Add feature flag for poppler signing API

Test and conditionally-compile pdf signing feature, depending
on poppler new-ness.

core/document.cpp

@@ -2799,6 +2799,11 @@ bool Document::canProvideFontInformation() const
     return d->m_generator ? d->m_generator->hasFeature(Generator::FontInfo) : false;
 }
 
+bool Document::canSign() const
+{
+    return d->m_generator ? d->m_generator->canSign() : false;
+}
+
 const QList<EmbeddedFile *> *Document::embeddedFiles() const
 {
     return d->m_generator ? d->m_generator->embeddedFiles() : nullptr;

core/document.h

@@ -281,6 +281,11 @@ public:
      */
     bool canProvideFontInformation() const;
 
+    /**
+     * Whether the current document can perform digital signing.
+     */
+    bool canSign() const;
+
     /**
      * Returns the list of embedded files or 0 if no embedded files
      * are available.

generators/poppler/CMakeLists.txt

@@ -15,6 +15,14 @@ int main()
 }
 " HAVE_POPPLER_0_87)
 
+check_cxx_source_compiles("
+#include <poppler-qt5.h>
+int main()
+{
+  auto f = &Poppler::Document::sign;
+}
+" HAVE_POPPLER_SIGNING)
+
 configure_file(
    ${CMAKE_CURRENT_SOURCE_DIR}/config-okular-poppler.h.cmake
    ${CMAKE_CURRENT_BINARY_DIR}/config-okular-poppler.h

generators/poppler/config-okular-poppler.h.cmake

@@ -1,3 +1,5 @@
 /* Defined if we have the 0.87 version of the Poppler library */
 #cmakedefine HAVE_POPPLER_0_87 1
 
+/* Defined if we have the pdf signature feature in the Poppler library */
+#cmakedefine HAVE_POPPLER_SIGNING 1

generators/poppler/generator_pdf.cpp

@@ -1856,10 +1856,14 @@ Okular::AnnotationProxy *PDFGenerator::annotationProxy() const
 
 void PDFGenerator::sign( const Okular::Annotation* pWhichAnnotation )
 {
+#ifdef HAVE_POPPLER_SIGNING
     const Okular::WidgetAnnotation* wa = dynamic_cast<const Okular::WidgetAnnotation*>(pWhichAnnotation);
 
     Poppler::Annotation *popplerAnn = qvariant_cast< Poppler::Annotation * >( pWhichAnnotation->nativeId() );
     pdfdoc->sign( popplerAnn, wa->certificateCN(), wa->password() );
+#else
+    Q_UNUSED( pWhichAnnotation );
+#endif
 }
 
 #include "generator_pdf.moc"

part/pageview.cpp

@@ -1218,7 +1218,10 @@ void PageView::updateActionState(bool haspages, bool hasformwidgets)
     }
 
     if ( d->aSignature )
-        d->aSignature->setEnabled( haspages );
+    {
+        const bool canSign = d->document->canSign();
+        d->aSignature->setEnabled( canSign && haspages );
+    }
 
 #ifdef HAVE_SPEECH
     if (d->aSpeakDoc) {

part/preferencesdialog.cpp

@@ -11,6 +11,7 @@
 #include "preferencesdialog.h"
 
 #include <KLocalizedString>
+#include "../generators/poppler/config-okular-poppler.h"
 
 // single config pages
 #include "dlgaccessibility.h"
@@ -48,11 +49,15 @@ PreferencesDialog::PreferencesDialog(QWidget *parent, KConfigSkeleton *skeleton,
         m_presentation = new DlgPresentation(this);
         m_annotations = new DlgAnnotations(this);
         m_editor = new DlgEditor(this);
+#ifdef HAVE_POPPLER_SIGNING
         m_signatures = new DlgSignatures(this);
+#endif
         addPage(m_presentation, i18n("Presentation"), QStringLiteral("view-presentation"), i18n("Options for Presentation Mode"));
         m_annotationsPage = addPage(m_annotations, i18n("Annotations"), QStringLiteral("draw-freehand"), i18n("Annotation Options"));
         addPage(m_editor, i18n("Editor"), QStringLiteral("accessories-text-editor"), i18n("Editor Options"));
+#ifdef HAVE_POPPLER_SIGNING
         addPage(m_signatures, i18n("Signatures"), QStringLiteral("application-pkcs7-signature"), i18n("Digital Signatures"));
+#endif
     }
 #ifdef OKULAR_DEBUG_CONFIGPAGE
     addPage(m_debug, "Debug", "system-run", "Debug options");