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qimagereader.cpp
1587 lines (1315 loc) · 50.3 KB
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qimagereader.cpp
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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
//#define QIMAGEREADER_DEBUG
/*!
\class QImageReader
\brief The QImageReader class provides a format independent interface
for reading images from files or other devices.
\inmodule QtGui
\reentrant
\ingroup painting
The most common way to read images is through QImage and QPixmap's
constructors, or by calling QImage::load() and
QPixmap::load(). QImageReader is a specialized class which gives
you more control when reading images. For example, you can read an
image into a specific size by calling setScaledSize(), and you can
select a clip rect, effectively loading only parts of an image, by
calling setClipRect(). Depending on the underlying support in the
image format, this can save memory and speed up loading of images.
To read an image, you start by constructing a QImageReader object.
Pass either a file name or a device pointer, and the image format
to QImageReader's constructor. You can then set several options,
such as the clip rect (by calling setClipRect()) and scaled size
(by calling setScaledSize()). canRead() returns the image if the
QImageReader can read the image (i.e., the image format is
supported and the device is open for reading). Call read() to read
the image.
If any error occurs when reading the image, read() will return a
null QImage. You can then call error() to find the type of error
that occurred, or errorString() to get a human readable
description of what went wrong.
\note QImageReader assumes exclusive control over the file or
device that is assigned. Any attempts to modify the assigned file
or device during the lifetime of the QImageReader object will
yield undefined results.
\section1 Formats
Call supportedImageFormats() for a list of formats that
QImageReader can read. QImageReader supports all built-in image
formats, in addition to any image format plugins that support
reading. Call supportedMimeTypes() to obtain a list of supported MIME
types, which for example can be passed to QFileDialog::setMimeTypeFilters().
QImageReader autodetects the image format by default, by looking at the
provided (optional) format string, the file name suffix, and the data
stream contents. You can enable or disable this feature, by calling
setAutoDetectImageFormat().
\section1 High Resolution Versions of Images
It is possible to provide high resolution versions of images should a scaling
between \e{device pixels} and \e{device independent pixels} be in effect.
The high resolution version is marked by the suffix \c @2x on the base name.
The image read will have its \e{device pixel ratio} set to a value of 2.
This can be disabled by setting the environment variable
\c QT_HIGHDPI_DISABLE_2X_IMAGE_LOADING.
\sa QImageWriter, QImageIOHandler, QImageIOPlugin, QMimeDatabase, QColorSpace
\sa QImage::devicePixelRatio(), QPixmap::devicePixelRatio(), QIcon, QPainter::drawPixmap(), QPainter::drawImage()
*/
/*!
\enum QImageReader::ImageReaderError
This enum describes the different types of errors that can occur
when reading images with QImageReader.
\value FileNotFoundError QImageReader was used with a file name,
but not file was found with that name. This can also happen if the
file name contained no extension, and the file with the correct
extension is not supported by Qt.
\value DeviceError QImageReader encountered a device error when
reading the image. You can consult your particular device for more
details on what went wrong.
\value UnsupportedFormatError Qt does not support the requested
image format.
\value InvalidDataError The image data was invalid, and
QImageReader was unable to read an image from it. The can happen
if the image file is damaged.
\value UnknownError An unknown error occurred. If you get this
value after calling read(), it is most likely caused by a bug in
QImageReader.
