C++ QFactoryLoader::keyMap方法代码示例

static QImageIOHandler *createReadHandlerHelper(QIODevice *device,
                                                const QByteArray &format,
                                                bool autoDetectImageFormat,
                                                bool ignoresFormatAndExtension)
{
    if (!autoDetectImageFormat && format.isEmpty())
        return 0;

    QByteArray form = format.toLower();
    QImageIOHandler *handler = 0;
    QByteArray suffix;

#ifndef QT_NO_IMAGEFORMATPLUGIN
    static QMutex mutex;
    QMutexLocker locker(&mutex);

    typedef QMultiMap<int, QString> PluginKeyMap;

    // check if we have plugins that support the image format
    QFactoryLoader *l = loader();
    const PluginKeyMap keyMap = l->keyMap();

#ifdef QIMAGEREADER_DEBUG
    qDebug() << "QImageReader::createReadHandler( device =" << (void *)device << ", format =" << format << "),"
             << keyMap.values().size() << "plugins available: " << keyMap.values();
#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.keys().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(QLatin1String(testFormat), -1);
            if (testIndex != -1) {
//.........这里部分代码省略.........

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

#ifndef QT_NO_IMAGEFORMATPLUGIN
    typedef QMultiMap<int, QString> PluginKeyMap;

    // check if any plugins can write the image
    QFactoryLoader *l = loader();
    const PluginKeyMap keyMap = l->keyMap();
    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()) {
#ifndef QT_NO_IMAGEFORMATPLUGIN
                const int index = keyMap.key(QString::fromLatin1(suffix), -1);
                if (index != -1)
                    suffixPluginIndex = index;
#endif
            }
        }
    }

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

#ifndef QT_NO_IMAGEFORMATPLUGIN
    if (suffixPluginIndex != -1) {
        // when format is missing, check if we can find a plugin for the
        // suffix.
        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, suffix) & QImageIOPlugin::CanWrite))
                handler = plugin->create(device, suffix);
        }
    }
#endif // QT_NO_IMAGEFORMATPLUGIN

    // 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_JPEG
        } else if (testFormat == "jpg" || testFormat == "jpeg") {
            handler = new QJpegHandler;
#endif
#ifdef QT_BUILTIN_GIF_READER
        } else if (testFormat == "gif") {
            handler = new QGifHandler;
#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
        }
    }

#ifndef QT_NO_IMAGEFORMATPLUGIN
    if (!testFormat.isEmpty()) {
        const int keyCount = keyMap.keys().size();
        for (int i = 0; i < keyCount; ++i) {
            QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(i));
            if (plugin && (plugin->capabilities(device, testFormat) & QImageIOPlugin::CanWrite)) {
                delete handler;
                handler = plugin->create(device, testFormat);
                break;
            }
        }
    }
#endif // QT_NO_IMAGEFORMATPLUGIN

    if (!handler)
//.........这里部分代码省略.........