Use QVector::reserve() all over the place.

Reduces internal memory fragmentation.

The search criteria was:
QVector::append(), QVector::push_back(), QVector::operator<<()
and QVector::operator+=() calls inside for, do and while loops.
Statements inside ifs and out of loops weren't considered.

Change-Id: Ie5aaf3cdfac938994e6e5dfa5f51de501ed79a0c
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/corelib/itemmodels/qsortfilterproxymodel.cpp

@@ -2128,6 +2128,7 @@ bool QSortFilterProxyModel::removeRows(int row, int count, const QModelIndex &pa
     // remove corresponding source intervals
     // ### if this proves to be slow, we can switch to single-row removal
     QVector<int> rows;
+    rows.reserve(count);
     for (int i = row; i < row + count; ++i)
         rows.append(m->source_rows.at(i));
     std::sort(rows.begin(), rows.end());
@@ -2167,6 +2168,7 @@ bool QSortFilterProxyModel::removeColumns(int column, int count, const QModelInd
     }
     // remove corresponding source intervals
     QVector<int> columns;
+    columns.reserve(count);
     for (int i = column; i < column + count; ++i)
         columns.append(m->source_columns.at(i));
 

src/corelib/tools/qeasingcurve.cpp

@@ -1219,6 +1219,7 @@ QVector<QPointF> static inline tcbToBezier(const TCBPoints &tcbPoints)
 {
     const int count = tcbPoints.count();
     QVector<QPointF> bezierPoints;
+    bezierPoints.reserve(3 * (count - 1));
 
     for (int i = 1; i < count; i++) {
         const qreal t_0 = tcbPoints.at(i - 1)._t;

src/corelib/tools/qtimezone.cpp

@@ -764,6 +764,7 @@ QTimeZone::OffsetDataList QTimeZone::transitions(const QDateTime &fromDateTime,
     if (hasTransitions()) {
         QTimeZonePrivate::DataList plist = d->transitions(fromDateTime.toMSecsSinceEpoch(),
                                                           toDateTime.toMSecsSinceEpoch());
+        list.reserve(plist.count());
         foreach (const QTimeZonePrivate::Data &pdata, plist)
             list.append(d->toOffsetData(pdata));
     }

src/corelib/tools/qtimezoneprivate_tz.cpp

@@ -630,6 +630,7 @@ void QTzTimeZonePrivate::init(const QByteArray &ianaId)
     }
 
     // Now for each transition time calculate our rule and save them
+    m_tranTimes.reserve(tranList.count());
     foreach (const QTzTransition &tz_tran, tranList) {
         QTzTransitionTime tran;
         QTzTransitionRule rule;

src/gui/image/qpaintengine_pic.cpp

@@ -398,6 +398,7 @@ void QPicturePaintEngine::drawPolygon(const QPointF *points, int numPoints, Poly
     int pos;
 
     QPolygonF polygon;
+    polygon.reserve(numPoints);
     for (int i=0; i<numPoints; ++i)
         polygon << points[i];
 

src/gui/painting/qplatformbackingstore.cpp

@@ -220,7 +220,9 @@ static QRegion deviceRegion(const QRegion &region, QWindow *window)
         return region;
 
     QVector<QRect> rects;
-    foreach (QRect rect, region.rects())
+    const QVector<QRect> regionRects = region.rects();
+    rects.reserve(regionRects.count());
+    foreach (const QRect &rect, regionRects)
         rects.append(deviceRect(rect, window));
 
     QRegion deviceRegion;

src/gui/painting/qtransform.cpp

@@ -1381,7 +1381,9 @@ static QPolygonF mapProjective(const QTransform &transform, const QPolygonF &pol
     path = transform.map(path);
 
