merchantgui.py

from PyQt4 import QtGui
from PyQt4 import QtCore

class MerchantGUI(QtGui.QWidget):
    def __init__(self, controller, currency, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.controller = controller
        self.currency = currency
        self.init_ui()

    def init_ui(self):
        self.status = QtGui.QLabel()
        self.status.setWordWrap(True)
        self.status.setMinimumHeight(100)
        self.status.setText("System ready.")

        amount = QtGui.QLabel()
        amount.setText("Amount:")
        self.edit = QtGui.QLineEdit()
        validator = QtGui.QDoubleValidator(self.edit)
        self.edit.setValidator(validator)

        self.combo = QtGui.QComboBox()
        self.combo.addItem("BTC")
        self.combo.addItem(self.currency)

        self.rate = QtGui.QLabel()
        self.rate.setText("Current exchange rate: ...        ")

        show = QtGui.QPushButton("Update display")
        self.connect(show, QtCore.SIGNAL('clicked()'), self.show_on_clicked)

        fullscreen = QtGui.QPushButton("Toggle fullscreen")
        self.connect(fullscreen, QtCore.SIGNAL('clicked()'), self.fullscreen_on_clicked)

        clear = QtGui.QPushButton("Clear display")
        self.connect(clear, QtCore.SIGNAL('clicked()'), self.clear_on_clicked)

        hbox1 = QtGui.QHBoxLayout()
        hbox1.addWidget(amount)
        hbox1.addWidget(self.edit)
        hbox1.addWidget(self.combo)
        hbox1.addWidget(self.rate)

        hbox2 = QtGui.QHBoxLayout()
        hbox2.addWidget(show)
        hbox2.addWidget(fullscreen)
        hbox2.addWidget(clear)

        vbox = QtGui.QVBoxLayout()
        vbox.addLayout(hbox1)
        vbox.addLayout(hbox2)
        vbox.addWidget(self.status)

        self.setLayout(vbox)
        self.setWindowTitle('Point of Sale System - Backend')

    def show_on_clicked(self):
        if self.edit.text() == "":
            amount = 0
        else:
            amount = float(self.edit.text())
        self.controller.init_new_transaction(amount, self.combo.currentText())

    def fullscreen_on_clicked(self):
        self.controller.toggle_fullscreen_mode()

    def clear_on_clicked(self):
        self.controller.clear_customer_display()

    def update_status(self, message):
        self.status.setText(message)

    def update_exchange_rate(self, rate):
        self.rate.setText("Current exchange rate: %f %s" % (rate, self.currency))

    def closeEvent(self, event):
        event.accept()
        QtGui.QApplication.exit()