kio: new djvulibre metadata extractor

Signed-off-by: Ivailo Monev <xakepa10@gmail.com>

CMakeLists.txt

@@ -274,6 +274,14 @@ set_package_properties(Freetype PROPERTIES
     PURPOSE "Fonts metadata extraction"
 )
 
+kde4_optional_find_package(DjVuLibre)
+set_package_properties(DjVuLibre PROPERTIES
+    DESCRIPTION "Open source DjVu library"
+    URL "https://djvu.sourceforge.net/"
+    TYPE RECOMMENDED
+    PURPOSE "DjVu metadata extraction"
+)
+
 kde4_optional_find_package(OpenSSL)
 set_package_properties(OpenSSL PROPERTIES
     DESCRIPTION "Robust, commercial-grade, full-featured toolkit for general-purpose cryptography and secure communication"

kio/metadata/CMakeLists.txt

@@ -147,3 +147,25 @@ if (FREETYPE_FOUND)
         DESTINATION ${KDE4_SERVICES_INSTALL_DIR}
     )
 endif()
+
+if (DJVULIBRE_FOUND)
+    include_directories(${DJVULIBRE_INCLUDE_DIR})
+
+    set(kfilemetadata_djvulibre_SRCS kfilemetadata_djvulibre.cpp)
+
+    kde4_add_plugin(kfilemetadata_djvulibre ${kfilemetadata_djvulibre_SRCS})
+    target_link_libraries(kfilemetadata_djvulibre
+        ${KDE4_KIO_LIBS}
+        ${DJVULIBRE_LIBRARY}
+    )
+
+    install(
+        TARGETS kfilemetadata_djvulibre
+        DESTINATION ${KDE4_PLUGIN_INSTALL_DIR}
+    )
+
+    install(
+        FILES kfilemetadata_djvulibre.desktop
+        DESTINATION ${KDE4_SERVICES_INSTALL_DIR}
+    )
+endif()

kio/metadata/kfilemetadata_djvulibre.cpp

@@ -0,0 +1,146 @@
+/*  This file is part of the KDE libraries
+    Copyright (C) 2022 Ivailo Monev <xakepa10@gmail.com>
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License version 2, as published by the Free Software Foundation.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Library General Public License for more details.
+
+    You should have received a copy of the GNU Library General Public License
+    along with this library; see the file COPYING.LIB.  If not, write to
+    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+    Boston, MA 02110-1301, USA.
+*/
+
+#include "kfilemetadata_djvulibre.h"
+#include "kpluginfactory.h"
+#include "kdebug.h"
+
+#include <QCoreApplication>
+#include <QThread>
+
+#include <libdjvu/ddjvuapi.h>
+#include <libdjvu/miniexp.h>
+
+static const int s_eventstime = 250;
+static const int s_sleeptime = 100;
+
+KFileMetaDataDjVuLibrePlugin::KFileMetaDataDjVuLibrePlugin(QObject* parent, const QVariantList &args)
+    : KFileMetaDataPlugin(parent)
+{
+    Q_UNUSED(args);
+}
+
+KFileMetaDataDjVuLibrePlugin::~KFileMetaDataDjVuLibrePlugin()
+{
+}
+
+QList<KFileMetaInfoItem> KFileMetaDataDjVuLibrePlugin::metaData(const KUrl &url, const KFileMetaInfo::WhatFlags flags)
+{
+    Q_UNUSED(flags);
+    QList<KFileMetaInfoItem> result;
+    const QByteArray urlpath = url.toLocalFile().toUtf8();
+    ddjvu_context_t* djvuctx = ddjvu_context_create("kfilemetadata_djvulibre");
+    if (!djvuctx) {
+        kWarning() << "Could not create DjVu context";
+        return result;
+    }
+    ddjvu_document_t* djvudoc = ddjvu_document_create_by_filename_utf8(djvuctx, urlpath.constData(), FALSE);
+    if (!djvudoc) {
+        kWarning() << "Could not create DjVu document";
+        ddjvu_context_release(djvuctx);
+        return result;
+    }
+    kDebug() << "Waiting for document decoding to complete";
+    while (!ddjvu_document_decoding_done(djvudoc)) {
+        QCoreApplication::processEvents(QEventLoop::AllEvents, s_eventstime);
+        QThread::msleep(s_sleeptime);
+    }
+    kDebug() << "Done waiting for document decoding to complete";
+    const int djvulibrepages = ddjvu_document_get_pagenum(djvudoc);
+    if (djvulibrepages > 0) {
+        result.append(
+            KFileMetaInfoItem(
+                QString::fromLatin1("http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#pageCount"),
+                QString::number(djvulibrepages)
+            )
+        );
+    }
+    kDebug() << "Waiting for document annotation decoding to complete";
+    miniexp_t djvulibreannotation = ddjvu_document_get_anno(djvudoc, 1);
+    while (djvulibreannotation == miniexp_dummy) {
+        QCoreApplication::processEvents(QEventLoop::AllEvents, s_eventstime);
+        QThread::msleep(s_sleeptime);
+    }
+    kDebug() << "Waiting for document annotation decoding to complete";
+    miniexp_t* djvulibremetadatakeys = ddjvu_anno_get_metadata_keys(djvulibreannotation);
+    if (djvulibremetadatakeys) {
+        int counter = 0;
+        while (djvulibremetadatakeys[counter]) {
+            // for reference:
+            // https://linux.die.net/man/1/djvused
+            const char* djvulibrekeyname = miniexp_to_name(djvulibremetadatakeys[counter]);
+            const char* djvulibremetadata = ddjvu_anno_get_metadata(djvulibreannotation, djvulibremetadatakeys[counter]);
+            // qDebug() << Q_FUNC_INFO << djvulibrekeyname << djvulibremetadata;
+            if (qstricmp(djvulibrekeyname, "title") == 0) {
+                result.append(
+                    KFileMetaInfoItem(
+                        QString::fromLatin1("http://www.semanticdesktop.org/ontologies/2007/01/19/nie#title"),
+                        QString::fromUtf8(djvulibremetadata)
+                    )
+                );
+            } else if (qstricmp(djvulibrekeyname, "author") == 0) {
+                result.append(
+                    KFileMetaInfoItem(
+                        QString::fromLatin1("http://www.semanticdesktop.org/ontologies/2007/05/10/nid3#textWriter"),
+                        QString::fromUtf8(djvulibremetadata)
+                    )
+                );
+            } else if (qstricmp(djvulibrekeyname, "creator") == 0) {
+                result.append(
+                    KFileMetaInfoItem(
+                        QString::fromLatin1("http://www.semanticdesktop.org/ontologies/2007/03/22/nco#creator"),
+                        QString::fromUtf8(djvulibremetadata)
+                    )
+                );
+            } else if (qstricmp(djvulibrekeyname, "subject") == 0) {
+                result.append(
+                    KFileMetaInfoItem(
+                        QString::fromLatin1("http://www.semanticdesktop.org/ontologies/2007/01/19/nie#subject"),
+                        QString::fromUtf8(djvulibremetadata)
+                    )
+                );
+            } else if (qstricmp(djvulibrekeyname, "creationdate") == 0) {
+                result.append(
+                    KFileMetaInfoItem(
+                        QString::fromLatin1("http://www.semanticdesktop.org/ontologies/2007/01/19/nie#contentCreated"),
+                        QString::fromUtf8(djvulibremetadata)
+                    )
+                );
+            } else if (qstricmp(djvulibrekeyname, "moddate") == 0) {
+                result.append(
+                    KFileMetaInfoItem(
+                        QString::fromLatin1("http://www.semanticdesktop.org/ontologies/2007/01/19/nie#contentLastModified"),
+                        QString::fromUtf8(djvulibremetadata)
+                    )
+                );
+            } else {
+                kDebug() << "Unknown DjVu metadata key" << djvulibrekeyname;
+            }
+            counter++;
+        }
+    }
+    ::free(djvulibremetadatakeys);
+    ddjvu_document_release(djvudoc);
+    ddjvu_context_release(djvuctx);
+    return result;
+}
+
+K_PLUGIN_FACTORY(KFileMetaDataDjVuLibrePluginFactory, registerPlugin<KFileMetaDataDjVuLibrePlugin>();)
+K_EXPORT_PLUGIN(KFileMetaDataDjVuLibrePluginFactory("kfilemetadata_djvulibre"))
+
+#include "moc_kfilemetadata_djvulibre.cpp"

