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How to show new QMainWindow in every loop in PyQT5?

I'm trying to write a Python program using PyQt5 that will display a window in each iteration of the for loop. I would like to close after incrementing and displaying the next window. However, I do not know how to stop the loop every iteration and at the moment I am getting 6 windows at once.
main.py
import sys
from PyQt5.QtWidgets import (QLineEdit, QVBoxLayout, QMainWindow,
QWidget, QDesktopWidget, QApplication, QPushButton, QLabel,
QComboBox, QFileDialog, QRadioButton)
from PyQt5.QtCore import pyqtSlot, QByteArray
from alert import Window2
from test import test
class SG(QWidget):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
self.resize(300, 150)
self.setWindowTitle('TEST')
self.resultsGen = QPushButton('TEST', self)
self.resultsGen.clicked.connect(lambda: self.on_click())
self.show()
#pyqtSlot()
def on_click(self):
test(self)
if __name__ == '__main__':
app = QApplication(sys.argv)
sg = SG()
sys.exit(app.exec_())
alert.py
from PyQt5.QtWidgets import (QLineEdit, QVBoxLayout, QMainWindow,
QWidget, QDesktopWidget, QApplication, QPushButton, QLabel,
QComboBox, QFileDialog, QRadioButton)
from PyQt5.QtCore import pyqtSlot, QByteArray
from PyQt5.QtGui import QPixmap
from PyQt5 import QtGui, QtCore
class Window2(QMainWindow):
def __init__(self):
super().__init__()
self.initPopup()
def initPopup(self):
self.resize(500, 500)
self.setWindowTitle("Window22222")
self.central_widget = QWidget()
self.setCentralWidget(self.central_widget)
lay = QVBoxLayout(self.central_widget)
label = QLabel(self)
pixmap = QPixmap('cropped/8.png')
label.setPixmap(pixmap)
self.resize(pixmap.width(), pixmap.height())
lay.addWidget(label)
self.textbox = QLineEdit(self)
self.textbox.move(20, 20)
self.textbox.resize(280, 40)
# Create a button in the window
self.button = QPushButton('Show text', self)
self.button.move(20, 80)
# connect button to function on_click
self.button.clicked.connect(lambda: self.on_clickX())
self.show()
#pyqtSlot()
def on_clickX(self):
textboxValue = self.textbox.text()
print(textboxValue)
self.textbox.setText("")
self.hide()
test.py
from alert import Window2
def test(self):
for x in range(6):
w = Window2()

As soon as you run the for cycle, all the code of the initialization will be executed, which includes the show() call you used at the end of initPopup().
A simple solution is to create a new signal that is emitted whenever you hide a window, and connect that signal to a function that creates a new one until it reaches the maximum number.
main.py:
import sys
from PyQt5.QtWidgets import QWidget, QApplication, QPushButton
from alert import Window2
class SG(QWidget):
def __init__(self):
super().__init__()
self.initUI()
self.alerts = []
def initUI(self):
self.resize(300, 150)
self.setWindowTitle('TEST')
self.resultsGen = QPushButton('TEST', self)
self.resultsGen.clicked.connect(self.nextAlert)
self.show()
def nextAlert(self):
if len(self.alerts) >= 6:
return
alert = Window2()
self.alerts.append(alert)
alert.setWindowTitle('Window {}'.format(len(self.alerts)))
alert.closed.connect(self.nextAlert)
alert.show()
if __name__ == '__main__':
app = QApplication(sys.argv)
sg = SG()
sys.exit(app.exec_())
alert.py:
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
class Window2(QMainWindow):
closed = pyqtSignal()
def __init__(self):
super().__init__()
self.initPopup()
def initPopup(self):
self.resize(500, 500)
self.central_widget = QWidget()
self.setCentralWidget(self.central_widget)
lay = QVBoxLayout(self.central_widget)
label = QLabel(self)
pixmap = QPixmap('cropped/8.png')
label.setPixmap(pixmap)
self.resize(pixmap.width(), pixmap.height())
lay.addWidget(label)
self.textbox = QLineEdit(self)
lay.addWidget(self.textbox)
# Create a button in the window
self.button = QPushButton('Show text', self)
lay.addWidget(self.button)
# connect button to function on_click
self.button.clicked.connect(lambda: self.on_clickX())
self.show()
#pyqtSlot()
def on_clickX(self):
textboxValue = self.textbox.text()
print(textboxValue)
self.textbox.setText("")
self.hide()
self.closed.emit()
Just note that with this very simplified example the user might click on the button of the "SG" widget even if an "alert" window is visibile. You might prefer to use a QDialog instead of a QMainWindow and make the main widget a parent of that dialog.
main.py:
class SG(QWidget):
# ...
def nextAlert(self):
if len(self.alerts) >= 6:
return
alert = Window2(self)
# ...
alert.py:
class Window2(QDialog):
closed = pyqtSignal()
def __init__(self, parent):
super().__init__()
self.initPopup()
def initPopup(self):
self.resize(500, 500)
# a QDialog doesn't need a central widget
lay = QVBoxLayout(self)
# ...
Also, if an alert window is closed using the "X" button the new one will not be shown automatically. To avoid that, you can implement the "closeEvent" and ignore the event, so that the user will not be able to close the window until the button is clicked. As QDialogs can close themself when pressing the escape key, I'm also ignoring that situation.
alert.py:
class Window2(QMainWindow):
# ...
def closeEvent(self, event):
event.ignore()
def keyPressEvent(self, event):
if event.key() != Qt.Key_Escape:
super().keyPressEvent(event)

