Qt Core C++ Classes

Provides core non-GUI functionality. More...

Reference

These are links to the API reference materials.

C++ Classes
- Animation Classes
- Threading Classes
- Container Classes
- Plugin Classes
- Implicitly Shared Classes
- State Machine Classes
- Input/Output Classes
- Event Classes

Namespaces

Qt	Contains miscellaneous identifiers used throughout the Qt library

Animation Framework

This page lists classes belonging to Qt Core‘s animation framework.

QAbstractAnimation	The base of all animations
QAnimationGroup	Abstract base class for groups of animations
QEasingCurve	Easing curves for controlling animation
QParallelAnimationGroup	Parallel group of animations
QPauseAnimation	Pause for QSequentialAnimationGroup
QPropertyAnimation	Animates Qt properties
QSequentialAnimationGroup	Sequential group of animations
QTimeLine	Timeline for controlling animations
QVariantAnimation	Abstract base class for animations

Threading Classes

These Qt Core classes provide threading support to applications. The Thread Support in Qt page covers how to use these classes.

Concurrent Filter and Filter-Reduce
Concurrent Map and Map-Reduce
Concurrent Run
QAtomicInteger	Platform-independent atomic operations on integers
QAtomicPointer	Template class that provides platform-independent atomic operations on pointers
QFuture	Represents the result of an asynchronous computation
QFutureSynchronizer	Convenience class that simplifies QFuture synchronization
QFutureWatcher	Allows monitoring a QFuture using signals and slots
QMutex	Access serialization between threads
QMutexLocker	Convenience class that simplifies locking and unlocking mutexes
QReadLocker	Convenience class that simplifies locking and unlocking read-write locks for read access
QReadWriteLock	Read-write locking
QRunnable	The base class for all runnable objects
QSemaphore	General counting semaphore
QThread	Platform-independent way to manage threads
QThreadPool	Manages a collection of QThreads
QThreadStorage	Per-thread data storage
QWaitCondition	Condition variable for synchronizing threads
QWriteLocker	Convenience class that simplifies locking and unlocking read-write locks for write access
QtConcurrent	High-level APIs that make it possible to write multi-threaded programs without using low-level threading primitives

The Container Classes

Qt provides the following sequential containers: QList, QLinkedList, QVector, QStack, and QQueue. For most applications, QList is the best type to use. Although it is implemented as an array-list, it provides very fast prepends and appends. If you really need a linked-list, use QLinkedList; if you want your items to occupy consecutive memory locations, use QVector. QStack and QQueue are convenience classes that provide LIFO and FIFO semantics.

Qt also provides these associative containers: QMap, QMultiMap, QHash, QMultiHash, and QSet. The "Multi" containers conveniently support multiple values associated with a single key. The "Hash" containers provide faster lookup by using a hash function instead of a binary search on a sorted set.

As special cases, the QCache and QContiguousCache classes provide efficient hash-lookup of objects in a limited cache storage.

Class	Summary
QList<T>	This is by far the most commonly used container class. It stores a list of values of a given type (T) that can be accessed by index. Internally, the QList is implemented using an array, ensuring that index-based access is very fast. Items can be added at either end of the list using QList::append() and QList::prepend(), or they can be inserted in the middle using QList::insert(). More than any other container class, QList is highly optimized to expand to as little code as possible in the executable. QStringList inherits from QList<QString>.
QLinkedList<T>	This is similar to QList, except that it uses iterators rather than integer indexes to access items. It also provides better performance than QList when inserting in the middle of a huge list, and it has nicer iterator semantics. (Iterators pointing to an item in a QLinkedList remain valid as long as the item exists, whereas iterators to a QList can become invalid after any insertion or removal.)
QVector<T>	This stores an array of values of a given type at adjacent positions in memory. Inserting at the front or in the middle of a vector can be quite slow, because it can lead to large numbers of items having to be moved by one position in memory.
QStack<T>	This is a convenience subclass of QVector that provides "last in, first out" (LIFO) semantics. It adds the following functions to those already present in QVector: push(), pop(), and top().
QQueue<T>	This is a convenience subclass of QList that provides "first in, first out" (FIFO) semantics. It adds the following functions to those already present in QList: enqueue(), dequeue(), and head().
QSet<T>	This provides a single-valued mathematical set with fast lookups.
QMap<Key, T>	This provides a dictionary (associative array) that maps keys of type Key to values of type T. Normally each key is associated with a single value. QMap stores its data in Key order; if order doesn‘t matter QHash is a faster alternative.
QMultiMap<Key, T>	This is a convenience subclass of QMap that provides a nice interface for multi-valued maps, i.e. maps where one key can be associated with multiple values.
QHash<Key, T>	This has almost the same API as QMap, but provides significantly faster lookups. QHash stores its data in an arbitrary order.
QMultiHash<Key, T>	This is a convenience subclass of QHash that provides a nice interface for multi-valued hashes.

