Book Image

Mastering Qt 5 - Second Edition

By : Guillaume Lazar, Robin Penea
Book Image

Mastering Qt 5 - Second Edition

By: Guillaume Lazar, Robin Penea

Overview of this book

Qt 5.11 is an app development framework that provides a great user experience and develops full capability applications with Qt Widgets, QML, and even Qt 3D. Whether you're building GUI prototypes or fully-fledged cross-platform GUI applications with a native look and feel, Mastering Qt 5 is your fastest, easiest, and most powerful solution. This book addresses various challenges and teaches you to successfully develop cross-platform applications using the Qt framework, with the help of well-organized projects. Working through this book, you will gain a better understanding of the Qt framework, as well as the tools required to resolve serious issues, such as linking, debugging, and multithreading. You'll start off your journey by discovering the new Qt 5.11 features, soon followed by exploring different platforms and learning to tame them. In addition to this, you'll interact with a gamepad using Qt Gamepad. Each chapter is a logical step for you to complete in order to master Qt. By the end of this book, you'll have created an application that has been tested and is ready to be shipped.
Table of Contents (16 chapters)

Distributing code responsibility

Great, the user can now specify a task name when created. What if they make an error when typing the name? The next logical step is to be able to rename the task after we create it. We'll take a slightly different approach. We want our Task to be as autonomous as possible. If we attach it to another component (rather than MainWindow), this renaming feature has to keep working. Thus, this responsibility has to be given to the Task class:

// In Task.h 
public slots: 
    void rename(); 
// In Task.cpp 
#include <QInputDialog> 
Task::Task(const QString& name, QWidget *parent) : 
       ui(new Ui::Task) 
   connect(ui->editButton, &QPushButton::clicked, this, &Task::rename); 
void Task::rename() 
    bool ok; 
    QString value = QInputDialog::getText(this, tr("Edit task"), 
                                          tr("Task name"), 
                                          this->name(), &ok); 
    if (ok && !value.isEmpty()) { 

We add a public rename() slot to connect it to a signal. The body of rename() reuses what we had previously covered with QInputDialog. The only difference is the QInputDialog default value, which is the current task name. When setName(value) is called, the UI is instantly refreshed with the new value; there's nothing to synchronize or update, the Qt main loop will do its job.

The nice thing is that Task::rename() is completely autonomous. Nothing has been modified in MainWindow, so we have effectively zero coupling between our Task and the parent QWidget.