tdf#166789: use text width from DXArray in MetaActionType::TEXTARRAY

DXArray gives much more reliable data compared to font width, which
is known to require complex corrections (see tdf#127471 and commit
3d33e4ce39).

This fix uses tspan's `lengthAdjust` and `textLength` attributes for
automatic justification, which are already documented as early as in
SVG 1.0 ( https://www.w3.org/TR/SVG10/text.html#TSpanElement ). This
works in LibreOffice and in Chrome, but is not supported in Firefox
yet ( see https://bugzilla.mozilla.org/show_bug.cgi?id=890692 ).

I considered using these attributes on `text` element level, which
is supported in both browsers - but that breaks text elements with
multiple tspans. The `transform` attribute can't be used with tspan
both in Chrome and in Firefox, which creates the same problem, and
has an additional drawback that tspan offsets need tweaks.

Change-Id: I7d4bbb7542a9d60e53bdf6f6cac7fae0729e6e48
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/186033
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

filter/qa/unit/data/fit-to-size-text.fodg

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<office:document xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0" xmlns:fo="urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0" xmlns:style="urn:oasis:names:tc:opendocument:xmlns:style:1.0" xmlns:text="urn:oasis:names:tc:opendocument:xmlns:text:1.0" xmlns:draw="urn:oasis:names:tc:opendocument:xmlns:drawing:1.0" xmlns:svg="urn:oasis:names:tc:opendocument:xmlns:svg-compatible:1.0" office:version="1.4" office:mimetype="application/vnd.oasis.opendocument.graphics">
+ <office:font-face-decls>
+  <style:font-face style:name="Liberation Sans" svg:font-family="&apos;Liberation Sans&apos;" style:font-family-generic="roman" style:font-pitch="variable"/>
+ </office:font-face-decls>
+ <office:styles>
+  <style:style style:name="standard" style:family="graphic">
+   <style:graphic-properties draw:stroke="solid" svg:stroke-color="#000000" svg:stroke-width="5" draw:fill="none" fo:padding-top="0" fo:padding-bottom="0" fo:padding-left="0" fo:padding-right="0"/>
+   <style:text-properties style:font-name="Liberation Sans" fo:font-size="18pt" fo:font-variant="normal" fo:language="zxx" fo:country="none" fo:font-style="normal" style:letter-kerning="true"/>
+  </style:style>
+ </office:styles>
+ <office:automatic-styles>
+  <style:page-layout style:name="PM0">
+   <style:page-layout-properties fo:margin-top="0" fo:margin-bottom="0" fo:margin-left="0" fo:margin-right="0" fo:page-width="8cm" fo:page-height="15mm"/>
+  </style:page-layout>
+  <style:style style:name="gr1" style:family="graphic" style:parent-style-name="standard">
+   <style:graphic-properties draw:auto-grow-height="false" draw:auto-grow-width="false" draw:fit-to-size="true" style:shrink-to-fit="false"/>
+  </style:style>
+ </office:automatic-styles>
+ <office:master-styles>
+  <style:master-page style:name="Standard" style:page-layout-name="PM0"/>
+ </office:master-styles>
+ <office:body>
+  <office:drawing>
+   <draw:page draw:name="page1" draw:master-page-name="Standard">
+    <draw:frame draw:style-name="gr1" svg:width="7cm" svg:height="5mm" svg:x="5mm" svg:y="5mm">
+     <draw:text-box>
+      <text:p>= Foo(Bar).method&lt;templateArg&gt;(arg1, arg2, ...)</text:p>
+     </draw:text-box>
+    </draw:frame>
+   </draw:page>
+  </office:drawing>
+ </office:body>
+</office:document>

filter/qa/unit/svg.cxx

@@ -20,6 +20,7 @@
 #include <com/sun/star/beans/XPropertySet.hpp>
 
 #include <comphelper/propertyvalue.hxx>
+#include <o3tl/string_view.hxx>
 #include <unotools/streamwrap.hxx>
 #include <unotools/mediadescriptor.hxx>
 #include <tools/stream.hxx>
@@ -379,6 +380,21 @@ CPPUNIT_TEST_FIXTURE(SvgFilterTest, testTdf91315)
     // - Actual  : 0
 }
 
