Exam (elaborations)
INF2611 Revision
- Course
- Visual Programming II
- Institution
- University Of South Africa
INF2611 Revision. Detailed work, solutions, memos, notes, and explanations
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INF2611 Revision., Chapter Summaries Module: INF2611
Chapter 9 – Advanced Widgets
9.1. Displaying System Clock Time in LCD Format
To display LCD‐like digits, you use the LCD Number widget, an instance of the QLCDNumber class.
To perform a repetitive task, you use a timer. A timer is an instance of the QTimer class.
To use, create an instance of QTimer and connect its timeout() signal to the slot that performs the
desired task.
To fetch the system clock time and measure a span of elapsed time, you use the QTime class. The
returned info can be converted into text with the toString() method.
CLASS METHODS USE
QLCDNumber setMode() Change the base of the numbers (Hex, Dec, Oct, Bin).
display() Display the specified content as LCD digits.
value() Return the value displayed by the widget.
QTimer timeout()
start(n) Generate a timeout() at n millisecond intervals.
setSingleShot(true) Generate a timeout() signal only once.
singleShot(n) Generate a timeout() signal only once after n milliseconds.
QTime currentTime() Fetches the system’s clock time as a QTime object.
hour(), minute(), Return the number of hours, minutes, seconds or millisecs.
seconds(), msecs()
addSecs(), addMSecs() Return time after adding specified number of seconds/msecs.
secsTo(), msecsTo() Return the number between two times.
In the following example, an instance of QTimer is created with the name timer, and it’s timeout() signal is
connected to showlcd(), a function that is invoked every 1000 milliseconds.
import sys
from disptime import *
class MyForm(QtGui.QDialog):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.ui = Ui_Dialog()
self.ui.setupUi(self)
timer = QtCore.QTimer(self)
timer.timeout.connect(self.showlcd)
timer.start(1000)
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, Chapter Summaries Module: INF2611
self.showlcd()
def showlcd(self):
time = QtCore.QTime.currentTime()
text = time.toString('hh:mm')
self.ui.lcdNumber.display(text)
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
myapp = MyForm()
myapp.show()
sys.exit(app.exec_())
Conversion of ui file to py file: > pyuic4 filename.ui -o filename.py
9.2. Working With Calendar and Displaying Dates in Different Formats
To display a monthly calendar, you use the Calendar widget, which is an instance of the
QCalendarWidget class. By default, current month and year are shown with days in abbreviated form
(Sun, Mon, Tue etc.). Weekends are marked in red and the first column day is Sunday.
The date that is selected is returned as a QDate object. It reads the current date from the system clock.
For displaying and editing dates, use the Date Edit widget, which is an instance of the QDateEdit class.
WIDGET PROPERTIES DESCRIPTION
Calendar minimumDate, maximumDate Used to specify the min/max date range.
selectionMode Set to NoSelection to prohibit user selection.
verticalHeaderFormat Set to NoVerticalHeader to remove week numbers.
gridVisible Set to True to turn on Calendar grid.
HorizontalHeaderFormat SingleLetterDayNames, ShortDatNames,
LongDayNames
Date Edit minimumDate, maximumDate
CLASS METHODS USE
QCalendarWidget selectedDate() Returns currently selected date, month, year.
monthShown()
yearShown()
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, Chapter Summaries Module: INF2611
setFirstDayOfWeek() Set the day in the first column.
selectionChanged() Emits when the user selects another date.
QDateEdit setDate()
setDisplayFormat() Options: dd.MM.yyyy, MMM.d.yy, MMM.d.yyyy,
MMMM.d.yy
QDate currentDate() Returns system date as QDate object.
setDate() Sets a date by specifying year, month, day.
year(), month(), day() Returns the year, month or day from the date object.
dayOfWeek() Returns the day of the week from the date object.
addDays(), addMonths(), Adds the specified number and returns new date.
addYears()
daysTo() Return the number of days between two dates.
daysInMonth(),
daysInYear()
isLeapYear() Returns true or false.
toPyDate() Returns date as a string. Accepts a format parameter, for
example: dd.MM.yyyy
Options are d (1‐31), dd (01‐31), ddd (Mon, Tue, etc.),
dddd (Monday, Tuesday, etc.), M (1‐12), MM (01‐12), MMM
(Jan, Feb, etc.), MMMM (January, February, etc.), yy (00‐99),
yyyy (1999, etc.).
In the example, the selectionChanged() signal of the Calendar widget is connected to dispdate(), a function
which retrieves the user selected date through the selectedDate() method, and displays it in the Date Edit
widget through setDate(). Optional: set the date format using setDisplayFormat().
import sys
from dispcalendar import *
class MyForm(QtGui.QDialog):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.ui = Ui_Dialog()
self.ui.setupUi(self)
QtCore.QObject.connect(self.ui.calendarWidget,
QtCore.SIGNAL('selectionChanged()'), self.dispdate)
def dispdate(self):
self.ui.dateEdit.setDisplayFormat('MMM d yyyy')
self.ui.dateEdit.setDate(self.ui.calendarWidget.selectedDate())
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
myapp = MyForm()
myapp.show()
sys.exit(app.exec_())
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