Book Image

Mastering Qt 5

By : Guillaume Lazar, Robin Penea
Book Image

Mastering Qt 5

By: Guillaume Lazar, Robin Penea

Overview of this book

Qt 5.7 is an application development framework that provides a great user experience and develops full-capability applications with Qt Widgets, QML, and even Qt 3D. This book will address challenges in successfully developing cross-platform applications with the Qt framework. Cross-platform development needs a well-organized project. Using this book, you will have a better understanding of the Qt framework and the tools to resolve serious issues such as linking, debugging, and multithreading. Your journey will start with the new Qt 5 features. Then you will explore different platforms and learn to tame them. Every chapter along the way is a logical step that you must take to master Qt. The journey will end in an application that has been tested and is ready to be shipped.

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Mastering Qt 5
Guillaume Lazar | Robin Penea
Dec, 2016 | 526 pages
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Table of Contents (20 chapters)
Mastering Qt 5
Mastering Qt 5
Credits
Credits
About the Authors
About the Authors
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Get Your Qt Feet Wet
Get Your Qt Feet Wet
Creating a project
MainWindow structure
Qt Designer
Signals and slots
Custom QWidget
Adding a task
Using a QDialog
Distributing code responsibility
Emitting a custom signal using lambdas
Simplifying with the auto type and a range-based for loop
Summary
2
Discovering QMake Secrets
Discovering QMake Secrets
Designing a cross-platform project
Transforming SysInfo into a singleton
Exploring Qt Charts
CpuWidget using QCharts
Memory using Qcharts
The .pro file in depth
Under the hood of qmake
Beneath Q_OBJECT and signals/slots
Summary
3
Dividing Your Project and Ruling Your Code
Dividing Your Project and Ruling Your Code
Designing a maintainable project
Defining data classes
Storing your data in a database
Protecting your code with a smart pointer
Implementing the model
Summary
4
Conquering the Desktop UI
Conquering the Desktop UI
Creating a GUI linked to a core shared library
Listing your albums with AlbumListWidget
Creating a ThumbnailProxyModel
Displaying the selected album with AlbumWidget
Enhancing thumbnails with PictureDelegate
Displaying a picture with PictureWidget
Composing your Gallery app
Summary
5
Dominating the Mobile UI
Dominating the Mobile UI
Starting with Qt Quick and QML
Checking your development environment
Creating a Qt Quick project
Preparing your Qt Quick gallery entry point
Displaying albums with ListView
Theming the application with a QML singleton
Loading a database on mobile
Creating a new album from a custom InputDialog
Loading images with an ImageProvider
Displaying thumbnails in a GridView
Swiping through full resolution pictures
Summary
6
Even Qt Deserves a Slice of Raspberry Pi
Even Qt Deserves a Slice of Raspberry Pi
Discovering Qt3D
Configuring Qt for your Raspberry Pi
Creating an entry point for your Qt3D code
Setting up the scene
Assembling your Qt3D entities
Preparing the board game
Crafting entities from the factory
Building a snake engine in JavaScript
Varying the HUD with QML states
Profiling your QML application
Summary
7
Third-Party Libraries Without a Headache
Third-Party Libraries Without a Headache
Creating your Qt Designer plugin
Configuring the project for Windows
Configuring the project for Linux
Configuring the project for Mac
Implementing your OpenCV filters
Designing the UI with FilterWidget
Exposing your plugin to Qt Designer
Using your Qt Designer plugin
Building the image-filter application
Summary
8
Animations - Its Alive, Alive!
Animations - Its Alive, Alive!
Preparing an SDK
Creating your plugins
Loading your plugins dynamically
Using the plugins inside the application
Discovering the Animation Framework
Making your thumbnails jump
Fading the picture in
Flashing the thumbnail in a sequence
Summary
9
Keeping Your Sanity with Multithreading
Keeping Your Sanity with Multithreading
Discovering QThread
Flying over Qt multithreading technologies
Architecting the Mandelbrot project
Defining a Job class with QRunnable
Using QThreadPool in MandelbrotCalculator
Displaying the fractal with MandelbrotWidget
Summary
10
Need IPC? Get Your Minions to Work
Need IPC? Get Your Minions to Work
Architecturing an IPC project
Laying down the foundations with an SDK
Working with QDataStream and QTcpSocket
Interacting with sockets in the worker
Interacting with sockets from the application
Building your own QTcpServer
Summary
11
Having Fun with Serialization
Having Fun with Serialization
Architecting the drum machine project
Creating a drum track
Making your objects serializable with QVariant
Serializing objects in JSON format
Serializing objects in XML format
Serializing objects in binary format
Playing low latency sounds with QSoundEffect
Triggering a QButton with your keyboard
Bringing PlaybackWorker to life
Accepting mouse drag and drop events
Summary
12
You Shall (Not) Pass with QTest
You Shall (Not) Pass with QTest
Discovering Qt Test
Executing your tests
Writing factorized tests with datasets
Benchmarking your code
Testing your GUI
Spying on your application with QSignalSpy
Summary
13
All Packed and Ready to Deploy
All Packed and Ready to Deploy
Packaging your application
Packaging for Windows
Packaging for Linux with a distribution package
Packaging for Linux with AppImage
Packaging for Mac OS X
Packaging for Android
Packaging for iOS
Summary
14
Qt Hat Tips and Tricks
Qt Hat Tips and Tricks
Managing your workspace with sessions
Searching with the Locator
Increasing the compilation speed
Examining the memory with Qt Creator
Generating random numbers
Silencing unused variable warnings
Logging custom objects to QDebug
Improving log messages
Saving your logs to a file
Generating a command-line interface
Sending and receiving HTTP data
Summary

Building the image-filter application

We can proceed to build the UI of the application. The idea is to open a picture from the filesystem and apply to it the various filters we developed in the filter-designer-plugin project. If you want to keep the result, you can save the resulting image.

We will start by designing the UI. Modify MainWindow.ui to look like this:

Here is the Object Inspector content to help you build this layout:

There are three elements of this UI:

  • The menuFile element, which contains three possible actions: actionOpenPicture, actionExit, and actionSaveAs. You can see the details of these actions in the Action Editor window.

  • The pictureLabel element, which will display the loaded picture in the empty top part.

  • The filtersLayout element, which contains the three instances of our FilterWidget class in the bottom part.

As you add a FilterWidget class in filtersLayout, you can see that you can customize the title and the filterType in the Property Editor window. The preview will...

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