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** This file is part of the test suite of the Qt Toolkit.
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#include <QtTest>
#include <QGraphicsLayout>
#include <QGraphicsLinearLayout>
#include <QGraphicsWidget>
#include <QGraphicsView>

class tst_QGraphicsLayout : public QObject
{
    Q_OBJECT
public:
    tst_QGraphicsLayout() {}
    ~tst_QGraphicsLayout() {}

private slots:
    void invalidate();
};


class RectWidget : public QGraphicsWidget
{
public:
    RectWidget(QGraphicsItem *parent = 0, Qt::WindowFlags wFlags = { }) : QGraphicsWidget(parent, wFlags), setGeometryCalls(0) {}

    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
    {
        Q_UNUSED(option);
        Q_UNUSED(widget);
        painter->drawRoundedRect(rect(), 25, 25, Qt::RelativeSize);
        painter->drawLine(rect().topLeft(), rect().bottomRight());
        painter->drawLine(rect().bottomLeft(), rect().topRight());
    }

    void setGeometry(const QRectF &rect)
    {
        //qDebug() << "setGeometry():" << this->data(0).toString();
        setGeometryCalls->insert(this, rect);
        QGraphicsWidget::setGeometry(rect);
    }

    void callUpdateGeometry() {
        QGraphicsWidget::updateGeometry();
    }

    QMap<RectWidget*, QRectF> *setGeometryCalls;
};

/**
 * Test to see how much time is needed to resize all widgets in a
 * layout-widget-layout-widget-.... hierarchy from the point where a
 * leaf widget changes its size hint. (updateGeometry() is called).
 *
 * If you run the test for 4.7 you'll get some really high numbers, but
 * that's because they also include painting (and possible processing of
 * some other events).
 */
void tst_QGraphicsLayout::invalidate()
{
    QGraphicsLayout::setInstantInvalidatePropagation(true);
    QGraphicsScene *scene = new QGraphicsScene;
    QGraphicsView *view = new QGraphicsView(scene);
    QMap<RectWidget*, QRectF> *setGeometryCalls = new QMap<RectWidget*, QRectF>;

    RectWidget *window = new RectWidget(0, Qt::Window);
    window->setGeometryCalls = setGeometryCalls;
    window->setData(0, QString(QChar('a')));

    scene->addItem(window);
    RectWidget *leaf = 0;
    const int depth = 100;
    RectWidget *parent = window;
    for (int i = 1; i < depth; ++i) {
        QGraphicsLinearLayout *l = new QGraphicsLinearLayout(parent);
        l->setContentsMargins(0,0,0,0);
        RectWidget *child = new RectWidget;
        child->setData(0, QString(QChar('a' + i)));
        child->setGeometryCalls = setGeometryCalls;
        l->addItem(child);
        parent = child;
    }
    leaf = parent;
    leaf->setMinimumSize(QSizeF(1,1));

    view->show();

    QVERIFY(QTest::qWaitForWindowExposed(view));

    // ...then measure...

    int pass = 1;

    // should be as small as possible, to reduce overhead of painting
    QSizeF size(1, 1);
    setGeometryCalls->clear();
    QBENCHMARK {
        leaf->setMinimumSize(size);
        leaf->setMaximumSize(size);
        while (setGeometryCalls->count() < depth) {
            QApplication::sendPostedEvents();
        }
        // force a resize on each widget, this will ensure
        // that each iteration will resize all 50 widgets
        int w = int(size.width());
        w^=2;
        size.setWidth(w);
    }
    window->setGeometryCalls = nullptr;
    delete view;
    delete scene;
    QGraphicsLayout::setInstantInvalidatePropagation(false);
    delete setGeometryCalls;
}

QTEST_MAIN(tst_QGraphicsLayout)

#include "tst_qgraphicslayout.moc"