Fix cursor positioning on bidi boundaries

When the cursor is positioned between to script items that have different
writing directions, prioritise the script item that has the same direction
as the paragraph (i.e. the QTextEngine) when deciding where and how to
display the cursor. If visual cursor movement is enabled, the behavior is
unchanged.

As a drive-by, clean up coding style and avoid shadowing of function-
local variables.

Task-number: QTBUG-88529
Pick-to: 6.2
Change-Id: I15227b10b1469d9caf1235b00e4d6f9f64a8b510
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 58 insertions, 0 deletions

diff --git a/tests/auto/gui/text/qtextlayout/tst_qtextlayout.cpp b/tests/auto/gui/text/qtextlayout/tst_qtextlayout.cpp
index a4c848c1ec..32a0374fcd 100644
--- a/tests/auto/gui/text/qtextlayout/tst_qtextlayout.cpp
+++ b/tests/auto/gui/text/qtextlayout/tst_qtextlayout.cpp
@@ -74,6 +74,8 @@ private slots:
     void cursorToXForTrailingSpaces_data();
     void cursorToXForTrailingSpaces();
     void cursorToXInvalidInput();
+    void cursorToXForBidiBoundaries_data();
+    void cursorToXForBidiBoundaries();
 
     void horizontalAlignment_data();
     void horizontalAlignment();
@@ -738,6 +740,58 @@ void tst_QTextLayout::cursorToXInvalidInput()
     QCOMPARE(cursorPos, 3);
 }
 
+void tst_QTextLayout::cursorToXForBidiBoundaries_data()
+{
+    QTest::addColumn<Qt::LayoutDirection>("textDirection");
+    QTest::addColumn<QString>("text");
+    QTest::addColumn<int>("cursorPosition");
+    QTest::addColumn<int>("expectedX");
+
+    QTest::addRow("LTR, abcشزذabc, 0") << Qt::LeftToRight << "abcشزذabc"
+        << 0 << 0;
+    QTest::addRow("RTL, abcشزذabc, 9") << Qt::RightToLeft << "abcشزذabc"
+        << 9 << TESTFONT_SIZE * 3;
+    QTest::addRow("LTR, abcشزذabc, 3") << Qt::LeftToRight << "abcشزذabc"
+        << 0 << 0;
+    QTest::addRow("RTL, abcشزذabc, 6") << Qt::RightToLeft << "abcشزذabc"
+        << 9 << TESTFONT_SIZE * 3;
+
+    QTest::addRow("LTR, شزذabcشزذ, 0") << Qt::LeftToRight << "شزذabcشزذ"
+        << 0 << TESTFONT_SIZE * 2;
+    QTest::addRow("RTL, شزذabcشزذ, 9") << Qt::RightToLeft << "شزذabcشزذ"
+        << 9 << 0;
+    QTest::addRow("LTR, شزذabcشزذ, 3") << Qt::LeftToRight << "شزذabcشزذ"
+        << 3 << TESTFONT_SIZE * 2;
+    QTest::addRow("RTL, شزذabcشزذ, 3") << Qt::RightToLeft << "شزذabcشزذ"
+        << 3 << TESTFONT_SIZE * 5;
+    QTest::addRow("LTR, شزذabcشزذ, 6") << Qt::LeftToRight << "شزذabcشزذ"
+        << 6 << TESTFONT_SIZE * 5;
+    QTest::addRow("RTL, شزذabcشزذ, 6") << Qt::RightToLeft << "شزذabcشزذ"
+        << 6 << TESTFONT_SIZE * 2;
+}
+
+void tst_QTextLayout::cursorToXForBidiBoundaries()
+{
+    QFETCH(Qt::LayoutDirection, textDirection);
+    QFETCH(QString, text);
+    QFETCH(int, cursorPosition);
+    QFETCH(int, expectedX);
+
+    QTextOption option;
+    option.setTextDirection(textDirection);
+
+    QTextLayout layout(text, testFont);
+    layout.setTextOption(option);
+    layout.beginLayout();
+
+    QTextLine line = layout.createLine();
+    line.setLineWidth(0x10000);
+
+    QCOMPARE(line.cursorToX(cursorPosition), expectedX);
+
+    layout.endLayout();
+}
+
 void tst_QTextLayout::horizontalAlignment_data()
 {
     qreal width = TESTFONT_SIZE * 4;
@@ -1146,6 +1200,10 @@ void tst_QTextLayout::xToCursorForBidiEnds_data()
         << 0 << 6;
     QTest::addRow("RTL, شزذabc") << Qt::RightToLeft << "شزذabc"
         << 6 << 0;
+    QTest::addRow("LTR, شزذ123") << Qt::LeftToRight << "شزذ123"
+        << 0 << 6;
+    QTest::addRow("RTL, شزذ123") << Qt::RightToLeft << "شزذ123"
+        << 6 << 0;
 
     QTest::addRow("LTR, abcشزذabc") << Qt::LeftToRight << "abcشزذabc"
         << 0 << 9;