*/
#include "qimagereader.h"
#include <qbytearray.h>
#ifdef QIMAGEREADER_DEBUG
#include <qdebug.h>
#endif
#include <qfile.h>
#include <qfileinfo.h>
#include <qimage.h>
#include <qimageiohandler.h>
#include <qlist.h>
#include <qrect.h>
#include <qsize.h>
#include <qcolor.h>
#include <qvariant.h>
// factory loader
#include <qcoreapplication.h>
#include <private/qfactoryloader_p.h>
#include <QtCore/private/qlocking_p.h>
// for qt_getImageText
#include <private/qimage_p.h>
// image handlers
#include <private/qbmphandler_p.h>
#include <private/qppmhandler_p.h>
#include <private/qxbmhandler_p.h>
#include <private/qxpmhandler_p.h>
#ifndef QT_NO_IMAGEFORMAT_PNG
#include <private/qpnghandler_p.h>
#endif
#include <private/qimagereaderwriterhelpers_p.h>
#include <qtgui_tracepoints_p.h>
#include <algorithm>
QT_BEGIN_NAMESPACE
using namespace QImageReaderWriterHelpers;
using namespace Qt::StringLiterals;
Q_TRACE_POINT(qtgui, QImageReader_read_before_reading, QImageReader *reader, const QString &filename);
Q_TRACE_POINT(qtgui, QImageReader_read_after_reading, QImageReader *reader, bool result);
static QImageIOHandler *createReadHandlerHelper(QIODevice *device,
const QByteArray &format,
bool autoDetectImageFormat,
bool ignoresFormatAndExtension)
{
if (!autoDetectImageFormat && format.isEmpty())
return nullptr;
QByteArray form = format.toLower();
QImageIOHandler *handler = nullptr;
QByteArray suffix;
#ifndef QT_NO_IMAGEFORMATPLUGIN
Q_CONSTINIT static QBasicMutex mutex;
const auto locker = qt_scoped_lock(mutex);
typedef QMultiMap<int, QString> PluginKeyMap;
// check if we have plugins that support the image format
auto l = QImageReaderWriterHelpers::pluginLoader();
const PluginKeyMap keyMap = l->keyMap();
#ifdef QIMAGEREADER_DEBUG
qDebug() << "QImageReader::createReadHandler( device =" << (void *)device << ", format =" << format << "),"
<< keyMap.uniqueKeys().size() << "plugins available: " << keyMap;
#endif
int suffixPluginIndex = -1;
#endif // QT_NO_IMAGEFORMATPLUGIN
if (device && format.isEmpty() && autoDetectImageFormat && !ignoresFormatAndExtension) {
// if there's no format, see if \a device is a file, and if so, find
// the file suffix and find support for that format among our plugins.
// this allows plugins to override our built-in handlers.
if (QFile *file = qobject_cast<QFile *>(device)) {
#ifdef QIMAGEREADER_DEBUG
qDebug() << "QImageReader::createReadHandler: device is a file:" << file->fileName();
#endif
if (!(suffix = QFileInfo(file->fileName()).suffix().toLower().toLatin1()).isEmpty()) {
#ifndef QT_NO_IMAGEFORMATPLUGIN
const int index = keyMap.key(QString::fromLatin1(suffix), -1);
if (index != -1) {
#ifdef QIMAGEREADER_DEBUG
qDebug() << "QImageReader::createReadHandler: suffix recognized; the"
<< suffix << "plugin might be able to read this";
#endif
suffixPluginIndex = index;
}
#endif // QT_NO_IMAGEFORMATPLUGIN
}
}
}
QByteArray testFormat = !form.isEmpty() ? form : suffix;
if (ignoresFormatAndExtension)
testFormat = QByteArray();
#ifndef QT_NO_IMAGEFORMATPLUGIN
if (suffixPluginIndex != -1) {
// check if the plugin that claims support for this format can load
// from this device with this format.
const qint64 pos = device ? device->pos() : 0;
const int index = keyMap.key(QString::fromLatin1(suffix), -1);
if (index != -1) {
QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(index));
if (plugin && plugin->capabilities(device, testFormat) & QImageIOPlugin::CanRead) {
handler = plugin->create(device, testFormat);
#ifdef QIMAGEREADER_DEBUG
qDebug() << "QImageReader::createReadHandler: using the" << suffix
<< "plugin";
#endif
}
}
if (device && !device->isSequential())
device->seek(pos);
}
if (!handler && !testFormat.isEmpty() && !ignoresFormatAndExtension) {
// check if any plugin supports the format (they are not allowed to
// read from the device yet).
