sw: layout: if fly's anchor moves forward, move fly off SwPageFrame

The problem is that on Show Changes->Hide Changes->Show Changes
in a 311 page document, the fly "Grafik1" was initially on page 203
but ends up on page 204, with a fly-sized gap on page 194.

In a 25 page cut down version of the bugdoc, on layout action 659
the fly's anchor SwTextFrame moves from page 21 to page 22, but
the fly remains in the SwPageFrame's m_pSortedObjs, because it's
not the anchor frame itself that moves but a distant previous frame,
and page 21 goes valid.

0  SwFlowFrame::PasteTree(SwFrame*, SwLayoutFrame*, SwFrame*, SwFrame*) (pStart=0x57c9e30, pParent=0xba15c50, pSibling=0x5a0f920, pOldParent=0xb057690) at sw/source/core/layout/flowfrm.cxx:586
1  SwFlowFrame::MoveSubTree(SwLayoutFrame*, SwFrame*) (this=0x57c9f48, pParent=0xba15c50, pSibling=0x5a0f920) at sw/source/core/layout/flowfrm.cxx:677
2  SwFlowFrame::MoveFwd(bool, bool, bool) (this=0x57c9f48, bMakePage=true, bPageBreak=false, bMoveAlways=false) at sw/source/core/layout/flowfrm.cxx:2061
3  SwContentFrame::MakeAll(OutputDevice*) (this=0x57c9e30) at sw/source/core/layout/calcmove.cxx:1831
4  SwFrame::OptPrepareMake() (this=0x57c9e30) at sw/source/core/layout/calcmove.cxx:399
5  SwFrame::OptCalc() const (this=0x57c9e30) at sw/source/core/inc/frame.hxx:1065
6  SwLayAction::FormatContent_(SwContentFrame const*, SwPageFrame const*) (this=0x7ffec0191b30, pContent=0x57c9e30, pPage=0xb9a1fd0) at sw/source/core/layout/layact.cxx:1833

In subsequent layout actions the anchor frame moves forward one
page at a time, until in action 665, when things get really interesting.

On page 24, the anchor text frame 582 is formatted for the first time,
and it moves the fly to page 24, after positioning it on the page.

2  SwPageFrame::MoveFly(SwFlyFrame*, SwPageFrame*) (this=0xb9a1fd0, pToMove=0x641d310, pDest=0x9125bb0) at sw/source/core/layout/flylay.cxx:972
3  SwFlyAtContentFrame::RegisterAtCorrectPage() (this=0x641d310) at sw/source/core/layout/flycnt.cxx:1432
4  SwAnchoredObject::SetVertPosOrientFrame(SwLayoutFrame const&) (this=0x641d468, _rVertPosOrientFrame=...) at sw/source/core/layout/anchoredobject.cxx:195
5  SwFlyAtContentFrame::MakeObjPos() (this=0x641d310) at sw/source/core/layout/flycnt.cxx:1466
6  SwFlyFreeFrame::MakeAll(OutputDevice*) (this=0x641d310) at sw/source/core/layout/flylay.cxx:223
7  SwFlyAtContentFrame::MakeAll(OutputDevice*) (this=0x641d310, pRenderContext=0x55b1f00) at sw/source/core/layout/flycnt.cxx:384
8  SwFrame::PrepareMake(OutputDevice*) (this=0x641d310, pRenderContext=0x55b1f00) at sw/source/core/layout/calcmove.cxx:375
9  SwFrame::Calc(OutputDevice*) const (this=0x641d310, pRenderContext=0x55b1f00) at sw/source/core/layout/trvlfrm.cxx:1791
10 SwFlyFrame::Calc(OutputDevice*) const (this=0x641d310, pRenderContext=0x55b1f00) at sw/source/core/layout/fly.cxx:2874
11 SwLayAction::FormatLayoutFly(SwFlyFrame*) (this=0x7ffec0191b30, pFly=0x641d310) at sw/source/core/layout/layact.cxx:1455
12 SwObjectFormatter::FormatObj_(SwAnchoredObject&) (this=0xa5c0d10, _rAnchoredObj=...) at sw/source/core/layout/objectformatter.cxx:286
13 SwObjectFormatterTextFrame::DoFormatObj(SwAnchoredObject&, bool) (this=0xa5c0d10, _rAnchoredObj=..., _bCheckForMovedFwd=false) at sw/source/core/layout/objectformattertxtfrm.cxx:135
14 SwObjectFormatter::FormatObjsAtFrame_(SwTextFrame*) (this=0xa5c0d10, _pMasterTextFrame=0x0) at sw/source/core/layout/objectformatter.cxx:408
15 SwObjectFormatterTextFrame::DoFormatObjs() (this=0xa5c0d10) at sw/source/core/layout/objectformattertxtfrm.cxx:337
16 SwObjectFormatter::FormatObjsAtFrame(SwFrame&, SwPageFrame const&, SwLayAction*) (_rAnchorFrame=..., _rPageFrame=..., _pLayAction=0x7ffec0191b30) at sw/source/core/layout/objectformatter.cxx:160
17 SwLayAction::FormatContent(SwPageFrame const*) (this=0x7ffec0191b30, pPage=0x9125bb0) at sw/source/core/layout/layact.cxx:1675
18 SwLayAction::InternalAction(OutputDevice*) (this=0x7ffec0191b30, pRenderContext=0x55b1f00) at sw/source/core/layout/layact.cxx:771

