tdf#36709 Add loext:text-indent supporting font-relative units

This change adds an ODF font-relative first-line indent paragraph style
attribute as a LibreOffice extension. The corresponding ODF standard
change is tracked by OFFICE-4165.

This change only implements what is minimally necessary to serialize,
deserialize, and check for ODF files containing this attribute. Further
changes are necessary.

* Added cssLength to schema, which is equivalent to length but also
  allows ic and em as units.
* Added loext:text-indent to schema as a paragraph style attribute. This
  attribute is equivalent to fo:text-indent, but accepts cssLength
  instead of length.
* Added XML_TYPE_UNIT_MEASURE to the ODF parser, which currently accepts
  only the font-relative measures and forces fallback in other cases.
* Added loext:text-indent to the ODF parser. This attribute accepts
  font-relative metrics, and will behave as an import-only alias for
  fo:text-indent in other cases.
* Updated SvxFirstLineIndentItem to handle unit-denominated measures.
* Added proof-of-concept indentation handler to Writer. This
  implementation is incomplete and temporary, and will be revised in
  future changes.

Change-Id: I7eb5c7382093cb18a9b0afbf93dacb34ba1d35ef
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/175941
Tested-by: Jenkins
Reviewed-by: Jonathan Clark <jonathan@libreoffice.org>

2 files changed, 56 insertions, 0 deletions

diff --git a/xmloff/source/style/prhdlfac.cxx b/xmloff/source/style/prhdlfac.cxx
index a14d61ea31c2..fd6dae604bf8 100644
--- a/xmloff/source/style/prhdlfac.cxx
+++ b/xmloff/source/style/prhdlfac.cxx
@@ -195,6 +195,9 @@ std::unique_ptr<XMLPropertyHandler> XMLPropertyHandlerFactory::CreatePropertyHan
         case XML_TYPE_MEASURE16:
             pPropHdl.reset(new XMLMeasurePropHdl( 2 ));
             break;
+        case XML_TYPE_UNIT_MEASURE:
+            pPropHdl = std::make_unique<XMLUnitMeasurePropHdl>();
+            break;
         case XML_TYPE_PERCENT :
             pPropHdl.reset(new XMLPercentPropHdl( 4 ));
             break;
diff --git a/xmloff/source/style/xmlbahdl.cxx b/xmloff/source/style/xmlbahdl.cxx
index a0aea8ccb1a4..02c271ad6a2e 100644
--- a/xmloff/source/style/xmlbahdl.cxx
+++ b/xmloff/source/style/xmlbahdl.cxx
@@ -27,6 +27,7 @@
 #include <sax/tools/converter.hxx>
 #include <xmloff/xmluconv.hxx>
 #include <com/sun/star/uno/Any.hxx>
+#include <com/sun/star/beans/Pair.hpp>
 #include <xmloff/xmltoken.hxx>
 
 #include <limits.h>
@@ -207,6 +208,58 @@ bool XMLMeasurePropHdl::exportXML( OUString& rStrExpValue, const Any& rValue, co
 }
 
 
+bool XMLUnitMeasurePropHdl::importXML( const OUString& rStrImpValue, Any& rValue, const SvXMLUnitConverter& ) const
+{
+    double fValue = 0.0;
+    std::optional<sal_Int16> nValueUnit;
+
+    auto bRet = ::sax::Converter::convertMeasureUnit( fValue, nValueUnit, rStrImpValue );
+
+    if(bRet)
+    {
+        // This importer may only accept font-relative units.
+        // Discard all other units to allow fall-through to other attributes.
+        if (css::util::MeasureUnit::FONT_EM != nValueUnit
+            && css::util::MeasureUnit::FONT_IC != nValueUnit)
+        {
+            return false;
+        }
+
+        css::beans::Pair<double, sal_Int16> stValue{fValue, nValueUnit.value()};
+        rValue <<= stValue;
+    }
+
+    return bRet;
+}
+
+bool XMLUnitMeasurePropHdl::exportXML( OUString& rStrExpValue, const Any& rValue, const SvXMLUnitConverter& ) const
+{
+    bool bRet = false;
+    css::beans::Pair<double, sal_Int16> stValue{0.0, css::util::MeasureUnit::MM_100TH};
+
+    if( rValue >>= stValue )
+    {
+        auto [fValue, nValueUnit] = stValue;
+
+        // This exporter may only produce font-relative units.
+        // Discard all other units to allow fall-through to other attributes.
+        if (css::util::MeasureUnit::FONT_EM != nValueUnit
+            && css::util::MeasureUnit::FONT_IC != nValueUnit)
+        {
+            return false;
+        }
+
+        OUStringBuffer aOut;
+        ::sax::Converter::convertMeasureUnit( aOut, fValue, nValueUnit );
+        rStrExpValue = aOut.makeStringAndClear();
+
+        bRet = true;
+    }
+
+    return bRet;
+}
+
+
 XMLBoolFalsePropHdl::~XMLBoolFalsePropHdl()
 {
     // nothing to do