tdf#86578: sw: fix rendering of legacy documents with fly achored at fly

Resurrect the special hack "lcl_SubtractFlys" that effectively paints
"lower" flys on top of "higher" flys, defying the z-ordering, if the
lower fly is *anchored* in or at the higher fly.

It turns out that this is not obvious to emulate in any other way that it
is currently implemented:

One idea would be to split up painting of the fly background from the
foreground, by creating 2 different view objects per fly as children
of the SdrPage when decomposing it in svx; but the problem is, they will
be ordered in z-order of the flys, and the point would be to paint the
backgrounds first and in a different order, call it "anchoring order".

What that order should be is hard to tell, there is a conflict between
the defined z-order and the flys that are part of one "anchoring
hierarchy" and should have their backgrounds re-ordered, because
entirely unrelated flys that could belong to different "anchoring
hierarchies" but overlap the first ones may result in a cyclic ordering.

Painting one "anchoring hierarchy" recursively would not get
z-order of flys from different anchoring hierarchies right.

Another difficulty is that heaven-layer backgrounds would need to be
painted before hell-layer ones.

Another aspect of the lcl_SubtractFlys is that it entirely ignores
drawing shapes; only Writer's own flys are handled.

Since none of the above makes much sense, we clearly want to
deprecate the lcl_SubtractFlys rendering.

Introduce a new compatibility flag "SubtractFlysAnchoredAtFlys" so that
the legacy rendering is only active for legacy documents, while new ones
remain free from its taint.

(regression from 6e61ecd09679a66060f932835622821d39e92f01)

(cherry picked from commit c5cf8824a619401627f18abc7b3049551c71ac2a)

Conflicts:
	sw/inc/IDocumentSettingAccess.hxx
	sw/source/core/doc/DocumentSettingManager.cxx
	sw/source/core/layout/paintfrm.cxx

Change-Id: I710fe79710b89c8f865ebb7162e14713aac6cc4a
Reviewed-on: https://gerrit.libreoffice.org/15238
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/sw/source/uibase/uno/SwXDocumentSettings.cxx b/sw/source/uibase/uno/SwXDocumentSettings.cxx
index aceed1f91318..33def9cda448 100644
--- a/sw/source/uibase/uno/SwXDocumentSettings.cxx
+++ b/sw/source/uibase/uno/SwXDocumentSettings.cxx
@@ -128,6 +128,7 @@ enum SwDocumentSettingsPropertyHandles
     HANDLE_SURROUND_TEXT_WRAP_SMALL,
     HANDLE_APPLY_PARAGRAPH_MARK_FORMAT_TO_NUMBERING,
     HANDLE_PROP_LINE_SPACING_SHRINKS_FIRST_LINE,
+    HANDLE_SUBTRACT_FLYS,
 };
 
 static MasterPropertySetInfo * lcl_createSettingsInfo()
@@ -200,6 +201,7 @@ static MasterPropertySetInfo * lcl_createSettingsInfo()
         { OUString("SurroundTextWrapSmall"), HANDLE_SURROUND_TEXT_WRAP_SMALL, cppu::UnoType<bool>::get(), 0, 0},
         { OUString("ApplyParagraphMarkFormatToNumbering"), HANDLE_APPLY_PARAGRAPH_MARK_FORMAT_TO_NUMBERING, cppu::UnoType<bool>::get(), 0, 0},
         { OUString("PropLineSpacingShrinksFirstLine"),       HANDLE_PROP_LINE_SPACING_SHRINKS_FIRST_LINE,         cppu::UnoType<bool>::get(),           0,   0},
+        { OUString("SubtractFlysAnchoredAtFlys"),       HANDLE_SUBTRACT_FLYS,         cppu::UnoType<bool>::get(),           0,   0},
 /*
  * As OS said, we don't have a view when we need to set this, so I have to
  * find another solution before adding them to this property set - MTG
@@ -817,6 +819,16 @@ void SwXDocumentSettings::_setSingleValue( const comphelper::PropertyInfo & rInf
             }
         }
         break;
+        case HANDLE_SUBTRACT_FLYS:
+        {
+            bool bTmp;
+            if (rValue >>= bTmp)
+            {
+                mpDoc->getIDocumentSettingAccess().set(
+                    IDocumentSettingAccess::SUBTRACT_FLYS, bTmp);
+            }
+        }
+        break;
         default:
             throw UnknownPropertyException();
     }
@@ -1253,6 +1265,13 @@ void SwXDocumentSettings::_getSingleValue( const comphelper::PropertyInfo & rInf
             rValue <<= bTmp;
         }
         break;
+        case HANDLE_SUBTRACT_FLYS:
+        {
+            bool const bTmp(mpDoc->getIDocumentSettingAccess().get(
+                IDocumentSettingAccess::SUBTRACT_FLYS));
+            rValue <<= bTmp;
+        }
+        break;
         default:
             throw UnknownPropertyException();
     }