const qint64 pos = device ? device->pos() : 0;
if (autoDetectImageFormat) {
const int keyCount = keyMap.size();
for (int i = 0; i < keyCount; ++i) {
if (i != suffixPluginIndex) {
QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(i));
if (plugin && plugin->capabilities(device, testFormat) & QImageIOPlugin::CanRead) {
#ifdef QIMAGEREADER_DEBUG
qDebug() << "QImageReader::createReadHandler: the" << keyMap.keys().at(i) << "plugin can read this format";
#endif
handler = plugin->create(device, testFormat);
break;
}
}
}
} else {
const int testIndex = keyMap.key(QLatin1StringView(testFormat), -1);
if (testIndex != -1) {
QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(testIndex));
if (plugin && plugin->capabilities(device, testFormat) & QImageIOPlugin::CanRead) {
#ifdef QIMAGEREADER_DEBUG
qDebug() << "QImageReader::createReadHandler: the" << testFormat << "plugin can read this format";
#endif
handler = plugin->create(device, testFormat);
}
}
}
if (device && !device->isSequential())
device->seek(pos);
}
#endif // QT_NO_IMAGEFORMATPLUGIN
// if we don't have a handler yet, check if we have built-in support for
// the format
if (!handler && !testFormat.isEmpty()) {
if (false) {
#ifndef QT_NO_IMAGEFORMAT_PNG
} else if (testFormat == "png") {
handler = new QPngHandler;
#endif
#ifndef QT_NO_IMAGEFORMAT_BMP
} else if (testFormat == "bmp") {
handler = new QBmpHandler;
} else if (testFormat == "dib") {
handler = new QBmpHandler(QBmpHandler::DibFormat);
#endif
#ifndef QT_NO_IMAGEFORMAT_XPM
} else if (testFormat == "xpm") {
handler = new QXpmHandler;
#endif
#ifndef QT_NO_IMAGEFORMAT_XBM
} else if (testFormat == "xbm") {
handler = new QXbmHandler;
handler->setOption(QImageIOHandler::SubType, testFormat);
#endif
#ifndef QT_NO_IMAGEFORMAT_PPM
} else if (testFormat == "pbm" || testFormat == "pbmraw" || testFormat == "pgm"
|| testFormat == "pgmraw" || testFormat == "ppm" || testFormat == "ppmraw") {
handler = new QPpmHandler;
handler->setOption(QImageIOHandler::SubType, testFormat);
#endif
}
#ifdef QIMAGEREADER_DEBUG
if (handler)
qDebug() << "QImageReader::createReadHandler: using the built-in handler for" << testFormat;
#endif
}
if (handler && device && !suffix.isEmpty()) {
Q_ASSERT(qobject_cast<QFile *>(device));
// We have a file claiming to be of a recognized format. Now confirm that
// the handler also recognizes the file contents.
const qint64 pos = device->pos();
handler->setDevice(device);
if (!form.isEmpty())
handler->setFormat(form);
bool canRead = handler->canRead();
device->seek(pos);
if (canRead) {
// ok, we're done.
return handler;
}
#ifdef QIMAGEREADER_DEBUG
qDebug() << "QImageReader::createReadHandler: the" << suffix << "handler can not read this file";
#endif
// File may still be valid, just with wrong suffix, so fall back to
// finding a handler based on contents, below.
delete handler;
handler = nullptr;
}
#ifndef QT_NO_IMAGEFORMATPLUGIN
if (!handler && (autoDetectImageFormat || ignoresFormatAndExtension)) {
// check if any of our plugins recognize the file from its contents.
const qint64 pos = device ? device->pos() : 0;
const int keyCount = keyMap.size();
for (int i = 0; i < keyCount; ++i) {
if (i != suffixPluginIndex) {
QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(i));
if (plugin && plugin->capabilities(device, QByteArray()) & QImageIOPlugin::CanRead) {
handler = plugin->create(device, testFormat);
#ifdef QIMAGEREADER_DEBUG
qDebug() << "QImageReader::createReadHandler: the" << keyMap.value(i) << "plugin can read this data";
#endif
break;
}
}
}
if (device && !device->isSequential())
device->seek(pos);
}
#endif // QT_NO_IMAGEFORMATPLUGIN
if (!handler && (autoDetectImageFormat || ignoresFormatAndExtension)) {
// check if any of our built-in handlers recognize the file from its
// contents.