kio/metadata/kfilemetadata_djvulibre.desktop

@@ -0,0 +1,10 @@
+[Desktop Entry]
+Type=Service
+Name=KFileMetaDataDjVuLibrePlugin
+GenericName=DjVuLibre
+Comment=Extracts metadata from DjVu documents
+MimeType=image/vnd.djvu;image/vnd.djvu+multipage;image/x.djvu
+X-KDE-Library=kfilemetadata_djvulibre
+X-KDE-ServiceTypes=KFileMetaData/Plugin
+X-KDE-MetadataKeys=http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#pageCount,http://www.semanticdesktop.org/ontologies/2007/01/19/nie#title,http://www.semanticdesktop.org/ontologies/2007/05/10/nid3#textWriter,http://www.semanticdesktop.org/ontologies/2007/03/22/nco#creator,http://www.semanticdesktop.org/ontologies/2007/01/19/nie#subject,http://www.semanticdesktop.org/ontologies/2007/01/19/nie#contentCreated,http://www.semanticdesktop.org/ontologies/2007/01/19/nie#contentLastModified
+InitialPreference=1

kio/metadata/kfilemetadata_djvulibre.h

@@ -0,0 +1,34 @@
+/*  This file is part of the KDE libraries
+    Copyright (C) 2022 Ivailo Monev <xakepa10@gmail.com>
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License version 2, as published by the Free Software Foundation.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Library General Public License for more details.
+
+    You should have received a copy of the GNU Library General Public License
+    along with this library; see the file COPYING.LIB.  If not, write to
+    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+    Boston, MA 02110-1301, USA.
+*/
+
+#ifndef KFILEMETADATA_DJVULIBRE_H
+#define KFILEMETADATA_DJVULIBRE_H
+
+#include "kfilemetadata.h"
+
+class KFileMetaDataDjVuLibrePlugin : public KFileMetaDataPlugin
+{
+    Q_OBJECT
+public:
+    KFileMetaDataDjVuLibrePlugin(QObject* parent, const QVariantList &args);
+    ~KFileMetaDataDjVuLibrePlugin();
+
+    QList<KFileMetaInfoItem> metaData(const KUrl &url, const KFileMetaInfo::WhatFlags flags) final;
+};
+
+#endif // KFILEMETADATA_DJVULIBRE_H