Nothing invalidates page 21 now that the fly is gone, and formatting
on page 24 is kind of pointless now because everything from page 21
on is wrongly positioned.  (It's possible to skip out of the main layout
action loop via SetNextCycle()/IsAgain(), but at this point it's in
layact:771 in the layout-all-the-visible-pages loop that follows
the main loop, and that one can't be cancelled.)

Then DoFormatObjs() is called on frame 582, and this calls
FormatAnchorFrameForCheckMoveFwd(), which formats previous frame 581,
splitting it and moving its follow along with 582 to page 25.

Here SwMovedFwdFramesByObjPos::Insert() is called, and now the anchor
text frame 582 cannot move back to page 24 because it's prevented by
SwMovedFwdFramesByObjPos::FrameMovedFwdByObjPos(), but that was all
based on the wrong assumption that the pages before 24 were
completely formatted (this happens in action 670).

Something later formats page 21 again, and so at the end there is a
fly-sized hole at the bottom of page 24, with frame 582 at the top
of page 25.

It won't help to detect a situation where the fly is on a page previous
to the page it's anchor frame is on in DoFormatObjs() because it was
actually moved to the same page in a previous formatting of the anchor
frame, in the same layout action.

To fix this, try to detect in SwLayAction::FormatContent() if the
anchor frame of any fly on the page has moved forward, and move those
flys off the page; this is enough for the 25 page document.

The 311 page document still has a hole on page 194 though; apparently
the last content frame on the page is never reformatted, so
invalidate its size.

Change-Id: I232c6b305e8593bfecd885c36058777f3980f82f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/114066
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>
(cherry picked from commit eb85de8e6b61fb3fcb6c03ae0145f7fe5478bccf)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/114519
Reviewed-by: Thorsten Behrens <thorsten.behrens@allotropia.de>

9 files changed, 76 insertions, 9 deletions

diff --git a/sw/inc/anchoreddrawobject.hxx b/sw/inc/anchoreddrawobject.hxx
index bd74d6ea479a..eb457701a98d 100644
--- a/sw/inc/anchoreddrawobject.hxx
+++ b/sw/inc/anchoreddrawobject.hxx
@@ -94,6 +94,7 @@ class SwAnchoredDrawObject final : public SwAnchoredObject
             page frame
         */
         virtual void RegisterAtCorrectPage() override;
+        virtual void RegisterAtPage(SwPageFrame &) override;
 
         virtual bool SetObjTop_( const SwTwips _nTop) override;
         virtual bool SetObjLeft_( const SwTwips _nLeft) override;
diff --git a/sw/inc/anchoredobject.hxx b/sw/inc/anchoredobject.hxx
index 5309602f9ef0..fa789d755d53 100644
--- a/sw/inc/anchoredobject.hxx
+++ b/sw/inc/anchoredobject.hxx
@@ -295,6 +295,8 @@ class SW_DLLPUBLIC SwAnchoredObject
         /** method to invalidate position of the anchored object */
         virtual void InvalidateObjPos() = 0;
 
