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/*!

    \class QImageIOHandler

    \brief The QImageIOHandler class defines the common image I/O

    interface for all image formats in Qt.

    \reentrant

    \inmodule QtGui

    Qt uses QImageIOHandler for reading and writing images through

    QImageReader and QImageWriter. You can also derive from this class

    to write your own image format handler using Qt's plugin mechanism.

    Call setDevice() to assign a device to the handler, and

    setFormat() to assign a format to it. One QImageIOHandler may

    support more than one image format. canRead() returns \c true if an

    image can be read from the device, and read() and write() return

    true if reading or writing an image was completed successfully.

    QImageIOHandler also has support for animations formats, through

    the functions loopCount(), imageCount(), nextImageDelay() and

    currentImageNumber().

    In order to determine what options an image handler supports, Qt

    will call supportsOption() and setOption(). Make sure to

    reimplement these functions if you can provide support for any of

    the options in the ImageOption enum.

    To write your own image handler, you must at least reimplement

    canRead() and read(). Then create a QImageIOPlugin that

    can create the handler. Finally, install your plugin, and

    QImageReader and QImageWriter will then automatically load the

    plugin, and start using it.

    \sa QImageIOPlugin, QImageReader, QImageWriter

*/

/*! \enum QImageIOHandler::ImageOption

    This enum describes the different options supported by

    QImageIOHandler.  Some options are used to query an image for

    properties, and others are used to toggle the way in which an

    image should be written.

    \value Size The original size of an image. A handler that supports

    this option is expected to read the size of the image from the

    image metadata, and return this size from option() as a QSize.

    \value ClipRect The clip rect, or ROI (Region Of Interest). A

    handler that supports this option is expected to only read the

    provided QRect area from the original image in read(), before any

    other transformation is applied.

    \value ScaledSize The scaled size of the image. A handler that

    supports this option is expected to scale the image to the

    provided size (a QSize), after applying any clip rect

    transformation (ClipRect). If the handler does not support this

    option, QImageReader will perform the scaling after the image has

    been read.

    \value ScaledClipRect The scaled clip rect (or ROI, Region Of

    Interest) of the image. A handler that supports this option is

    expected to apply the provided clip rect (a QRect), after applying

    any scaling (ScaleSize) or regular clipping (ClipRect). If the

    handler does not support this option, QImageReader will apply the

    scaled clip rect after the image has been read.

    \value Description The image description. Some image formats,

    such as GIF and PNG, allow embedding of text

    or comments into the image data (e.g., for storing copyright

    information). It's common that the text is stored in key-value

    pairs, but some formats store all text in one continuous block.

    QImageIOHandler returns the text as one

    QString, where keys and values are separated by a ':', and

    keys-value pairs are separated by two newlines (\\n\\n). For example,

    "Title: Sunset\\n\\nAuthor: Jim Smith\\nSarah Jones\\n\\n". Formats that

    store text in a single block can use "Description" as the key.

    \value CompressionRatio The compression ratio of the image data. A

    handler that supports this option is expected to set its

    compression rate depending on the value of this option (an int)

    when writing.

    \value Gamma The gamma level of the image. A handler that supports

    this option is expected to set the image gamma level depending on

    the value of this option (a float) when writing.

    \value Quality The quality level of the image. A handler that

    supports this option is expected to set the image quality level

    depending on the value of this option (an int) when writing.

    \value Name The name of the image. A handler that supports this

    option is expected to read the name from the image metadata and

    return this as a QString, or when writing an image it is expected

    to store the name in the image metadata.

    \value SubType The subtype of the image. A handler that supports

    this option can use the subtype value to help when reading and

    writing images. For example, a PPM handler may have a subtype

    value of "ppm" or "ppmraw".

    \value IncrementalReading A handler that supports this option is

    expected to read the image in several passes, as if it was an

    animation. QImageReader will treat the image as an animation.

    \value Endianness The endianness of the image. Certain image

    formats can be stored as BigEndian or LittleEndian. A handler that

    supports Endianness uses the value of this option to determine how

    the image should be stored.

