PyQt4 signals and slots - QToolButton - python

In PyQt4 I have a main window which when the settings button is clicked opens the settings dialog
from PyQt4 import QtCore, QtGui
import ui_Design, ui_Settings_Design
class MainDialog(QtGui.QMainWindow, ui_Design.Ui_arbCrunchUI):
def __init__(self, parent=None):
super(MainDialog, self).__init__(parent)
self.setupUi(self)
self.settingsBtn.clicked.connect(lambda: self.showSettings())
def showSettings(self):
dialog = QtGui.QDialog()
dialog.ui = SettingsDialog()
dialog.ui.setupUi(dialog)
dialog.exec_()
The above works and my SettingsDialog is displayed but I cant get the setPageIndex to work
class SettingsDialog(QtGui.QDialog, ui_Settings_Design.Ui_SettingsDialog):
def __init__(self, parent=None):
super(SettingsDialog, self).__init__(parent)
self.setupUi(self)
self.bookSettingsBtn.clicked.connect(self.setPageIndex)
#QtCore.pyqtSlot()
def setPageIndex(self):
print 'selected'
self.settingsStackedWidget.setCurrentIndex(0)
The bookSettingsBtn is a QToolButton
self.bookSettingsBtn = QtGui.QToolButton(self.navigationFrame)
And the settingsStackedWidget is a QStackedWidget
self.settingsStackedWidget = QtGui.QStackedWidget(SettingsDialog)
At this point I am pretty confused on signals and slots and nothing I have read clears this up - if anyone can point out what I am doing wrong above and also potentially direct me to a good (beginners) guide / tutorial on signals and slots it would be greatly appreciated
I would also like to know how to make setPageIndex work as follows:
def setPageIndex(self, selection):
self.settingsStackedWidget.setCurrentIndex(selection)

I'm not sure why you're doing the following, but that's the issue:
def showSettings(self):
dialog = QtGui.QDialog()
dialog.ui = SettingsDialog()
dialog.ui.setupUi(dialog)
dialog.exec_()
SettingsDialog itself is a proper QDialog. You don't need to instantiate another QDialog.
Right now, you're creating an empty QDialog and then populate it with the same ui as SettingsDialog (i.e. setupUi(dialog)), then you show this dialog. But... The signal connection is for SettingsDialog, and the dialog you're showing doesn't have that.
Basically, you don't need that extra QDialog at all. The following should be enough:
def showSettings(self):
dialog = SettingsDialog()
dialog.exec_()

Ok. So here is an example how you pass an argument to a slot
from functools import partial
# here you have a button bookSettingsBtn:
self.bookSettingsBtn = QtGui.QPushButton("settings")
self.bookSettingsBtn.clicked.connect(partial(self.setPageIndex, self.bookSettingsBtn.text()))
#pyqtSlot(str) # this means the function expects 1 string parameter (str, str) 2 string parameters etc.
def setPageIndex(self, selection):
print "you pressed button " + selection
In your case the argument would be an int. Of course you have to get the value from somewhere
and then put it in the partial part as the argument (here I just used the text of the button),
but you can use int, bool etc. Just watch the slot signature.
Here is a tutorial that helped me:
http://zetcode.com/gui/pyqt4/
I hope this helps.

Hey here I have a fully running example (just copy paste it in a python file and run it):
Maybe this helps you. It's a small example but here you see how it works.
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from functools import partial
class MyForm(QMainWindow):
def __init__(self, parent=None):
super(MyForm, self).__init__(parent)
button1 = QPushButton('Button 1')
button2 = QPushButton('Button 2')
button1.clicked.connect(partial(self.on_button, button1.text()))
button2.clicked.connect(partial(self.on_button, button1.text()))
layout = QHBoxLayout()
layout.addWidget(button1)
layout.addWidget(button2)
main_frame = QWidget()
main_frame.setLayout(layout)
self.setCentralWidget(main_frame)
#pyqtSlot(str)
def on_button(self, n):
print "Text of button is: " + str(n)
if __name__ == "__main__":
import sys
app = QApplication(sys.argv)
form = MyForm()
form.show()
app.exec_()

