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Refactor QStatusBar to reduce memory allocation

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Reading through the code contemplating what might have caused QTBUG-89141
brought up some opportunities for improvement.

* updated coding style and variable names
* use ranged for where possible and meaningful
* replacing a QList of pointers to heap-allocated structs with a list of
  values

Since the QList population code makes sure that we never have gaps (we
only insert within the existing range), the test for null-entries is not
needed, and was perhaps just precausion to avoid nullptr dereference.

Task-number: QTBUG-89141
Change-Id: I4694d820427a221f1334d2428f50069751919aef
Reviewed-by: Oliver Eftevaag <oliver.eftevaag@qt.io>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
This commit is contained in:
Volker Hilsheimer 2021-08-28 00:22:03 +02:00
parent 9f13842fe6
commit 7166a82844
1 changed files with 63 additions and 81 deletions
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144
src/widgets/widgets/qstatusbar.cpp
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@ -69,22 +69,27 @@ class QStatusBarPrivate : public QWidgetPrivate
public:
QStatusBarPrivate() {}
struct SBItem {
SBItem(QWidget* widget, int stretch, bool permanent)
: s(stretch), w(widget), p(permanent) {}
int s;
QWidget * w;
bool p;
enum ItemCategory
{
Normal,
Permanent
};
QList<SBItem *> items;
struct SBItem {
QWidget *widget = nullptr;
int stretch = 0;
ItemCategory category = Normal;
bool isPermanent() const { return category == Permanent; }
};
QList<SBItem> items;
QString tempItem;
QBoxLayout * box;
QTimer * timer;
QBoxLayout *box;
QTimer *timer;
#if QT_CONFIG(sizegrip)
QSizeGrip * resizer;
QSizeGrip *resizer;
bool showSizeGrip;
#endif
@ -94,8 +99,8 @@ public:
{
int i = items.size() - 1;
for (; i >= 0; --i) {
SBItem *item = items.at(i);
if (!(item && item->p))
const SBItem &item = items.at(i);
if (!item.isPermanent())
break;
}
return i;
@ -122,7 +127,7 @@ public:
QRect QStatusBarPrivate::messageRect() const
{
Q_Q(const QStatusBar);
bool rtl = q->layoutDirection() == Qt::RightToLeft;
const bool rtl = q->layoutDirection() == Qt::RightToLeft;
int left = 6;
int right = q->width() - 12;
@ -136,18 +141,13 @@ QRect QStatusBarPrivate::messageRect() const
}
#endif
for (int i=0; i<items.size(); ++i) {
QStatusBarPrivate::SBItem* item = items.at(i);
if (!item)
for (const auto &item : items) {
if (item.isPermanent() && item.widget->isVisible()) {
if (rtl)
left = qMax(left, item.widget->x() + item.widget->width() + 2);
else
right = qMin(right, item.widget->x() - 2);
break;
if (item->p && item->w->isVisible()) {
if (item->p) {
if (rtl)
left = qMax(left, item->w->x() + item->w->width() + 2);
else
right = qMin(right, item->w->x() - 2);
}
break;
}
}
return QRect(left, 0, right-left, q->height());
@ -246,9 +246,6 @@ QStatusBar::QStatusBar(QWidget * parent)
*/
QStatusBar::~QStatusBar()
{
Q_D(QStatusBar);
while (!d->items.isEmpty())
delete d->items.takeFirst();
}
@ -298,7 +295,7 @@ int QStatusBar::insertWidget(int index, QWidget *widget, int stretch)
return -1;
Q_D(QStatusBar);
QStatusBarPrivate::SBItem* item = new QStatusBarPrivate::SBItem(widget, stretch, false);
QStatusBarPrivate::SBItem item{widget, stretch, QStatusBarPrivate::Normal};
int idx = d->indexToLastNonPermanentWidget();
if (Q_UNLIKELY(index < 0 || index > d->items.size() || (idx >= 0 && index > idx + 1))) {
@ -363,7 +360,7 @@ int QStatusBar::insertPermanentWidget(int index, QWidget *widget, int stretch)
return -1;
Q_D(QStatusBar);
QStatusBarPrivate::SBItem* item = new QStatusBarPrivate::SBItem(widget, stretch, true);
QStatusBarPrivate::SBItem item{widget, stretch, QStatusBarPrivate::Permanent};
int idx = d->indexToLastNonPermanentWidget();
if (Q_UNLIKELY(index < 0 || index > d->items.size() || (idx >= 0 && index <= idx))) {
@ -396,15 +393,11 @@ void QStatusBar::removeWidget(QWidget *widget)
Q_D(QStatusBar);
bool found = false;
QStatusBarPrivate::SBItem* item;
for (int i=0; i<d->items.size(); ++i) {
item = d->items.at(i);
if (!item)
break;
