6. Even Qt Deserves a Slice of Raspberry Pi | Mastering Qt 5

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Table Of Contents

Mastering Qt 5

By : Guillaume Lazar, Robin Penea

3.2 (10)

Mastering Qt 5

3.2 (10)

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.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Get Your Qt Feet Wet

1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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!

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

Assembling your Qt3D entities

We will now proceed to create the building blocks of the game, each in the form of an Entity element:

Wall: This represents the limit of where the snake cannot go
SnakePart: This represents a part of the snake's body
Apple: This represents the apple (no way!) spawned at a random location
Background: This represents a good-looking background behind the snake and the apple

Each entity will be placed on a grid handled by the engine and will have a type identifier to make it easier to find. To factorize these properties, let's create a parent QML file named GameEntity.qml:

import Qt3D.Core 2.0 
 
Entity { 
    property int type: 0 
    property vector2d gridPosition: Qt.vector2d(0, 0) 
}

This Entity element only defines a type property and a gridPosition property , which will be used by the engine to lay out the content on the grid.

The first item we will build is the Wall.qml file:

import Qt3D.Core 2.0 
 
GameEntity { 
    id: root 
 
    property alias position: transform...

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