fdo#47764 fix RTF import of automatic paragraph background color

Change-Id: I4b3a4bd6ce45cffc5b2c23052c49ff98579c5564

sw/qa/extras/rtftok/data/fdo47764.rtf

@@ -0,0 +1,4 @@
+{\rtf1
+\cbpat0\cf0
+bug
+}

sw/qa/extras/rtftok/rtftok.cxx

@@ -91,6 +91,7 @@ public:
     void testFdo48193();
     void testFdo44211();
     void testFdo48037();
+    void testFdo47764();
 
     CPPUNIT_TEST_SUITE(Test);
 #if !defined(MACOSX) && !defined(WNT)
@@ -120,6 +121,7 @@ public:
     CPPUNIT_TEST(testFdo48193);
     CPPUNIT_TEST(testFdo44211);
     CPPUNIT_TEST(testFdo48037);
+    CPPUNIT_TEST(testFdo47764);
 #endif
     CPPUNIT_TEST_SUITE_END();
 
@@ -660,6 +662,20 @@ void Test::testFdo48037()
     CPPUNIT_ASSERT_EQUAL(nExpected, nActual);
 }
 
+void Test::testFdo47764()
+{
+    load("fdo47764.rtf");
+
+    uno::Reference<text::XTextDocument> xTextDocument(mxComponent, uno::UNO_QUERY);
+    uno::Reference<container::XEnumerationAccess> xParaEnumAccess(xTextDocument->getText(), uno::UNO_QUERY);
+    uno::Reference<container::XEnumeration> xParaEnum = xParaEnumAccess->createEnumeration();
+    uno::Reference<beans::XPropertySet> xPropertySet(xParaEnum->nextElement(), uno::UNO_QUERY);
+    sal_Int32 nValue = 0;
+    // \cbpat with zero argument should mean the auto (-1) color, not a default color (black)
+    xPropertySet->getPropertyValue("ParaBackColor") >>= nValue;
+    CPPUNIT_ASSERT_EQUAL(sal_Int32(-1), nValue);
+}
+
 CPPUNIT_TEST_SUITE_REGISTRATION(Test);
 
 CPPUNIT_PLUGIN_IMPLEMENT();

writerfilter/source/rtftok/rtfdocumentimpl.cxx

@@ -2331,6 +2331,7 @@ int RTFDocumentImpl::dispatchValue(RTFKeyword nKeyword, int nParam)
             }
             break;
         case RTF_CBPAT:
+            if (nParam)
             {
                 RTFValue::Pointer_t pValue(new RTFValue(getColorTable(nParam)));
                 lcl_putNestedAttribute(m_aStates.top().aParagraphSprms, NS_sprm::LN_PShd, NS_ooxml::LN_CT_Shd_fill, pValue);