- Qt 5.5
- Qt Widgets
- Easing Curves Example
- window.cpp Example File
- Qt 5.5.1 Reference Documentation

# window.cpp Example File

animation/easing/window.cpp

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    #include "window.h"

    Window::Window(QWidget *parent)
        : QWidget(parent),
        m_iconSize(64, 64)
    {
        m_ui.setupUi(this);
        QButtonGroup *buttonGroup = findChild<QButtonGroup *>();     // ### workaround for uic in 4.4
        m_ui.easingCurvePicker->setIconSize(m_iconSize);
        m_ui.easingCurvePicker->setMinimumHeight(m_iconSize.height() + 50);
        buttonGroup->setId(m_ui.lineRadio, 0);
        buttonGroup->setId(m_ui.circleRadio, 1);

        QEasingCurve dummy;
        m_ui.periodSpinBox->setValue(dummy.period());
        m_ui.amplitudeSpinBox->setValue(dummy.amplitude());
        m_ui.overshootSpinBox->setValue(dummy.overshoot());

        connect(m_ui.easingCurvePicker, SIGNAL(currentRowChanged(int)), this, SLOT(curveChanged(int)));
        connect(buttonGroup, SIGNAL(buttonClicked(int)), this, SLOT(pathChanged(int)));
        connect(m_ui.periodSpinBox, SIGNAL(valueChanged(double)), this, SLOT(periodChanged(double)));
        connect(m_ui.amplitudeSpinBox, SIGNAL(valueChanged(double)), this, SLOT(amplitudeChanged(double)));
        connect(m_ui.overshootSpinBox, SIGNAL(valueChanged(double)), this, SLOT(overshootChanged(double)));
        createCurveIcons();

        QPixmap pix(QLatin1String(":/images/qt-logo.png"));
        m_item = new PixmapItem(pix);
        m_scene.addItem(m_item);
        m_ui.graphicsView->setScene(&m_scene);

        m_anim = new Animation(m_item, "pos");
        m_anim->setEasingCurve(QEasingCurve::OutBounce);
        m_ui.easingCurvePicker->setCurrentRow(int(QEasingCurve::OutBounce));

        startAnimation();
    }

    QEasingCurve createEasingCurve(QEasingCurve::Type curveType)
    {
        QEasingCurve curve(curveType);

        if (curveType == QEasingCurve::BezierSpline) {
            curve.addCubicBezierSegment(QPointF(0.4, 0.1), QPointF(0.6, 0.9), QPointF(1.0, 1.0));

        } else if (curveType == QEasingCurve::TCBSpline) {
            curve.addTCBSegment(QPointF(0.0, 0.0), 0, 0, 0);
            curve.addTCBSegment(QPointF(0.3, 0.4), 0.2, 1, -0.2);
            curve.addTCBSegment(QPointF(0.7, 0.6), -0.2, 1, 0.2);
            curve.addTCBSegment(QPointF(1.0, 1.0), 0, 0, 0);
        }

        return curve;
    }

    void Window::createCurveIcons()
    {
        QPixmap pix(m_iconSize);
        QPainter painter(&pix);
        QLinearGradient gradient(0,0, 0, m_iconSize.height());
        gradient.setColorAt(0.0, QColor(240, 240, 240));
        gradient.setColorAt(1.0, QColor(224, 224, 224));
        QBrush brush(gradient);
        const QMetaObject &mo = QEasingCurve::staticMetaObject;
        QMetaEnum metaEnum = mo.enumerator(mo.indexOfEnumerator("Type"));
        // Skip QEasingCurve::Custom
        for (int i = 0; i < QEasingCurve::NCurveTypes - 1; ++i) {
            painter.fillRect(QRect(QPoint(0, 0), m_iconSize), brush);
            QEasingCurve curve = createEasingCurve((QEasingCurve::Type) i);
            painter.setPen(QColor(0, 0, 255, 64));
            qreal xAxis = m_iconSize.height()/1.5;
            qreal yAxis = m_iconSize.width()/3;
            painter.drawLine(0, xAxis, m_iconSize.width(),  xAxis);
            painter.drawLine(yAxis, 0, yAxis, m_iconSize.height());

            qreal curveScale = m_iconSize.height()/2;

            painter.setPen(Qt::NoPen);

            // start point
            painter.setBrush(Qt::red);
            QPoint start(yAxis, xAxis - curveScale * curve.valueForProgress(0));
            painter.drawRect(start.x() - 1, start.y() - 1, 3, 3);

            // end point
            painter.setBrush(Qt::blue);
            QPoint end(yAxis + curveScale, xAxis - curveScale * curve.valueForProgress(1));
            painter.drawRect(end.x() - 1, end.y() - 1, 3, 3);

            QPainterPath curvePath;
            curvePath.moveTo(start);
            for (qreal t = 0; t <= 1.0; t+=1.0/curveScale) {
                QPoint to;
                to.setX(yAxis + curveScale * t);
                to.setY(xAxis - curveScale * curve.valueForProgress(t));
                curvePath.lineTo(to);
            }
            painter.setRenderHint(QPainter::Antialiasing, true);
            painter.strokePath(curvePath, QColor(32, 32, 32));
            painter.setRenderHint(QPainter::Antialiasing, false);
            QListWidgetItem *item = new QListWidgetItem;
            item->setIcon(QIcon(pix));
            item->setText(metaEnum.key(i));
            m_ui.easingCurvePicker->addItem(item);
        }
    }

    void Window::startAnimation()
    {
        m_anim->setStartValue(QPointF(0, 0));
        m_anim->setEndValue(QPointF(100, 100));
        m_anim->setDuration(2000);
        m_anim->setLoopCount(-1); // forever
        m_anim->start();
    }

    void Window::curveChanged(int row)
    {
        QEasingCurve::Type curveType = (QEasingCurve::Type)row;
        m_anim->setEasingCurve(createEasingCurve(curveType));
        m_anim->setCurrentTime(0);

        bool isElastic = curveType >= QEasingCurve::InElastic && curveType <= QEasingCurve::OutInElastic;
        bool isBounce = curveType >= QEasingCurve::InBounce && curveType <= QEasingCurve::OutInBounce;
        m_ui.periodSpinBox->setEnabled(isElastic);
        m_ui.amplitudeSpinBox->setEnabled(isElastic || isBounce);
        m_ui.overshootSpinBox->setEnabled(curveType >= QEasingCurve::InBack && curveType <= QEasingCurve::OutInBack);
    }

    void Window::pathChanged(int index)
    {
        m_anim->setPathType((Animation::PathType)index);
    }

    void Window::periodChanged(double value)
    {
        QEasingCurve curve = m_anim->easingCurve();
        curve.setPeriod(value);
        m_anim->setEasingCurve(curve);
    }

    void Window::amplitudeChanged(double value)
    {
        QEasingCurve curve = m_anim->easingCurve();
        curve.setAmplitude(value);
        m_anim->setEasingCurve(curve);
    }

    void Window::overshootChanged(double value)
    {
        QEasingCurve curve = m_anim->easingCurve();
        curve.setOvershoot(value);
        m_anim->setEasingCurve(curve);
    }