     QPolygonF result;
-    for (int i = 0; i < path.elementCount(); ++i)
+    const int elementCount = path.elementCount();
+    result.reserve(elementCount);
+    for (int i = 0; i < elementCount; ++i)
         result << path.elementAt(i);
     return result;
 }

src/network/ssl/qsslsocket_openssl.cpp

@@ -671,6 +671,7 @@ void QSslSocketPrivate::resetDefaultEllipticCurves()
     QVarLengthArray<EC_builtin_curve> builtinCurves(static_cast<int>(curveCount));
 
     if (q_EC_get_builtin_curves(builtinCurves.data(), curveCount) == curveCount) {
+        curves.reserve(int(curveCount));
         for (size_t i = 0; i < curveCount; ++i) {
             QSslEllipticCurve curve;
             curve.id = builtinCurves[int(i)].nid;

src/platformsupport/dbustray/qdbustraytypes.cpp

@@ -82,6 +82,8 @@ QXdgDBusImageVector iconToQXdgDBusImageVector(const QIcon &icon)
         sizes.append(QSize(IconNormalSmallSize * dpr, IconNormalSmallSize * dpr));
     if (!hasMediumIcon)
         sizes.append(QSize(IconNormalMediumSize * dpr, IconNormalMediumSize * dpr));
+
+    ret.reserve(sizes.size());
     foreach (QSize size, sizes) {
         // Protocol specifies ARGB32 format in network byte order
         QImage im = icon.pixmap(size).toImage().convertToFormat(QImage::Format_ARGB32);

src/platformsupport/fbconvenience/qfbscreen.cpp

@@ -206,10 +206,11 @@ void QFbScreen::generateRects()
         }
 #endif
     }
-    foreach (const QRect &rect, remainingScreen.rects())
+    const QVector<QRect> remainingScreenRects = remainingScreen.rects();
+    mCachedRects.reserve(mCachedRects.count() + remainingScreenRects.count());
+    foreach (const QRect &rect, remainingScreenRects)
         mCachedRects += QPair<QRect, int>(rect, -1);
     mIsUpToDate = true;
-    return;
 }
 
 QRegion QFbScreen::doRedraw()

src/plugins/platforms/xcb/qxcbdrag.cpp

@@ -689,6 +689,7 @@ void QXcbDrag::handleEnter(QWindow *window, const xcb_client_message_event_t *ev
                 length = xdnd_max_type;
 
             xcb_atom_t *atoms = (xcb_atom_t *)xcb_get_property_value(reply);
+            xdnd_types.reserve(length);
             for (int i = 0; i < length; ++i)
                 xdnd_types.append(atoms[i]);
         }

src/plugins/platforms/xcb/qxcbwindow.cpp

@@ -2688,7 +2688,9 @@ void QXcbWindow::setMask(const QRegion &region)
     } else {
         const int dpr = devicePixelRatio();
         QVector<xcb_rectangle_t> rects;
-        foreach (const QRect &r, region.rects())
+        const QVector<QRect> regionRects = region.rects();
+        rects.reserve(regionRects.count());
+        foreach (const QRect &r, regionRects)
             rects.push_back(qRectToXCBRectangle(mapLocalGeometryToNative(r, dpr)));
         xcb_shape_rectangles(connection()->xcb_connection(), XCB_SHAPE_SO_SET,
                              XCB_SHAPE_SK_BOUNDING, XCB_CLIP_ORDERING_UNSORTED,

src/plugins/printsupport/cups/qppdprintdevice.cpp

@@ -267,6 +267,7 @@ void QPpdPrintDevice::loadInputSlots() const
     if (m_ppd) {
         ppd_option_t *inputSlots = ppdFindOption(m_ppd, "InputSlot");
         if (inputSlots) {
+            m_inputSlots.reserve(inputSlots->num_choices);
             for (int i = 0; i < inputSlots->num_choices; ++i)
                 m_inputSlots.append(QPrintUtils::ppdChoiceToInputSlot(inputSlots->choices[i]));
         }
@@ -307,6 +308,7 @@ void QPpdPrintDevice::loadOutputBins() const
     if (m_ppd) {
         ppd_option_t *outputBins = ppdFindOption(m_ppd, "OutputBin");
         if (outputBins) {
+            m_outputBins.reserve(outputBins->num_choices);
             for (int i = 0; i < outputBins->num_choices; ++i)
                 m_outputBins.append(QPrintUtils::ppdChoiceToOutputBin(outputBins->choices[i]));
         }
@@ -348,6 +350,7 @@ void QPpdPrintDevice::loadDuplexModes() const
     if (m_ppd) {
         ppd_option_t *duplexModes = ppdFindOption(m_ppd, "Duplex");
         if (duplexModes) {
+            m_duplexModes.reserve(duplexModes->num_choices);
             for (int i = 0; i < duplexModes->num_choices; ++i)
                 m_duplexModes.append(QPrintUtils::ppdChoiceToDuplexMode(duplexModes->choices[i].choice));
         }

src/widgets/dialogs/qwizard.cpp

@@ -751,6 +751,7 @@ void QWizardPrivate::init()
 
     updateButtonLayout();
 