+        virtual void RegisterAtPage(SwPageFrame &) = 0;
+
         /** method to perform necessary invalidations for the positioning of
             objects, for whose the wrapping style influence has to be considered
             on the object positioning.
diff --git a/sw/source/core/inc/flyfrm.hxx b/sw/source/core/inc/flyfrm.hxx
index df39df57e176..f01c9262ec05 100644
--- a/sw/source/core/inc/flyfrm.hxx
+++ b/sw/source/core/inc/flyfrm.hxx
@@ -135,6 +135,7 @@ protected:
         page frame
     */
     virtual void RegisterAtCorrectPage() override;
+    virtual void RegisterAtPage(SwPageFrame &) override;
 
     virtual bool SetObjTop_( const SwTwips _nTop ) override;
     virtual bool SetObjLeft_( const SwTwips _nLeft ) override;
diff --git a/sw/source/core/inc/flyfrms.hxx b/sw/source/core/inc/flyfrms.hxx
index 82a67b9b5342..66e0b27e0655 100644
--- a/sw/source/core/inc/flyfrms.hxx
+++ b/sw/source/core/inc/flyfrms.hxx
@@ -170,6 +170,7 @@ protected:
         #i28701#
     */
     virtual void RegisterAtCorrectPage() override;
+    virtual void RegisterAtPage(SwPageFrame &) override;
     virtual void Modify( const SfxPoolItem*, const SfxPoolItem* ) override;
 
 public:
diff --git a/sw/source/core/inc/layact.hxx b/sw/source/core/inc/layact.hxx
index a5ed0c4eb37e..433d4b70e59a 100644
--- a/sw/source/core/inc/layact.hxx
+++ b/sw/source/core/inc/layact.hxx
@@ -111,7 +111,7 @@ class SwLayAction
 
     bool FormatLayout( OutputDevice* pRenderContext, SwLayoutFrame *, bool bAddRect = true );
     bool FormatLayoutTab( SwTabFrame *, bool bAddRect );
-    bool FormatContent( const SwPageFrame* pPage );
+    bool FormatContent(SwPageFrame * pPage);
     void FormatContent_( const SwContentFrame* pContent,
                        const SwPageFrame* pPage );
     bool IsShortCut( SwPageFrame *& );
diff --git a/sw/source/core/layout/anchoreddrawobject.cxx b/sw/source/core/layout/anchoreddrawobject.cxx
index a5631667c1e5..deee176713e9 100644
--- a/sw/source/core/layout/anchoreddrawobject.cxx
+++ b/sw/source/core/layout/anchoreddrawobject.cxx
@@ -918,10 +918,18 @@ void SwAnchoredDrawObject::RegisterAtCorrectPage()
     }
     if ( pPageFrame && GetPageFrame() != pPageFrame )
     {
-        if ( GetPageFrame() )
-            GetPageFrame()->RemoveDrawObjFromPage( *this );
-        pPageFrame->AppendDrawObjToPage( *this );
+        RegisterAtPage(*pPageFrame);
     }
 }
 
+void SwAnchoredDrawObject::RegisterAtPage(SwPageFrame & rPageFrame)
+{
+    assert(GetPageFrame() != &rPageFrame);
+    if (GetPageFrame())
+    {
+        GetPageFrame()->RemoveDrawObjFromPage( *this );
+    }
+    rPageFrame.AppendDrawObjToPage( *this );
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/sw/source/core/layout/fly.cxx b/sw/source/core/layout/fly.cxx
index 6e7fad1fcb82..d5b7f5427992 100644
--- a/sw/source/core/layout/fly.cxx
+++ b/sw/source/core/layout/fly.cxx
@@ -2840,6 +2840,11 @@ void SwFlyFrame::RegisterAtCorrectPage()
     // default behaviour is to do nothing.
 }
 
