diff --git a/kdocumentviewer.h b/kdocumentviewer.h
deleted file mode 100644
index 4aee11f59..000000000
--- a/kdocumentviewer.h
+++ /dev/null
@@ -1,58 +0,0 @@
-/***************************************************************************
- *   Copyright (C) 2007 by Pino Toscano <pino@kde.org>                     *
- *                                                                         *
- *   This program is free software; you can redistribute it and/or modify  *
- *   it under the terms of the GNU General Public License as published by  *
- *   the Free Software Foundation; either version 2 of the License, or     *
- *   (at your option) any later version.                                   *
- ***************************************************************************/
-
-#ifndef _KDOCUMENTVIEWER_H_
-#define _KDOCUMENTVIEWER_H_
-
-#include "okularpart_export.h"
-
-#include <QStringList>
-
-class QUrl;
-
-/**
- * @short Abstract interface for a document viewer
- *
- * This interface describes the basic functions of a document viewer.
- */
-class OKULARPART_EXPORT KDocumentViewer
-{
-public:
-    KDocumentViewer()
-    {
-    }
-    virtual ~KDocumentViewer();
-
-    KDocumentViewer(const KDocumentViewer &) = delete;
-    KDocumentViewer &operator=(const KDocumentViewer &) = delete;
-
-    /**
-     * Open the document at the specified @p url at page @p page.
-     */
-    virtual bool openDocument(const QUrl &url, uint page) = 0;
-
-    /**
-     * Change to @p page the currently shown page.
-     */
-    virtual void goToPage(uint page) = 0;
-
-    /**
-     * Start the presentation mode.
-     */
-    virtual void startPresentation() = 0;
-
-    /**
-     * Return a list with the supported mimetypes.
-     */
-    virtual QStringList supportedMimeTypes() const = 0;
-};
-
-Q_DECLARE_INTERFACE(KDocumentViewer, "org.kde.kdocumentviewer/0.1")
-
-#endif
diff --git a/part.cpp b/part.cpp
index 2117d27f7..90abefb71 100644
--- a/part.cpp
+++ b/part.cpp
@@ -119,8 +119,6 @@
 #include "xmlgui_helper.h"
 #include <memory>
 
-KDocumentViewer::~KDocumentViewer() = default;
-
 #ifdef OKULAR_KEEP_FILE_OPEN
 class FileKeeper
 {
@@ -979,18 +977,6 @@ Part::~Part()
 #endif
 }
 
-bool Part::openDocument(const QUrl &url, uint page)
-{
-    Okular::DocumentViewport vp(page - 1);
-    vp.rePos.enabled = true;
-    vp.rePos.normalizedX = 0;
-    vp.rePos.normalizedY = 0;
-    vp.rePos.pos = Okular::DocumentViewport::TopLeft;
-    if (vp.isValid())
-        m_document->setNextDocumentViewport(vp);
-    return openUrl(url);
-}
-
 void Part::startPresentation()
 {
     m_cliPresentation = true;
diff --git a/part.h b/part.h
index 54ab40020..2adb3c724 100644
--- a/part.h
+++ b/part.h
@@ -35,7 +35,6 @@
 #include "core/document.h"
 #include "core/observer.h"
 #include "interfaces/viewerinterface.h"
-#include "kdocumentviewer.h"
 
 #include "okularpart_export.h"
 
@@ -109,11 +108,10 @@ enum EmbedMode {
  * @author Wilco Greven <greven@kde.org>
  * @version 0.2
  */
-class OKULARPART_EXPORT Part : public KParts::ReadWritePart, public Okular::DocumentObserver, public KDocumentViewer, public Okular::ViewerInterface
+class OKULARPART_EXPORT Part : public KParts::ReadWritePart, public Okular::DocumentObserver, public Okular::ViewerInterface
 {
     Q_OBJECT
     Q_CLASSINFO("D-Bus Interface", "org.kde.okular")
-    Q_INTERFACES(KDocumentViewer)
     Q_INTERFACES(Okular::ViewerInterface)
 
     friend class PartTest;
@@ -136,9 +134,8 @@ public:
     void notifyViewportChanged(bool smoothMove) override;
     void notifyPageChanged(int page, int flags) override;
 
-    bool openDocument(const QUrl &url, uint page) override;
-    void startPresentation() override;
-    QStringList supportedMimeTypes() const override;
+    Q_INVOKABLE void startPresentation();
+    Q_INVOKABLE QStringList supportedMimeTypes() const;
 
     QUrl realUrl() const;
 
@@ -152,7 +149,7 @@ public:
     Q_INVOKABLE bool activateTabIfAlreadyOpenFile() const;
 
 public Q_SLOTS: // dbus
-    Q_SCRIPTABLE Q_NOREPLY void goToPage(uint page) override;
+    Q_SCRIPTABLE Q_NOREPLY void goToPage(uint page);
     Q_SCRIPTABLE Q_NOREPLY void openDocument(const QString &doc);
     Q_SCRIPTABLE uint pages();
     Q_SCRIPTABLE uint currentPage();
diff --git a/shell/shell.cpp b/shell/shell.cpp
index 84f4a775d..8203a16e9 100644
--- a/shell/shell.cpp
+++ b/shell/shell.cpp
@@ -56,7 +56,6 @@
 
 // local includes
 #include "../interfaces/viewerinterface.h"
-#include "kdocumentviewer.h"
 #include "shellutils.h"
 
 static const char *shouldShowMenuBarComingFromFullScreen = "shouldShowMenuBarComingFromFullScreen";
@@ -424,9 +423,7 @@ void Shell::fileOpen()
     // button is clicked
     const int activeTab = m_tabWidget->currentIndex();
     if (!m_fileformatsscanned) {
-        const KDocumentViewer *const doc = qobject_cast<KDocumentViewer *>(m_tabs[activeTab].part);
-        if (doc)
-            m_fileformats = doc->supportedMimeTypes();
+        QMetaObject::invokeMethod(m_tabs[activeTab].part, "supportedMimeTypes", Q_RETURN_ARG(QStringList, m_fileformats));
 
         if (m_fileformats.isEmpty())
             m_fileformats = fileFormats();
@@ -700,10 +697,9 @@ void Shell::openNewTab(const QUrl &url, const QString &serializedOptions)
 
 void Shell::applyOptionsToPart(QObject *part, const QString &serializedOptions)
 {
-    KDocumentViewer *const doc = qobject_cast<KDocumentViewer *>(part);
     const QString find = ShellUtils::find(serializedOptions);
     if (ShellUtils::startInPresentation(serializedOptions))
-        doc->startPresentation();
+        QMetaObject::invokeMethod(part, "startPresentation");
     if (ShellUtils::showPrintDialog(serializedOptions))
         QMetaObject::invokeMethod(part, "enableStartWithPrint");
     if (ShellUtils::showPrintDialogAndExit(serializedOptions))