I am trying to change this event code to standard signal-slot format.
But it does not work.
Can I get help?
this is slide number changing to lcd display number.
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
import sys
from PyQt4 import QtGui, QtCore
class Example(QtGui.QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
self.lcd = QtGui.QLCDNumber(self)
self.sld = QtGui.QSlider(QtCore.Qt.Horizontal, self)
vbox = QtGui.QVBoxLayout()
vbox.addWidget(self.lcd)
vbox.addWidget(self.sld)
self.setLayout(vbox)
#sld.valueChanged.connect(lcd.display)
QtCore.QObject.connect(self.sld, QtCore.SIGNAL(str1), self, QtCore.SLOT("SHOW()"))
#QtCore.pyqtSlot()
def SHOW(str1):
self.lcd.display()
self.setGeometry(300, 300, 250, 150)
self.setWindowTitle('Signal & slot')
self.show()
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
You were very close with your first attempt. All you need is:
self.sld.valueChanged.connect(self.lcd.display)
(The other lines up to self.setGeometry can be deleted).
Related
Force repainting does not repaint PyQt5 widget (Qlabel, QTextEdit, even QProgressBar and etc)
Tested platforms: Linux, MacOS
PyQt5 version: 5.15.7
Installed from pip
As example I created simple app that updating text in QLabel widget in for loop. Force repainting doesnt working
import sys
from time import sleep
from PyQt5.QtWidgets import (QWidget, QApplication, QPushButton, QLabel)
class Example(QWidget):
def __init__(self):
super().__init__()
self.text = QLabel('Test', self)
self.text.move(10, 10)
self.text.resize(60,20)
self.button = QPushButton('Run', self)
self.button.move(17,40)
self.button.clicked.connect(self.some_activity)
self.setGeometry(300, 300, 100, 80)
self.show()
def some_activity(self):
for i in range(100):
text = f'i = {i}'
self.text.setText(text)
# self.text.update() -> Nothing happens (it shouldnt: https://doc.qt.io/qt-5/qwidget.html#update)
self.text.repaint() # -> Nothing happens
self.repaint() # -> Nothing happens
print(f'Text updated: {text}')
sleep(0.03)
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
Video demonstration: link
Just needed to use QThread to use for loop in my program
Thanks #musicamante for helping.
import sys
from time import sleep
from PyQt5 import QtCore
from PyQt5.QtWidgets import (QWidget, QApplication, QPushButton, QLabel)
class Thread(QtCore.QThread):
signal = QtCore.pyqtSignal(str)
def __init__(self, parent=None): QtCore.QThread.__init__(self, parent)
def run(self):
for i in range(100):
text = f'i = {i}'
print(f'Text updated: {text}')
self.signal.emit(text)
sleep(.3)
class Example(QWidget):
def __init__(self):
super().__init__()
self.text = QLabel('Test', self)
self.text.move(10, 10)
self.text.resize(60,20)
self.thread = Thread()
self.thread.signal.connect(self.signal, QtCore.Qt.QueuedConnection)
self.button = QPushButton('Run', self)
self.button.move(17,40)
self.button.clicked.connect(self.thread.start)
self.setGeometry(300, 300, 100, 80)
self.show()
def signal(self, text): self.text.setText(text)
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
I can pass values between two windows using signal,
and I want the plain text change, while I press a button from another window.
but the insertPlainText and even text.show() are not working
I've tried sending the signal to the init part of the Mainwindow,
tried update, repaint, but none of them works.
appreciate for any of your help, thanks!
the search_send method in class SearchWindow to MainWindow method test_
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.ui = Ui_Dialog()
self.ui.setupUi(self)
self.ui.tag_box.hide()
def test_(self, i): # -------problem here------------------
print(i) // <- value here were right
self.ui.tag_box.insertPlainText(i) # -------Plain Text does not change-------
self.ui.tag_box.show()# -------Plain Text does not show either--------------
class SearchWindow(QtWidgets.QMainWindow):
signal=pyqtSignal(str)
def __init__(self, endpoint=None, user=None, password=None, points_link=None):
super(SearchWindow, self).__init__()
self.ui = Ui_Search()
self.ui.setupUi(self)
self.ui.pushButton_2.clicked.connect(self.search_send)
def search_send(self): # -------problem here------------------
tag_list = [tag1,tag2, tag3]
otherClass = MainWindow()
self.signal.connect(otherClass.test_)
for k in tag_list:
self.signal.emit(k)
if __name__ == '__main__':
app = QtWidgets.QApplication([])
window = MainWindow()
window.show()
sys.exit(app.exec_())
As we're unclear what Ui_Dialog contains, I can't tell what's wrong exactly, but can show you how Signal should be used.
