sc-perf: bundle SdrObject::BroadcastObjectChange() calls during Save

Test doc https://bugs.documentfoundation.org/attachment.cgi?id=128252 from
https://bugs.documentfoundation.org/show_bug.cgi?id=103493

ScPostIt::CreateCaptionFromInitData() called through
ScDocument::CreateAllNoteCaptions()

          Incl.     Self  Called
Before:
326,418,830,114  487,308   6,645
After:
145,055,889,118  511,681   6,645

Reduced to 44% or speed-up by factor 2.25

Overall ScDocShell::SaveXML()
Before: 370,433,720,090
 After: 189,120,982,786

Reduced to 51% or speed-up by factor 1.96

There's still too much broadcasting to accessibility going on though..

Change-Id: I50555fd9751ac24006cc96b2fa8e82b32aba0748

include/svx/svdobj.hxx

@@ -295,6 +295,7 @@ private:
     friend class                SdrObjListIter;
     friend class                SdrVirtObj;
     friend class                SdrRectObj;
+    friend class                SdrDelayBroadcastObjectChange;
 
 protected:
     Rectangle                   aOutRect;     // surrounding rectangle for Paint (incl. LineWdt, ...)
@@ -351,6 +352,11 @@ protected:
     // #i25616#
     bool                        mbSupportTextIndentingOnLineWidthChange : 1;
 
+private:
+    bool                        mbDelayBroadcastObjectChange : 1;
+    mutable bool                mbBroadcastObjectChangePending : 1;
+
+protected:
     // on import of OLE object from MS documents the BLIP size might be retrieved,
     // in this case the following member is initialized as nonempty rectangle
     Rectangle                   maBLIPSizeRectangle;
@@ -968,6 +974,20 @@ private:
     bool mbDoNotInsertIntoPageAutomatically;
 };
 
+/** Suppress BroadcastObjectChange() until destruction of the (last) instance.
+    Prevents multiple broadcasts for a sequence of calls that would trigger a
+    broadcast each. Instances may be nested in levels, the outer instance will
+    trigger the final broadcast.
+ */
+class SVX_DLLPUBLIC SdrDelayBroadcastObjectChange
+{
+    SdrObject&  mrObj;
+    bool        mbOldDelayBroadcastObjectChange;
+public:
+    SdrDelayBroadcastObjectChange( SdrObject& rObj );
+    ~SdrDelayBroadcastObjectChange();
+};
+
 struct SdrObjCreatorParams
 {
     sal_uInt32 nInventor;

sc/source/core/data/postit.cxx

@@ -640,6 +640,11 @@ void ScPostIt::CreateCaptionFromInitData( const ScAddress& rPos ) const
             ScNoteCaptionCreator aCreator( mrDoc, rPos, maNoteData );
             if( maNoteData.mpCaption )
             {
+                // Prevent triple change broadcasts of the same object, which
+                // during Save triggered by ScDocument::CreateAllNoteCaptions()
+                // creates a major performance bottleneck.
+                SdrDelayBroadcastObjectChange aDelayChange( *maNoteData.mpCaption);
+
                 ScCaptionInitData& rInitData = *maNoteData.mxInitData;
 
                 // transfer ownership of outliner object to caption, or set simple text

svx/source/svdraw/svdobj.cxx

@@ -302,6 +302,8 @@ SdrObject::SdrObject() :
     ,pGrabBagItem(nullptr)
     ,mnNavigationPosition(SAL_MAX_UINT32)
     ,mnLayerID(0)
+    ,mbDelayBroadcastObjectChange(false)
+    ,mbBroadcastObjectChangePending(false)
     ,mpSvxShape( nullptr )
     ,maWeakUnoShape()
     ,mbDoNotInsertIntoPageAutomatically(false)
@@ -880,6 +882,12 @@ void SdrObject::BroadcastObjectChange() const
     if( pModel && pModel->isLocked() )
         return;
 
+    if (mbDelayBroadcastObjectChange)
+    {
+        mbBroadcastObjectChangePending = true;
+        return;
+    }
+
     bool bPlusDataBroadcast(pPlusData && pPlusData->pBroadcast);
     bool bObjectChange(IsInserted() && pModel);
 
@@ -3092,6 +3100,27 @@ bool SdrObject::HasText() const
     return false;
 }
 
+
+SdrDelayBroadcastObjectChange::SdrDelayBroadcastObjectChange( SdrObject& rObj ) :
+    mrObj(rObj), mbOldDelayBroadcastObjectChange( rObj.mbDelayBroadcastObjectChange)
+{
+    mrObj.mbDelayBroadcastObjectChange = true;
+}
+
+SdrDelayBroadcastObjectChange::~SdrDelayBroadcastObjectChange()
+{
+    if (!mbOldDelayBroadcastObjectChange)
+    {
+        mrObj.mbDelayBroadcastObjectChange = false;
+        if (mrObj.mbBroadcastObjectChangePending)
+        {
+            mrObj.mbBroadcastObjectChangePending = false;
+            mrObj.BroadcastObjectChange();
+        }
+    }
+}
+
+
 SdrObject* SdrObjFactory::CreateObjectFromFactory( sal_uInt32 nInventor, sal_uInt16 nObjIdentifier, SdrPage* , SdrModel*  )
 {
     SdrObjCreatorParams aParams { nInventor, nObjIdentifier };