(self.data)
if __name__ == '__main__':
app = QtGui.QApplication([])
window = MainWindow()
window.show()
app.exec_()
That gives me an error at Plots.plotter:
self.data = [0]
AttributeError: 'bool' object has no attribute 'data'
If in the MainWindow class I substitute the 'button.connect' argument with Plots.print, it works fine. So I can see there is something wrong with the fact that I make an LoginWidget object in MainWindow, and then Plots inherits from MainWindow, calling that same LoginWidget object again.
I have tried a proposed solution where the father (MainWindow) does not access the methods of the children (Plots). But if, from Plots, I want to call the class where I aim placing my thread in, I get the same error again....
import sys
from PyQt4 import QtCore, QtGui
import pyqtgraph as pg
import random
class LoginWidget(QtGui.QWidget):
def __init__(self, parent=None):
super(LoginWidget, self).__init__(parent)
layout = QtGui.QHBoxLayout()
self.button = QtGui.QPushButton('Start Plotting')
layout.addWidget(self.button)
self.plot = pg.PlotWidget()
layout.addWidget(self.plot)
self.setLayout(layout)
class MainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.central_widget = QtGui.QStackedWidget()
self.setCentralWidget(self.central_widget)
self.login_widget = LoginWidget(self)
self.central_widget.addWidget(self.login_widget)
class Plots(MainWindow):
def __init__(self, parent=None):
super(Plots, self).__init__(parent=parent)
self.login_widget.button.clicked.connect(MyThread.plotter)
class MyThread(MainWindow):
def __init__(self, parent=None):
super(Aname, self).__init__(parent=parent)
def print(self):
print('hello World')
def plotter(self):
self.data = [0]
self.curve = self.login_widget.plot.getPlotItem().plot()
self.timer = QtCore.QTimer()
self.timer.timeout.connect(self.updater)
self.timer.start(0)
def updater(self):
self.data.append(self.data[-1]+0.2*(0.5-random.random()))
self.curve.setData(self.data)
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
w = Plots()
w.show()
sys.exit(app.exec_())

In inheritance the father should not access the methods of the children, It is better to inherit and implement new methods that have nothing to do with the parent in the child class.
Timer Version
import random
import sys
import pyqtgraph as pg
from PyQt4 import QtGui, QtCore
class LoginWidget(QtGui.QWidget):
def __init__(self, parent=None):
super(LoginWidget, self).__init__(parent)
layout = QtGui.QHBoxLayout()
self.button = QtGui.QPushButton('Start Plotting')
layout.addWidget(self.button)
self.plot = pg.PlotWidget()
layout.addWidget(self.plot)
self.setLayout(layout)
self.button.clicked.connect(self.plotter)
def plotter(self):
self.data = [0]
self.curve = self.plot.getPlotItem().plot()
self.timer = QtCore.QTimer()
self.timer.timeout.connect(self.updater)
self.timer.start(0)
def updater(self):
self.data.append(self.data[-1] + 0.2 * (0.5 - random.random()))
self.curve.setData(self.data)
class MainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.centralwidget = QtGui.QWidget(self)
self.setCentralWidget(self.centralwidget)
self.horizontalLayout = QtGui.QHBoxLayout(self.centralwidget)
self.login_widget_1 = LoginWidget(self)
self.horizontalLayout.addWidget(self.login_widget_1)
self.login_widget_2 = LoginWidget(self)
self.horizontalLayout.addWidget(self.login_widget_2)
self.setCentralWidget(self.centralwidget)
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())

How to add a Status to this PySide based ui

Look at the code
import sys
from PySide import QtCore, QtGui
class MyWidget(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.quit = QtGui.QPushButton("Quit", self)
self.setGeometry(300, 300, 250, 150)
self.statusBar().showMessage('Ready')
app = QtGui.QApplication(sys.argv)
widget = MyWidget()
widget.show()
sys.exit(app.exec_())
Now all I want to do , is add a Status. Now status is available in QtGui.QMainWindow
How can i use this fact to add it in the above program? In pyside coding , seems like for every component , we need to make a class and some connect to the main class..whata s the theory here?
I tried myself like this , but it did not work.
import sys
from PySide import QtCore, QtGui
class MyWidget(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.quit = QtGui.QPushButton("Quit", self)
self.setGeometry(300, 300, 250, 150)
self.statusBar().showMessage('Ready')
self.s = MyStatus()
class MyStatus(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QMainWindow.__init__(self, parent)
self.statusBar().showMessage('Ready')
app = QtGui.QApplication(sys.argv)
widget = MyWidget()
widget.show()
sys.exit(app.exec_())

You do not need to make a class for every component, but if you want to modify/override each component's built-in function you need to make a class for it.
To add something to your main window, you simply have to create an object and add it to the layout. As follow:
import sys
from PySide import QtGui , QtCore
class MyStatusBar(QtGui.QStatusBar):
def __init__(self, parent=None):
super(MyStatusBar, self).__init__(parent)
#Override any functions, or define new function for our status bar here
class MyMainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QMainWindow.__init__(self, parent)
#Set the size of the window
self.setMinimumSize(300,300)
#Create a status bar, from our OWN class
self.status_bar = MyStatusBar(self)
self.status_bar.setGeometry(QtCore.QRect(0, 0, 50, 50))
self.status_bar.showMessage('Ready')
#Add a simple quit button, from the DEFAULT class
self.quit_button = QtGui.QPushButton(self)
self.quit_button.clicked.connect(self.close)
self.quit_button.setGeometry(QtCore.QRect(100, 100, 100, 35))
self.quit_button.setText("Close")
#Start the application
app = QtGui.QApplication(sys.argv)
top = MyMainWindow()
top.show()
app.exec_()

If you want a window with a status-bar, use QMainWindow: it has one built-in (and also a menu-bar, tool-bars, dock-widgets, etc). Other widgets don't have these built-in features, and so, quite naturally, they don't have things like a statusBar method. If you insist on doing things the hard way by not using QMainWindow, you will have to add all these features yourself.
Although I wouldn't recommend doing things this way, here is a simple demo that adds a status-bar to a QWidget:
import sys
from PySide import QtCore, QtGui
class MyWidget(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.central_widget = QtGui.QWidget(self)
self.quit = QtGui.QPushButton("Quit", self)
self.setGeometry(300, 300, 250, 150)
layout = QtGui.QVBoxLayout(self.central_widget)
layout.addWidget(self.quit)
self.status = QtGui.QStatusBar(self)
layout = QtGui.QVBoxLayout(self)
layout.setContentsMargins(0, 0, 0, 0)
layout.addWidget(self.widget)
layout.addStretch()
layout.addWidget(self.status)
self.status.showMessage('Ready')
app = QtGui.QApplication(sys.argv)
widget = MyWidget()
widget.show()
sys.exit(app.exec_())