sw: refactor SwPageFrame::HandleWhitespaceHiddenDiff()

As suggested at <https://gerrit.libreoffice.org/21445>.

Change-Id: Id1e7a6381954c6d56a2593a064c37cc185475a56
Reviewed-on: https://gerrit.libreoffice.org/21899
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>

4 files changed, 14 insertions, 8 deletions

diff --git a/sw/source/core/inc/pagefrm.hxx b/sw/source/core/inc/pagefrm.hxx
index 2df4c1d58a37..3fae2a30bbc8 100644
--- a/sw/source/core/inc/pagefrm.hxx
+++ b/sw/source/core/inc/pagefrm.hxx
@@ -335,8 +335,9 @@ public:
 
     static SwTwips GetSidebarBorderWidth( const SwViewShell* );
 
-    /// Adjust a bottom-of-page-frame - bottom-of-text-frame difference in case whitespace is hidden.
-    void HandleWhitespaceHiddenDiff(SwTwips& nDiff);
+    /// Is bottom-of-page-frame - bottom-of-text-frame difference valid in case whitespace is hidden?
+    /// If false is returned, then the caller should handle negative difference as (at least) zero difference instead.
+    bool CheckPageHeightValidForHideWhitespace(SwTwips nDiff);
 };
 
 inline SwContentFrame *SwPageFrame::FindFirstBodyContent()
diff --git a/sw/source/core/layout/calcmove.cxx b/sw/source/core/layout/calcmove.cxx
index aa4e4a5106da..a5fd16c971b4 100644
--- a/sw/source/core/layout/calcmove.cxx
+++ b/sw/source/core/layout/calcmove.cxx
@@ -1525,10 +1525,12 @@ void SwContentFrame::MakeAll(vcl::RenderContext* /*pRenderContext*/)
 
         // Hide whitespace may require not to insert a new page.
         SwPageFrame* pPageFrame = FindPageFrame();
-        long nOldBottomDist = nBottomDist;
-        pPageFrame->HandleWhitespaceHiddenDiff(nBottomDist);
-        if (nOldBottomDist != nBottomDist)
+        const bool bHeightValid = pPageFrame->CheckPageHeightValidForHideWhitespace(nBottomDist);
+        if (!bHeightValid)
+        {
             pPageFrame->InvalidateSize();
+            nBottomDist = 0;
+        }
 
         if( nBottomDist >= 0 )
         {
diff --git a/sw/source/core/layout/pagechg.cxx b/sw/source/core/layout/pagechg.cxx
index 967ee2fe5305..42ae8acbe5d9 100644
--- a/sw/source/core/layout/pagechg.cxx
+++ b/sw/source/core/layout/pagechg.cxx
@@ -2287,7 +2287,7 @@ bool SwPageFrame::IsOverHeaderFooterArea( const Point& rPt, FrameControlType &rC
     return false;
 }
 
-void SwPageFrame::HandleWhitespaceHiddenDiff(SwTwips& nDiff)
+bool SwPageFrame::CheckPageHeightValidForHideWhitespace(SwTwips nDiff)
 {
     SwViewShell* pShell = getRootFrame()->GetCurrShell();
     if (pShell && pShell->GetViewOptions()->IsWhitespaceHidden())
@@ -2309,10 +2309,12 @@ void SwPageFrame::HandleWhitespaceHiddenDiff(SwTwips& nDiff)
             {
                 // It does: don't move it and invalidate our page frame so
                 // that it gets a larger height.
-                nDiff = 0;
+                return false;
             }
         }
     }
+
+    return true;
 }
 
 SwTextGridItem const* GetGridItem(SwPageFrame const*const pPage)
diff --git a/sw/source/core/text/widorp.cxx b/sw/source/core/text/widorp.cxx
index c75a9586ef19..7c22b120d3a4 100644
--- a/sw/source/core/text/widorp.cxx
+++ b/sw/source/core/text/widorp.cxx
@@ -131,7 +131,8 @@ bool SwTextFrameBreak::IsInside( SwTextMargin &rLine ) const
 
         // Hide whitespace may require not to insert a new page.
         SwPageFrame* pPageFrame = m_pFrame->FindPageFrame();
-        pPageFrame->HandleWhitespaceHiddenDiff(nDiff);
+        if (!pPageFrame->CheckPageHeightValidForHideWhitespace(nDiff))
+            nDiff = 0;
 
         // If everything is inside the existing frame the result is true;
         bFit = nDiff >= 0;