+    defaultPropertyTable.reserve(NFallbackDefaultProperties);
     for (uint i = 0; i < NFallbackDefaultProperties; ++i)
         defaultPropertyTable.append(QWizardDefaultProperty(fallbackProperties[i].className,
                                                            fallbackProperties[i].property,

src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp

@@ -751,6 +751,7 @@ static AnchorData *createSequence(Graph<AnchorVertex, AnchorData> *graph,
 
     AnchorVertex *prev = before;
     QVector<AnchorData *> edges;
+    edges.reserve(vertices.count() + 1);
 
     const int numVertices = vertices.count();
     edges.reserve(numVertices + 1);

src/widgets/graphicsview/qgraphicsview.cpp

@@ -2464,6 +2464,7 @@ QPolygonF QGraphicsView::mapToScene(const QRect &rect) const
 QPolygonF QGraphicsView::mapToScene(const QPolygon &polygon) const
 {
     QPolygonF poly;
+    poly.reserve(polygon.count());
     foreach (const QPoint &point, polygon)
         poly << mapToScene(point);
     return poly;
@@ -2559,6 +2560,7 @@ QPolygon QGraphicsView::mapFromScene(const QRectF &rect) const
 QPolygon QGraphicsView::mapFromScene(const QPolygonF &polygon) const
 {
     QPolygon poly;
+    poly.reserve(polygon.count());
     foreach (const QPointF &point, polygon)
         poly << mapFromScene(point);
     return poly;
@@ -2673,7 +2675,9 @@ void QGraphicsView::updateScene(const QList<QRectF> &rects)
     // Extract and reset dirty scene rect info.
     QVector<QRect> dirtyViewportRects;
     const QVector<QRect> &dirtyRects = d->dirtyRegion.rects();
-    for (int i = 0; i < dirtyRects.size(); ++i)
+    const int dirtyRectsCount = dirtyRects.size();
+    dirtyViewportRects.reserve(dirtyRectsCount + rects.count());
+    for (int i = 0; i < dirtyRectsCount; ++i)
         dirtyViewportRects += dirtyRects.at(i);
     d->dirtyRegion = QRegion();
     d->dirtyBoundingRect = QRect();

src/widgets/itemviews/qcolumnview.cpp

@@ -861,11 +861,15 @@ void QColumnView::setColumnWidths(const QList<int> &list)
 {
     Q_D(QColumnView);
     int i = 0;
-    for (; (i < list.count() && i < d->columns.count()); ++i) {
+    const int listCount = list.count();
+    const int count = qMin(listCount, d->columns.count());
+    for (; i < count; ++i) {
         d->columns.at(i)->resize(list.at(i), d->columns.at(i)->height());
         d->columnSizes[i] = list.at(i);
     }
-    for (; i < list.count(); ++i)
+
+    d->columnSizes.reserve(listCount);
+    for (; i < listCount; ++i)
         d->columnSizes.append(list.at(i));
 }
 

src/widgets/widgets/qmenubar.cpp

@@ -195,7 +195,9 @@ void QMenuBarPrivate::updateGeometries()
         for(int j = 0; j < shortcutIndexMap.size(); ++j)
             q->releaseShortcut(shortcutIndexMap.value(j));
         shortcutIndexMap.resize(0); // faster than clear
-        for(int i = 0; i < actions.count(); i++)
+        const int actionsCount = actions.count();
+        shortcutIndexMap.reserve(actionsCount);
+        for (int i = 0; i < actionsCount; i++)
             shortcutIndexMap.append(q->grabShortcut(QKeySequence::mnemonic(actions.at(i)->text())));
     }
 #endif