    \value Animation Image formats that support animation return

    true for this value in supportsOption(); otherwise, false is returned.

    \value BackgroundColor Certain image formats allow the

    background color to be specified. A handler that supports

    BackgroundColor initializes the background color to this option

    (a QColor) when reading an image.

    \value ImageFormat The image's data format returned by the handler.

    This can be any of the formats listed in QImage::Format.

    \value SupportedSubTypes Image formats that support different saving

    variants should return a list of supported variant names

    (QList<QByteArray>) in this option.

    \value OptimizedWrite. A handler which supports this option

    is expected to turn on optimization flags when writing.

    \value ProgressiveScanWrite. A handler which supports

    this option is expected to write the image as a progressive scan image.

    \value ImageTransformation. A handler which supports this option can read

    the transformation metadata of an image. A handler that supports this option

    should not apply the transformation itself.

    \value TransformedByDefault. A handler that reports support for this feature

    will have image transformation metadata applied by default on read.

*/

/*! \enum QImageIOHandler::Transformation

    \since 5.5

    This enum describes the different transformations or orientations

    supported by some image formats, usually through EXIF.

    \value TransformationNone No transformation should be applied.

    \value TransformationMirror Mirror the image horizontally.

    \value TransformationFlip Mirror the image vertically.

    \value TransformationRotate180 Rotate the image 180 degrees.

    This is the same as mirroring it both horizontally and vertically.

    \value TransformationRotate90 Rotate the image 90 degrees.

    \value TransformationMirrorAndRotate90 Mirror the image horizontally

    and then rotate it 90 degrees.

    \value TransformationFlipAndRotate90 Mirror the image vertically

    and then rotate it 90 degrees.

    \value TransformationRotate270 Rotate the image 270 degrees.

    This is the same as mirroring it both horizontally, vertically and

    then rotating it 90 degrees.

    \sa QImageReader::transformation(), QImageReader::setAutoTransform(), QImageWriter::setTransformation()

*/

/*!

    \class QImageIOPlugin

    \inmodule QtGui

    \brief The QImageIOPlugin class defines an interface for writing

    an image format plugin.

    \reentrant

    \ingroup plugins

    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()

    and create(), and exporting the class with the

    Q_PLUGIN_METADATA() macro. See \l{How to Create Qt Plugins} for details.

    An image format plugin can support three capabilities: reading (\l

    CanRead), writing (\l CanWrite) and \e incremental reading (\l

    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.

    The json metadata file for the plugin needs to contain information

    about the image formats the plugins supports, together with the

    corresponding MIME types (one for each format). For a jpeg plugin, this

    could, for example, look as follows:

    \code

    {

      "Keys": [ "jpg", "jpeg" ],

      "MimeTypes": [ "image/jpeg", "image/jpeg" ]

    }

    \endcode

    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.

    \sa QImageIOHandler, {How to Create Qt Plugins}

*/

/*!

    \enum QImageIOPlugin::Capability

    This enum describes the capabilities of a QImageIOPlugin.

    \value CanRead The plugin can read images.

    \value CanWrite The plugin can write images.

    \value CanReadIncremental The plugin can read images incrementally.

*/

#include "qimageiohandler.h"

#include <qbytearray.h>

#include <qimage.h>

#include <qvariant.h>

QT_BEGIN_NAMESPACE

class QIODevice;

class QImageIOHandlerPrivate

{

    Q_DECLARE_PUBLIC(QImageIOHandler)

public:

    QImageIOHandlerPrivate(QImageIOHandler *q);

    virtual ~QImageIOHandlerPrivate();

    QIODevice *device;

    mutable QByteArray format;

    QImageIOHandler *q_ptr;

};

QImageIOHandlerPrivate::QImageIOHandlerPrivate(QImageIOHandler *q)

{

    device = nullptr;

    q_ptr = q;

}

QImageIOHandlerPrivate::~QImageIOHandlerPrivate()

{

}

/*!

    Constructs a QImageIOHandler object.