int currentFormat = 0;
if (!suffix.isEmpty()) {
// If reading from a file with a suffix, start testing our
// built-in handler for that suffix first.
for (int i = 0; i < _qt_NumFormats; ++i) {
if (_qt_BuiltInFormats[i].extension == suffix) {
currentFormat = i;
break;
}
}
}
QByteArray subType;
int numFormats = _qt_NumFormats;
while (device && numFormats >= 0) {
const qint64 pos = device->pos();
switch (currentFormat) {
#ifndef QT_NO_IMAGEFORMAT_PNG
case _qt_PngFormat:
if (QPngHandler::canRead(device))
handler = new QPngHandler;
break;
#endif
#ifndef QT_NO_IMAGEFORMAT_BMP
case _qt_BmpFormat:
if (QBmpHandler::canRead(device))
handler = new QBmpHandler;
break;
#endif
#ifndef QT_NO_IMAGEFORMAT_XPM
case _qt_XpmFormat:
if (QXpmHandler::canRead(device))
handler = new QXpmHandler;
break;
#endif
#ifndef QT_NO_IMAGEFORMAT_PPM
case _qt_PbmFormat:
case _qt_PgmFormat:
case _qt_PpmFormat:
if (QPpmHandler::canRead(device, &subType)) {
handler = new QPpmHandler;
handler->setOption(QImageIOHandler::SubType, subType);
}
break;
#endif
#ifndef QT_NO_IMAGEFORMAT_XBM
case _qt_XbmFormat:
if (QXbmHandler::canRead(device))
handler = new QXbmHandler;
break;
#endif
default:
break;
}
if (!device->isSequential())
device->seek(pos);
if (handler) {
#ifdef QIMAGEREADER_DEBUG
qDebug("QImageReader::createReadHandler: the %s built-in handler can read this data",
_qt_BuiltInFormats[currentFormat].extension);
#endif
break;
}
--numFormats;
++currentFormat;
if (currentFormat >= _qt_NumFormats)
currentFormat = 0;
}
}
if (!handler) {
#ifdef QIMAGEREADER_DEBUG
qDebug("QImageReader::createReadHandler: no handlers found. giving up.");
#endif
// no handler: give up.
return nullptr;
}
handler->setDevice(device);
if (!form.isEmpty())
handler->setFormat(form);
return handler;
}
class QImageReaderPrivate
{
public:
QImageReaderPrivate(QImageReader *qq);
~QImageReaderPrivate();
// device
QByteArray format;
bool autoDetectImageFormat;
bool ignoresFormatAndExtension;
QIODevice *device;
bool deleteDevice;
QImageIOHandler *handler;
bool initHandler();
// image options
QRect clipRect;
QSize scaledSize;
QRect scaledClipRect;
int quality;
QMap<QString, QString> text;
void getText();
enum {
UsePluginDefault,
ApplyTransform,
DoNotApplyTransform
} autoTransform;
// error
QImageReader::ImageReaderError imageReaderError;
QString errorString;
QImageReader *q;
static int maxAlloc;
};
int QImageReaderPrivate::maxAlloc = 128; // 128 MB is enough for an 8K 32bpp image
/*!
\internal
*/
QImageReaderPrivate::QImageReaderPrivate(QImageReader *qq)
: autoDetectImageFormat(true), ignoresFormatAndExtension(false)
{
device = nullptr;
deleteDevice = false;
handler = nullptr;
quality = -1;
imageReaderError = QImageReader::UnknownError;
autoTransform = UsePluginDefault;
q = qq;
}
/*!
\internal
*/
QImageReaderPrivate::~QImageReaderPrivate()
{
delete handler;
if (deleteDevice)
delete device;
}
/*!
\internal
*/
bool QImageReaderPrivate::initHandler()
{
if (handler)
return true;
// check some preconditions
if (!device || (!deleteDevice && !device->isOpen() && !device->open(QIODevice::ReadOnly))) {
imageReaderError = QImageReader::DeviceError;
errorString = QImageReader::tr("Invalid device");
return false;
}
// probe the file extension
if (deleteDevice && !device->isOpen() && !device->open(QIODevice::ReadOnly) && autoDetectImageFormat) {
Q_ASSERT(qobject_cast<QFile*>(device) != nullptr); // future-proofing; for now this should always be the case, so...
