tdf#97663 SVGIO: Fix line spacing for <tspan>

tdf#97663 is a regression caused by the commit
701324a1e1f7e0c181ff1a50956ced686785ea53. The previous patch caused
LO to forget the size of the font which was needed to calculate line
height based on em units.

em, px, pt, cm, in...
https://www.w3.org/Style/Examples/007/units.en.html

Accompanied with this fix is a unit test provided to avoid this
issue in the future.

The fix can be tested with:

    make CPPUNIT_TEST_NAME="testTdf97663" -sr \
        CppunitTest_svgio

The em_units.svg is opened with Firefox, Chrome and Inkscape and the
rendering in LibreOffice is compatible with the rendering in these
applications.

Change-Id: Idaecd9fb18101f7925fe2a917f7fc3fe7257ebc5
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/127130
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <thorsten.behrens@allotropia.de>
(cherry picked from commit 4e2e57b530544736804ab663f832173ba1d78559)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/127376
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

6 files changed, 36 insertions, 8 deletions

diff --git a/svgio/inc/svgnode.hxx b/svgio/inc/svgnode.hxx
index 63c6b2318406..58b1682506f2 100644
--- a/svgio/inc/svgnode.hxx
+++ b/svgio/inc/svgnode.hxx
@@ -159,7 +159,7 @@ namespace svgio::svgreader
             virtual double getCurrentFontSizeInherited() const override;
             virtual double getCurrentXHeightInherited() const override;
 
-            virtual double getCurrentFontSize() const;
+            double getCurrentFontSize() const;
             double getCurrentXHeight() const;
 
             /// Id access
diff --git a/svgio/inc/svgtextnode.hxx b/svgio/inc/svgtextnode.hxx
index b72d1043b8c0..37983ad31531 100644
--- a/svgio/inc/svgtextnode.hxx
+++ b/svgio/inc/svgtextnode.hxx
@@ -58,8 +58,6 @@ namespace svgio::svgreader
             virtual void parseAttribute(const OUString& rTokenName, SVGToken aSVGToken, const OUString& aContent) override;
             virtual void decomposeSvgNode(drawinglayer::primitive2d::Primitive2DContainer& rTarget, bool bReferenced) const override;
 
-            virtual double getCurrentFontSize() const override;
-
             /// transform content, set if found in current context
             const std::optional<basegfx::B2DHomMatrix>& getTransform() const { return mpaTransform; }
             void setTransform(const std::optional<basegfx::B2DHomMatrix>& pMatrix) { mpaTransform = pMatrix; }
diff --git a/svgio/inc/svgtspannode.hxx b/svgio/inc/svgtspannode.hxx
index af4ae8268b5c..10a7b7ee16a9 100644
--- a/svgio/inc/svgtspannode.hxx
+++ b/svgio/inc/svgtspannode.hxx
@@ -42,7 +42,7 @@ namespace svgio::svgreader
             virtual const SvgStyleAttributes* getSvgStyleAttributes() const override;
             virtual void parseAttribute(const OUString& rTokenName, SVGToken aSVGToken, const OUString& aContent) override;
 
-            virtual double getCurrentFontSize() const override;
+            double getCurrentFontSize() const;
 
             /// access to SvgTextPositions
             const SvgTextPositions& getSvgTextPositions() const { return maSvgTextPositions; }
diff --git a/svgio/qa/cppunit/SvgImportTest.cxx b/svgio/qa/cppunit/SvgImportTest.cxx
index 25baf76fdad8..3034c997015e 100644
--- a/svgio/qa/cppunit/SvgImportTest.cxx
+++ b/svgio/qa/cppunit/SvgImportTest.cxx
@@ -69,6 +69,7 @@ class Test : public test::BootstrapFixture, public XmlTestTools
     void testTdf101237();
     void testTdf94765();
     void testBehaviourWhenWidthAndHeightIsOrIsNotSet();
+    void testTdf97663();
 
     Primitive2DSequence parseSvg(std::u16string_view aSource);
 
@@ -104,6 +105,7 @@ public:
     CPPUNIT_TEST(testTdf101237);
     CPPUNIT_TEST(testTdf94765);
     CPPUNIT_TEST(testBehaviourWhenWidthAndHeightIsOrIsNotSet);
+    CPPUNIT_TEST(testTdf97663);
     CPPUNIT_TEST_SUITE_END();
 };
 
@@ -804,6 +806,24 @@ void Test::testBehaviourWhenWidthAndHeightIsOrIsNotSet()
     }
 }
 
+void Test::testTdf97663()
+{
+    Primitive2DSequence aSequence = parseSvg(u"/svgio/qa/cppunit/data/em_units.svg");
+    CPPUNIT_ASSERT_EQUAL(1, static_cast<int>(aSequence.getLength()));
+
+    drawinglayer::Primitive2dXmlDump dumper;
+    // This can be dumped to a file using dumper.dump(container, file_url)
+    Primitive2DContainer container = comphelper::sequenceToContainer<Primitive2DContainer>(aSequence);
+    xmlDocUniquePtr pDocument = dumper.dumpAndParse(container);
+
+    CPPUNIT_ASSERT (pDocument);
+
+    // tdf#97663: Without the fix in place, this test would have failed with
+    // - Expected: 236
+    // - Actual  : 204
+    assertXPath(pDocument, "/primitive2D/transform/textsimpleportion[2]", "y", "236");
+}
+
 CPPUNIT_TEST_SUITE_REGISTRATION(Test);
 
 }
diff --git a/svgio/qa/cppunit/data/em_units.svg b/svgio/qa/cppunit/data/em_units.svg
new file mode 100644
index 000000000000..1ad4d3e3a769
--- /dev/null
+++ b/svgio/qa/cppunit/data/em_units.svg
@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="10cm" height="10cm">
+
+  <style>
+    text {font-family: sans-serif; font-size: 36pt;}
+    new {font-family: sans-serif; font-size: 1em;}
+  </style>
+
+  <line x1="5cm" y1="5cm" x2="8cm" y2="5cm" stroke="black" />
+  <!-- 0.5in = 1.27cm = 36pt !-->
+  <line x1="5cm" y1="6.27cm" x2="8cm" y2="6.27cm" stroke="black" />
+  <text x="5cm" y="5cm" class="new">AWlll<tspan x="5cm" dy="1em">AWlll</tspan>
+  </text>
+</svg>
+
diff --git a/svgio/source/svgreader/svgtextnode.cxx b/svgio/source/svgreader/svgtextnode.cxx
index 25ad066e9bbc..a7c8cae8b8ce 100644
--- a/svgio/source/svgreader/svgtextnode.cxx
+++ b/svgio/source/svgreader/svgtextnode.cxx
@@ -255,10 +255,6 @@ namespace svgio::svgreader
             }
         }
 
-        double SvgTextNode::getCurrentFontSize() const
-        {
-            return getCurrentFontSizeInherited();
-        }
 } // end of namespace svgio::svgreader
 
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