qpicture.cpp

奇趣公司比较新的qt/emd版本

    \skipto USE SVG
    \skipto add
    \printuntil ...

    Before the regular expression test, all the 0 bytes in the file header are
    converted to 1 bytes. This is done because when Qt was ASCII-based, QRegExp
    could not handle 0 bytes in strings.

    The regexp is only applied on the first 14 bytes of the file.

    (Note that if one handlerIO supports writing a format and another
    supports reading it, Qt supports both reading and writing. If two
    handlers support the same operation, Qt chooses one arbitrarily.)
*/

void QPictureIO::defineIOHandler(const char *format,
                                const char *header,
                                const char *flags,
                                picture_io_handler readPicture,
                                picture_io_handler writePicture)
{
    qt_init_picture_handlers();
    QPictureHandler *p;
    p = new QPictureHandler(format, header, QByteArray(flags), readPicture, writePicture);
    pictureHandlers.prepend(p);
}


/*****************************************************************************
  QPictureIO normal member functions
 *****************************************************************************/

/*!
    Returns the picture currently set.

    \sa setPicture()
*/
const QPicture &QPictureIO::picture() const { return d->pi; }

/*!
    Returns the picture's IO status. A non-zero value indicates an
    error, whereas 0 means that the IO operation was successful.

    \sa setStatus()
*/
int QPictureIO::status() const { return d->iostat; }

/*!
    Returns the picture format string or 0 if no format has been
    explicitly set.
*/
const char *QPictureIO::format() const { return d->frmt; }

/*!
    Returns the IO device currently set.

    \sa setIODevice()
*/
QIODevice *QPictureIO::ioDevice() const { return d->iodev; }

/*!
    Returns the file name currently set.

    \sa setFileName()
*/
QString QPictureIO::fileName() const { return d->fname; }


/*!
    Returns the picture description string.

    \sa setDescription()
*/
QString QPictureIO::description() const { return d->descr; }

/*!
    Sets the picture to \a picture.

    \sa picture()
*/
void QPictureIO::setPicture(const QPicture &picture)
{
    d->pi = picture;
}

/*!
    Sets the picture IO status to \a status. A non-zero value indicates
    an error, whereas 0 means that the IO operation was successful.

    \sa status()
*/
void QPictureIO::setStatus(int status)
{
    d->iostat = status;
}

/*!
    Sets the picture format to \a format for the picture to be read or
    written.

    It is necessary to specify a format before writing an picture, but
    it is not necessary to specify a format before reading an picture.

    If no format has been set, Qt guesses the picture format before
    reading it. If a format is set the picture will only be read if it
    has that format.

    \sa read() write() format()
*/
void QPictureIO::setFormat(const char *format)
{
    d->frmt = format;
}

/*!
    Sets the IO device to be used for reading or writing an picture.

    Setting the IO device allows pictures to be read/written to any
    block-oriented QIODevice.

    If \a ioDevice is not null, this IO device will override file name
    settings.

    \sa setFileName()
*/
void QPictureIO::setIODevice(QIODevice *ioDevice)
{
    d->iodev = ioDevice;
}

/*!
    Sets the name of the file to read or write an picture from to \a
    fileName.

    \sa setIODevice()
*/
void QPictureIO::setFileName(const QString &fileName)
{
    d->fname = fileName;
}

/*!
    Returns the quality of the written picture, related to the
    compression ratio.

    \sa setQuality() QPicture::save()
*/
int QPictureIO::quality() const
{
    return d->quality;
}

/*!
    Sets the quality of the written picture to \a q, related to the
    compression ratio.

    \a q must be in the range -1..100. Specify 0 to obtain small
    compressed files, 100 for large uncompressed files. (-1 signifies
    the default compression.)

    \sa quality() QPicture::save()
*/

void QPictureIO::setQuality(int q)
{
    d->quality = q;
}

/*!
    Returns the picture's parameters string.