So I dont really understand why but changing the way the settingsDialog is called from the MainWindow has fixed my problem. I guess the parent window needed to be specified??:
class MainDialog(QtGui.QMainWindow, ui_Design.Ui_arbCrunchUI):
....
def showSettings(self):
self.settingsDialog = QtGui.QDialog(self)
self.settingsDialog.ui = SettingsDialog(self)
self.settingsDialog.ui.show()
class SettingsDialog(QtGui.QDialog, ui_Settings_Design.Ui_SettingsDialog):
def __init__(self, parent=None):
super(SettingsDialog, self).__init__(parent)
self.setupUi(self)
self.bookSettingsBtn.clicked.connect(partial(self.setPageIndex, 1))
#QtCore.pyqtSlot(int)
def setPageIndex(self, selection):
self.settingsStackedWidget.setCurrentIndex(selection)

Related

PyQt5in Python - Use a QLabel like a button [duplicate]

I have a Qlabel filled with QPixmap and I want to start a process/function once this label clicked. I had extended QLabel class as follows:
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
class QLabel_alterada(QLabel):
clicked=pyqtSignal()
def __init(self, parent):
QLabel.__init__(self, QMouseEvent)
def mousePressEvent(self, ev):
self.clicked.emit()
Then, in my pyuic5-based .py file (I used QtDesigner to do the layout) after importing the module where I save the extended QLabel class, inside the automatically generated setupui, function I changed my Label from
self.label1=QtWidgets.QLabel(self.centralwidget)
to
self.label1 = QLABEL2.QLabel_alterada(self.centralwidget)
Finally, in the core app Python file where I put all the procedures/classes whetever needed to the application functionality I added
self.ui.label1.clicked.connect(self.dosomestuff)
The application does not crashes but the labels still not clickable. Can someone give me some help on this?
I do not understand why you pass QMouseEvent to the parent constructor, you must pass the parent attribute as shown below:
class QLabel_alterada(QLabel):
clicked=pyqtSignal()
def mousePressEvent(self, ev):
self.clicked.emit()
To avoid having problems with imports we can directly promote the widget as shown below:
We place a QLabel and right click and choose Promote to ...:
We get the following dialog and place the QLABEL2.h in header file and QLabel_changed in Promoted class Name, then press Add and Promote
Then we generate the .ui file with the help of pyuic. Obtaining the following structure:
├── main.py
├── QLABEL2.py
└── Ui_main.ui
Obtaining the following structure:
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
QtWidgets.QMainWindow.__init__(self, parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
self.ui.label.clicked.connect(self.dosomestuff)
def dosomestuff(self):
print("click")
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
Since Python can pass function as object, I think make a class inherit QLabel only to make it clickable is overkill. Instead I do like this:
import sys
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QFrame, QLabel
def foo(*arg, **kwargs):
print("Bar")
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
Frame = QFrame()
label = QLabel(Frame)
label.mousePressEvent = foo
label.setText("Label")
Frame.show()
sys.exit(app.exec_())
class ClickableLabel(QtWidgets.QLabel):
def __init__(self, whenClicked, parent=None):
QtWidgets.QLabel.__init__(self, parent)
self._whenClicked = whenClicked
def mouseReleaseEvent(self, event):
self._whenClicked(event)
and then:
my_label = ClickableLabel(self.my_label_clicked)
...
def my_label_clicked(self, event):
button = event.button()
modifiers = event.modifiers()
if modifiers == Qt.NoModifier and button == Qt.LeftButton:
logger.debug('my_label_clicked: hooray!')
return
LOGGER.debug('my_label_clicked: unhandled %r', event)
In PyQT5, you can try to add code in setupUi and create clicked method:
def setupUi()
...
self.label1.linkActivated.connect(self.clicked)
...
def clicked(self):
print(self.label1.text()) #For example, printing the label text...
Hope this helps!