+CPPUNIT_TEST_FIXTURE(SvgFilterTest, testTdf166789)
+{
+    // A fit-to-size text
+    loadFromFile(u"fit-to-size-text.fodg");
+
+    save(u"impress_svg_Export"_ustr);
+
+    xmlDocUniquePtr pXmlDoc = parseExportedFile();
+
+    // Without the accompanying fix, the text wasn't adjusted to the given width
+    OUString length = getXPath(pXmlDoc, "//svg:text//svg:tspan[@lengthAdjust='spacingAndGlyphs']",
+                               "textLength");
+    CPPUNIT_ASSERT_DOUBLES_EQUAL(7000, length.toInt32(), 70); // allow 1% for rounding errors
+}
+
 CPPUNIT_PLUGIN_IMPLEMENT();
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

filter/source/svg/svgwriter.cxx

@@ -1623,8 +1623,7 @@ void SVGTextWriter::implWriteEmbeddedBitmaps()
 }
 
 
-void SVGTextWriter::writeTextPortion( const Point& rPos,
-                                      const OUString& rText )
+void SVGTextWriter::writeTextPortion(const Point& rPos, const OUString& rText, tools::Long nWidth)
 {
     if( rText.isEmpty() )
         return;
@@ -1703,7 +1702,7 @@ void SVGTextWriter::writeTextPortion( const Point& rPos,
         // to be implemented
     }
 #else
-    implWriteTextPortion( rPos, rText, mpVDev->GetTextColor() );
+    implWriteTextPortion( rPos, rText, mpVDev->GetTextColor(), nWidth );
 #endif
 
     if( bStandAloneTextPortion )
@@ -1713,9 +1712,8 @@ void SVGTextWriter::writeTextPortion( const Point& rPos,
 }
 
 
-void SVGTextWriter::implWriteTextPortion( const Point& rPos,
-                                          const OUString& rText,
-                                          Color aTextColor )
+void SVGTextWriter::implWriteTextPortion(const Point& rPos, const OUString& rText, Color aTextColor,
+                                         tools::Long nWidth)
 {
     Point                                   aPos;
     Point                                   aBaseLinePos( rPos );
@@ -1808,6 +1806,18 @@ void SVGTextWriter::implWriteTextPortion( const Point& rPos,
 
     addFontAttributes( /* isTexTContainer: */ false );
 
+    tools::Long nTextWidth;
+    if (nWidth)
+    {
+        Size size;
+        implMap(Size(nWidth, 0), size);
+        nTextWidth = size.Width();
+        mrExport.AddAttribute(XML_NAMESPACE_NONE, u"lengthAdjust"_ustr, u"spacingAndGlyphs"_ustr);
+        mrExport.AddAttribute(XML_NAMESPACE_NONE, u"textLength"_ustr, OUString::number(nTextWidth));
+    }
+    else
+        nTextWidth = mpVDev->GetTextWidth(rText);
+
     if (!maTextOpacity.isEmpty())
     {
         mrExport.AddAttribute(XML_NAMESPACE_NONE, u"fill-opacity"_ustr, maTextOpacity);
@@ -1843,7 +1853,7 @@ void SVGTextWriter::implWriteTextPortion( const Point& rPos,
         mrExport.GetDocHandler()->characters( rText );
     }
 
-    mnTextWidth += mpVDev->GetTextWidth( rText );
+    mnTextWidth += nTextWidth;
 }
 
 
@@ -4013,7 +4023,10 @@ void SVGActionWriter::ImplWriteActions( const GDIMetaFile& rMtf,
                         }
                         else
                         {
-                            maTextWriter.writeTextPortion( pA->GetPoint(), aText );
+                            tools::Long nWidth = 0;
+                            if (pA->GetDXArray().size() >= o3tl::make_unsigned(aText.getLength()))
+                                nWidth = std::round(pA->GetDXArray()[aText.getLength() - 1]);
+                            maTextWriter.writeTextPortion(pA->GetPoint(), aText, nWidth);
                         }
                     }
                 }

filter/source/svg/svgwriter.hxx

@@ -259,9 +259,9 @@ class SVGTextWriter final
     template< typename MetaBitmapActionType >
     void writeBitmapPlaceholder( const MetaBitmapActionType* pAction );
     void implWriteEmbeddedBitmaps();
-    void writeTextPortion( const Point& rPos, const OUString& rText );
+    void writeTextPortion(const Point& rPos, const OUString& rText, tools::Long nWidth = 0);
     void implWriteTextPortion( const Point& rPos, const OUString& rText,
-                               Color aTextColor );
+                               Color aTextColor, tools::Long nWidth );
 
     void setVirtualDevice( VirtualDevice* pVDev, MapMode& rTargetMapMode )
     {