    \sa setParameters()
*/

const char *QPictureIO::parameters() const
{
    return d->parameters;
}

/*!
    Sets the picture's parameter string to \a parameters. This is for
    picture handlers that require special parameters.

    Although the current picture formats supported by Qt ignore the
    parameters string, it may be used in future extensions or by
    contributions (for example, JPEG).

    \sa parameters()
*/

void QPictureIO::setParameters(const char *parameters)
{
    if (d->parameters)
        delete [] (char*)d->parameters;
    d->parameters = qstrdup(parameters);
}

/*!
    Sets the gamma value at which the picture will be viewed to \a
    gamma. If the picture format stores a gamma value for which the
    picture is intended to be used, then this setting will be used to
    modify the picture. Setting to 0.0 will disable gamma correction
    (i.e. any specification in the file will be ignored).

    The default value is 0.0.

    \sa gamma()
*/
void QPictureIO::setGamma(float gamma)
{
    d->gamma=gamma;
}

/*!
    Returns the gamma value at which the picture will be viewed.

    \sa setGamma()
*/
float QPictureIO::gamma() const
{
    return d->gamma;
}

/*!
    Sets the picture description string for picture handlers that support
    picture descriptions to \a description.

    Currently, no picture format supported by Qt uses the description
    string.
*/

void QPictureIO::setDescription(const QString &description)
{
    d->descr = description;
}


/*!
    Returns a string that specifies the picture format of the file \a
    fileName, or null if the file cannot be read or if the format is
    not recognized.
*/

QByteArray QPictureIO::pictureFormat(const QString &fileName)
{
    QFile file(fileName);
    QByteArray format;
    if (!file.open(QIODevice::ReadOnly))
        return format;
    format = pictureFormat(&file);
    file.close();
    return format;
}

/*!
    \overload

    Returns a string that specifies the picture format of the picture read
    from IO device \a d, or 0 if the device cannot be read or if the
    format is not recognized.

    Make sure that \a d is at the right position in the device (for
    example, at the beginning of the file).

    \sa QIODevice::at()
*/

QByteArray QPictureIO::pictureFormat(QIODevice *d)
{
    // if you change this change the documentation for defineIOHandler()
    const int buflen = 14;

    char buf[buflen];
    char buf2[buflen];
    qt_init_picture_handlers();
    qt_init_picture_plugins();
    int pos = d->pos();                      // save position
    int rdlen = d->read(buf, buflen);        // read a few bytes

    QByteArray format;
    if (rdlen != buflen)
        return format;

    memcpy(buf2, buf, buflen);

    for (int n = 0; n < rdlen; n++)
        if (buf[n] == '\0')
            buf[n] = '\001';
    if (rdlen > 0) {
        buf[rdlen - 1] = '\0';
        QString bufStr = QString::fromLatin1(buf);
        for (int i = 0; i < pictureHandlers.size(); ++i) {
            if (pictureHandlers.at(i)->header.indexIn(bufStr) != -1) { // try match with headers
                format = pictureHandlers.at(i)->format;
                break;
            }
        }
    }
    d->seek(pos);                                // restore position
    return format;
}

/*!
    Returns a sorted list of picture formats that are supported for
    picture input.
*/
QList<QByteArray> QPictureIO::inputFormats()
{
    QList<QByteArray> result;

    qt_init_picture_handlers();
    qt_init_picture_plugins();

    for (int i = 0; i < pictureHandlers.size(); ++i) {
        QPictureHandler *p = pictureHandlers.at(i);
        if (p->read_picture && !p->obsolete  && !result.contains(p->format))
            result.append(p->format);
    }
    qSort(result);

    return result;
}

/*!
    Returns a sorted list of picture formats that are supported for
    picture output.
*/
QList<QByteArray> QPictureIO::outputFormats()
{
    qt_init_picture_handlers();
    qt_init_picture_plugins();

    QList<QByteArray> result;
    for (int i = 0; i < pictureHandlers.size(); ++i) {
        QPictureHandler *p = pictureHandlers.at(i);
        if (p->write_picture && !p->obsolete && !result.contains(p->format))
            result.append(p->format);
    }
    return result;
}



/*!
    Reads an picture into memory and returns true if the picture was
    successfully read; otherwise returns false.

