tdf#99227: use correct serializer when exporting drawing

Failing to do that leads to write-past-end-of-document, drawing
loss and SAXParseException if the drawing is part of a footnote.

A unit test is included.

Change-Id: Ie7d8263dc72dfef1e9827cc0579a5eaaf5819410
Reviewed-on: https://gerrit.libreoffice.org/31871Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

sw/qa/extras/ooxmlexport/ooxmlexport9.cxx

@@ -166,6 +166,19 @@ DECLARE_OOXMLEXPORT_TEST(testTdf103651, "tdf103651.docx")
     CPPUNIT_ASSERT_EQUAL( sal_Int32( -1 ) , sContent.indexOf( sal_Unicode( 0xf04a ) ));
 }
 
+DECLARE_OOXMLEXPORT_TEST(testTdf99227, "tdf99227.docx")
+{
+    // A drawing anchored as character to a footnote caused write past end of document.xml at export to docx.
+    // After that, importing after export failed with
+    // SAXParseException: '[word/document.xml line 2]: Extra content at the end of the document', Stream 'word / document.xml',
+    // and before commit ebf767eeb2a169ba533e1b2ffccf16f41d95df35, the drawing was silently lost.
+    xmlDocPtr pXmlDoc = parseExport("word/footnotes.xml");
+    if (!pXmlDoc)
+        return;
+
+    assertXPath(pXmlDoc, "//w:footnote[3]/w:p/w:r[5]/w:drawing", 1);
+}
+
 CPPUNIT_PLUGIN_IMPLEMENT();
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

sw/source/filter/ww8/docxattributeoutput.cxx

@@ -4269,6 +4269,8 @@ void DocxAttributeOutput::FlyFrameGraphic( const SwGrfNode* pGrfNode, const Size
         CharGrabBag(*pGrabBag);
     }
 
+    //  tdf#99227: to be sure that we write to the right stream
+    m_rExport.SdrExporter().setSerializer(m_pSerializer);
     m_rExport.SdrExporter().startDMLAnchorInline(pFrameFormat, rSize);
 
     // picture description (used for pic:cNvPr later too)