The QImageIOPlugin class defines an interface for writing an image format plugin. More...

#include <qimageiohandler.h>

Inheritance diagram for QImageIOPlugin:

Public Types
enum	Capability { CanRead = 0x1, CanWrite = 0x2, CanReadIncremental = 0x4 }
	This enum describes the capabilities of a QImageIOPlugin. More...

Public Functions
virtual Capabilities	capabilities (QIODevice *device, const QByteArray &format) const =0
	Returns the capabilities on the plugin, based on the data in device and the format format. More...

virtual QImageIOHandler *	create (QIODevice *device, const QByteArray &format=QByteArray()) const =0
	Creates and returns a QImageIOHandler subclass, with device and format set. More...

virtual QStringList	keys () const =0
	Returns the list of image keys this plugin supports. More...

	QImageIOPlugin (QObject *parent=0)
	Constructs an image plugin with the given parent. More...

virtual	~QImageIOPlugin ()
	Destroys the picture format plugin. More...

Public Functions inherited from QObject
bool	blockSignals (bool b)
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). More...

const QObjectList &	children () const
	Returns a list of child objects. More...

bool	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=0, const QObject receiver=0, const char *member=0)

bool	disconnect (const QObject receiver, const char member=0)

void	dumpObjectInfo ()
	Dumps information about signal connections, etc. More...

void	dumpObjectTree ()
	Dumps a tree of children to the debug output. More...

QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...

virtual bool	event (QEvent *)
	This virtual function receives events to an object and should return true if the event e was recognized and processed. More...

virtual bool	eventFilter (QObject , QEvent )
	Filters events if this object has been installed as an event filter for the watched object. More...

template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...

template<typename T >
QList< T >	findChildren (const QString &aName=QString()) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects. More...

template<typename T >
QList< T >	findChildren (const QRegExp &re) const

bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false. More...

void	installEventFilter (QObject *)
	Installs an event filter filterObj on this object. More...

bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false. More...

void	killTimer (int id)
	Kills the timer with timer identifier, id. More...

virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...

void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children. More...

QString	objectName () const

QObject *	parent () const
	Returns a pointer to the parent object. More...

QVariant	property (const char *name) const
	Returns the value of the object's name property. More...

Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...

void	removeEventFilter (QObject *)
	Removes an event filter object obj from this object. More...

void	setObjectName (const QString &name)

void	setParent (QObject *)
	Makes the object a child of parent. More...

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value. More...

void	setUserData (uint id, QObjectUserData *data)

bool	signalsBlocked () const
	Returns true if signals are blocked; otherwise returns false. More...

int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...

QThread *	thread () const
	Returns the thread in which the object lives. More...

QObjectUserData *	userData (uint id) const

virtual	~QObject ()
	Destroys the object, deleting all its child objects. More...

Public Functions inherited from QFactoryInterface
virtual	~QFactoryInterface ()

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...

Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...

Static Public Functions inherited from QObject
static bool	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...

static bool	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	Disconnects signal in object sender from method in object receiver. More...

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static uint	registerUserData ()

static QString	tr (const char sourceText, const char comment=0, int n=-1)

static QString	trUtf8 (const char sourceText, const char comment=0, int n=-1)

Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...

Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...

virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...

virtual void	customEvent (QEvent *)
	This event handler can be reimplemented in a subclass to receive custom events. More...

virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...

	QObject (QObjectPrivate &dd, QObject *parent=0)

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal. More...

QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. More...

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *)
	This event handler can be reimplemented in a subclass to receive timer events for the object. More...

Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject

Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()

T *	qobject_cast (QObject *object)

	QObjectList

void *	qt_find_obj_child (QObject parent, const char type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

The QImageIOPlugin class defines an interface for writing an image format plugin.

Note: This class or function is reentrant.

QImageIOPlugin is a factory for creating QImageIOHandler objects, which are used internally by QImageReader and QImageWriter to add support for different image formats to Qt.

Writing an image I/O plugin is achieved by subclassing this base class, reimplementing the pure virtual functions capabilities(), create(), and keys(), and exporting the class with the Q_EXPORT_PLUGIN2() macro. See How to Create Qt Plugins for details.

An image format plugin can support three capabilities: reading (CanRead ), writing (CanWrite ) and incremental reading (CanReadIncremental ). Reimplement capabilities() in you subclass to expose the capabilities of your image format.

create() should create an instance of your QImageIOHandler subclass, with the provided device and format properly set, and return this handler. You must also reimplement keys() so that Qt knows which image formats your plugin supports.

Different plugins can support different capabilities. For example, you may have one plugin that supports reading the GIF format, and another that supports writing. Qt will select the correct plugin for the job, depending on the return value of capabilities(). If several plugins support the same capability, Qt will select one arbitrarily.

See also: QImageIOHandler, {How to Create Qt Plugins}

Definition at line 126 of file qimageiohandler.h.

Enumerations

◆ Capability

enum QImageIOPlugin::Capability

This enum describes the capabilities of a QImageIOPlugin.

CanRead The plugin can read images.
CanWrite The plugin can write images.
CanReadIncremental The plugin can read images incrementally.

Enumerator
CanRead
CanWrite
CanReadIncremental

Definition at line 134 of file qimageiohandler.h.

                     {
         CanRead = 0x1,
         CanWrite = 0x2,
         CanReadIncremental = 0x4
     };

Constructors and Destructors

◆ QImageIOPlugin()

QImageIOPlugin::QImageIOPlugin ( QObject * parent = 0 )

explicit

Constructs an image plugin with the given parent.

This is invoked automatically by the Q_EXPORT_PLUGIN2() macro.

Definition at line 545 of file qimageiohandler.cpp.

     : QObject(parent)
 {
 }

◆ ~QImageIOPlugin()

QImageIOPlugin::~QImageIOPlugin ( )

virtual

Destroys the picture format plugin.

You never have to call this explicitly. Qt destroys a plugin automatically when it is no longer used.

Definition at line 556 of file qimageiohandler.cpp.

557 {

558 }

Functions

◆ capabilities()

QImageIOPlugin::capabilities	(	QIODevice *	device,
		const QByteArray &	format
	)		const

pure virtual

Returns the capabilities on the plugin, based on the data in device and the format format.

For example, if the QImageIOHandler supports the BMP format, and the data in the device starts with the characters "BM", this function should return CanRead . If format is "bmp" and the handler supports both reading and writing, this function should return CanRead | CanWrite .

Implemented in QGifPlugin, QMngPlugin, QSvgPlugin, QICOPlugin, QJpegPlugin, QTgaPlugin, and QTiffPlugin.

Referenced by createReadHandlerHelper(), if(), QImageWriter::supportedImageFormats(), and QImageReader::supportedImageFormats().