if (item->w == widget) {
for (int i = 0; i < d->items.size(); ++i) {
const auto &item = d->items.at(i);
if (item.widget == widget) {
d->items.removeAt(i);
item->w->hide();
delete item;
item.widget->hide();
found = true;
break;
}
@ -495,25 +488,22 @@ void QStatusBar::reformat()
int maxH = fontMetrics().height();
int i;
QStatusBarPrivate::SBItem* item;
for (i=0,item=nullptr; i<d->items.size(); ++i) {
item = d->items.at(i);
if (!item || item->p)
qsizetype i;
for (i = 0; i < d->items.size(); ++i) {
const auto &item = d->items.at(i);
if (item.isPermanent())
break;
l->addWidget(item->w, item->s);
int itemH = qMin(qSmartMinSize(item->w).height(), item->w->maximumHeight());
l->addWidget(item.widget, item.stretch);
int itemH = qMin(qSmartMinSize(item.widget).height(), item.widget->maximumHeight());
maxH = qMax(maxH, itemH);
}
l->addStretch(0);
for (item=nullptr; i<d->items.size(); ++i) {
item = d->items.at(i);
if (!item)
break;
l->addWidget(item->w, item->s);
int itemH = qMin(qSmartMinSize(item->w).height(), item->w->maximumHeight());
for (; i < d->items.size(); ++i) {
const auto &item = d->items.at(i);
l->addWidget(item.widget, item.stretch);
int itemH = qMin(qSmartMinSize(item.widget).height(), item.widget->maximumHeight());
maxH = qMax(maxH, itemH);
}
#if QT_CONFIG(sizegrip)
@ -617,16 +607,14 @@ void QStatusBar::hideOrShow()
Q_D(QStatusBar);
bool haveMessage = !d->tempItem.isEmpty();
QStatusBarPrivate::SBItem* item = nullptr;
for (int i=0; i<d->items.size(); ++i) {
item = d->items.at(i);
if (!item || item->p)
for (const auto &item : qAsConst(d->items)) {
if (item.isPermanent())
break;
if (haveMessage && item->w->isVisible()) {
item->w->hide();
item->w->setAttribute(Qt::WA_WState_ExplicitShowHide, false);
} else if (!haveMessage && !item->w->testAttribute(Qt::WA_WState_ExplicitShowHide)) {
item->w->show();
if (haveMessage && item.widget->isVisible()) {
item.widget->hide();
item.widget->setAttribute(Qt::WA_WState_ExplicitShowHide, false);
} else if (!haveMessage && !item.widget->testAttribute(Qt::WA_WState_ExplicitShowHide)) {
item.widget->show();
}
}
@ -671,16 +659,15 @@ void QStatusBar::paintEvent(QPaintEvent *event)
opt.initFrom(this);
style()->drawPrimitive(QStyle::PE_PanelStatusBar, &opt, &p, this);
for (int i=0; i<d->items.size(); ++i) {
QStatusBarPrivate::SBItem* item = d->items.at(i);
if (item && item->w->isVisible() && (!haveMessage || item->p)) {
QRect ir = item->w->geometry().adjusted(-2, -1, 2, 1);
for (const auto &item : qAsConst(d->items)) {
if (item.widget->isVisible() && (!haveMessage || item.isPermanent())) {
QRect ir = item.widget->geometry().adjusted(-2, -1, 2, 1);
if (event->rect().intersects(ir)) {
QStyleOption opt(0);
opt.rect = ir;
opt.palette = palette();
opt.state = QStyle::State_None;
style()->drawPrimitive(QStyle::PE_FrameStatusBarItem, &opt, &p, item->w);
style()->drawPrimitive(QStyle::PE_FrameStatusBarItem, &opt, &p, item.widget);
}
}
}
@ -706,17 +693,13 @@ bool QStatusBar::event(QEvent *e)
{
Q_D(QStatusBar);
if (e->type() == QEvent::LayoutRequest
) {
switch (e->type()) {
case QEvent::LayoutRequest: {
// Calculate new strut height and call reformat() if it has changed
int maxH = fontMetrics().height();
QStatusBarPrivate::SBItem* item = nullptr;
for (int i=0; i<d->items.size(); ++i) {
item = d->items.at(i);
if (!item)
break;
int itemH = qMin(qSmartMinSize(item->w).height(), item->w->maximumHeight());
for (const auto &item : qAsConst(d->items)) {
const int itemH = qMin(qSmartMinSize(item.widget).height(), item.widget->maximumHeight());
maxH = qMax(maxH, itemH);
}
@ -729,18 +712,17 @@ bool QStatusBar::event(QEvent *e)
reformat();
else
update();
break;
}
if (e->type() == QEvent::ChildRemoved) {
QStatusBarPrivate::SBItem* item = nullptr;
for (int i=0; i<d->items.size(); ++i) {
item = d->items.at(i);
if (!item)
break;
if (item->w == ((QChildEvent*)e)->child()) {
case QEvent::ChildRemoved:
for (int i = 0; i < d->items.size(); ++i) {
const auto &item = d->items.at(i);
if (item.widget == static_cast<QChildEvent *>(e)->child())
d->items.removeAt(i);
delete item;
}
}
break;
default:
break;
}
return QWidget::event(e);