+void SwFlyFrame::RegisterAtPage(SwPageFrame &)
+{
+    // default behaviour is to do nothing.
+}
+
 /** method to determine, if a <MakeAll()> on the Writer fly frame is possible
 
     OD 2004-05-11 #i28701#
diff --git a/sw/source/core/layout/flycnt.cxx b/sw/source/core/layout/flycnt.cxx
index 4dc2db5921d7..bcc75a032e31 100644
--- a/sw/source/core/layout/flycnt.cxx
+++ b/sw/source/core/layout/flycnt.cxx
@@ -1418,10 +1418,20 @@ void SwFlyAtContentFrame::RegisterAtCorrectPage()
     }
     if ( pPageFrame && GetPageFrame() != pPageFrame )
     {
-        if ( GetPageFrame() )
-            GetPageFrame()->MoveFly( this, pPageFrame );
-        else
-            pPageFrame->AppendFlyToPage( this );
+        RegisterAtPage(*pPageFrame);
+    }
+}
+
+void SwFlyAtContentFrame::RegisterAtPage(SwPageFrame & rPageFrame)
+{
+    assert(GetPageFrame() != &rPageFrame);
+    if (GetPageFrame())
+    {
+        GetPageFrame()->MoveFly( this, &rPageFrame );
+    }
+    else
+    {
+        rPageFrame.AppendFlyToPage( this );
     }
 }
 
diff --git a/sw/source/core/layout/layact.cxx b/sw/source/core/layout/layact.cxx
index 45ac680c8f4f..a46a94ff8cd5 100644
--- a/sw/source/core/layout/layact.cxx
+++ b/sw/source/core/layout/layact.cxx
@@ -61,6 +61,8 @@
 #include <sortedobjs.hxx>
 #include <objectformatter.hxx>
 #include <fntcache.hxx>
+#include <fmtanchr.hxx>
+#include <comphelper/scopeguard.hxx>
 #include <vector>
 #include <tools/diagnose_ex.h>
 
@@ -1618,8 +1620,45 @@ bool SwLayAction::FormatLayoutTab( SwTabFrame *pTab, bool bAddRect )
     return bChanged;
 }
 
-bool SwLayAction::FormatContent( const SwPageFrame *pPage )
+bool SwLayAction::FormatContent(SwPageFrame *const pPage)
 {
+    ::comphelper::ScopeGuard g([this, pPage]() {
+        if (IsAgain())
+        {
+            return; // pPage probably deleted
+        }
+        if (auto const* pObjs = pPage->GetSortedObjs())
+        {
+            std::vector<std::pair<SwAnchoredObject*, SwPageFrame*>> moved;
+            for (auto const pObj : *pObjs)
+            {
+                SwPageFrame *const pAnchorPage(pObj->FindPageFrameOfAnchor());
+                assert(pAnchorPage);
+                if (pAnchorPage != pPage
+                    && pPage->GetPhyPageNum() < pAnchorPage->GetPhyPageNum()
+                    && pObj->GetFrameFormat().GetAnchor().GetAnchorId()
+                        != RndStdIds::FLY_AS_CHAR)
+                {
+                    moved.emplace_back(pObj, pAnchorPage);
+                }
+            }
+            for (auto const& [pObj, pAnchorPage] : moved)
+            {
+                pObj->RegisterAtPage(*pAnchorPage);
+                ::Notify_Background(pObj->GetDrawObj(), pPage,
+                    pObj->GetObjRect(), PrepareHint::FlyFrameLeave, false);
+            }
+            if (!moved.empty())
+            {
+                pPage->InvalidateFlyLayout();
+                if (auto *const pContent = pPage->FindLastBodyContent())
+                {
+                    pContent->InvalidateSize();
+                }
+            }
+        }
+    });
+
     const SwContentFrame *pContent = pPage->ContainsContent();
     const SwViewShell *pSh = m_pRoot->GetCurrShell();
     const bool bBrowse = pSh && pSh->GetViewOptions()->getBrowseMode();