tdf#146500 sw: try to fix some layout loops caused by fly in table cell

Reportedly regression from commit 1cb7e4899b5ada902e99a0c964ee047950c07044
but reverting that on master doesn't seem to help.

Inserting paragraphs with single letters into the first cell on page 2,
once we get to "s" and press Enter, the infinite loop happens as text
frame 56 is split at index 0 (where a fly is anchored), the new follow
moves to page 3, and very quickly frame 56 is formatted again and all
text in the follow moves back to page 2, where it doesn't fit with its
anchored fly.

The problem here is that the (Word format) file sets the
ConsiderObjWrapInfluenceOnObjPos mode, which disables any use of the
SwLayouter::FrameMovedFwdByObjPos() etc. functions.

Oddly enough the spec obj-pos-without-wrapping.sxw claims that in this
mode, "If a paragraph respectively one of the anchor characters moves to
the next page during its format in step (2) or (4), the process is
re-started with this paragraph, the complete paragraph is moved to the
next page and it is assured that the paragraph doesn't move back again."

What happens instead is that when a fly position is changed, its
mbRestartLayoutProcess flag is set.

So let's try to check this flag during SwTextFrame::Format(): stop at a
position where a fly is anchored in a follow frame that has the flag
set, via rInf.SetStop(true).

This is similar to a check in SwFlowFrame::MoveBwd() that prevents a
frame from moving back if it has an anchored fly with this flag set.

Now we get a different loop, where the text frame moves forward, then
back and then splits again.

This is because ShouldBwdMoved() sees that the first line of the text
frame fits into the cell of the previous page - but the first line
consists only of a SwFlyPortion and a SwMarginPortion, for the fly
anchored in the same text frame.

So change WidowsAndOrphans::WouldFit() to continue until the first line
that doesn't consist entirely of flys.

Then there's another loop where the follow flow row is joined and then
splits again - this is very similar to the previous problem, change
SwTextFrame::FirstLineHeight() (which is only called from table code) to
continue until a non-fly line as well.

Unforunately this is all not so clear because we can't actually tell
which text frame contains the anchor of a SwFlyPortion, so let's see
what's going to break with these changes.

Change-Id: Ia6e80f86f6ca3d2e3d91651b6a403c050d74ebfa
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/141383
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit 8c32cc17ce914188ea6783b0f79e19c5ddbf0b8d)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/146698
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/sw/source/core/layout/calcmove.cxx b/sw/source/core/layout/calcmove.cxx
index c9d5622ba02d..184373585928 100644
--- a/sw/source/core/layout/calcmove.cxx
+++ b/sw/source/core/layout/calcmove.cxx
@@ -1761,7 +1761,7 @@ void SwContentFrame::MakeAll(vcl::RenderContext* /*pRenderContext*/)
                 SwTwips nTmp = aRectFnSet.GetHeight(GetUpper()->getFramePrintArea()) -
                                aRectFnSet.GetTop(getFramePrintArea());
                 bool bSplit = !IsFwdMoveAllowed();
-                if ( nTmp > 0 && WouldFit( nTmp, bSplit, false ) )
+                if (nTmp > 0 && WouldFit(nTmp, bSplit, false, false))
                 {
                     Prepare( PrepareHint::WidowsOrphans, nullptr, false );
                     setFrameAreaSizeValid(false);
@@ -2046,7 +2046,7 @@ bool SwContentFrame::WouldFit_( SwTwips nSpace,
                 bRet = static_cast<SwTextFrame*>(pFrame)->TestFormat( pTmpPrev, nSpace, bSplit );
             }
             else
-                bRet = pFrame->WouldFit( nSpace, bSplit, false );
+                bRet = pFrame->WouldFit(nSpace, bSplit, false, true);
 
             pTmpFrame->RemoveFromLayout();
             pTmpFrame->InsertBefore( pUp, pOldNext );
@@ -2054,7 +2054,7 @@ bool SwContentFrame::WouldFit_( SwTwips nSpace,
         }
         else
         {
-            bRet = pFrame->WouldFit( nSpace, bSplit, false );
+            bRet = pFrame->WouldFit(nSpace, bSplit, false, true);
             nSecondCheck = !bSplit ? 1 : 0;
         }
 
@@ -2123,7 +2123,7 @@ bool SwContentFrame::WouldFit_( SwTwips nSpace,
                     // We do a second check with the original remaining space
                     // reduced by the required upper space:
                     nOldSpace -= nSecondCheck;
-                    const bool bSecondRet = nOldSpace >= 0 && pFrame->WouldFit( nOldSpace, bOldSplit, false );
+                    const bool bSecondRet = nOldSpace >= 0 && pFrame->WouldFit(nOldSpace, bOldSplit, false, true);
                     if ( bSecondRet && bOldSplit && nOldSpace >= 0 )
                     {
                         bRet = true;