From 330f6e359897f77cf50f67141d09e94c371121ff Mon Sep 17 00:00:00 2001
From: Konstantin Ritt <ritt.ks@gmail.com>
Date: Fri, 4 Apr 2014 07:31:24 +0300
Subject: QTextLayout: Fix cursor movement from invalid position

Actually guarantee cursor doesn't move in this case for both logical
and visual modes (just what the documentation says we already do ;)

Change-Id: Iabdca7aa1d205672386a0095e3487e585611cdb5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
---
 src/gui/text/qtextengine.cpp                       | 15 ++++++----
 src/gui/text/qtextlayout.cpp                       |  5 +++-
 tests/auto/other/qcomplextext/tst_qcomplextext.cpp | 33 ++++++++++++++++++++++
 3 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index 53fd37abba..35950c709b 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -3138,11 +3138,12 @@ int QTextEngine::positionInLigature(const QScriptItem *si, int end,
 int QTextEngine::previousLogicalPosition(int oldPos) const
 {
     const QCharAttributes *attrs = attributes();
-    if (!attrs || oldPos < 0)
+    int len = block.isValid() ? block.length() - 1
+                              : layoutData->string.length();
+    Q_ASSERT(len <= layoutData->string.length());
+    if (!attrs || oldPos <= 0 || oldPos > len)
         return oldPos;
 
-    if (oldPos <= 0)
-        return 0;
     oldPos--;
     while (oldPos && !attrs[oldPos].graphemeBoundary)
         oldPos--;
@@ -3224,8 +3225,7 @@ int QTextEngine::beginningOfLine(int lineNum)
 
 int QTextEngine::positionAfterVisualMovement(int pos, QTextCursor::MoveOperation op)
 {
-    if (!layoutData)
-        itemize();
+    itemize();
 
     bool moveRight = (op == QTextCursor::Right);
     bool alignRight = isRightToLeft();
@@ -3233,7 +3233,8 @@ int QTextEngine::positionAfterVisualMovement(int pos, QTextCursor::MoveOperation
         return moveRight ^ alignRight ? nextLogicalPosition(pos) : previousLogicalPosition(pos);
 
     int lineNum = lineNumberForTextPosition(pos);
-    Q_ASSERT(lineNum >= 0);
+    if (lineNum < 0)
+        return pos;
 
     QVector<int> insertionPoints;
     insertionPointsForLine(lineNum, insertionPoints);
@@ -3256,6 +3257,8 @@ int QTextEngine::positionAfterVisualMovement(int pos, QTextCursor::MoveOperation
                 if (lineNum > 0)
                     return alignRight ? beginningOfLine(lineNum - 1) : endOfLine(lineNum - 1);
             }
+
+            break;
         }
 
     return pos;
diff --git a/src/gui/text/qtextlayout.cpp b/src/gui/text/qtextlayout.cpp
index 0c9866c6cf..c3cf2e56bb 100644
--- a/src/gui/text/qtextlayout.cpp
+++ b/src/gui/text/qtextlayout.cpp
@@ -674,7 +674,10 @@ int QTextLayout::nextCursorPosition(int oldPos, CursorMode mode) const
 int QTextLayout::previousCursorPosition(int oldPos, CursorMode mode) const
 {
     const QCharAttributes *attributes = d->attributes();
-    if (!attributes || oldPos <= 0 || oldPos > d->layoutData->string.length())
+    int len = d->block.isValid() ? d->block.length() - 1
+                                 : d->layoutData->string.length();
+    Q_ASSERT(len <= d->layoutData->string.length());
+    if (!attributes || oldPos <= 0 || oldPos > len)
         return oldPos;
 
     if (mode == SkipCharacters) {
diff --git a/tests/auto/other/qcomplextext/tst_qcomplextext.cpp b/tests/auto/other/qcomplextext/tst_qcomplextext.cpp
index 7eb8479372..cc444872ec 100644
--- a/tests/auto/other/qcomplextext/tst_qcomplextext.cpp
+++ b/tests/auto/other/qcomplextext/tst_qcomplextext.cpp
@@ -71,6 +71,8 @@ private slots:
     void bidiCursorMovement();
     void bidiCursorLogicalMovement_data();
     void bidiCursorLogicalMovement();
+    void bidiInvalidCursorNoMovement_data();
+    void bidiInvalidCursorNoMovement();
 };
 
 tst_QComplexText::tst_QComplexText()
@@ -272,6 +274,37 @@ void tst_QComplexText::bidiCursorLogicalMovement()
     } while (moved);
 }
 
+void tst_QComplexText::bidiInvalidCursorNoMovement_data()
+{
+    bidiCursorMovement_data();
+}
+
+void tst_QComplexText::bidiInvalidCursorNoMovement()
+{
+    QFETCH(QString, logical);
+    QFETCH(int,  basicDir);
+
+    QTextLayout layout(logical);
+
+    QTextOption option = layout.textOption();
+    option.setTextDirection(basicDir == QChar::DirL ? Qt::LeftToRight : Qt::RightToLeft);
+    layout.setTextOption(option);
+
+    // visual
+    QCOMPARE(layout.rightCursorPosition(-1000), -1000);
+    QCOMPARE(layout.rightCursorPosition(1000), 1000);
+
+    QCOMPARE(layout.leftCursorPosition(-1000), -1000);
+    QCOMPARE(layout.leftCursorPosition(1000), 1000);
+
+    // logical
+    QCOMPARE(layout.nextCursorPosition(-1000), -1000);
+    QCOMPARE(layout.nextCursorPosition(1000), 1000);
+
+    QCOMPARE(layout.previousCursorPosition(-1000), -1000);
+    QCOMPARE(layout.previousCursorPosition(1000), 1000);
+}
+
 void tst_QComplexText::bidiCursor_PDF()
 {
     QString str = QString::fromUtf8("\342\200\252hello\342\200\254");
-- 
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