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Mastering Qt  5

You're reading from   Mastering Qt 5 Create stunning cross-platform applications using C++ with Qt Widgets and QML with Qt Quick

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Product type Paperback
Published in Aug 2018
Publisher Packt
ISBN-13 9781788995399
Length 534 pages
Edition 2nd Edition
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Authors (2):
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Robin Penea Robin Penea
Author Profile Icon Robin Penea
Robin Penea
Guillaume Lazar Guillaume Lazar
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Guillaume Lazar
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Table of Contents (16) Chapters Close

Preface 1. Get Your Qt Feet Wet FREE CHAPTER 2. Discovering qmake Secrets 3. Dividing Your Project and Ruling Your Code 4. Conquering the Desktop UI 5. Dominating the Mobile UI 6. Even Qt Deserves a Slice of Raspberry Pi 7. Third-Party Libraries without a Headache 8. Animations - Its Alive, Alive! 9. Keeping Your Sanity with Multithreading 10. Need IPC? Get Your Minions to Work 11. Having Fun with Multimedia and Serialization 12. You Shall (Not) Pass with QTest 13. All Packed and Ready to Deploy 14. Qt Hat Tips and Tricks 15. Other Books You May Enjoy

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) : 
       QWidget(parent), 
       ui(new Ui::Task) 
{ 
   ui->setupUi(this); 
   setName(name); 
   connect(ui->editButton, &QPushButton::clicked, this, &Task::rename); 
} 
... 
void Task::rename() 
{ 
    bool ok; 
    QString value = QInputDialog::getText(this, tr("Edit task"), 
                                          tr("Task name"), 
                                          QLineEdit::Normal, 
                                          this->name(), &ok); 
    if (ok && !value.isEmpty()) { 
        setName(value); 
    } 
} 

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.

You have been reading a chapter from
Mastering Qt 5 - Second Edition
Published in: Aug 2018
Publisher: Packt
ISBN-13: 9781788995399
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