tdf#135638 drawinglayer,svx,sw: PDF/UA export: put SdrObjects on anchor

... frame in the structure tree.

The problem is that in sw, the anchored objects are painted
outside of the call to paint the page frame, which is what generates the
/Document structure element.

For Writer fly frames, this is handled via their SwFlyDrawObj painting,
where SwTaggedPDFHelper::CheckReopenTag() finds the anchor frame and
temporarily sets it as the structure parent, even if it's on a previous
page.

But all the SdrObjects on a page are painted by 2 calls to PaintLayer()
and there isn't a call back into Writer now.

Somehow this even causes a spurious line like "/Document<</MCID 7>>BDC"
to be emitted outside any PDF object, which looks clearly wrong.

Try to extend the SdrObjUserCall to get a way to retrieve the anchor
frame's structure element index.

Another option would be to extend ViewObjectContactRedirector to return
the PDF Id in its subclass SwViewObjectContactRedirector, and it seems
possible since its only one caller is
ViewObjectContact::getPrimitive2DSequence(), but Armin adivses that the
ViewObjectContactRedirector might go away in the future so it's better
to use SdrObjUserCall.

It's annoying that the mapping is a static members of
SwEnhancedPDFExportHelper; possibly it could be in OutputDevice's
PDFExtOutDevData instead?

Change-Id: Id61faae469aba4f0bd278ab2324aae06c1fdde64
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/143027
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>

2 files changed, 26 insertions, 1 deletions

diff --git a/drawinglayer/source/primitive2d/structuretagprimitive2d.cxx b/drawinglayer/source/primitive2d/structuretagprimitive2d.cxx
index c82b0088e29d..01d09d8372d5 100644
--- a/drawinglayer/source/primitive2d/structuretagprimitive2d.cxx
+++ b/drawinglayer/source/primitive2d/structuretagprimitive2d.cxx
@@ -30,11 +30,13 @@ namespace drawinglayer::primitive2d
             const vcl::PDFWriter::StructElement& rStructureElement,
             bool bBackground,
             bool bIsImage,
-            Primitive2DContainer&& aChildren)
+            Primitive2DContainer&& aChildren,
+            sal_Int32 const nAnchorStructureElementId)
         :   GroupPrimitive2D(std::move(aChildren)),
             maStructureElement(rStructureElement),
             mbBackground(bBackground),
             mbIsImage(bIsImage)
+        ,   m_nAnchorStructureElementId(nAnchorStructureElementId)
         {
         }
 
diff --git a/drawinglayer/source/processor2d/vclmetafileprocessor2d.cxx b/drawinglayer/source/processor2d/vclmetafileprocessor2d.cxx
index 3af04ee0c335..09ee03bba126 100644
--- a/drawinglayer/source/processor2d/vclmetafileprocessor2d.cxx
+++ b/drawinglayer/source/processor2d/vclmetafileprocessor2d.cxx
@@ -2364,12 +2364,27 @@ void VclMetafileProcessor2D::processStructureTagPrimitive2D(
     // structured tag primitive
     const vcl::PDFWriter::StructElement& rTagElement(rStructureTagCandidate.getStructureElement());
     bool bTagUsed((vcl::PDFWriter::NonStructElement != rTagElement));
+    sal_Int32 nPreviousElement(-1);
 
     if (mpPDFExtOutDevData && bTagUsed)
     {
         // foreground object: tag as regular structure element
         if (!rStructureTagCandidate.isBackground())
         {
+            if (rStructureTagCandidate.GetAnchorStructureElementId() != -1)
+            {
+                auto const nTemp = mpPDFExtOutDevData->GetCurrentStructureElement();
+                bool const bSuccess = mpPDFExtOutDevData->SetCurrentStructureElement(
+                    rStructureTagCandidate.GetAnchorStructureElementId());
+                if (bSuccess)
+                {
+                    nPreviousElement = nTemp;
+                }
+                else
+                {
+                    SAL_WARN("drawinglayer", "anchor structure element not found?");
+                }
+            }
             mpPDFExtOutDevData->BeginStructureElement(rTagElement);
             switch (rTagElement)
             {
@@ -2434,6 +2449,14 @@ void VclMetafileProcessor2D::processStructureTagPrimitive2D(
     {
         // write end tag
         mpPDFExtOutDevData->EndStructureElement();
+        if (nPreviousElement != -1)
+        {
+#ifndef NDEBUG
+            bool const bSuccess =
+#endif
+                mpPDFExtOutDevData->SetCurrentStructureElement(nPreviousElement);
+            assert(bSuccess);
+        }
     }
 }