*/

QImageIOHandler::QImageIOHandler()

    : d_ptr(new QImageIOHandlerPrivate(this))

{

}

/*! \internal

    Constructs a QImageIOHandler object, using the private member \a

    dd.

*/

QImageIOHandler::QImageIOHandler(QImageIOHandlerPrivate &dd)

    : d_ptr(&dd)

{

}

/*!

    Destructs the QImageIOHandler object.

*/

QImageIOHandler::~QImageIOHandler()

{

}

/*!

    Sets the device of the QImageIOHandler to \a device. The image

    handler will use this device when reading and writing images.

    The device can only be set once and must be set before calling

    canRead(), read(), write(), etc. If you need to read multiple

    files, construct multiple instances of the appropriate

    QImageIOHandler subclass.

    \sa device()

*/

void QImageIOHandler::setDevice(QIODevice *device)

{

    Q_D(QImageIOHandler);

    d->device = device;

}

/*!

    Returns the device currently assigned to the QImageIOHandler. If

    not device has been assigned, \nullptr is returned.

*/

QIODevice *QImageIOHandler::device() const

{

    Q_D(const QImageIOHandler);

    return d->device;

}

/*!

    Sets the format of the QImageIOHandler to \a format. The format is

    most useful for handlers that support multiple image formats.

    \sa format()

*/

void QImageIOHandler::setFormat(const QByteArray &format)

{

    Q_D(QImageIOHandler);

    d->format = format;

}

/*!

    Sets the format of the QImageIOHandler to \a format. The format is

    most useful for handlers that support multiple image formats.

    This function is declared const so that it can be called from canRead().

    \sa format()

*/

void QImageIOHandler::setFormat(const QByteArray &format) const

{

    Q_D(const QImageIOHandler);

    d->format = format;

}

/*!

    Returns the format that is currently assigned to

    QImageIOHandler. If no format has been assigned, an empty string

    is returned.

    \sa setFormat()

*/

QByteArray QImageIOHandler::format() const

{

    Q_D(const QImageIOHandler);

    return d->format;

}

/*!

    \fn bool QImageIOHandler::read(QImage *image)

    Read an image from the device, and stores it in \a image.

    Returns \c true if the image is successfully read; otherwise returns

    false.

    For image formats that support incremental loading, and for animation

    formats, the image handler can assume that \a image points to the

    previous frame.

    \sa canRead()

*/

/*!

    \fn bool QImageIOHandler::canRead() const

    Returns \c true if an image can be read from the device (i.e., the

    image format is supported, the device can be read from and the

    initial header information suggests that the image can be read);

    otherwise returns \c false.

    When reimplementing canRead(), make sure that the I/O device

    (device()) is left in its original state (e.g., by using peek()

    rather than read()).

    \sa read(), QIODevice::peek()

*/

/*!

    \obsolete

    Use format() instead.

*/

QByteArray QImageIOHandler::name() const // ### Qt6: remove

{

    return format();

}

/*!

    Writes the image \a image to the assigned device. Returns \c true on

    success; otherwise returns \c false.

    The default implementation does nothing, and simply returns \c false.

*/

bool QImageIOHandler::write(const QImage &image)

{

    Q_UNUSED(image);

    return false;

}

/*!

    Sets the option \a option with the value \a value.

    \sa option(), ImageOption

*/

void QImageIOHandler::setOption(ImageOption option, const QVariant &value)

{

    Q_UNUSED(option);

    Q_UNUSED(value);

}

/*!

    Returns the value assigned to \a option as a QVariant. The type of

    the value depends on the option. For example, option(Size) returns

    a QSize variant.

    \sa setOption(), supportsOption()

*/

QVariant QImageIOHandler::option(ImageOption option) const

{

    Q_UNUSED(option);

    return QVariant();

}

/*!

    Returns \c true if the QImageIOHandler supports the option \a option;

    otherwise returns \c false. For example, if the QImageIOHandler

    supports the \l Size option, supportsOption(Size) must return

    true.

