Revert "trac#34262 Revert "Do not count pages for initial page breaks, tdf#124983 follow-up""

The actual root cause of the WollMux mail merge issue
(too little Java heap space) has been identified in the
meantime.

In addition, when reverting, I was confused by the fact that the
commit msg was only that of the follow-up commit

        commit 129c680f02564c8bee93930dec9f2ad80980cc1c
        Author: Eike Rathke <erack@redhat.com>
        Date:   Wed Aug 18 23:42:45 2021 +0200

            Do not count pages for initial page breaks, tdf#124983 follow-up

but the second version of the underlying fix

         commit 86e300df241312f6152da1cfa3cb2b8c668d1df5
        Author: Ilhan Yesil <ilhanyesil@gmx.de>
        Date:   Fri Mar 6 13:40:59 2020 +0100

            tdf#124983 In calc make printable page borders initially visible

as well as a cherry-pick of the follow-up

        commit 3d7007ef8784e92bb56a91c40e7bdff812251677
        Author: Eike Rathke <erack@redhat.com>
        Date:   Tue Jun 29 14:31:19 2021 +0200

            maShowPageBreaksTimer.Stop() in ScGridWindow::dispose(), tdf#124983 follow-up

were actually all already contained in that single commit
as well, without being mentioned explicitly.

This reverts commit 1f966bb3e38a028c82cee40f6c5a17fe9619b53c.

Change-Id: Ib42a2612843bd78ecb9aa538ab64f2a953a3c093
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/132572
Tested-by: Michael Weghorn <m.weghorn@posteo.de>
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

4 files changed, 97 insertions, 0 deletions

diff --git a/sc/source/ui/inc/gridwin.hxx b/sc/source/ui/inc/gridwin.hxx
index 5ebb26241d10..e9363a1f96d2 100644
--- a/sc/source/ui/inc/gridwin.hxx
+++ b/sc/source/ui/inc/gridwin.hxx
@@ -190,6 +190,8 @@ class SAL_DLLPUBLIC_RTTI ScGridWindow : public vcl::Window, public DropTargetHel
 
     RfCorner                aRFSelectedCorned;
 
+    Timer                   maShowPageBreaksTimer;
+
     bool                    bEEMouse:1;               // Edit Engine has mouse
     bool                    bDPMouse:1;               // DataPilot D&D (new Pivot table)
     bool                    bRFMouse:1;               // RangeFinder drag
@@ -200,6 +202,7 @@ class SAL_DLLPUBLIC_RTTI ScGridWindow : public vcl::Window, public DropTargetHel
     bool                    bNeedsRepaint:1;
     bool                    bAutoMarkVisible:1;
     bool                    bListValButton:1;
+    bool                    bInitialPageBreaks:1;
 
     DECL_LINK( PopupModeEndHdl, FloatingWindow*, void );
     DECL_LINK( PopupSpellingHdl, SpellCallbackInfo&, void );
@@ -288,6 +291,8 @@ class SAL_DLLPUBLIC_RTTI ScGridWindow : public vcl::Window, public DropTargetHel
 
     void            GetSelectionRects( ::std::vector< tools::Rectangle >& rPixelRects );
 
+    void            SetupInitialPageBreaks(const ScDocument& rDoc, SCTAB nTab);
+    DECL_LINK(InitiatePageBreaksTimer, Timer*, void);
 
 protected:
     virtual void    PrePaint(vcl::RenderContext& rRenderContext) override;
@@ -462,6 +467,8 @@ public:
 
     void updateLOKValListButton(bool bVisible, const ScAddress& rPos) const;
 
+    void initiatePageBreaks();
+
 protected:
     void ImpCreateOverlayObjects();
     void ImpDestroyOverlayObjects();
diff --git a/sc/source/ui/view/gridwin.cxx b/sc/source/ui/view/gridwin.cxx
index 0ed015bb31da..aa540b5d5134 100644
--- a/sc/source/ui/view/gridwin.cxx
+++ b/sc/source/ui/view/gridwin.cxx
@@ -482,6 +482,10 @@ ScGridWindow::ScGridWindow( vcl::Window* pParent, ScViewData* pData, ScSplitPos
 
     SetDigitLanguage( SC_MOD()->GetOptDigitLanguage() );
     EnableRTL( false );
+
+    bInitialPageBreaks = true;
+    maShowPageBreaksTimer.SetInvokeHandler(LINK(this, ScGridWindow, InitiatePageBreaksTimer));
+    maShowPageBreaksTimer.SetTimeout(1);
 }
 
