sw layout: allow negative page border distances

Writer follows the CSS box model when it comes to page borders: there
can be a positive distance between the edge of the page and the border,
and again a positive distance between the border and the body frame.

This ensures that the page border never intersect with the body frame,
which is usually what users expect. Word, however, can work with 2
distances for border and text, both measured from the edge of the page,
leading to a page border, which is inside the body text. This is
described at great detail at
<https://wiki.openoffice.org/wiki/Writer/MSInteroperability/PageBorder#Importing_case_3:>.

Fix the problem by allowing negative border distances: this doesn't
influence the position or the size of the body frame, but it gives us a
way to position the border more towards the center of the page, leading
the matching layout between Writer and Word.

The doc model (to allow negative border distances), UNO API and DOCX
filter is updated in this commit. The ODT filter works without explicit
effort. Other filters are not yet updated in this commit.

Change-Id: I723e1bdb8dc6391129f1686f88826cc089f6fd67
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/135462
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

1 files changed, 49 insertions, 19 deletions

diff --git a/editeng/source/items/frmitems.cxx b/editeng/source/items/frmitems.cxx
index a31df88ca0f0..9780af4904c0 100644
--- a/editeng/source/items/frmitems.cxx
+++ b/editeng/source/items/frmitems.cxx
@@ -1313,6 +1313,20 @@ SvxBoxItem::~SvxBoxItem()
 {
 }
 
+void SvxBoxItem::dumpAsXml(xmlTextWriterPtr pWriter) const
+{
+    (void)xmlTextWriterStartElement(pWriter, BAD_CAST("SvxBoxItem"));
+    (void)xmlTextWriterWriteAttribute(pWriter, BAD_CAST("top-dist"),
+                                      BAD_CAST(OString::number(nTopDist).getStr()));
+    (void)xmlTextWriterWriteAttribute(pWriter, BAD_CAST("bottom-dist"),
+                                      BAD_CAST(OString::number(nBottomDist).getStr()));
+    (void)xmlTextWriterWriteAttribute(pWriter, BAD_CAST("left-dist"),
+                                      BAD_CAST(OString::number(nLeftDist).getStr()));
+    (void)xmlTextWriterWriteAttribute(pWriter, BAD_CAST("right-dist"),
+                                      BAD_CAST(OString::number(nRightDist).getStr()));
+    SfxPoolItem::dumpAsXml(pWriter);
+    (void)xmlTextWriterEndElement(pWriter);
+}
 
 boost::property_tree::ptree SvxBoxItem::dumpAsJSON() const
 {
@@ -1380,7 +1394,7 @@ bool SvxBoxItem::QueryValue( uno::Any& rVal, sal_uInt8 nMemberId ) const
 {
     bool bConvert = 0!=(nMemberId&CONVERT_TWIPS);
     table::BorderLine2 aRetLine;
-    sal_uInt16 nDist = 0;
+    sal_Int16 nDist = 0;
     bool bDistMember = false;
     nMemberId &= ~CONVERT_TWIPS;
     switch(nMemberId)
@@ -1670,7 +1684,6 @@ bool SvxBoxItem::PutValue( const uno::Any& rVal, sal_uInt8 nMemberId )
         if(!(rVal >>= nDist))
             return false;
 
-        if(nDist >= 0)
         {
             if( bConvert )
                 nDist = o3tl::toTwips(nDist, o3tl::Length::mm100);
@@ -1883,10 +1896,10 @@ void SvxBoxItem::ScaleMetrics( tools::Long nMult, tools::Long nDiv )
     if ( pBottom )  pBottom->ScaleMetrics( nMult, nDiv );
     if ( pLeft )    pLeft->ScaleMetrics( nMult, nDiv );
     if ( pRight )   pRight->ScaleMetrics( nMult, nDiv );
-    nTopDist = static_cast<sal_uInt16>(BigInt::Scale( nTopDist, nMult, nDiv ));
-    nBottomDist = static_cast<sal_uInt16>(BigInt::Scale( nBottomDist, nMult, nDiv ));
-    nLeftDist = static_cast<sal_uInt16>(BigInt::Scale( nLeftDist, nMult, nDiv ));
-    nRightDist = static_cast<sal_uInt16>(BigInt::Scale( nRightDist, nMult, nDiv ));
+    nTopDist = static_cast<sal_Int16>(BigInt::Scale( nTopDist, nMult, nDiv ));
+    nBottomDist = static_cast<sal_Int16>(BigInt::Scale( nBottomDist, nMult, nDiv ));
+    nLeftDist = static_cast<sal_Int16>(BigInt::Scale( nLeftDist, nMult, nDiv ));
+    nRightDist = static_cast<sal_Int16>(BigInt::Scale( nRightDist, nMult, nDiv ));
 }
 
