cache location and mime type when saving a graphic to a storage

Change-Id: If27a5f617a103da235d6690ea0447d6c64538dea
Reviewed-on: https://gerrit.libreoffice.org/50810Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

include/svx/xmlgrhlp.hxx

@@ -63,7 +63,7 @@ private:
     ::std::set< OUString >      maURLSet;
 
     std::unordered_map<OUString, css::uno::Reference<css::graphic::XGraphic>> maGraphicObjects;
-    std::unordered_map<Graphic, OUString> maExportGraphics;
+    std::unordered_map<Graphic, std::pair<OUString, OUString>> maExportGraphics;
 
     SvXMLGraphicHelperMode      meCreateMode;
     OUString                    maOutputMimeType;

svx/source/xml/xmlgrhlp.cxx

@@ -49,6 +49,7 @@
 
 #include <algorithm>
 #include <memory>
+#include <utility>
 
 using namespace com::sun::star;
 using namespace com::sun::star::uno;
@@ -1070,7 +1071,9 @@ OUString SvXMLGraphicHelper::implSaveGraphic(css::uno::Reference<css::graphic::X
     auto aIterator = maExportGraphics.find(aGraphic);
     if (aIterator != maExportGraphics.end())
     {
-        return aIterator->second;
+        auto const & aURLAndMimePair = aIterator->second;
+        rOutSavedMimeType = aURLAndMimePair.second;
+        return aURLAndMimePair.first;
     }
 
     GraphicObject aGraphicObject(aGraphic);
@@ -1275,7 +1278,7 @@ OUString SvXMLGraphicHelper::implSaveGraphic(css::uno::Reference<css::graphic::X
             aStoragePath += rPictureStreamName;
 
             // put into cache
-            maExportGraphics[aGraphic] = aStoragePath;
+            maExportGraphics[aGraphic] = std::make_pair(aStoragePath, rOutSavedMimeType);
 
             return aStoragePath;
         }