python_calc

Python GUI using PyQt

Install

PIP install PyQt5

Test installation of PyQt5

import module

import sys
from PyQt5.QtWidgets import QApplication
from PyQt5.QtWidgets import QLabel
from PyQt5.QtWidgets import QWidget

Create GUI

app = QApplication(sys.argv)
window = QWidget()
window.setWindowTitle('PyQt5 App')
window.setGeometry(100, 100, 280, 80)
window.move(600, 15)
helloMsg = QLabel('This is Test', parent=window)
helloMsg.move(60, 30)
window.show()

Retain GUI Window

sys.exit(app.exec_())

Calculator Using PyQt5

View of application

1. Create view.py

2. Import following modules

from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QMainWindow
from PyQt5.QtWidgets import QWidget
from PyQt5.QtWidgets import QGridLayout
from PyQt5.QtWidgets import QLineEdit
from PyQt5.QtWidgets import QPushButton
from PyQt5.QtWidgets import QVBoxLayout

3. Create GUI class and extend QMainWindow class

class GUI(QMainWindow):

• Add constructor and Parameter

  • SuperClass Constructor
  • setWindowTitle
  • setFixedSize
  • generalLayout
  • centralWidget
  • createDisplayLED
  • createButtons

• Define Methods

  (Which will create method for Display Panel, Buttons layout and method for set/get/clear display)

  • createDisplayLED()
  • createButtons()
  • setDisplayText()
  • getDisplayText()
  • clearDisplay()

Model of application

1. Create model.py

2. Create function for calculator's operation

ERROR_MSG = 'ERROR'
def evaluateExpression(expression):
try:
result = str(eval(expression, {}, {}))
except Exception:
result = ERROR_MSG
return result

Controller of application

1. Create controller.py

2. Import following module

from functools import partial

3. Create Controller class

class Controller:

• Add constructor

  def init(self, model, view):
  self._evaluate = model
  self._view = view
  self._connectSignals()

• Define Methods

  (Which will create method for CalculateResult Build expression Connect signals and slots.)

  • calculateResult()
  • buildExpression()
  • connectSignals()

Main Class

1. Create main.py

2. Import following module

import sys
from PyQt5.QtWidgets import QApplication
from view import GUI
from model import evaluateExpression
from controller import Controller

3. Create Main Function

def main():
pycalc = QApplication(sys.argv)
view = GUI()
view.show()
model = evaluateExpression
Controller(model=model, view=view)
sys.exit(pycalc.exec_())
if name == "main":
main()