QTextEngine: micro optimize insertionPointsForLine

Don't use out param, use return by value instead.
Also since we don't need CoW replace QVector with std::vector

Change-Id: I5b6ea286b83e2ab959b5734cc1af31cc63c06553
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/gui/text/qtextengine.cpp

@@ -3309,11 +3309,12 @@ int QTextEngine::lineNumberForTextPosition(int pos)
     return -1;
 }
 
-void QTextEngine::insertionPointsForLine(int lineNum, QVector<int> &insertionPoints)
+std::vector<int> QTextEngine::insertionPointsForLine(int lineNum)
 {
     QTextLineItemIterator iterator(this, lineNum);
 
-    insertionPoints.reserve(iterator.line.length);
+    std::vector<int> insertionPoints;
+    insertionPoints.reserve(size_t(iterator.line.length));
 
     bool lastLine = lineNum >= lines.size() - 1;
 
@@ -3331,25 +3332,22 @@ void QTextEngine::insertionPointsForLine(int lineNum, QVector<int> &insertionPoi
                 insertionPoints.push_back(i);
         }
     }
+    return insertionPoints;
 }
 
 int QTextEngine::endOfLine(int lineNum)
 {
-    QVector<int> insertionPoints;
-    insertionPointsForLine(lineNum, insertionPoints);
-
+    const auto insertionPoints = insertionPointsForLine(lineNum);
     if (insertionPoints.size() > 0)
-        return insertionPoints.constLast();
+        return insertionPoints.back();
     return 0;
 }
 
 int QTextEngine::beginningOfLine(int lineNum)
 {
-    QVector<int> insertionPoints;
-    insertionPointsForLine(lineNum, insertionPoints);
-
+    const auto insertionPoints = insertionPointsForLine(lineNum);
     if (insertionPoints.size() > 0)
-        return insertionPoints.constFirst();
+        return insertionPoints.front();
     return 0;
 }
 
@@ -3366,10 +3364,8 @@ int QTextEngine::positionAfterVisualMovement(int pos, QTextCursor::MoveOperation
     if (lineNum < 0)
         return pos;
 
-    QVector<int> insertionPoints;
-    insertionPointsForLine(lineNum, insertionPoints);
-    int i, max = insertionPoints.size();
-    for (i = 0; i < max; i++)
+    const auto insertionPoints = insertionPointsForLine(lineNum);
+    for (size_t i = 0, max = insertionPoints.size(); i < max; ++i)
         if (pos == insertionPoints[i]) {
             if (moveRight) {
                 if (i + 1 < max)

src/gui/text/qtextengine_p.h

@@ -74,6 +74,7 @@
 #include <private/qunicodetools_p.h>
 
 #include <stdlib.h>
+#include <vector>
 
 QT_BEGIN_NAMESPACE
 
@@ -624,7 +625,7 @@ public:
     int nextLogicalPosition(int oldPos) const;
     int lineNumberForTextPosition(int pos);
     int positionAfterVisualMovement(int oldPos, QTextCursor::MoveOperation op);
-    void insertionPointsForLine(int lineNum, QVector<int> &insertionPoints);
+    std::vector<int> insertionPointsForLine(int lineNum);
     void resetFontEngineCache();
 
     void enableDelayDecorations(bool enable = true) { delayDecorations = enable; }

src/gui/text/qtextlayout.cpp

@@ -2840,9 +2840,7 @@ int QTextLine::xToCursor(qreal _x, CursorPosition cpos) const
         bool rtl = eng->isRightToLeft();
 
         eng->shapeLine(line);
-        QVector<int> insertionPoints;
-        if (visual && rtl)
-            eng->insertionPointsForLine(lineNum, insertionPoints);
+        const auto insertionPoints = (visual && rtl) ? eng->insertionPointsForLine(lineNum) : std::vector<int>();
         int nchars = 0;
         for (int i = 0; i < nItems; ++i) {
             int item = visualOrder[i]+firstItem;
@@ -2974,7 +2972,7 @@ int QTextLine::xToCursor(qreal _x, CursorPosition cpos) const
                             continue;
                         }
                         if (rtl && nchars > 0)
-                            return insertionPoints[lastLine ? nchars : nchars - 1];
+                            return insertionPoints[size_t(lastLine ? nchars : nchars - 1)];
                     }
                     return eng->positionInLigature(&si, end, x, pos, -1,
                                                    cpos == QTextLine::CursorOnCharacter);