 ScGridWindow::~ScGridWindow()
@@ -491,6 +495,8 @@ ScGridWindow::~ScGridWindow()
 
 void ScGridWindow::dispose()
 {
+    maShowPageBreaksTimer.Stop();
+
     ImpDestroyOverlayObjects();
 
     mpFilterBox.disposeAndClear();
diff --git a/sc/source/ui/view/gridwin4.cxx b/sc/source/ui/view/gridwin4.cxx
index 9426c8842bf0..aa7ad1312acc 100644
--- a/sc/source/ui/view/gridwin4.cxx
+++ b/sc/source/ui/view/gridwin4.cxx
@@ -1055,6 +1055,28 @@ void ScGridWindow::DrawContent(OutputDevice &rDevice, const ScTableInfo& rTableI
 
     if (mpNoteMarker)
         mpNoteMarker->Draw(); // Above the cursor, in drawing map mode
+
+    if (bPage && bInitialPageBreaks)
+        SetupInitialPageBreaks(rDoc, nTab);
+}
+
+
+void ScGridWindow::SetupInitialPageBreaks(const ScDocument& rDoc, SCTAB nTab)
+{
+    // tdf#124983, if option LibreOfficeDev Calc/View/Visual Aids/Page breaks
+    // is enabled, breaks should be visible. If the document is opened the first
+    // time, the breaks are not calculated yet, so for this initialization
+    // a timer will be triggered here.
+    std::set<SCCOL> aColBreaks;
+    std::set<SCROW> aRowBreaks;
+    rDoc.GetAllColBreaks(aColBreaks, nTab, true, false);
+    rDoc.GetAllRowBreaks(aRowBreaks, nTab, true, false);
+    if (aColBreaks.size() == 0 || aRowBreaks.size() == 0)
+    {
+        maShowPageBreaksTimer.SetPriority(TaskPriority::DEFAULT_IDLE);
+        maShowPageBreaksTimer.Start();
+    }
+    bInitialPageBreaks = false;
 }
 
 namespace
@@ -2005,4 +2027,55 @@ void ScGridWindow::DataChanged( const DataChangedEvent& rDCEvt )
     }
 }
 
+void ScGridWindow::initiatePageBreaks()
+{
+    bInitialPageBreaks = true;
+}
+
+IMPL_LINK(ScGridWindow, InitiatePageBreaksTimer, Timer*, pTimer, void)
+{
+    if (pTimer == &maShowPageBreaksTimer)
+    {
+        const ScViewOptions& rOpts = pViewData->GetOptions();
+        const bool bPage = rOpts.GetOption(VOPT_PAGEBREAKS);
+        // tdf#124983, if option LibreOfficeDev Calc/View/Visual Aids/Page
+        // breaks is enabled, breaks should be visible. If the document is
+        // opened the first time or a tab is activated the first time, the
+        // breaks are not calculated yet, so this initialization is done here.
+        if (bPage)
+        {
+            const SCTAB nCurrentTab = pViewData->GetTabNo();
+            ScDocument* pDoc = pViewData->GetDocument();
+            const Size aPageSize = pDoc->GetPageSize(nCurrentTab);
+            // Do not attempt to calculate a page size here if it is empty if
+            // that involves counting pages.
+            // An earlier implementation did
+            //   ScPrintFunc(pDocSh, pDocSh->GetPrinter(), nCurrentTab);
+            //   rDoc.SetPageSize(nCurrentTab, rDoc.GetPageSize(nCurrentTab));
+            // which resulted in tremendous waiting times after having loaded
+            // larger documents i.e. imported from CSV, in which UI is entirely
+            // blocked. All time is spent under ScPrintFunc::CountPages() in
+            // ScTable::ExtendPrintArea() in the loop that calls
+            // MaybeAddExtraColumn() to do stuff for each text string content
+            // cell (each row in each column). Maybe that can be optimized, or
+            // obtaining page size without that overhead would be possible, but
+            // as is calling that from here is a no-no so this is a quick
+            // disable things.
+            if (aPageSize.Width()>0&&aPageSize.Height())
+            {
+                ScDocShell* pDocSh = pViewData->GetDocShell();
+                const bool bModified = pDocSh->IsModified();
+                // Even setting the same size sets page size valid, so
+                // UpdatePageBreaks() actually does something.
+                pDoc->SetPageSize( nCurrentTab, aPageSize);
+                pDoc->UpdatePageBreaks(nCurrentTab);
+                pDocSh->PostPaint(0, 0, nCurrentTab, pDoc->MaxCol(), pDoc->MaxRow(), nCurrentTab, PaintPartFlags::Grid);
+                pDocSh->SetModified(bModified);
+            }
+        }
+
+        Invalidate();
+    }
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/sc/source/ui/view/tabview5.cxx b/sc/source/ui/view/tabview5.cxx
index b075b748f0e3..635b40e97ab5 100644
--- a/sc/source/ui/view/tabview5.cxx
+++ b/sc/source/ui/view/tabview5.cxx
@@ -315,6 +315,17 @@ void ScTabView::TabChanged( bool bSameTabButMoved )
         }
     }
 
+    for (int i = 0; i < 4; i++)
+    {
+        if (pGridWin[i])
+        {
+            pGridWin[i]->initiatePageBreaks();
+            // Trigger calculating page breaks only once.
+            break;
+        }
+    }
+
+
     if (comphelper::LibreOfficeKit::isActive())
     {
         ScDocShell* pDocSh = GetViewData().GetDocShell();