QFile *file = static_cast<QFile *>(device);
if (file->error() == QFileDevice::ResourceError) {
// this is bad. we should abort the open attempt and note the failure.
imageReaderError = QImageReader::DeviceError;
errorString = file->errorString();
return false;
}
QList<QByteArray> extensions = QImageReader::supportedImageFormats();
if (!format.isEmpty()) {
// Try the most probable extension first
int currentFormatIndex = extensions.indexOf(format.toLower());
if (currentFormatIndex > 0)
extensions.swapItemsAt(0, currentFormatIndex);
}
int currentExtension = 0;
QString fileName = file->fileName();
do {
file->setFileName(fileName + u'.'
+ QLatin1StringView(extensions.at(currentExtension++).constData()));
file->open(QIODevice::ReadOnly);
} while (!file->isOpen() && currentExtension < extensions.size());
if (!device->isOpen()) {
imageReaderError = QImageReader::FileNotFoundError;
errorString = QImageReader::tr("File not found");
file->setFileName(fileName); // restore the old file name
return false;
}
}
// assign a handler
if ((handler = createReadHandlerHelper(device, format, autoDetectImageFormat, ignoresFormatAndExtension)) == nullptr) {
imageReaderError = QImageReader::UnsupportedFormatError;
errorString = QImageReader::tr("Unsupported image format");
return false;
}
return true;
}
/*!
\internal
*/
void QImageReaderPrivate::getText()
{
if (text.isEmpty() && initHandler() && handler->supportsOption(QImageIOHandler::Description))
text = qt_getImageTextFromDescription(handler->option(QImageIOHandler::Description).toString());
}
/*!
Constructs an empty QImageReader object. Before reading an image,
call setDevice() or setFileName().
*/
QImageReader::QImageReader()
: d(new QImageReaderPrivate(this))
{
}
/*!
Constructs a QImageReader object with the device \a device and the
image format \a format.
*/
QImageReader::QImageReader(QIODevice *device, const QByteArray &format)
: d(new QImageReaderPrivate(this))
{
d->device = device;
d->format = format;
}
/*!
Constructs a QImageReader object with the file name \a fileName
and the image format \a format.
\sa setFileName()
*/
QImageReader::QImageReader(const QString &fileName, const QByteArray &format)
: QImageReader(new QFile(fileName), format)
{
d->deleteDevice = true;
}
/*!
Destructs the QImageReader object.
*/
QImageReader::~QImageReader()
{
delete d;
}
/*!
Sets the format QImageReader will use when reading images, to \a
format. \a format is a case insensitive text string. Example:
\snippet code/src_gui_image_qimagereader.cpp 0
You can call supportedImageFormats() for the full list of formats
QImageReader supports.
\sa format()
*/
void QImageReader::setFormat(const QByteArray &format)
{
d->format = format;
}
/*!
Returns the format QImageReader uses for reading images.
You can call this function after assigning a device to the
reader to determine the format of the device. For example:
\snippet code/src_gui_image_qimagereader.cpp 1
If the reader cannot read any image from the device (e.g., there is no
image there, or the image has already been read), or if the format is
unsupported, this function returns an empty QByteArray().
\sa setFormat(), supportedImageFormats()
*/
QByteArray QImageReader::format() const
{
if (d->format.isEmpty()) {
if (!d->initHandler())
return QByteArray();
return d->handler->canRead() ? d->handler->format() : QByteArray();
}
return d->format;
}
/*!
If \a enabled is true, image format autodetection is enabled; otherwise,
it is disabled. By default, autodetection is enabled.
QImageReader uses an extensive approach to detecting the image format;
firstly, if you pass a file name to QImageReader, it will attempt to
detect the file extension if the given file name does not point to an
existing file, by appending supported default extensions to the given file
name, one at a time. It then uses the following approach to detect the
image format:
\list
\li Image plugins are queried first, based on either the optional format
string, or the file name suffix (if the source device is a file). No
content detection is done at this stage. QImageReader will choose the
first plugin that supports reading for this format.
