lok: avoid painting writer windows to a giant virtual-device.

When layout changes, we don't want to immediately redraw lots of
windows; we should be able to wait for tiles to be rendered
instead. Certainly we don't want to allocate a giant virtual
device.

Unfortunately we also believe that full document invalidations
are cheap - so warn about that.

Change-Id: Ib56320d4860c4b6f4e100b30cc6d3e490a1c7a90
Signed-off-by: Michael Meeks <michael.meeks@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/149601
Tested-by: Jenkins

sw/source/core/layout/layact.cxx

@@ -2352,6 +2352,7 @@ SwLayIdle::SwLayIdle( SwRootFrame *pRt, SwViewShellImp *pI ) :
                 bool bUnlock = false;
                 if ( pViewImp->HasPaintRegion() )
                 {
+                    SAL_INFO("sw.idle", "Disappointing full document invalidation");
                     pViewImp->DeletePaintRegion();
 
                     // Cause a repaint with virtual device.

sw/source/core/view/viewsh.cxx

@@ -475,7 +475,7 @@ void SwViewShell::ImplStartAction()
 
 void SwViewShell::ImplLockPaint()
 {
-    if ( GetWin() && GetWin()->IsVisible() )
+    if ( GetWin() && GetWin()->IsVisible() && !comphelper::LibreOfficeKit::isActive())
         GetWin()->EnablePaint( false ); //Also cut off the controls.
     Imp()->LockPaint();
 }
@@ -485,7 +485,7 @@ void SwViewShell::ImplUnlockPaint( bool bVirDev )
     CurrShell aCurr( this );
     if ( GetWin() && GetWin()->IsVisible() )
     {
-        if ( (bInSizeNotify || bVirDev ) && VisArea().HasArea() )
+        if ( (bInSizeNotify || bVirDev ) && VisArea().HasArea() && !comphelper::LibreOfficeKit::isActive())
         {
             //Refresh with virtual device to avoid flickering.
             VclPtrInstance<VirtualDevice> pVout( *mpOut );