I started coding a simple text editor in Python with PyQt and I ran into this problem: for the "New document" button I want to open a new empty text editor which stays open no matter what happened to the first window. The problem is that the only way I got it to show the window is if I send self as a parameter(making it the parent) which leads to the second window closing when the parent closes.
Here's my constructor:
class Main(QtGui.QMainWindow):
def __init__(self, ctrl, parent=None):
QtGui.QMainWindow.__init__(self, parent)
and here's the method that opens a new window:
def new(self):
repo = Repository()
ctrl = Controller(repo)
new_win = Main(ctrl)
new_win.show()
Note: when the code that is here doesn't work, it just doesn't show the second window
Edit: decided I should post all my code, so here it goes:
import sys
from PyQt4 import QtGui
from src.controller import Controller
from src.repository import Repository
class Main(QtGui.QMainWindow):
nr_of_instances = -1
def __init__(self, ctrl, parent=None):
QtGui.QMainWindow.__init__(self, parent)
Main.nr_of_instances += 1
#ui elements
self._toolbar = None
self._menuBar = None
self._file = None
self._edit = None
self._view = None
self._formatBar = None
self._statusBar = None
self._text = None
#actions
self._newAction = None
self._openAction = None
self._saveAction = None
self._saveAsAction = None
#
self._controller = ctrl
self.init_ui()
def init_ui(self):
self._text = QtGui.QTextEdit(self)
self.setCentralWidget(self._text)
self.init_toolbar()
self.init_formatBar()
self.init_menuBar()
self._statusBar = self.statusBar()
self.setGeometry(50+(50*Main.nr_of_instances), 100+(50*Main.nr_of_instances), 800, 400)
self.setWindowTitle("KekWriter")
@staticmethod
def new(self):
repo = Repository()
ctrl = Controller(repo)
spawn = Main(ctrl)
spawn.show()
def set_title(self):
if self._controller.get_file_name() != 0:
new_title = self.windowTitle().split(" - ")
new_title[0].strip()
self.setWindowTitle(new_title[0]+" - "+self._controller.get_file_name())
def open(self):
fn = QtGui.QFileDialog.getOpenFileName(self, 'Open File', ".")
self._controller.set_file_name(fn)
try:
if fn != '':
self._text.setText(self._controller.open())
self.set_title()
except UnicodeDecodeError as msg:
QtGui.QMessageBox.information(self, "Eroare!", "Tip de fisier invalid!")
def _save_as(self):
fn = QtGui.QFileDialog.getSaveFileName(self, 'Save File As', ".")
print(fn)
if fn != '':
self._controller.set_file_name(fn)
self._controller.save(self._text.toPlainText())
self.set_title()
def save(self):
fn = self._controller.get_file_name()
if fn == '':
self._save_as()
else:
self._controller.save(self._text.toPlainText())
self.set_title()
def init_toolbar(self):
self._newAction = QtGui.QAction(QtGui.QIcon("icons/new.png"), "New", self)
self._newAction.setStatusTip("Creates a new document")
self._newAction.setShortcut("Ctrl+N")
self._newAction.triggered.connect(self.new)
self._openAction = QtGui.QAction(QtGui.QIcon("icons/open.png"), "Open", self)
self._openAction.setStatusTip("Opens existing document")
self._openAction.setShortcut("Ctrl+O")
self._openAction.triggered.connect(self.open)
self._saveAction = QtGui.QAction(QtGui.QIcon("icons/save.png"), "Save", self)
self._saveAction.setStatusTip("Saves current document")
self._saveAction.setShortcut("Ctrl+S")
self._saveAction.triggered.connect(self.save)
self._saveAsAction = QtGui.QAction(QtGui.QIcon("icons/save_as.png"), "Save as", self)
self._saveAsAction.setStatusTip("Saves current document with another name")
self._saveAsAction.setShortcut("Ctrl+Shift+S")
self._saveAsAction.triggered.connect(self._save_as)
self._toolbar = self.addToolBar("Options")
self._toolbar.addAction(self._newAction)
self._toolbar.addAction(self._openAction)
self._toolbar.addAction(self._saveAction)
self._toolbar.addAction(self._saveAsAction)
self.addToolBarBreak()
def init_menuBar(self):
self._menuBar = self.menuBar()
self._file = self._menuBar.addMenu("File")
self._edit = self._menuBar.addMenu("Edit")
self._view = self._menuBar.addMenu("View")
#file
self._file.addAction(self._newAction)
self._file.addAction(self._openAction)
self._file.addAction(self._saveAction)
self._file.addAction(self._saveAsAction)
def init_formatBar(self):
self._formatBar = self.addToolBar("Format")
self.addToolBarBreak()
def main():
app = QtGui.QApplication(sys.argv)
repo = Repository()
ctrl = Controller(repo)
main = Main(ctrl)
main.show()
sys.exit(app.exec_())
if __name__ == "__main__":
main()
The reason your second window doesn't show is because the window object goes out of scope and is garbage collected. You need to store a reference to the second window somewhere which won't be deleted until the window is closed.
There are a few ways to do this that I can think of, but it is really up to you with how you want to structure your program.
Have a class attribute of Main which is a list. This list will thus be common to all instances and you can append a new instance to that list when it is created. As long as one instance exists, the window shouldn't be garbage collected (I think)
Don't instantiate a QMainWindow initially, but instead instantiate a class that will hold references to windows. When a new window is created, sore the reference to the new window in this object.
Hopefully this gives you an idea of what is wrong so you can solve it in a way that suits the layout of your program
For a rough guide of how you would do option 2:
class WindowContainer(object):
def __init__(self):
self.window_list = []
self.add_new_window()
def add_new_window(self):
repo = Repository()
ctrl = Controller(repo)
spawn = Main(ctrl, self)
self.window_list.append(spawn)
spawn.show()
class Main(QtGui.QMainWindow):
def __init__(self, ctrl, window_container, parent=None):
QtGui.QMainWindow.__init__(self, parent)
...
self.window_container = window_container
...
...
def init_toolbar(self):
...
self._newAction.triggered.connect(self.window_container.add_new_window)
...
...
def main():
app = QtGui.QApplication(sys.argv)
# this variable will never go out of scope
window_container = WindowContainer()
sys.exit(app.exec_())