\li If no plugin supports the image format, Qt's built-in handlers are
checked based on either the optional format string, or the file name
suffix.
\li If no capable plugins or built-in handlers are found, each plugin is
tested by inspecting the content of the data stream.
\li If no plugins could detect the image format based on data contents,
each built-in image handler is tested by inspecting the contents.
\li Finally, if all above approaches fail, QImageReader will report failure
when trying to read the image.
\endlist
By disabling image format autodetection, QImageReader will only query the
plugins and built-in handlers based on the format string (i.e., no file
name extensions are tested).
\sa QImageIOHandler::canRead(), QImageIOPlugin::capabilities()
*/
void QImageReader::setAutoDetectImageFormat(bool enabled)
{
d->autoDetectImageFormat = enabled;
}
/*!
Returns \c true if image format autodetection is enabled on this image
reader; otherwise returns \c false. By default, autodetection is enabled.
\sa setAutoDetectImageFormat()
*/
bool QImageReader::autoDetectImageFormat() const
{
return d->autoDetectImageFormat;
}
/*!
If \a ignored is set to true, then the image reader will ignore
specified formats or file extensions and decide which plugin to
use only based on the contents in the datastream.
Setting this flag means that all image plugins gets loaded. Each
plugin will read the first bytes in the image data and decide if
the plugin is compatible or not.
This also disables auto detecting the image format.
\sa decideFormatFromContent()
*/
void QImageReader::setDecideFormatFromContent(bool ignored)
{
d->ignoresFormatAndExtension = ignored;
}
/*!
Returns whether the image reader should decide which plugin to use
only based on the contents of the datastream rather than on the file
extension.
\sa setDecideFormatFromContent()
*/
bool QImageReader::decideFormatFromContent() const
{
return d->ignoresFormatAndExtension;
}
/*!
Sets QImageReader's device to \a device. If a device has already
been set, the old device is removed from QImageReader and is
otherwise left unchanged.
If the device is not already open, QImageReader will attempt to
open the device in \l {QIODeviceBase::}{ReadOnly} mode by calling
open(). Note that this does not work for certain devices, such as
QProcess, QTcpSocket and QUdpSocket, where more logic is required
to open the device.
\sa device(), setFileName()
*/
void QImageReader::setDevice(QIODevice *device)
{
delete d->handler;
d->handler = nullptr;
if (d->device && d->deleteDevice)
delete d->device;
d->device = device;
d->deleteDevice = false;
d->text.clear();
}
/*!
Returns the device currently assigned to QImageReader, or \nullptr
if no device has been assigned.
*/
QIODevice *QImageReader::device() const
{
return d->device;
}
/*!
Sets the file name of QImageReader to \a fileName. Internally,
QImageReader will create a QFile object and open it in \l
{QIODeviceBase::}{ReadOnly} mode, and use this when reading images.
If \a fileName does not include a file extension (e.g., .png or .bmp),
QImageReader will cycle through all supported extensions until it finds
a matching file.
\sa fileName(), setDevice(), supportedImageFormats()
*/
void QImageReader::setFileName(const QString &fileName)
{
setDevice(new QFile(fileName));
d->deleteDevice = true;
}
/*!
If the currently assigned device is a QFile, or if setFileName()
has been called, this function returns the name of the file
QImageReader reads from. Otherwise (i.e., if no device has been
assigned or the device is not a QFile), an empty QString is
returned.
\sa setFileName(), setDevice()
*/
QString QImageReader::fileName() const
{
QFile *file = qobject_cast<QFile *>(d->device);
return file ? file->fileName() : QString();
}
/*!
\since 4.2
Sets the quality setting of the image format to \a quality.
Some image formats, in particular lossy ones, entail a tradeoff between a)
visual quality of the resulting image, and b) decoding execution time.
This function sets the level of that tradeoff for image formats that
support it.
In case of scaled image reading, the quality setting may also influence the
tradeoff level between visual quality and execution speed of the scaling
algorithm.
The value range of \a quality depends on the image format. For example,
the "jpeg" format supports a quality range from 0 (low visual quality) to
100 (high visual quality).