How to detect any mouse click on PySide Gui?

I am trying implement a feature such that when a mouse is clicked on the gui, a function is triggered
Below is my mouse click detection, it doesn't work when I click on any part of the gui
from PySide.QtCore import *
from PySide.QtGui import *
import sys
class Main(QWidget):
def __init__(self, parent=None):
super(Main, self).__init__(parent)
layout = QHBoxLayout(self)
layout.addWidget(QLabel("this is the main frame"))
layout.gui_clicked.connect(self.anotherSlot)
def anotherSlot(self, passed):
print passed
print "now I'm in Main.anotherSlot"
class MyLayout(QHBoxLayout):
gui_clicked = Signal(str)
def __init__(self, parent=None):
super(MyLayout, self).__init__(parent)
def mousePressEvent(self, event):
print "Mouse Clicked"
self.gui_clicked.emit("emit the signal")
a = QApplication([])
m = Main()
m.show()
sys.exit(a.exec_())
This is my goal
Mouseclick.gui_clicked.connect(do_something)
Any advice would be appreciated
Define mousePressEvent inside Main:
from PySide.QtCore import *
from PySide.QtGui import *
import sys
class Main(QWidget):
def __init__(self, parent=None):
super(Main, self).__init__(parent)
layout = QHBoxLayout(self)
layout.addWidget(QLabel("this is the main frame"))
def mousePressEvent(self, QMouseEvent):
#print mouse position
print QMouseEvent.pos()
a = QApplication([])
m = Main()
m.show()
sys.exit(a.exec_())
This can get complicated depending on your needs. In short, the solution is an eventFilter installed on the application. This will listen the whole application for an event. The problem is "event propagation". If a widget doesn't handle an event, it'll be passed to the parent (and so on). You'll see those events multiple times. In your case, for example QLabel doesn't do anything with a mouse press event, therefore the parent (your main window) gets it.
If you actually filter the event (i.e. you don't want the original widget to respond to the event), you won't get that problem. But, I doubt that this is your intent.
A simple example for just monitoring:
import sys
from PySide import QtGui, QtCore
class MouseDetector(QtCore.QObject):
def eventFilter(self, obj, event):
if event.type() == QtCore.QEvent.MouseButtonPress:
print 'mouse pressed', obj
return super(MouseDetector, self).eventFilter(obj, event)
class MainWindow(QtGui.QWidget):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
layout = QtGui.QHBoxLayout()
layout.addWidget(QtGui.QLabel('this is a label'))
layout.addWidget(QtGui.QPushButton('Button'))
self.setLayout(layout)
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
mouseFilter = MouseDetector()
app.installEventFilter(mouseFilter)
main = MainWindow()
main.show()
sys.exit(app.exec_())
You can see that, clicking on the QLabel will give you something like:
mouse pressed <PySide.QtGui.QLabel object at 0x02B92490>
mouse pressed <__main__.MainWindow object at 0x02B92440>
Because, QLabel receives the event and since it doesn't do anything with it, it's ignored and passed to the parent (MainWindow). And it's caught by the filter/monitor again.
Clicking on the QPushButton doesn't have any problem because it uses that event and does not pass to the parent.
PS: Also note that this can cause performance problems since you are inspecting every single event in the application.

