tdf#160278: restore cursor bounds properly

The passed string length is not a correct measure of how many steps
should the selection expand in the resulting text: the cursor goes
over glyphs, not over UTF-16 code units. Thus, it's easier to store
the position prior to insertion, and restore it from the indexes.

Change-Id: I1d592ff30199007ba3a99d7e1a6d2db2da35f1cb
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/165056
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

2 files changed, 30 insertions, 3 deletions

diff --git a/sw/qa/extras/unowriter/unowriter.cxx b/sw/qa/extras/unowriter/unowriter.cxx
index c4bcbb7f5dd6..a11e928e8c1d 100644
--- a/sw/qa/extras/unowriter/unowriter.cxx
+++ b/sw/qa/extras/unowriter/unowriter.cxx
@@ -1200,6 +1200,27 @@ CPPUNIT_TEST_FIXTURE(SwUnoWriter, testTdf129841)
     CPPUNIT_ASSERT_EQUAL(aRefColor, aColor);
 }
 
+CPPUNIT_TEST_FIXTURE(SwUnoWriter, testTdf160278)
+{
+    createSwDoc();
+    auto xTextDocument(mxComponent.queryThrow<css::text::XTextDocument>());
+    auto xText(xTextDocument->getText());
+    xText->setString(u"123"_ustr);
+    CPPUNIT_ASSERT_EQUAL(u"123"_ustr, xText->getString());
+    auto xCursor = xText->createTextCursorByRange(xText->getEnd());
+    xCursor->goLeft(1, true);
+    CPPUNIT_ASSERT_EQUAL(u"3"_ustr, xCursor->getString());
+    // Insert an SMP character U+1f702 (so it's two UTF-16 code units, 0xd83d 0xdf02):
+    xCursor->setString(u"🜂"_ustr);
+    // Without the fix, the replacement would expand the cursor one too many characters to the left,
+    // and the cursor text would become "2🜂", failing the next test:
+    CPPUNIT_ASSERT_EQUAL(u"🜂"_ustr, xCursor->getString());
+    xCursor->setString(u"test"_ustr);
+    CPPUNIT_ASSERT_EQUAL(u"test"_ustr, xCursor->getString());
+    // This test would fail, too; the text would be "1test":
+    CPPUNIT_ASSERT_EQUAL(u"12test"_ustr, xText->getString());
+}
+
 } // end of anonymous namespace
 CPPUNIT_PLUGIN_IMPLEMENT();
 
diff --git a/sw/source/core/unocore/unoobj.cxx b/sw/source/core/unocore/unoobj.cxx
index 3c5f34f1940a..69fa9d3be300 100644
--- a/sw/source/core/unocore/unoobj.cxx
+++ b/sw/source/core/unocore/unoobj.cxx
@@ -752,13 +752,19 @@ void SwXTextCursor::DeleteAndInsert(std::u16string_view aText,
         }
         if(nTextLen)
         {
+            // Store node and content indexes prior to insertion: to select the inserted text,
+            // we need to account for possible surrogate pairs, combining characters, etc.; it
+            // is easier to just restore the correct position from the indexes.
+            const auto start = pCurrent->Start();
+            const auto nodeIndex = start->GetNodeIndex();
+            const auto contentIndex = start->GetContentIndex();
             const bool bSuccess(
                 SwUnoCursorHelper::DocInsertStringSplitCR(
-                    rDoc, *pCurrent, aText, bool(eMode & ::sw::DeleteAndInsertMode::ForceExpandHints)));
+                    rDoc, SwPaM(*start, pCurrent), aText, bool(eMode & ::sw::DeleteAndInsertMode::ForceExpandHints)));
             OSL_ENSURE( bSuccess, "Doc->Insert(Str) failed." );
 
-            SwUnoCursorHelper::SelectPam(*pUnoCursor, true);
-            pCurrent->Left(aText.size());
+            pCurrent->SetMark();
+            pCurrent->GetPoint()->Assign(nodeIndex, contentIndex);
         }
         pCurrent = pCurrent->GetNext();
     } while (pCurrent != pUnoCursor);