sw XHTML export: handle alt text for OLE objects

The XHTML export is now on par with the import wrt OLE objects.

Change-Id: I736c1f03b0e3d8b84b8ebe08eb1b1cfa247cefbd
Reviewed-on: https://gerrit.libreoffice.org/50966Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

sw/qa/extras/htmlexport/htmlexport.cxx

@@ -390,11 +390,7 @@ DECLARE_HTMLEXPORT_ROUNDTRIP_TEST(testReqIfOleImg, "reqif-ole-img.xhtml")
     // This was empty when either import or export handling was missing.
     CPPUNIT_ASSERT_EQUAL(OUString("text/rtf"), getProperty<OUString>(xStream, "MediaType"));
 
-    if (mbExported)
-        // The below is not yet working for export.
-        return;
-
-    // Check alternate text (it was empty).
+    // Check alternate text (it was empty, for export the 'alt' attribute was used).
     CPPUNIT_ASSERT_EQUAL(OUString("OLE Object"), getProperty<OUString>(xObject, "Title").trim());
 }
 

sw/source/filter/html/htmlflywriter.cxx

@@ -1427,6 +1427,11 @@ Writer& OutHTML_Image( Writer& rWrt, const SwFrameFormat &rFrameFormat,
         aHtml.attribute(OOO_STRING_SVTOOLS_HTML_O_usemap, "#" + aIMapName);
     }
 
+    if ((nFrameOpts & HtmlFrmOpts::Replacement) && !rAlternateText.isEmpty())
+        // XHTML object replacement image's alternate text doesn't use the
+        // "alt" attribute.
+        aHtml.characters(rAlternateText.toUtf8());
+
     aHtml.flushStack();
 
     if( !rHTMLWrt.m_aINetFormats.empty() )