Embed QGraphics in widget

I have a main widget inside a window who contains a lot of widgets. How can I insert a QGraphics view and a QGraphicsScene in that widget? I have not found a direct insertion method, so I am trying using a wrapper, in this case a box layout but it is not a good solution. The QGraphicsScene stands out from the layout limits.
Code:
class UiVentana(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
self.setFixedSize(1500, 1015)
widget_central = QtWidgets.QWidget(self)
wrapper = QtWidgets.QHBoxLayout(widget_central)
scene = QtWidgets.QGraphicsScene(wrapper)
vista = QtWidgets.QGraphicsView(scene)
wrapper.addWidget(vista)
self.diedrico = Diedrico() # This is a class who draw things, not relevant
self.diedrico.setFixedSize(2000, 2000)
scene.addWidget(self.diedrico)
self.setCentralWidget(widget_central)
I would like to get this result:
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QWidget
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPainter, QPen, QColor
import sys
class Diedrico(QWidget):
def __init__(self, parent):
super().__init__(parent)
def paintEvent(self, event):
qp = QPainter(self)
qp.setPen(QPen(QColor(Qt.black), 5))
qp.drawRect(500, 500, 1000, 1000)
class UiVentana(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(UiVentana, self).__init__(parent)
self.resize(520, 520)
self.widget_central = QtWidgets.QWidget(self)
scrol = QtWidgets.QScrollArea(self.widget_central)
scrol.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
scrol.setGeometry(QtCore.QRect(30, 30, 500, 500))
scrol.setWidgetResizable(False)
contenido = QtWidgets.QWidget()
contenido.setGeometry(QtCore.QRect(0, 0, 2000, 2000))
scrol.setWidget(contenido)
self.Diedrico = Diedrico(contenido)
self.Diedrico.setGeometry(QtCore.QRect(0, 0, 2000, 2000))
self.setCentralWidget(self.widget_central)
if __name__ == "__main__":
app = QtWidgets.QApplication(sys.argv)
ui = UiVentana()
ui.show()
sys.exit(app.exec_())
But using QGraphics instead of a scroll area

The QGraphicsProxyWidget that is created using the widget takes into account the minimum size of the widget to set the boundingRect, and the QGraphicsScene uses the boundingRect to set the initial scene rect.
from PyQt5 import QtCore, QtGui, QtWidgets
class Diedrico(QtWidgets.QWidget):
def paintEvent(self, event):
qp = QtGui.QPainter(self)
pen = QtGui.QPen(QtGui.QColor(QtCore.Qt.black), 5)
qp.setPen(pen)
qp.drawRect(500, 500, 1000, 1000)
def minimumSizeHint(self):
return QtCore.QSize(2000, 2000)
class UiVentana(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(UiVentana, self).__init__(parent)
self.resize(520, 520)
widget_central = QtWidgets.QWidget()
self.setCentralWidget(widget_central)
lay = QtWidgets.QVBoxLayout(widget_central)
scene = QtWidgets.QGraphicsScene(self)
view = QtWidgets.QGraphicsView(scene)
diedrico = Diedrico()
scene.addWidget(diedrico)
lay.addWidget(view)
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
ui = UiVentana()
ui.show()
sys.exit(app.exec_())

