tdf#83227 oox: reuse RelId in DML/VML export for the same graphic

So that large images are written only once to the ZIP container when
they are exported using both markups. This affects drawinglayer images,
the Writer ones are handled directly in sw and were already
deduplicated.

(cherry picked from commit b484e9814c66d8d51cea974390963a6944bc9d73)

Conflicts:
oox/source/export/drawingml.cxx

Change-Id: Iff7c769329b42939833056b727b070f6a60da5e3
Reviewed-on: https://gerrit.libreoffice.org/18581
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

2 files changed, 37 insertions, 5 deletions

diff --git a/oox/source/export/drawingml.cxx b/oox/source/export/drawingml.cxx
index edff9b933dd1..66dfb1ffcbf4 100644
--- a/oox/source/export/drawingml.cxx
+++ b/oox/source/export/drawingml.cxx
@@ -762,7 +762,7 @@ void DrawingML::WriteOutline( Reference<XPropertySet> rXPropSet )
     mpFS->endElementNS( XML_a, XML_ln );
 }
 
-OUString DrawingML::WriteImage( const OUString& rURL, bool bRelPathToMedia )
+bool lcl_URLToGraphic(const OUString& rURL, Graphic& rGraphic)
 {
     OString aURLBS(OUStringToOString(rURL, RTL_TEXTENCODING_UTF8));
 
@@ -771,9 +771,18 @@ OUString DrawingML::WriteImage( const OUString& rURL, bool bRelPathToMedia )
 
     if ( index != -1 )
     {
-        DBG(fprintf (stderr, "begin: %ld %s\n", long( sizeof( aURLBegin ) ), USS( rURL ) + RTL_CONSTASCII_LENGTH( aURLBegin ) ));
-        Graphic aGraphic = GraphicObject( aURLBS.copy(RTL_CONSTASCII_LENGTH(aURLBegin)) ).GetTransformedGraphic ();
+        rGraphic = GraphicObject(aURLBS.copy(RTL_CONSTASCII_LENGTH(aURLBegin))).GetTransformedGraphic();
+        return true;
+    }
+
+    return false;
+}
 
+OUString DrawingML::WriteImage( const OUString& rURL, bool bRelPathToMedia )
+{
+    Graphic aGraphic;
+    if (lcl_URLToGraphic(rURL, aGraphic))
+    {
         return WriteImage( aGraphic , bRelPathToMedia );
     }
     else
@@ -923,7 +932,23 @@ OUString DrawingML::WriteImage( const Graphic& rGraphic , bool bRelPathToMedia )
 
 OUString DrawingML::WriteBlip( Reference< XPropertySet > rXPropSet, const OUString& rURL, bool bRelPathToMedia, const Graphic *pGraphic )
 {
-    OUString sRelId = pGraphic ? WriteImage( *pGraphic, bRelPathToMedia ) : WriteImage( rURL, bRelPathToMedia );
+    OUString sRelId;
+    sal_uInt32 nChecksum = 0;
+    if (!rURL.isEmpty() && mpTextExport)
+    {
+        Graphic aGraphic;
+        if (lcl_URLToGraphic(rURL, aGraphic))
+        {
+            nChecksum = aGraphic.GetChecksum();
+            sRelId = mpTextExport->FindRelId(nChecksum);
+        }
+    }
+    if (sRelId.isEmpty())
+    {
+        sRelId = pGraphic ? WriteImage( *pGraphic, bRelPathToMedia ) : WriteImage( rURL, bRelPathToMedia );
+        if (!rURL.isEmpty() && mpTextExport)
+            mpTextExport->CacheRelId(nChecksum, sRelId);
+    }
     sal_Int16 nBright = 0;
     sal_Int32 nContrast = 0;
 
diff --git a/oox/source/export/vmlexport.cxx b/oox/source/export/vmlexport.cxx
index a0a1ac7677db..557bb8c18d9e 100644
--- a/oox/source/export/vmlexport.cxx
+++ b/oox/source/export/vmlexport.cxx
@@ -605,7 +605,14 @@ void VMLExport::Commit( EscherPropertyContainer& rProps, const Rectangle& rRect
                         aStream.Seek(0);
                         Graphic aGraphic;
                         GraphicConverter::Import(aStream, aGraphic);
-                        OUString aImageId = m_pTextExport->GetDrawingML().WriteImage( aGraphic );
+
+                        sal_uInt32 nChecksum = aGraphic.GetChecksum();
+                        OUString aImageId = m_pTextExport->FindRelId(nChecksum);
+                        if (aImageId.isEmpty())
+                        {
+                            aImageId = m_pTextExport->GetDrawingML().WriteImage( aGraphic );
+                            m_pTextExport->CacheRelId(nChecksum, aImageId);
+                        }
                         pAttrList->add(FSNS(XML_r, XML_id), OUStringToOString(aImageId, RTL_TEXTENCODING_UTF8));
                         imageData = true;
                     }