Book Image

Application Development with Qt Creator - Third Edition

By : Lee Zhi Eng, Ray Rischpater
Book Image

Application Development with Qt Creator - Third Edition

By: Lee Zhi Eng, Ray Rischpater

Overview of this book

Qt is a powerful development framework that serves as a complete toolset for building cross-platform applications, helping you reduce development time and improve productivity. Completely revised and updated to cover C++17 and the latest developments in Qt 5.12, this comprehensive guide is the third edition of Application Development with Qt Creator. You'll start by designing a user interface using Qt Designer and learn how to instantiate custom messages, forms, and dialogues. You'll then understand Qt's support for multithreading, a key tool for making applications responsive, and the use of Qt's Model-View-Controller (MVC) to display data and content. As you advance, you'll learn to draw images on screen using Graphics View Framework and create custom widgets that interoperate with Qt Widgets. This Qt programming book takes you through Qt Creator's latest features, such as Qt Quick Controls 2, enhanced CMake support, a new graphical editor for SCXML, and a model editor. You'll even work with multimedia and sensors using Qt Quick, and finally develop applications for mobile, IoT, and embedded devices using Qt Creator. By the end of this Qt book, you'll be able to create your own cross-platform applications from scratch using Qt Creator and the C++ programming language.
Table of Contents (19 chapters)
1
Section 1: The Basics
7
Section 2: Advanced Features
12
Section 3: Practical Matters

Accessing the camera

To access the camera when it is supported by the hardware and Qt Multimedia, use the Camera type and its associated types to control the camera's capture behavior, exposure, flash, focus, and image processing settings. A simple use of the camera to show a viewfinder is done with the following code:

import QtQuick 2.12
import QtQuick.Window 2.12
import QtMultimedia 5.12

Window {
visible: true
width: 640
height: 480
title: qsTr("Webcam")

Item {
width: 640
height: 480

Camera {
id: camera
}

VideoOutput {
source: camera
anchors.fill: parent
}
}
}

The preceding code produces the following result:

In short, the Camera type acts like a source for the video just as a MediaPlayer instance does.

The Camera type provides a few properties to control its behavior. They...