Plugin Classes

These Qt Core classes deal with shared libraries, (for example, .so and DLL files), and with Qt plugins.

See the How to Create Qt Plugins page for more information.

Defining Plugins	The <QtPlugin> header file defines macros for defining plugins.
QAccessiblePlugin	Abstract base class for plugins provinding accessibility information for user interface elements
QGenericPlugin	Abstract base class for plugins
QGenericPluginFactory	Creates plugin drivers
QIconEnginePlugin	Abstract base for custom QIconEngine plugins
QImageIOPlugin	Defines an interface for writing an image format plugin
QLibrary	Loads shared libraries at runtime
QPluginLoader	Loads a plugin at run-time
QQmlExtensionPlugin	Abstract base for custom QML extension plugins
QScriptExtensionPlugin	Abstract base for custom QScript extension plugins
QSqlDriverPlugin	Abstract base for custom QSqlDriver plugins
QStylePlugin	Abstract base for custom QStyle plugins

Implicit Sharing

Warning: Be careful with copying an implicitly shared container (QMap, QVector, etc.) while you use STL-style iterator. See Implicit sharing iterator problem.

QBitArray	Array of bits
QBitmap	Monochrome (1-bit depth) pixmaps
QBrush	Defines the fill pattern of shapes drawn by QPainter
QByteArray	Array of bytes
QByteArrayList	List of byte arrays
QCache	Template class that provides a cache
QCollator	Compares strings according to a localized collation algorithm
QCollatorSortKey	Can be used to speed up string collation
QCommandLineOption	Defines a possible command-line option
QContiguousCache	Template class that provides a contiguous cache
QCursor	Mouse cursor with an arbitrary shape
QDBusPendingCall	Refers to one pending asynchronous call
QDBusUnixFileDescriptor	Holds one Unix file descriptor
QDateTime	Date and time functions
QDebug	Output stream for debugging information
QDir	Access to directory structures and their contents
QDnsDomainNameRecord	Stores information about a domain name record
QDnsHostAddressRecord	Stores information about a host address record
QDnsMailExchangeRecord	Stores information about a DNS MX record
QDnsServiceRecord	Stores information about a DNS SRV record
QDnsTextRecord	Stores information about a DNS TXT record
QFileInfo	System-independent file information
QFont	Specifies a font used for drawing text
QFontInfo	General information about fonts
QFontMetrics	Font metrics information
QFontMetricsF	Font metrics information
QGlyphRun	Direct access to the internal glyphs in a font
QGradient	Used in combination with QBrush to specify gradient fills
QHash	Template class that provides a hash-table-based dictionary
QHttpPart	Holds a body part to be used inside a HTTP multipart MIME message
QIcon	Scalable icons in different modes and states
QImage	Hardware-independent image representation that allows direct access to the pixel data, and can be used as a paint device
QKeySequence	Encapsulates a key sequence as used by shortcuts
QLinkedList	Template class that provides linked lists
QList	Template class that provides lists
QLocale	Converts between numbers and their string representations in various languages
QMap	Template class that provides a red-black-tree-based dictionary
QMimeType	Describes types of file or data, represented by a MIME type string
QMultiHash	Convenience QHash subclass that provides multi-valued hashes
QMultiMap	Convenience QMap subclass that provides multi-valued maps
QNetworkAddressEntry	Stores one IP address supported by a network interface, along with its associated netmask and broadcast address
QNetworkCacheMetaData	Cache information
QNetworkConfiguration	Abstraction of one or more access point configurations
QNetworkCookie	Holds one network cookie
QNetworkInterface	Listing of the host‘s IP addresses and network interfaces
QNetworkProxy	Network layer proxy
QNetworkProxyQuery	Used to query the proxy settings for a socket
QNetworkRequest	Holds a request to be sent with QNetworkAccessManager