This is example of Signal that's transferring text to Slot. Name may differ in PyQt5 - change accordingly.
from PySide2.QtWidgets import QWidget, QApplication, QPlainTextEdit, QTextEdit, QVBoxLayout
from PySide2.QtCore import Signal, Slot
import sys
class MainWindow(QWidget):
sig = Signal(str)
def __init__(self):
super(MainWindow, self).__init__()
self.setWindowTitle("Main")
self.layout = QVBoxLayout()
self.text = QTextEdit()
self.layout.addWidget(self.text)
self.setLayout(self.layout)
self.text.textChanged.connect(self.onChange)
def onChange(self):
self.sig.emit(self.text.toPlainText())
class SubWindow(QWidget):
def __init__(self, connect_target: MainWindow):
super(SubWindow, self).__init__()
self.setWindowTitle("Sub")
self.layout = QVBoxLayout()
self.text = QPlainTextEdit()
self.layout.addWidget(self.text)
self.setLayout(self.layout)
connect_target.sig.connect(self.onSignal)
#Slot(str)
def onSignal(self, text):
self.text.insertPlainText(text + '\r\n')
if __name__ == '__main__':
app = QApplication(sys.argv)
window = MainWindow()
window.show()
window_sub = SubWindow(window)
window_sub.show()
sys.exit(app.exec_())
Anything inside Main will be inserted to QPlainTextEdit as you wanted.
I am trying to design data input form that will add text to a label when the text is entered into a line edit widget when the ok button is pressed, but the answer is completely eluding me:
#!/usr/bin/python3
#-*- coding: utf-8 -*-
"""
Set label text from line edit with
ok click
"""
import sys
from PyQt4 import QtGui, QtCore
class Example(QtGui.QMainWindow):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
self.qle = QtGui.QLineEdit(self)
self.qle.move(100, 0)
sometext = self.qle.text
self.lbl = QtGui.QLabel(self)
self.lbl.move(100, 100)
btn = QtGui.QPushButton("Ok", self)
btn.move(30, 100)
btn.clicked.connect(self.buttonClicked)
self.setGeometry(200, 200, 300, 200)
self.show
def buttonClicked(self, sometext):
sender = self.sender()
self.lbl.setText(sometext)
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
How do you get this to work please?
You can use this to set text to a label: QLabel.setText("string text")
Combined with: QPushButton.clicked.connect(lambda: func())
And get the text in the Line Edit: QLineEdit.text()
So complete code should look something like:
#!/usr/bin/python3
#-*- coding: utf-8 -*-
"""
Set label text from line edit with
ok click
"""
import sys
from PyQt4 import QtGui, QtCore
class Example(QtGui.QMainWindow):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
self.qle = QtGui.QLineEdit(self)
self.qle.move(100, 0)
sometext = self.qle.text
self.lbl = QtGui.QLabel(self)
self.lbl.move(100, 100)
btn = QtGui.QPushButton("Ok", self)
btn.move(30, 100)
self.setGeometry(200, 200, 300, 200)
self.show
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
ex = Example()
def setLabelText():
text = qle.text()
ex.lbl.setText(text)
ex.btn.clicked.connect(lambda: setLabelText())
sys.exit(app.exec_())
I can't actually test this code, but it should work fine.
Tell me if you have any problems, and please give us a traceback.
You might also want to consider moving to PyQt5.6 (Slightly older than the newest, but it has the QtDesigner built in. A quick google search should find you the right executable installer, it's not on their website anymore. If you can't find it I can send it to you.)
Hope it works, and wish you luck!
Edit:
I just thought of a simpler way. Should have just said this.
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
ex = Example()
ex.btn.clicked.connect(lambda: ex.lbl.setText(qle.text()))
sys.exit(app.exec_())
A bit of a simplified answer. Did some edits to your code. It works fine, and runs successfully.
import sys
from PyQt4 import QtGui, QtCore
class Example(QtGui.QMainWindow):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
self.qle = QtGui.QLineEdit(self)
self.qle.move(10, 10)
self.lbl = QtGui.QLabel(self)
self.lbl.setGeometry(10, 55,200,20)
self.lbl.setText("Type Something and Press Ok!")
btn = QtGui.QPushButton("Ok", self)
btn.move(10, 100)
btn.clicked.connect(self.buttonClicked)
self.setGeometry(200, 200, 300, 200)
self.show
def buttonClicked(self):
sender = self.sender()
self.lbl.setText(self.qle.text())
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
ex.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
Also you QLabel was invisible because it was out of your QMainWindow area.