 
@@ -1962,9 +1975,9 @@ sal_uInt16 SvxBoxItem::GetSmallestDistance() const
 }
 
 
-sal_uInt16 SvxBoxItem::GetDistance( SvxBoxItemLine nLine ) const
+sal_Int16 SvxBoxItem::GetDistance( SvxBoxItemLine nLine, bool bAllowNegative ) const
 {
-    sal_uInt16 nDist = 0;
+    sal_Int16 nDist = 0;
     switch ( nLine )
     {
         case SvxBoxItemLine::TOP:
@@ -1983,11 +1996,15 @@ sal_uInt16 SvxBoxItem::GetDistance( SvxBoxItemLine nLine ) const
             OSL_FAIL( "wrong line" );
     }
 
+    if (!bAllowNegative && nDist < 0)
+    {
+        nDist = 0;
+    }
     return nDist;
 }
 
 
-void SvxBoxItem::SetDistance( sal_uInt16 nNew, SvxBoxItemLine nLine )
+void SvxBoxItem::SetDistance( sal_Int16 nNew, SvxBoxItemLine nLine )
 {
     switch ( nLine )
     {
@@ -2036,10 +2053,10 @@ sal_uInt16 SvxBoxItem::CalcLineWidth( SvxBoxItemLine nLine ) const
     return nWidth;
 }
 
-sal_uInt16 SvxBoxItem::CalcLineSpace( SvxBoxItemLine nLine, bool bEvenIfNoLine ) const
+sal_Int16 SvxBoxItem::CalcLineSpace( SvxBoxItemLine nLine, bool bEvenIfNoLine, bool bAllowNegative ) const
 {
     SvxBorderLine* pTmp = nullptr;
-    sal_uInt16 nDist = 0;
+    sal_Int16 nDist = 0;
     switch ( nLine )
     {
     case SvxBoxItemLine::TOP:
@@ -2068,6 +2085,12 @@ sal_uInt16 SvxBoxItem::CalcLineSpace( SvxBoxItemLine nLine, bool bEvenIfNoLine )
     }
     else if( !bEvenIfNoLine )
         nDist = 0;
+
+    if (!bAllowNegative && nDist < 0)
+    {
+        nDist = 0;
+    }
+
     return nDist;
 }
 
@@ -2429,7 +2452,7 @@ namespace editeng
 {
 
 void BorderDistanceFromWord(bool bFromEdge, sal_Int32& nMargin, sal_Int32& nBorderDistance,
-    sal_Int32 nBorderWidth)
+    sal_Int32 nBorderWidth, bool bAllowNegativeBorderDistance)
 {
     // See https://wiki.openoffice.org/wiki/Writer/MSInteroperability/PageBorder
 
@@ -2456,8 +2479,15 @@ void BorderDistanceFromWord(bool bFromEdge, sal_Int32& nMargin, sal_Int32& nBord
     }
     else if (nNewBorderDistance < 0)
     {
-        nNewMargin = std::max<sal_Int32>(nMargin - nBorderWidth, 0);
-        nNewBorderDistance = 0;
+        if (bAllowNegativeBorderDistance)
+        {
+            nNewMargin = nMargin;
+        }
+        else
+        {
+            nNewMargin = std::max<sal_Int32>(nMargin - nBorderWidth, 0);
+            nNewBorderDistance = 0;
+        }
     }
 
     nMargin = nNewMargin;
@@ -2481,10 +2511,10 @@ void BorderDistancesToWord(const SvxBoxItem& rBox, const WordPageMargins& rMargi
     WordBorderDistances& rDistances)
 {
     // Use signed sal_Int32 that can hold sal_uInt16, to prevent overflow at subtraction below
-    const sal_Int32 nT = rBox.GetDistance(SvxBoxItemLine::TOP);
-    const sal_Int32 nL = rBox.GetDistance(SvxBoxItemLine::LEFT);
-    const sal_Int32 nB = rBox.GetDistance(SvxBoxItemLine::BOTTOM);
-    const sal_Int32 nR = rBox.GetDistance(SvxBoxItemLine::RIGHT);
+    const sal_Int32 nT = rBox.GetDistance(SvxBoxItemLine::TOP, /*bAllowNegative=*/true);
+    const sal_Int32 nL = rBox.GetDistance(SvxBoxItemLine::LEFT, /*bAllowNegative=*/true);
+    const sal_Int32 nB = rBox.GetDistance(SvxBoxItemLine::BOTTOM, /*bAllowNegative=*/true);
+    const sal_Int32 nR = rBox.GetDistance(SvxBoxItemLine::RIGHT, /*bAllowNegative=*/true);
 
     // Only take into account existing borders
     const SvxBorderLine* pLnT = rBox.GetLine(SvxBoxItemLine::TOP);
@@ -2512,7 +2542,7 @@ void BorderDistancesToWord(const SvxBoxItem& rBox, const WordPageMargins& rMargi
 
     const sal_Int32 n32pt = 32 * 20;
     // 1. If all borders are in range of 31 pts from text
-    if (nT2BT < n32pt && nT2BL < n32pt && nT2BB < n32pt && nT2BR < n32pt)
+    if (nT2BT >= 0 && nT2BT < n32pt && nT2BL >= 0 && nT2BL < n32pt && nT2BB >= 0 && nT2BB < n32pt && nT2BR >= 0 && nT2BR < n32pt)
     {
         rDistances.bFromEdge = false;
     }