QOpenGLDebugMessage	Wraps an OpenGL debug message
QPainterPath	Container for painting operations, enabling graphical shapes to be constructed and reused
QPalette	Contains color groups for each widget state
QPen	Defines how a QPainter should draw lines and outlines of shapes
QPersistentModelIndex	Used to locate data in a data model
QPicture	Paint device that records and replays QPainter commands
QPixmap	Off-screen image representation that can be used as a paint device
QPolygon	Vector of points using integer precision
QPolygonF	Vector of points using floating point precision
QProcessEnvironment	Holds the environment variables that can be passed to a program
QQueue	Generic container that provides a queue
QRawFont	Access to a single physical instance of a font
QRegExp	Pattern matching using regular expressions
QRegion	Specifies a clip region for a painter
QRegularExpression	Pattern matching using regular expressions
QRegularExpressionMatch	The results of a matching a QRegularExpression against a string
QRegularExpressionMatchIterator	Iterator on the results of a global match of a QRegularExpression object against a string
QSet	Template class that provides a hash-table-based set
QSqlField	Manipulates the fields in SQL database tables and views
QSqlQuery	Means of executing and manipulating SQL statements
QSqlRecord	Encapsulates a database record
QSslCertificate	Convenient API for an X509 certificate
QSslCertificateExtension	API for accessing the extensions of an X509 certificate
QSslCipher	Represents an SSL cryptographic cipher
QSslConfiguration	Holds the configuration and state of an SSL connection
QSslError	SSL error
QSslKey	Interface for private and public keys
QStack	Template class that provides a stack
QStaticText	Enables optimized drawing of text when the text and its layout is updated rarely
QStorageInfo	Provides information about currently mounted storage and drives
QString	Unicode character string
QStringList	List of strings
QTextBlockFormat	Formatting information for blocks of text in a QTextDocument
QTextBoundaryFinder	Way of finding Unicode text boundaries in a string
QTextCharFormat	Formatting information for characters in a QTextDocument
QTextCursor	Offers an API to access and modify QTextDocuments
QTextDocumentFragment	Represents a piece of formatted text from a QTextDocument
QTextFormat	Formatting information for a QTextDocument
QTextFrameFormat	Formatting information for frames in a QTextDocument
QTextImageFormat	Formatting information for images in a QTextDocument
QTextListFormat	Formatting information for lists in a QTextDocument
QTextTableCellFormat	Formatting information for table cells in a QTextDocument
QTextTableFormat	Formatting information for tables in a QTextDocument
QUrl	Convenient interface for working with URLs
QUrlQuery	Way to manipulate a key-value pairs in a URL‘s query
QVariant	Acts like a union for the most common Qt data types
QVector	Template class that provides a dynamic array

State Machine Classes

These Qt Core classes are part of the State Machine Framework.

QAbstractState	The base class of states of a QStateMachine
QAbstractTransition	The base class of transitions between QAbstractState objects
QEventTransition	QObject-specific transition for Qt events
QFinalState	Final state
QHistoryState	Means of returning to a previously active substate
QKeyEventTransition	Transition for key events
QMouseEventTransition	Transition for mouse events
QSignalTransition	Transition based on a Qt signal
QState	General-purpose state for QStateMachine
QStateMachine	Hierarchical finite state machine
QStateMachine::SignalEvent	Represents a Qt signal event
QStateMachine::WrappedEvent	Inherits QEvent and holds a clone of an event associated with a QObject

Input/Output and Networking

These Qt Core classes are used to handle input and output to and from external devices, processes, files etc. as well as manipulating files and directories.