\sa quality() setScaledSize()
*/
void QImageReader::setQuality(int quality)
{
d->quality = quality;
}
/*!
\since 4.2
Returns the quality setting of the image format.
\sa setQuality()
*/
int QImageReader::quality() const
{
return d->quality;
}
/*!
Returns the size of the image, without actually reading the image
contents.
If the image format does not support this feature, this function returns
an invalid size. Qt's built-in image handlers all support this feature,
but custom image format plugins are not required to do so.
\sa QImageIOHandler::ImageOption, QImageIOHandler::option(), QImageIOHandler::supportsOption()
*/
QSize QImageReader::size() const
{
if (!d->initHandler())
return QSize();
if (d->handler->supportsOption(QImageIOHandler::Size))
return d->handler->option(QImageIOHandler::Size).toSize();
return QSize();
}
/*!
\since 4.5
Returns the format of the image, without actually reading the image
contents. The format describes the image format \l QImageReader::read()
returns, not the format of the actual image.
If the image format does not support this feature, this function returns
an invalid format.
\sa QImageIOHandler::ImageOption, QImageIOHandler::option(), QImageIOHandler::supportsOption()
*/
QImage::Format QImageReader::imageFormat() const
{
if (!d->initHandler())
return QImage::Format_Invalid;
if (d->handler->supportsOption(QImageIOHandler::ImageFormat))
return (QImage::Format)d->handler->option(QImageIOHandler::ImageFormat).toInt();
return QImage::Format_Invalid;
}
/*!
\since 4.1
Returns the text keys for this image. You can use
these keys with text() to list the image text for
a certain key.
Support for this option is implemented through
QImageIOHandler::Description.
\sa text(), QImageWriter::setText(), QImage::textKeys()
*/
QStringList QImageReader::textKeys() const
{
d->getText();
return d->text.keys();
}
/*!
\since 4.1
Returns the image text associated with \a key.
Support for this option is implemented through
QImageIOHandler::Description.
\sa textKeys(), QImageWriter::setText()
*/
QString QImageReader::text(const QString &key) const
{
d->getText();
return d->text.value(key);
}
/*!
Sets the image clip rect (also known as the ROI, or Region Of
Interest) to \a rect. The coordinates of \a rect are relative to
the untransformed image size, as returned by size().
\sa clipRect(), setScaledSize(), setScaledClipRect()
*/
void QImageReader::setClipRect(const QRect &rect)
{
d->clipRect = rect;
}
/*!
Returns the clip rect (also known as the ROI, or Region Of
Interest) of the image. If no clip rect has been set, an invalid
QRect is returned.
\sa setClipRect()
*/
QRect QImageReader::clipRect() const
{
return d->clipRect;
}
/*!
Sets the scaled size of the image to \a size. The scaling is
performed after the initial clip rect, but before the scaled clip
rect is applied. The algorithm used for scaling depends on the
image format. By default (i.e., if the image format does not
support scaling), QImageReader will use QImage::scale() with
Qt::SmoothScaling.
\sa scaledSize(), setClipRect(), setScaledClipRect()
*/
void QImageReader::setScaledSize(const QSize &size)
{
d->scaledSize = size;
}
/*!
Returns the scaled size of the image.
\sa setScaledSize()
*/
QSize QImageReader::scaledSize() const
{
return d->scaledSize;
}
/*!
Sets the scaled clip rect to \a rect. The scaled clip rect is the
clip rect (also known as ROI, or Region Of Interest) that is
applied after the image has been scaled.
\sa scaledClipRect(), setScaledSize()
*/
void QImageReader::setScaledClipRect(const QRect &rect)
{
d->scaledClipRect = rect;
}
/*!
Returns the scaled clip rect of the image.
\sa setScaledClipRect()
*/
QRect QImageReader::scaledClipRect() const
{
return d->scaledClipRect;
}
/*!
\since 4.1
Sets the background color to \a color.
Image formats that support this operation are expected to
initialize the background to \a color before reading an image.
\sa backgroundColor(), read()
*/
void QImageReader::setBackgroundColor(const QColor &color)
{
if (!d->initHandler())
return;