class MainWindow(QtGui.QMainWindow):
"""This is the Main Window inside which everything happens
This application needs to have various pages for various tasks. For example it needs a page for adding employee, one
for editing, one for deleting, one for Salary calculation, etc. Each of these pages are individually created by
extending ``QWidget``. We also need to be able to jump from one page to other or go back to previous page easily.
The trick used to achieve this easily can be understood with a simple example.
Lets say we have two classes Apple and Banana. We need to create an instance of
any one of them as required. We can do the following::
fruits = { "apple" : Apple, "banana" : Banana }
# we can get an Apple instance by writing -
a = fruits["apple"]() # same as writing a = Apple()
# as fruits["apple"] is substituted with Apple
# We can take this further by putting it in a function -
def make_fruit(name):
return fruits[name]() # This would return an instance of required fruit
a = make_fruit("apple") # Returns an Apple object
b = make_fruit("banana") # Returns a Banana object
So all the classes for the pages are stored in a dictionary with a page name string as their key.
So passing the page name to the dictionary will return an instance required page class. A ``gotoPage()`` method
is made to take the page name and show corresponding page.
Now the problem of dynamically creating an instance of required page is solved
but we still need to be able to smoothly switch from one page to other.
This is done using ``QStackedWidget`` which is like a stack of ``QWidgets`` that we can switch through.
A ``goBack()`` method is made which goes back to previous page and deletes the current page instance.
The central widget for the ``QMainWindow``is set to a blank widget which contains a ``Header`` widget at the top
and a ``QStackedWidget`` ofr the rest of it.
See Also:
- :py:mod:`Header` module
"""
def __init__(self):
QtGui.QMainWindow.__init__(self)
self.username = None
self.setWindowTitle("Salary Manager")
self.setGeometry(50, 50, 900, 700)
self.setWindowState(QtCore.Qt.WindowMaximized)
self.setWindowIcon(QtGui.QIcon("Resources/rupee.png"))
self.bgWidget = QtGui.QWidget()
self.header = Header()
self.header.setLogo("Resources/iiitk.png")
self.header.setHeaderText(
"Salary Management System",
"Indian Institute of Information Technology Kalyani")
self.widgetStack = QtGui.QStackedWidget()
self.setCentralWidget(self.bgWidget)
self.setupUI()
self.pages = {
"Login": LoginWidget,
"Home": HomeWidget,
"Add Employee": AddEmployeeWidget,
"Del Employee": DelEmployeeWidget,
"Edit Employee": EditEmployeeWidget,
"Show Employee": ShowEmployeeWidget,
"Add Designation": AddDesignationWidget,
"Del Designation": DelDesignationWidget,
"Edit Designation": EditDesignationWidget,
"Show Designation": ShowDesigationWidget,
"Calc Salary": CalculateSalaryWidget,
"Result": ShowPaySlipWidget,
"Change Password": ChangePasswordWidget,
"Log Out": LoginWidget
}
self.gotoPage("Login")
def gotoPage(self, name, *args):
"""A method to open page corresponding to given name
This method takes the page ``name`` and passes it to the pages dictionary to get corresponding class and
creates a new instance of the class. The ``*args`` (if any) are passed to the constructor of that class.
This newly created page is then added to the ``QStackedWidget`` and this new page is set as current page.
As all pages are initialized in this class, this class is passed as an argument in the constructor
and stored in __parent attribute. So, now we can use ``self.__parent.gotoPage()`` to access
this ``gotoPage()`` from any class. Thus we now have the ability to go from any page to any page.
Also, similarly they can use ``self.__parent.goBack()`` to access ``goBack()`` method of this class.
Args:
name (str): Name of the page
*args: variable length argument list
"""
print "Goto page", name, "; args=", args
try:
if len(args) == 0:
newPage = self.pages[name](self)
else:
newPage = self.pages[name](self, *args)
self.widgetStack.addWidget(newPage)
self.widgetStack.setCurrentWidget(newPage)
try:
self.setTitle(newPage.title)
except AttributeError as e:
self.setTitle("")
except mysql.connector.Error as e:
ShowMysqlError(e, self)
def goBack(self):
"""Method to go back to previous page
This method sets the index of ``QWidgetStack`` used in this class to ``currentIndex - 1`` (hence effectively
going to previous page). It then removes the previous page from the stack and deletes it.
"""
print "Going Back"
try:
currentIndex = self.widgetStack.currentIndex()
if currentIndex > 0:
currentPage = self.widgetStack.currentWidget()
self.widgetStack.setCurrentIndex(currentIndex - 1)
try:
self.setTitle(self.widgetStack.currentWidget().title)
except AttributeError as e:
self.setTitle("")
currentPage.deleteLater()
self.widgetStack.removeWidget(currentPage)
except mysql.connector.Error as e:
ShowMysqlError(e, self)
def setupUI(self):
layout = QtGui.QVBoxLayout()
layout.setContentsMargins(0, 0, 0, 0)
layout.setSpacing(0)
layout.addWidget(self.header)
layout.addWidget(self.widgetStack)
self.bgWidget.setLayout(layout)
def setTitle(self, titleText=""):
"""Sets the title text in the Header by calling setTile() method of the header
Args:
titleText (str): Title to be set
See Also:
:py:meth:`setTitle() <Header.Header.setTitle>` method of Header module
"""
self.header.setTitle(titleText)
