Installation

Download the community version from:

• Qt Official Website
• Qt Downloads

Common Shortcuts

[Image placeholder]

Developing Qt with CLion

CLion Qt Development Guide

Signals and Slots

• Signals and slots are one of Qt's proudest mechanisms. Mastering them helps design decoupled, elegant programs.
• Signals and slots implement the observer pattern. When an event occurs (e.g., a button click), a signal is emitted. Any object interested in this signal can connect to it using the connect() function, specifying a slot (function) to handle the signal.

connect(sender, SIGNAL(signal), receiver, SLOT(slot), Qt::DirectConnection);

Connection Types

Parameter	Description
Qt::AutoConnection	Default. Uses Qt::DirectConnection if sender and receiver are in the same thread; otherwise, Qt::QueuedConnection.
Qt::DirectConnection	Slot is called immediately in the sender's thread. Risky in multithreading.
Qt::QueuedConnection	Slot is called when the receiver's event loop processes it. Safe for multithreading.
Qt::BlockingQueuedConnection	Similar to Qt::QueuedConnection, but the sender blocks untill the slot completes. Deadlocks if sender and receiver are in the same thread.
Qt::UniqueConnection	Prevents duplicate connections when combined with other flags.

Meta-Object System

QObject *obj = new QPushButton;
obj->metaObject()->className(); // Returns "QPushButton"

QTimer *timer = new QTimer;
timer->inherits("QTimer"); // true
timer->inherits("QObject"); // true
timer->inherits("QAbstractButton"); // false

Property System

Defining Properties

Q_PROPERTY(type name READ name WRITE setName NOTIFY nameChanged)
Q_PROPERTY(bool enabled READ isEnabled WRITE setEnabled NOTIFY enabledChanged)

Dynamic Properties

bool setProperty(const char *name, const QVariant &value);
QObject obj;
obj.setProperty("flat", true);

Class Metadata

Q_CLASSINFO("AUTHOR", "John Doe")
Q_CLASSINFO("VERSION", "1.0")

// Retrieve metadata
this->metaObject()->classInfo(0).name();
this->metaObject()->classInfo(0).value();

Qt Global Definitions

forever {
    // Infinite loop
}

Qt Container Classes

Example Usage

QList<QString> list;
list << "one" << "two" << "three";
QString str = list.at(0); // "one"

QStack<int> stack;
stack.push(1);
stack.push(2);
qDebug() << stack.pop(); // 2

QMap<QString, int> map;
map["key"] = 42;
qDebug() << map.value("key"); // 42

Iterators

Container	Read-Only Iterator	Read-Write Iterator
QList, QQueue	QList::const_iterator	QList::iterator
QVector, QStack	QVector::const_iterator	QVector::iterator
QMap, QMultiMap	QMap::const_iterator	QMap::iterator

Core Modules

Module	Description
Qt Core	Non-GUI foundational classes.
Qt GUI	GUI foundational classes.
Qt Network	Simplified networking classes.
Qt SQL	Database operations.
Qt Widgets	UI elements for classic interfaces.

Additional Modules

Module	Description
Qt Bluetooth	Bluetooth hardware access.
Qt WebEngine	Embed web content in apps.
Qt Charts	2D charting components.

Tools

Tool	Description
Qt Designer	UI design tool.
Qt Assistant	Documentation viewer.

QSpinBox Example

void Widget::setTotal() {
    int quantity = ui->spinBoxQuantity->value();
    float price = ui->spinBoxPrice->value();
    ui->spinBoxTotal->setValue(quantity * price);
}

QFile Operations

Reading a File

QFile file("path/to/file.txt");
if (file.open(QIODevice::ReadOnly)) {
    QByteArray content = file.readAll();
    file.close();
}

Recursive Directory Traversal

QStringList getFiles(const QString &path) {
    QStringList files;
    QDir dir(path);
    for (const QFileInfo &info : dir.entryInfoList(QDir::Files | QDir::Dirs | QDir::NoDotAndDotDot)) {
        if (info.isDir()) {
            files.append(getFiles(info.absoluteFilePath()));
        } else {
            files.append(info.absoluteFilePath());
        }
    }
    return files;
}

QMessageBox

QMessageBox::information(this, "Info", "Operation completed.");
QMessageBox::warning(this, "Warning", "File not saved.");

Model/View Architecture

QFileSystemModel

QFileSystemModel *model = new QFileSystemModel;
model->setRootPath(QDir::currentPath());
ui->treeView->setModel(model);

QStandardItemModel

QStandardItemModel *model = new QStandardItemModel;
model->setHorizontalHeaderLabels({"Name", "Value"});
QStandardItem *item = new QStandardItem("Data");
model->appendRow(item);
ui->tableView->setModel(model);

Custom Dialogs

Create a new QDialog subclass for custom dialogs.

MDI Applications

QMdiArea *mdiArea = new QMdiArea;
QMdiSubWindow *subWindow = mdiArea->addSubWindow(new QWidget);
subWindow->setWindowTitle("Document");