When executing thread, the first execution fails in try statement

from PyQt5.QtWidgets import QMainWindow, QApplication,QLineEdit, QPushButton, QWidget, QAction, QTabWidget,QVBoxLayout
from PyQt5.QtCore import (QCoreApplication, QObject, QRunnable, QThread,
QThreadPool, pyqtSignal)
import sys
import os
from shutil import copy2
import _thread
import time
class AThread(QThread):
def run(self):
count = 0
while count < 5:
time.sleep(1)
print("A Increasing")
count += 1
class Example(QWidget):
def __init__(self):
super().__init__()
self.setAcceptDrops(True)
self.setWindowTitle('Learn')
self.setGeometry(300, 300, 300, 150)
self.layout = QVBoxLayout(self)
# Initialize tab screen
self.tabs = QTabWidget()
self.tab1 = QWidget()
self.tab2 = QWidget()
self.tabs.resize(300,200)
# Add tabs
self.tabs.addTab(self.tab1,"Tab 1")
self.tabs.addTab(self.tab2,"Tab 2")
# Create first tab
self.tab1.layout = QVBoxLayout(self)
self.pushButton1 = QPushButton("PyQt5 button")
self.pushButton1.clicked.connect(self.ON_PRESS)
self.textbox = QLineEdit(self)
self.tab1.layout.addWidget(self.textbox )
self.tab1.layout.addWidget(self.pushButton1)
self.tab1.setLayout(self.tab1.layout)
#Create Textbox inputs
# Add tabs to widget
self.layout.addWidget(self.tabs)
self.setLayout(self.layout)
def using_q_thread(self):
app = Example()
thread = AThread()
thread.start()
sys.exit(app.exec_())
def ON_PRESS(self):
###Here is the Issue
try:
self.using_q_thread()
except:
print ("Error: unable to start thread")
###Drag and Drop files to directory
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Example()
ex.show()
Hoping I am asking this correctly, but whenever using QThread there appears to be a bit of a hiccup. the first attempt to access the threaded function causes the try statement to fail, but then it immediately works. Im just curious if this is part of the functionality or if there is any issue with my code.

Avoid using try-except as you see hidden the error, in my personal case I avoid using it as far as I can for this type of problems.
I do not see it necessary to create another Example within using_q_thread, another problem is that thread is a local variable that will be eliminated, so thread must be a member of the class for its scope to increase.
import sys
import time
from PyQt5.QtCore import QThread
from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QTabWidget, QPushButton, QLineEdit
class AThread(QThread):
def run(self):
count = 0
while count < 5:
time.sleep(1)
print("A Increasing")
count += 1
class Example(QWidget):
def __init__(self):
super().__init__()
self.setAcceptDrops(True)
self.setWindowTitle('Learn')
self.setGeometry(300, 300, 300, 150)
self.layout = QVBoxLayout(self)
# Initialize tab screen
self.tabs = QTabWidget()
self.tab1 = QWidget()
self.tab2 = QWidget()
self.tabs.resize(300,200)
# Add tabs
self.tabs.addTab(self.tab1,"Tab 1")
self.tabs.addTab(self.tab2,"Tab 2")
# Create first tab
self.tab1.layout = QVBoxLayout()
self.pushButton1 = QPushButton("PyQt5 button")
self.pushButton1.clicked.connect(self.ON_PRESS)
self.textbox = QLineEdit(self)
self.tab1.layout.addWidget(self.textbox )
self.tab1.layout.addWidget(self.pushButton1)
self.tab1.setLayout(self.tab1.layout)
#Create Textbox inputs
# Add tabs to widget
self.layout.addWidget(self.tabs)
def using_q_thread(self):
self.thread = AThread()
self.thread.start()
def ON_PRESS(self):
self.using_q_thread()
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Example()
ex.show()
sys.exit(app.exec_())

