QPngHandler Class Reference

#include <qpnghandler_p.h>

Inheritance diagram for QPngHandler:

Public Functions
bool	canRead () const
	Returns true if an image can be read from the device (i. More...
QByteArray	name () const
	Use format() instead. More...
QVariant	option (ImageOption option) const
	Returns the value assigned to option as a QVariant. More...
	QPngHandler ()
bool	read (QImage *image)
	Read an image from the device, and stores it in image. More...
void	setOption (ImageOption option, const QVariant &value)
	Sets the option option with the value value. More...
bool	supportsOption (ImageOption option) const
	Returns true if the QImageIOHandler supports the option option; otherwise returns false. More...
bool	write (const QImage &image)
	Writes the image image to the assigned device. More...
	~QPngHandler ()
Public Functions inherited from QImageIOHandler
virtual int	currentImageNumber () const
	For image formats that support animation, this function returns the sequence number of the current image in the animation. More...
virtual QRect	currentImageRect () const
	Returns the rect of the current image. More...
QIODevice *	device () const
	Returns the device currently assigned to the QImageIOHandler. More...
QByteArray	format () const
	Returns the format that is currently assigned to QImageIOHandler. More...
virtual int	imageCount () const
	For image formats that support animation, this function returns the number of images in the animation. More...
virtual bool	jumpToImage (int imageNumber)
	For image formats that support animation, this function jumps to the image whose sequence number is imageNumber. More...
virtual bool	jumpToNextImage ()
	For image formats that support animation, this function jumps to the next image. More...
virtual int	loopCount () const
	For image formats that support animation, this function returns the number of times the animation should loop. More...
virtual int	nextImageDelay () const
	For image formats that support animation, this function returns the number of milliseconds to wait until reading the next image. More...
	QImageIOHandler ()
	Constructs a QImageIOHandler object. More...
void	setDevice (QIODevice *device)
	Sets the device of the QImageIOHandler to device. More...
void	setFormat (const QByteArray &format)
	Sets the format of the QImageIOHandler to format. More...
void	setFormat (const QByteArray &format) const
	Sets the format of the QImageIOHandler to format. More...
virtual	~QImageIOHandler ()
	Destructs the QImageIOHandler object. More...

Static Public Functions
static bool	canRead (QIODevice *device)

Properties
QPngHandlerPrivate *	d

Additional Inherited Members
Public Types inherited from QImageIOHandler
enum	ImageOption {   Size, ClipRect, Description, ScaledClipRect,   ScaledSize, CompressionRatio, Gamma, Quality,   Name, SubType, IncrementalReading, Endianness,   Animation, BackgroundColor, ImageFormat }
	This enum describes the different options supported by QImageIOHandler. More...
Protected Functions inherited from QImageIOHandler
	QImageIOHandler (QImageIOHandlerPrivate &dd)
	Constructs a QImageIOHandler object, using the private member dd. More...
Protected Variables inherited from QImageIOHandler
QScopedPointer< QImageIOHandlerPrivate >	d_ptr

Detailed Description

Definition at line 63 of file qpnghandler_p.h.

Constructors and Destructors

QPngHandler()

QPngHandler::QPngHandler

(

)

Definition at line 927 of file qpnghandler.cpp.

    : d(new QPngHandlerPrivate(this))
{
}

~QPngHandler()

QPngHandler::~QPngHandler

(

)

Definition at line 932 of file qpnghandler.cpp.

{
    if (d->png_ptr)
        png_destroy_read_struct(&d->png_ptr, &d->info_ptr, &d->end_info);
    delete d;
}

Functions

canRead() [1/2]

bool QPngHandler::canRead ( ) const

virtual

Returns 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 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()).

See also

read(), QIODevice::peek()

Implements QImageIOHandler.

Definition at line 939 of file qpnghandler.cpp.

Referenced by createReadHandlerHelper(), and read().

{
    if (d->state == QPngHandlerPrivate::Ready && !canRead(device()))
        return false;

    if (d->state != QPngHandlerPrivate::Error) {
        setFormat("png");
        return true;
    }

    return false;
}

canRead() [2/2]

bool QPngHandler::canRead ( QIODevice *  device )

static

Definition at line 952 of file qpnghandler.cpp.

{
    if (!device) {
        qWarning("QPngHandler::canRead() called with no device");
        return false;
    }

    return device->peek(8) == "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A";
}

name()

QByteArray QPngHandler::name ( ) const

virtual

Use format() instead.

Reimplemented from QImageIOHandler.

Definition at line 1014 of file qpnghandler.cpp.

{
    return "png";
}

option()

QVariant QPngHandler::option ( ImageOption  option ) const

virtual

Returns the value assigned to option as a QVariant.

The type of the value depends on the option. For example, option(Size) returns a QSize variant.

See also

setOption(), supportsOption()

Reimplemented from QImageIOHandler.

Definition at line 983 of file qpnghandler.cpp.

{
    if (d->state == QPngHandlerPrivate::Error)
        return QVariant();
    if (d->state == QPngHandlerPrivate::Ready && !d->readPngHeader())
        return QVariant();

    if (option == Gamma)
        return d->gamma;
    else if (option == Quality)
        return d->quality;
    else if (option == Description)
        return d->description;
    else if (option == Size)
        return QSize(png_get_image_width(d->png_ptr, d->info_ptr),
                     png_get_image_height(d->png_ptr, d->info_ptr));
    else if (option == ImageFormat)
        return d->readImageFormat();
    return 0;
}

read()

bool QPngHandler::read ( QImage *  image )

virtual

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

Returns 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 image points to the previous frame.

See also

canRead()

Implements QImageIOHandler.

Definition at line 962 of file qpnghandler.cpp.

{
    if (!canRead())
        return false;
    return d->readPngImage(image);
}

setOption()

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

virtual

Sets the option option with the value value.

See also

option(), ImageOption

Reimplemented from QImageIOHandler.

Definition at line 1004 of file qpnghandler.cpp.

{
    if (option == Gamma)
        d->gamma = value.toFloat();
    else if (option == Quality)
        d->quality = value.toInt();
    else if (option == Description)
        d->description = value.toString();
}

supportsOption()

bool QPngHandler::supportsOption ( ImageOption  option ) const

virtual

Returns true if the QImageIOHandler supports the option option; otherwise returns false.

For example, if the QImageIOHandler supports the Size option, supportsOption(Size) must return true.

See also

setOption(), option()

Reimplemented from QImageIOHandler.

Definition at line 974 of file qpnghandler.cpp.

{
    return option == Gamma
        || option == Description
        || option == ImageFormat
        || option == Quality
        || option == Size;
}

write()

bool QPngHandler::write ( const QImage &  image )

virtual

Writes the image image to the assigned device.

Returns true on success; otherwise returns false.

The default implementation does nothing, and simply returns false.

Reimplemented from QImageIOHandler.

Definition at line 969 of file qpnghandler.cpp.

{
    return write_png_image(image, device(), d->quality, d->gamma, d->description);
}

Properties

d

QPngHandlerPrivate* QPngHandler::d

private

Definition at line 82 of file qpnghandler_p.h.

Referenced by canRead(), option(), read(), setOption(), write(), and ~QPngHandler().

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The documentation for this class was generated from the following files:

• /src/gui/image/qpnghandler_p.h
• /src/gui/image/qpnghandler.cpp