Load other windows when button clicked. PyQt

I am trying to call another window from a button click in python 2.7 using PyQt4. The code below opens the AddBooking dialog but immediately closes it. Im new to Gui programming, can somebody please tell me what is wrong with my code?
from PyQt4 import QtGui
from HomeScreen import Ui_HomeScreen
from AddBooking import Ui_AddBooking
import sys
class HomeScreen(QtGui.QWidget, Ui_HomeScreen):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.setupUi(self)
self.show()
self.Add_Booking_Button.clicked.connect(self.handleButton)
def handleButton(self):
AddBooking2()
class AddBooking2(QtGui.QWidget, Ui_AddBooking):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.setupUi(self)
self.show()
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
window = HomeScreen()
window.show()
sys.exit(app.exec_())
Don't use multi-inheritance and neither call show function inside class initializer. The problem is that the object you are creating with AddBooking2() is a temporal and it's destroyed automatically when the function ends. So you need use some variable to reference that object something like:
addbooking = AddBooking2()
addbooking.show()
Also, since you are working with QtDesigner and pyuic4 tools you can make connections a little bit easier. Said that, your code can be modified:
from PyQt4 import QtGui
from PyQt4.QtCore import pyqtSlot
from HomeScreen import Ui_HomeScreen
from AddBooking import Ui_AddBooking
import sys
class HomeScreen(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.ui = Ui_HomeScreen()
self.ui.setupUi(self)
#pyqtSlot("")
def on_Add_Booking_Button_clicked(self): # The connection is carried by the Ui_* classes generated by pyuic4
addbooking = AddBooking2()
addbooking.show()
class AddBooking2(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.ui = Ui_AddBooking()
self.ui.setupUi(self)
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
window = HomeScreen()
window.show()
sys.exit(app.exec_())
The dialog closes immediately because you are not keeping a reference to it, and so it will get garbage-collected as soon as it goes out of scope.
The simplest way to fix it would be to do something like this:
def handleButton(self):
self.dialog = AddBooking2()
self.dialog.show()
and you can also remove the self.show() lines from AddBooking2.__init__ and HomeScreen.__init__, which are redundant. Other than that, your code looks fine.

Pulling text from QLineEdit

I made a dialog with a simple QLineEdit and QbuttonBox (lineEdit and buttonBox respectively), now I'm trying to use what is in the line edit when I press OK. It simply comes out blank and doesn't print during go and prints "None" for the bottom of print(base). Surfed and found the text() but still no love. Any help is appreciated.
from PyQt4 import QtGui, QtCore
import sys
import x
class Dialog(QtGui.QDialog, x.Ui_Dialog):
def __init__(self):
super(Dialog, self).__init__()
self.setupUi(self)
global base
base = self.buttonBox.accepted.connect(self.go)
def go(self):
what = self.lineEdit.text()
return what
print(what)
app = QtGui.QApplication(sys.argv)
form = Dialog()
form.show()
app.exec_()
print(base)
The example code is mostly correct, except that the go() method is returning before it has a chance to print anything. So if you remove that line, it should work as expected, i.e:
class Dialog(QtGui.QDialog, x.Ui_Dialog):
def __init__(self):
super(Dialog, self).__init__()
self.setupUi(self)
self.buttonBox.accepted.connect(self.go)
def go(self):
what = self.lineEdit.text()
print(what)
Also, there is no point in grabbing the return value when you connect a signal to a handler. If the connection is invalid, it will just raise an error.
EDIT:
If you want to access the text of the line-edit from outside of the dialog, then you don't really need a signal. Just make sure the dialog blocks until the user has entered the text, and then access the line-edit directly:
dialog = Dialog()
if dialog.exec_() == QtGui.QDialog.Accepted:
text = dialog.lineEdit.text()
# do stuff with text...
else:
print('cancelled')

How to connect a signal from the controller in PyQt4? (iOS like MVC structure in PyQt4)