QBuffer	QIODevice interface for a QByteArray
QDataStream	Serialization of binary data to a QIODevice
QDir	Access to directory structures and their contents
QFile	Interface for reading from and writing to files
QFileDevice	Interface for reading from and writing to open files
QFileInfo	System-independent file information
QFileSystemWatcher	Interface for monitoring files and directories for modifications
QIODevice	The base interface class of all I/O devices in Qt
QImageReader	Format independent interface for reading images from files or other devices
QImageWriter	Format independent interface for writing images to files or other devices
QProcess	Used to start external programs and to communicate with them
QProcessEnvironment	Holds the environment variables that can be passed to a program
QResource	Interface for reading directly from resources
QSaveFile	Interface for safely writing to files
QSettings	Persistent platform-independent application settings
QSocketNotifier	Support for monitoring activity on a file descriptor
QStorageInfo	Provides information about currently mounted storage and drives
QTemporaryDir	Creates a unique directory for temporary use
QTemporaryFile	I/O device that operates on temporary files
QTextDocumentWriter	Format-independent interface for writing a QTextDocument to files or other devices
QTextStream	Convenient interface for reading and writing text
QUrl	Convenient interface for working with URLs
QUrlQuery	Way to manipulate a key-value pairs in a URL‘s query

Event Classes

These Qt Core classes are used to create and handle events.

For more information see the Event System page.

QAbstractEventDispatcher	Interface to manage Qt‘s event queue
QActionEvent	Event that is generated when a QAction is added, removed, or changed
QBasicTimer	Timer events for objects
QChildEvent	Contains event parameters for child object events
QCloseEvent	Contains parameters that describe a close event
QContextMenuEvent	Contains parameters that describe a context menu event
QDragEnterEvent	Event which is sent to a widget when a drag and drop action enters it
QDragLeaveEvent	Event that is sent to a widget when a drag and drop action leaves it
QDragMoveEvent	Event which is sent while a drag and drop action is in progress
QDropEvent	Event which is sent when a drag and drop action is completed
QDynamicPropertyChangeEvent	Contains event parameters for dynamic property change events
QEnterEvent	Contains parameters that describe an enter event
QEvent	The base class of all event classes. Event objects contain event parameters
QExposeEvent	Contains event parameters for expose events
QFileOpenEvent	Event that will be sent when there is a request to open a file or a URL
QFocusEvent	Contains event parameters for widget focus events
QGestureEvent	The description of triggered gestures
QHelpEvent	Event that is used to request helpful information about a particular point in a widget
QHideEvent	Event which is sent after a widget is hidden
QHoverEvent	Contains parameters that describe a mouse event
QIconDragEvent	Indicates that a main icon drag has begun
QInputEvent	The base class for events that describe user input
QInputMethodEvent	Parameters for input method events
QKeyEvent	Describes a key event
QMouseEvent	Contains parameters that describe a mouse event
QMoveEvent	Contains event parameters for move events
QNativeGestureEvent	Contains parameters that describe a gesture event
QPaintEvent	Contains event parameters for paint events
QResizeEvent	Contains event parameters for resize events
QScrollEvent	Sent when scrolling
QScrollPrepareEvent	Sent in preparation of scrolling
QShortcut	Used to create keyboard shortcuts
QShortcutEvent	Event which is generated when the user presses a key combination
QShowEvent	Event that is sent when a widget is shown
QStatusTipEvent	Event that is used to show messages in a status bar
QTabletEvent	Contains parameters that describe a Tablet event
QTimer	Repetitive and single-shot timers
QTimerEvent	Contains parameters that describe a timer event
QTouchEvent	Contains parameters that describe a touch event
QWhatsThisClickedEvent	Event that can be used to handle hyperlinks in a "What‘s This?" text
QWheelEvent	Contains parameters that describe a wheel event
QWindowStateChangeEvent	The window state before a window state change

QtCore Module's Classes

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