Python Qt - MedTec4SusDev – MACbioIDi.eu

PythonQtMACbioIDi – February – March 2018

Qt Framework Qt is a cross-platform application developmentframework:– Can be used for application development for a widerange of target platformsIt is a framework written in C –Preprocessor MOC (Meta-Object Compiler) is usedto extend the C language2

Qt Framework Libraries and development tools in order todevelop multiple task:–Graphical user interfaces–Networking–Threads–Regular Expressions–OpenGL–XML.3

Qt Framework Qt Company–Started in 1990 by Eirik Chambe-Eng and HaavardNord as Trolltech–Main driver behind QtQt Project–A meritocratic, consensus-based communityinterested in Qt–There are many companies and individuals aroundthe globe4

Commercial and OpenSource Commercial – costs money–Your application can be closed–Changes to Qt can be kept closedGPL – free–Your application must be open–Changes to Qt must be fedback to the communityLGPL – free–Your application can be open or closed–Changes to Qt must be fedback to the community5

PyQt5 PyQt5 is a binding of Qt 5 framework– Python Wrapper generated using SIP binding generatorComponents:–Modules for different purposes–Plugins that enable Qt Designer and qmlscene to be extendedusing Python code–Utility programs: Pyuic5Pyrcc5pyupdate56

Qt Designer Qt comes with its own IDE, Qt Creator, and atool to design and building GUIs, Qt Designer7

Get familiar with QtDesigner Qt Designer generates a XML file– Pyuic parse the XML file and generates the pythoncodeWe can generate the python code directly–It is a more complicated option to maintain longterm8

Example We will create a simple widget that contains aPush Button9

Example Create your own window for you application:–Create a python class that inherits fromQMainWindow–Uses the Pyuic5 in order to relation your ui file withthe class The ui file was generated with Qt DesignerCreate the QApplication that will show ourwindow10

Exampleimport sysfrom PyQt5.QtWidgets import QmainWindowfrom PyQt5 import uicclass MyWindow(QMainWindow):def init (self):QMainWindow. init (self)uic.loadUi(“[Path to your file]”, self)self.setWindowTitle("MyWindow")app QApplication(sys.argv)mainWindow MyWindow()mainWindow.show()app.exec()11

Example12

Get familiar with QtDesigner13

Signals and Slots Used for communication between objects–Thanks to Qt’s meta-object system (MOC)–Signals can transmit variables values14

Signals and Slots Emitted by an object when its internal state haschanged–Public access–Can be emmited from anywhereSignals are automatically generated by the MOC– They can never have return typesSlots are called when a signal connected to it isemited–Slots can be called like a method too15

Signals and SlotsExample#include QObject class Counter : public QObject{Q OBJECTpublic:Counter() { m value 0; }int value() const { return m value; }from PyQt5.Qt import QObject, pyqtSlot,pyqtSignalclass Counter(QObject):valueChanged pyqtSignal(int)def init (self):self.value 0public slots:void setValue(int value);def value(self):return self.valuesignals:void valueChanged(int newValue);@pyqtSlot(int)def setValue(self, value):self.value valueprivate:int m value;};16

Signal and SlotsExercise We will create a very simple text viewer from our examplegenerated in this session–Assign actions to the QToolButtons and QpushButtons–Generates a new thread in order to read the files It will not block the GUI if we read a larger fileTake a look to:–QFileDialog.getOpenFilename()–QFile class–QAction class–QPushButton class–QThread class17

PythonQtMACbioIDi – February – March 2018

PyQt5 PyQt5 is a binding of Qt 5 framework – Python Wrapper generated using SIP binding generator Components: – Modules for different purposes – Plugins that enable Qt Designer and qmlscene to be extended usin