    Before reading an picture you must set an IO device or a file name.
    If both an IO device and a file name have been set, the IO device
    will be used.

    Setting the picture file format string is optional.

    Note that this function does \e not set the \link format()
    format\endlink used to read the picture. If you need that
    information, use the pictureFormat() static functions.

    Example:

    \quotefromfile snippets/picture/picture.cpp
    \skipto PIC
    \skipto QPictureIO
    \printuntil }

    \sa setIODevice() setFileName() setFormat() write() QPixmap::load()
*/
bool QPictureIO::read()
{
    QFile           file;
    const char          *picture_format;
    QPictureHandler *h;

    if (d->iodev) {                                // read from io device
        // ok, already open
    } else if (!d->fname.isEmpty()) {                // read from file
        file.setFileName(d->fname);
        if (!file.open(QIODevice::ReadOnly))
            return false;                        // cannot open file
        d->iodev = &file;
    } else {                                        // no file name or io device
        return false;
    }
    if (d->frmt.isEmpty()) {
        // Try to guess format
        picture_format = pictureFormat(d->iodev);        // get picture format
        if (!picture_format) {
            if (file.isOpen()) {                        // unknown format
                file.close();
                d->iodev = 0;
            }
            return false;
        }
    } else {
        picture_format = d->frmt;
    }

    h = get_picture_handler(picture_format);
    if (file.isOpen()) {
#if !defined(Q_OS_UNIX)
        if (h && h->text_mode) {                // reopen in translated mode
            file.close();
            file.open(QIODevice::ReadOnly | QIODevice::Text);
        }
        else
#endif
            file.seek(0);                        // position to start
    }
    d->iostat = 1;                                        // assume error

    if (h && h->read_picture)
        (*h->read_picture)(this);

    if (file.isOpen()) {                        // picture was read using file
        file.close();
        d->iodev = 0;
    }
    return d->iostat == 0;                                // picture successfully read?
}


/*!
    Writes an picture to an IO device and returns true if the picture was
    successfully written; otherwise returns false.

    Before writing an picture you must set an IO device or a file name.
    If both an IO device and a file name have been set, the IO device
    will be used.

    The picture will be written using the specified picture format.

    Example:
    \quotefromfile snippets/picture/picture.cpp
    \skipto PIC WRITE
    \skipto QPictureIO
    \printuntil returned

    \sa setIODevice() setFileName() setFormat() read() QPixmap::save()
*/
bool QPictureIO::write()
{
    if (d->frmt.isEmpty())
        return false;
    QPictureHandler *h = get_picture_handler(d->frmt);
    if (!h || !h->write_picture) {
        qWarning("QPictureIO::write: No such picture format handler: %s",
                 format());
        return false;
    }
    QFile file;
    if (!d->iodev && !d->fname.isEmpty()) {
        file.setFileName(d->fname);
        bool translate = h->text_mode==QPictureHandler::TranslateInOut;
        QIODevice::OpenMode fmode = translate ? QIODevice::WriteOnly | QIODevice::Text : QIODevice::OpenMode(QIODevice::WriteOnly);
        if (!file.open(fmode))                // couldn't create file
            return false;
        d->iodev = &file;
    }
    d->iostat = 1;
    (*h->write_picture)(this);
    if (file.isOpen()) {                        // picture was written using file
        file.close();
        d->iodev = 0;
    }
    return d->iostat == 0;                                // picture successfully written?
}
#endif //QT_NO_PICTUREIO

/*!
    \fn QPicture QPicture::copy() const

    Use simple assignment instead.
*/

#endif // QT_NO_PICTURE

/*!
    \typedef QPicture::DataPtr
    \internal
*/

/*!
    \fn DataPtr &QPicture::data_ptr()
    \internal
*/