    \sa setOption(), option()

*/

bool QImageIOHandler::supportsOption(ImageOption option) const

{

    Q_UNUSED(option);

    return false;

}

/*!

    For image formats that support animation, this function returns

    the sequence number of the current image in the animation. If

    this function is called before any image is read(), -1 is

    returned. The number of the first image in the sequence is 0.

    If the image format does not support animation, 0 is returned.

    \sa read()

*/

int QImageIOHandler::currentImageNumber() const

{

    return 0;

}

/*!

    Returns the rect of the current image. If no rect is defined for the

    image, and empty QRect() is returned.

    This function is useful for animations, where only parts of the frame

    may be updated at a time.

*/

QRect QImageIOHandler::currentImageRect() const

{

    return QRect();

}

/*!

    For image formats that support animation, this function returns

    the number of images in the animation. If the image format does

    not support animation, or if it is unable to determine the number

    of images, 0 is returned.

    The default implementation returns 1 if canRead() returns \c true;

    otherwise 0 is returned.

*/

int QImageIOHandler::imageCount() const

{

    return canRead() ? 1 : 0;

}

/*!

   For image formats that support animation, this function jumps to the

   next image.

   The default implementation does nothing, and returns \c false.

*/

bool QImageIOHandler::jumpToNextImage()

{

    return false;

}

/*!

   For image formats that support animation, this function jumps to the image

   whose sequence number is \a imageNumber. The next call to read() will

   attempt to read this image.

   The default implementation does nothing, and returns \c false.

*/

bool QImageIOHandler::jumpToImage(int imageNumber)

{

    Q_UNUSED(imageNumber);

    return false;

}

/*!

    For image formats that support animation, this function returns

    the number of times the animation should loop. If the image format

    does not support animation, 0 is returned.

*/

int QImageIOHandler::loopCount() const

{

    return 0;

}

/*!

    For image formats that support animation, this function returns

    the number of milliseconds to wait until reading the next

    image. If the image format does not support animation, 0 is

    returned.

*/

int QImageIOHandler::nextImageDelay() const

{

    return 0;

}

#ifndef QT_NO_IMAGEFORMATPLUGIN

/*!

    Constructs an image plugin with the given \a parent. This is

    invoked automatically by the moc generated code that exports the plugin.

*/

QImageIOPlugin::QImageIOPlugin(QObject *parent)

    : QObject(parent)

{

}

/*!

    Destroys the picture format plugin.

    You never have to call this explicitly. Qt destroys a plugin

    automatically when it is no longer used.

*/

QImageIOPlugin::~QImageIOPlugin()

{

}

/*! \fn QImageIOPlugin::capabilities(QIODevice *device, const QByteArray &format) const

    Returns the capabilities of the plugin, based on the data in \a

    device and the format \a format.  If \a device is \c 0, it should

    simply report whether the format can be read or written.  Otherwise,

    it should attempt to determine whether the given format (or any

    format supported by the plugin if \a format is empty) can be read

    from or written to \a device.  It should do this without changing

    the state of \a device (typically by using QIODevice::peek()).

    For example, if the QImageIOPlugin supports the BMP format, \a format

    is either empty or \c "bmp", and the data in the device starts with the

    characters \c "BM", this function should return \l CanRead. If \a format

    is \c "bmp", \a device is \c 0 and the handler supports both reading and

    writing, this function should return \l CanRead | \l CanWrite.

    Format names are always given in lower case.

*/

/*!

    \fn QImageIOHandler *QImageIOPlugin::create(QIODevice *device, const QByteArray &format) const

    Creates and returns a QImageIOHandler subclass, with \a device

    and \a format set. The \a format must come from the values listed

    in the \c "Keys" entry in the plugin metadata, or be empty.  If it is

    empty, the data in \a device must have been recognized by the

    capabilities() method (with a likewise empty format).

    Format names are always given in lower case.

*/

#endif // QT_NO_IMAGEFORMATPLUGIN

QT_END_NAMESPACE

#include "moc_qimageiohandler.cpp"