How to trigger a timeline created with Design Studio from C++?

coldspark29

I have created simple timeline in Design Studio, which scales an image up and down. I now want to trigger the start from C++.

Here is my QML code

    Timeline {
        id: timeline
        animations: [
            TimelineAnimation {
                id: timelineAnimation
                duration: 1000
                loops: 0
                running: true
                to: 1000
                from: 0
            }
        ]
        endFrame: 1000
        startFrame: 0
        enabled: true

        KeyframeGroup {
            target: image
            property: "scale"
            Keyframe {
                value: 1.25
                frame: 100
            }

            Keyframe {
                value: 1
                frame: 1000
            }
        }

I have found this documenation

https://doc.qt.io/qt-5/qtimeline.html

and from what I understand I first have to expose the scale property, which is then triggered by the timeline which is created in C++.. I have written this function.

#include <QObject>
#include <QTimeLine>
#include <qqml.h>

class Scaler: public QObject
{
    Q_OBJECT
    Q_PROPERTY(QVariant scale WRITE setScale NOTIFY scaleSet)
    QML_ELEMENT
    QVariant m_scale;

public:
    explicit Scaler(QObject *parent = nullptr);

    void setScale(QVariant scale);

signals:
    void scaleChanged(QVariant scale);

};

#include "Scaler.h"

Scaler::Scaler(QObject *parent) :
    QObject(parent)
{
}


void Scaler::setScale(QVariant scale)
{
    if (m_scale == scale)
        return;
    m_scale = scale;
    emit scaleChanged(m_scale);
}

Now I want to use the timeline from the example

   Scaler scaler;

    QTimeLine *timeLine = new QTimeLine(1000, engine.rootContext());
    timeLine->setFrameRange(0, 100);
    connect(timeLine, &QTimeLine::frameChanged, scaler, &Scaler::setScale(1.25))

but I am not sure how to use the connect function. I want the cale to go from 1 to 1.25 betwenn 0 and 100 ms and back to 1 from 100 to 1000.