Hope it Helps!
Can't work out how to embed a window in a main window using classes:
#!/usr/bin/python3
# -*- coding: utf-8 -*-
"""
Qt4 tutorial using classes
This example will be built
on over time.
"""
import sys
from PyQt4 import QtGui, QtCore
class Form(QtGui.QWidget):
def __init__(self, MainWindow):
super(Form, self).__init__()
class MainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__()
self.setGeometry(50, 50, 1600, 900)
new_window = Form(self)
self.show()
def main():
app = QtGui.QApplication(sys.argv)
main_window = MainWindow()
sys.exit(app.exec_())
if __name__ == "__main__":
main()
This is supposed to be the single most basic bit of code using classes. How do I get the second window to show please.
As ekhumoro already pointed out, your widget needs to be a child of your mainWindow. However, I do not think that you need to call show for the widget, since it anyways gets called as soon as its parent (MainWindow) calls show. As mata pointed out correctly, the proper way to add a Widget to a MainWindow instance is to use setCentralWidget. Here is a working example for clarification:
import sys
from PyQt4 import QtGui, QtCore
class Form(QtGui.QWidget):
def __init__(self, parent):
super(Form, self).__init__(parent)
self.lbl = QtGui.QLabel("Test", self)
class MainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__()
self.setGeometry(50, 50, 1600, 900)
new_window = Form(self)
self.setCentralWidget(new_window)
self.show()
def main():
app = QtGui.QApplication(sys.argv)
main_window = MainWindow()
sys.exit(app.exec_())
if __name__ == "__main__":
main()
When I click the button, "ChildWindow" will flash and disappear. Then If I add the function exec_(), it will report an "AttributeError" because "QMainWindow" don't have this attribute.
How to modify the function "showChildWindow" so that it can work well? Thank you.
import sys
from PyQt4 import QtCore, QtGui
class MainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.setWindowTitle("MainWindow Window!")
self.setGeometry(400, 400, 100, 100)
self.centerWidget = QtGui.QWidget()
self.setCentralWidget(self.centerWidget)
self.pushButton = QtGui.QPushButton("&Button")
layout = QtGui.QVBoxLayout()
layout.addWidget(self.pushButton)
self.centerWidget.setLayout(layout)
class ChildWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.setWindowTitle("Child Window!")
def showChildWindow():
mw = MainWindow()
child_win = ChildWindow(mw)
child_win.show()
#child_win.exec_() #AttributeError: 'ChildWindow' object has no attribute 'exec_'
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
myapp = MainWindow()
myapp.show()
QtCore.QObject.connect(myapp.pushButton,QtCore.SIGNAL("clicked()"),showChildWindow)
sys.exit(app.exec_())
This program can work well.
import sys
from PyQt4 import QtCore, QtGui
class MainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.setWindowTitle("MainWindow Window!")
self.setGeometry(400, 400, 100, 100)
self.centerWidget = QtGui.QWidget()
self.setCentralWidget(self.centerWidget)
pushButton = QtGui.QPushButton("&Button")
layout = QtGui.QVBoxLayout()
layout.addWidget(pushButton)
self.centerWidget.setLayout(layout)
QtCore.QObject.connect(pushButton,QtCore.SIGNAL("clicked()"),self.showChildWindow)
def showChildWindow(self):
self.child_win = ChildWindow(self)
self.child_win.show()
class ChildWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.setWindowTitle("Child Window!")
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
myapp = MainWindow()
myapp.show()
sys.exit(app.exec_())
The real question appears to be: how do I access the main-window from other modules in my application?
My preferred general solution to this problem is to sub-class QApplication and add a simple accessor method, like this:
class Application(QtGui.QApplication):
def __init__(self):
QtGui.QApplication.__init__(self, sys.argv)
self._window = None
def window(self):
if self._window is None:
self._window = MainWindow()
return self._window
if __name__ == "__main__":
app = QtGui.qApp = Application()
app.window().show()
sys.exit(app.exec_())
With that in place, you can easily get access the methods of the main-window in other modules like this:
from PyQt4 import QtGui
QtGui.qApp.window().showChildWindow()
I had the same problem. The child QMainWindow would randomly disappear while interacting with the parent window.
This is the bad source code that causes this problem:
def showChildWindow(self):
child_win = ChildWindow()
child_win.show()
This is the good source code that fixes the problem:
def showChildWindow(self):
child_win = ChildWindow(self)
child_win.show()
When you instantiate the child window, make sure you pass the parent self.