Why doesn't the following example work?
from PyQt4 import QtGui
import sys
class TestView(QtGui.QWidget):
def __init__(self):
super(TestView, self).__init__()
self.initUI()
def initUI(self):
self.btn = QtGui.QPushButton('Button', self)
self.btn.resize(self.btn.sizeHint())
self.btn.move(50, 50)
class TestViewController():
def __init__(self, view):
view.btn.clicked.connect(self.buttonClicked)
view.show()
def buttonClicked(self):
print 'clicked'
def main():
app = QtGui.QApplication(sys.argv)
view = TestView()
TestViewController(view)
app.exec_()
if __name__ == '__main__':
main()
The example is supposed to represent an MVC structure (like the one in Figure 4 -- without the Model) where the controller (TestViewController) receives a reference to the view (TestView) and connects the clicked signal from the view's button view.btn to its function self.buttonClicked.
I'm sure the line view.btn.clicked.connect(self.buttonClicked) is executed but, apparently, it has no effect. Does anyone knows how to solve that?
Update (awful solution):
In the example, if I replace the line
view.btn.clicked.connect(self.buttonClicked)
with
view.clicked = self.clicked
view.btn.clicked.connect(view.clicked)
it works. I'm still not happy with that.
The reason it is not working is because the controller class is being garbage collected before you can ever click anything for it.
When you set view.clicked = self.clicked, what you're actually doing is making one of the objects from the controller persist on the view object so it never gets cleaned up - which isn't really the solution.
If you store your controller to a variable, it will protect it from collection.
So if you change your code above to read:
ctrl = TestViewController(view)
You'll be all set.
That being said - what exactly you are trying to do here, I am not sure...it seems you're trying to setup an MVC system for Qt - but Qt already has a pretty good system for that using the Qt Designer to separate the interface components into UI (view/template) files from controller logic (QWidget subclasses). Again, I don't know what you are trying to do and this may be a dumb down version of it, but I'd recommend making it all one class like so:
from PyQt4 import QtGui
import sys
class TestView(QtGui.QWidget):
def __init__(self):
super(TestView, self).__init__()
self.initUI()
def initUI(self):
self.btn = QtGui.QPushButton('Button', self)
self.btn.resize(self.btn.sizeHint())
self.btn.move(50, 50)
self.btn.clicked.connect(self.buttonClicked)
def buttonClicked(self):
print 'clicked'
def main():
app = QtGui.QApplication(sys.argv)
view = TestView()
view.show()
app.exec_()
if __name__ == '__main__':
main()
Edit: Clarifying the MVC of Qt
So this above example doesn't actually load the ui dynamically and create a controller/view separation. Its a bit hard to show on here. Best to work through some Qt/Designer based examples/tutorials - I have one here http://bitesofcode.blogspot.com/2011/10/introduction-to-designer.html but many can be found online.
The short answer is, your loadUi method can be replace with a PyQt4.uic dynamic load (and there are a number of different ways to set that up) such that your code ultimately reads something like this:
from PyQt4 import QtGui
import PyQt4.uic
import sys
class TestController(QtGui.QWidget):
def __init__(self):
super(TestController, self).__init__()
# load view
uifile = '/path/to/some/widget.ui'
PyQt4.uic.loadUi(uifile, self)
# create connections (assuming there is a widget called 'btn' that is loaded)
self.btn.clicked.connect(self.buttonClicked)
def buttonClicked(self):
print 'clicked'
def main():
app = QtGui.QApplication(sys.argv)
view = TestController()
view.show()
app.exec_()
if __name__ == '__main__':
main()
Edit 2: Storing UI references
If it is easier to visualize this concept, you Can also store a reference to the generated UI object:
from PyQt4 import QtGui
import PyQt4.uic
import sys
class TestController(QtGui.QWidget):
def __init__(self):
super(TestController, self).__init__()
# load a view from an external template
uifile = '/path/to/some/widget.ui'
self.ui = PyQt4.uic.loadUi(uifile, self)
# create connections (assuming there is a widget called 'btn' that is loaded)
self.ui.btn.clicked.connect(self.buttonClicked)
def buttonClicked(self):
print 'clicked'
def main():
app = QtGui.QApplication(sys.argv)
view = TestController()
view.show()
app.exec_()
if __name__ == '__main__':
main()

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