Refactor(messageviewer): Use onlySingleNode instead of direct boolean check.

messageviewer/src/viewer/viewer_p.cpp

@@ -830,20 +830,21 @@ void ViewerPrivate::parseContent(KMime::Content *content)
     }
 
     auto *message = dynamic_cast<KMime::Message *>(content);
+    bool onlySingleNode = mMessage.data() != content;
 
     // Pass control to the OTP now, which does the real work
     mNodeHelper->setNodeUnprocessed(mMessage.data(), true);
     MailViewerSource otpSource(this);
     MimeTreeParser::ObjectTreeParser otp(&otpSource, mNodeHelper);
-    // TODO: needs to end up in renderer: mMessage.data() != content /* show only single node */);
+
     otp.setAllowAsync(!mPrinting);
-    otp.parseObjectTree(content, mMessage.data() != content /* parse/show only single node */);
+    otp.parseObjectTree(content, onlySingleNode);
     htmlWriter()->setCodec(otp.plainTextContentCharset());
     if (message) {
         htmlWriter()->write(writeMessageHeader(message, hasVCard ? vCardContent : nullptr, true));
     }
 
-    otpSource.render(otp.parsedPart(), mMessage.data() != content /* parse/show only single node */);
+    otpSource.render(otp.parsedPart(), onlySingleNode);
 
     // TODO: Setting the signature state to nodehelper is not enough, it should actually
     // be added to the store, so that the message list correctly displays the signature state