How to stick widgets side by side

The code below creates a dialog window with three widgets: QLabel, QComboBox and QButton.
I want QLabel and QComboBox to be sitting on a same line. That is why both of these widgets are assigned to the same horizontal layout.
Resizing the dialog creates a huge empty space between the Label and ComboBox. How to assure that the left side of the Combo sticks to the right side of Label when dialog is resizing?
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
app = QApplication([])
class Dialog(QDialog):
def __init__(self, parent=None):
super(Dialog, self).__init__(parent)
self.setLayout(QVBoxLayout())
h_layout = QHBoxLayout()
self.layout().addLayout(h_layout)
label = QLabel(self)
label.setText('Month:')
combo = QComboBox(self)
h_layout.addWidget(label)
h_layout.addWidget(combo)
button = QPushButton('Ok')
self.layout().addWidget(button)
self.resize(200, 50)
self.show()
dialog = Dialog()
app.exec_()

You have to establish the size policy through QSizePolicy, in your case you must set the policy QSizePolicy::Expanding in the horizontal component of the QComboBox:
import sys
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
app = QApplication(sys.argv)
class Dialog(QDialog):
def __init__(self, parent=None):
super(Dialog, self).__init__(parent)
self.setLayout(QVBoxLayout())
h_layout = QHBoxLayout()
self.layout().addLayout(h_layout)
label = QLabel(self)
label.setText('Month:')
combo = QComboBox(self)
policy = combo.sizePolicy()
policy.setHorizontalPolicy(QSizePolicy.Expanding)
combo.setSizePolicy(policy)
h_layout.addWidget(label)
h_layout.addWidget(combo)
button = QPushButton('Ok')
self.layout().addWidget(button)
self.resize(200, 50)
self.show()
dialog = Dialog()
sys.exit(app.exec_())

Shorter and better solution is add parameter stretch=1 to addWidget() function:
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
app = QApplication([])
class Dialog(QDialog):
def __init__(self, parent=None):
super(Dialog, self).__init__(parent)
self.setLayout(QVBoxLayout())
h_layout = QHBoxLayout()
self.layout().addLayout(h_layout)
label = QLabel(self)
label.setText('Month:')
combo = QComboBox(self)
h_layout.addWidget(label)
h_layout.addWidget(combo, stretch=1)
button = QPushButton('Ok')
self.layout().addWidget(button)
self.resize(200, 50)
self.show()
dialog = Dialog()
app.exec_()

PyQt window closes after launch

I'm trying to use a QPushButton to call a function that opens a new instance of QWebView. Works but as soon as the window opens it closes again.
I've read this - PyQt window closes immediately after opening but I don't understand how to reference the window to keep it open.
import sys
from PyQt4 import QtCore, QtGui, QtWebKit
from PyQt4.QtWebKit import QWebSettings
from PyQt4.QtNetwork import QNetworkAccessManager
from PyQt4.QtNetwork import *
UA_STRING = """Test Test Test"""
vidurl = ("empty")
def web1():
class YWebPage(QtWebKit.QWebPage):
def __init__(self):
super(QtWebKit.QWebPage, self).__init__()
def userAgentForUrl(self, url):
return UA_STRING
class Browser(QtGui.QMainWindow): # "Browser" window
def __init__(self):
QtGui.QMainWindow.__init__(self)
self.resize(800,600) # Viewport size
self.centralwidget = QtGui.QWidget(self)
self.html = QtWebKit.QWebView()
def browse(self):
self.webView = QtWebKit.QWebView()
self.yPage = YWebPage()
self.webView.setPage(self.yPage)
self.webView.load(QtCore.QUrl(vidurl)) # Video URL
self.webView.settings().setAttribute(QtWebKit.QWebSettings.PluginsEnabled,True) # Enables flash player
self.webView.show()
x = Browser()
# QNetworkProxy.setApplicationProxy(QNetworkProxy(QNetworkProxy.HttpProxy, "proxy.example.com", 8080)) # Proxy setting
x.browse()
def main(): # Dialog window
app = QtGui.QApplication(sys.argv)
w = QtGui.QWidget()
w.resize(200, 450)
w.setFixedSize(200, 350)
w.move(300, 300)
w.setWindowTitle('U-bot 0.1')
# Setup GUI
# Start Button
w.__button = QtGui.QPushButton(w)
w.__button.clicked.connect(lambda: web1())
# Text area
w.__qle = QtGui.QLineEdit(w)
w.__qle.setText ("http://")
vidurl = w.__qle.text # Get video url from user
# Images
pixmap1 = QtGui.QPixmap("ubot.png")
lbl1 = QtGui.QLabel(w)
lbl1.resize(200, 150)
lbl1.setPixmap(pixmap1)
lbl1.setScaledContents(True)
w.__button.setText('Start')
layout = QtGui.QVBoxLayout()
layout.addStretch(1)
layout.addWidget(w.__qle)
layout.addWidget(w.__button)
w.setLayout(layout)
w.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
app.exec_()

