source: trunk/src/gui/image/qimagewriter.cpp@ 463

/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information ([email protected])
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at [email protected].
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \class QImageWriter
    \brief The QImageWriter class provides a format independent interface
    for writing images to files or other devices.

    \reentrant
    \ingroup multimedia
    \ingroup io

    QImageWriter supports setting format specific options, such as the
    gamma level, compression level and quality, prior to storing the
    image. If you do not need such options, you can use QImage::save()
    or QPixmap::save() instead.

    To store an image, you start by constructing a QImageWriter
    object.  Pass either a file name or a device pointer, and the
    image format to QImageWriter's constructor. You can then set
    several options, such as the gamma level (by calling setGamma())
    and quality (by calling setQuality()). canWrite() returns true if
    QImageWriter can write the image (i.e., the image format is
    supported and the device is open for writing). Call write() to
    write the image to the device.

    If any error occurs when writing the image, write() will return
    false. 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.

    Call supportedImageFormats() for a list of formats that
    QImageWriter can write. QImageWriter supports all built-in image
    formats, in addition to any image format plugins that support
    writing.

    \sa QImageReader, QImageIOHandler, QImageIOPlugin
*/

/*!
    \enum QImageWriter::ImageWriterError

    This enum describes errors that can occur when writing images with
    QImageWriter.

    \value DeviceError QImageWriter encountered a device error when
    writing the image data. Consult your device for more details on
    what went wrong.

    \value UnsupportedFormatError Qt does not support the requested
    image format.

    \value UnknownError An unknown error occurred. If you get this
    value after calling write(), it is most likely caused by a bug in
    QImageWriter.
*/

#include "qimagewriter.h"

#include <qbytearray.h>
#include <qfile.h>
#include <qfileinfo.h>
#include <qimageiohandler.h>
#include <qset.h>
#include <qvariant.h>

// factory loader
#include <qcoreapplication.h>
#include <private/qfactoryloader_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

QT_BEGIN_NAMESPACE

#if !defined (QT_NO_LIBRARY) && !defined(QT_NO_SETTINGS)
Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, loader,
                          (QImageIOHandlerFactoryInterface_iid, QLatin1String("/imageformats")))
#endif

static QImageIOHandler *createWriteHandlerHelper(QIODevice *device,
    const QByteArray &format)
{
    QByteArray form = format.toLower();
    QByteArray suffix;
    QImageIOHandler *handler = 0;

#if !defined (QT_NO_LIBRARY) && !defined(QT_NO_SETTINGS)
    // check if any plugins can write the image
    QFactoryLoader *l = loader();
    QStringList keys = l->keys();
    int suffixPluginIndex = -1;
#endif

    if (device && format.isEmpty()) {
        // 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)) {
            if (!(suffix = QFileInfo(file->fileName()).suffix().toLower().toLatin1()).isEmpty()) {
#if !defined (QT_NO_LIBRARY) && !defined(QT_NO_SETTINGS)
                int index = keys.indexOf(QString::fromLatin1(suffix));
                if (index != -1)
                    suffixPluginIndex = index;
#endif
            }
        }
    }

    QByteArray testFormat = !form.isEmpty() ? form : suffix;

#if !defined (QT_NO_LIBRARY) && !defined(QT_NO_SETTINGS)
    if (suffixPluginIndex != -1) {
        // when format is missing, check if we can find a plugin for the
        // suffix.
        QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(QString::fromLatin1(suffix)));
        if (plugin && (plugin->capabilities(device, suffix) & QImageIOPlugin::CanWrite))
            handler = plugin->create(device, suffix);
    }
#endif // Q_NO_LIBRARY

    // check if any built-in handlers can write the image
    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;
#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
        }
    }

#if !defined (QT_NO_LIBRARY) && !defined(QT_NO_SETTINGS)
    if (!testFormat.isEmpty()) {
        for (int i = 0; i < keys.size(); ++i) {
            QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(keys.at(i)));
            if (plugin && (plugin->capabilities(device, testFormat) & QImageIOPlugin::CanWrite)) {
                handler = plugin->create(device, testFormat);
                break;
            }
        }
    }
#endif

    if (!handler)
        return 0;

    handler->setDevice(device);
    if (!testFormat.isEmpty())
        handler->setFormat(testFormat);
    return handler;
}

class QImageWriterPrivate
{
public:
    QImageWriterPrivate(QImageWriter *qq);

    // device
    QByteArray format;
    QIODevice *device;
    bool deleteDevice;
    QImageIOHandler *handler;

    // image options
    int quality;
    int compression;
    float gamma;
    QString description;
    QString text;

    // error
    QImageWriter::ImageWriterError imageWriterError;
    QString errorString;

    QImageWriter *q;
};

/*!
    \internal
*/
QImageWriterPrivate::QImageWriterPrivate(QImageWriter *qq)
{
    device = 0;
    deleteDevice = false;
    handler = 0;
    quality = -1;
    compression = 0;
    gamma = 0.0;
    imageWriterError = QImageWriter::UnknownError;
    errorString = QT_TRANSLATE_NOOP(QImageWriter, QLatin1String("Unknown error"));

    q = qq;
}

/*!
    Constructs an empty QImageWriter object. Before writing, you must
    call setFormat() to set an image format, then setDevice() or
    setFileName().
*/
QImageWriter::QImageWriter()
    : d(new QImageWriterPrivate(this))
{
}

/*!
    Constructs a QImageWriter object using the device \a device and
    image format \a format.
*/
QImageWriter::QImageWriter(QIODevice *device, const QByteArray &format)
    : d(new QImageWriterPrivate(this))
{
    d->device = device;
    d->format = format;
}

/*!
    Constructs a QImageWriter objects that will write to a file with
    the name \a fileName, using the image format \a format. If \a
    format is not provided, QImageWriter will detect the image format
    by inspecting the extension of \a fileName.
*/
QImageWriter::QImageWriter(const QString &fileName, const QByteArray &format)
    : d(new QImageWriterPrivate(this))
{
    QFile *file = new QFile(fileName);
    d->device = file;
    d->deleteDevice = true;
    d->format = format;
}

/*!
    Destructs the QImageWriter object.
*/
QImageWriter::~QImageWriter()
{
    if (d->deleteDevice)