Create a MainWindow class that keeps a list of open Browsers, and every time when you open a browser, just add it to the list. And when a browser window closes, it will remove itself from the list, see closeEvent.
import sys
from PyQt4 import QtCore, QtGui, QtWebKit
from PyQt4.QtWebKit import QWebSettings
from PyQt4.QtNetwork import QNetworkAccessManager
from PyQt4.QtNetwork import *
UA_STRING = """Test Test Test"""
vidurl = ("empty")
class YWebPage(QtWebKit.QWebPage):
def __init__(self):
super(YWebPage, self).__init__()
def userAgentForUrl(self, url):
return UA_STRING
class Browser(QtGui.QMainWindow): # "Browser" window
def __init__(self, main, url):
QtGui.QMainWindow.__init__(self)
self.main = main
self.resize(800,600) # Viewport size
self.webView = QtWebKit.QWebView()
self.setCentralWidget(self.webView)
self.yPage = YWebPage()
self.webView.setPage(self.yPage)
self.webView.load(QtCore.QUrl(url)) # Video URL
self.webView.settings().setAttribute(QtWebKit.QWebSettings.PluginsEnabled, True) # Enables flash player
def closeEvent(self, event):
self.main.browsers.remove(self)
super(Browser, self).closeEvent(event)
class MainWindow(QtGui.QWidget):
def __init__(self):
super(MainWindow, self).__init__()
self.browsers = []
self.resize(200, 450)
self.setFixedSize(200, 350)
self.move(300, 300)
self.setWindowTitle('U-bot 0.1')
# Setup GUI
# Start Button
self.__button = QtGui.QPushButton('Start')
self.__button.clicked.connect(self.open)
# Text area
self.__qle = QtGui.QLineEdit()
self.__qle.setText("http://")
# Images
pixmap1 = QtGui.QPixmap("ubot.png")
lbl1 = QtGui.QLabel()
lbl1.resize(200, 150)
lbl1.setPixmap(pixmap1)
lbl1.setScaledContents(True)
layout = QtGui.QVBoxLayout()
layout.addStretch(1)
layout.addWidget(self.__qle)
layout.addWidget(self.__button)
self.setLayout(layout)
def open(self):
b = Browser(self, self.__qle.text())
b.show()
self.browsers.append(b)
def main():
app = QtGui.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()

To keep a reference to a QObject, you can either keep the variable in scope, or add it as the child of another QObject which variable already stays in scope.
And for QWidget, the parent should also be a QWidget, so, in your case, you'd want to make w as the parent of all your QMainWindows.
def web1(parent):
...
class Browser(QtGui.QMainWindow): # "Browser" window
def __init__(self, parent):
QtGui.QMainWindow.__init__(self, parent)
...
def main():
...
w.__button.clicked.connect(lambda: web1(w))
This also avoid maintaining manually a list of opened windows, since the object hierarchy can do that for you.
PS: The child windows are shown as toplevel windows and not inside the w window, because QMainWindow (and QDialog) has the Qt::Window flag set by default.