如何集成c ++和qml。 无法使用QML中的属性

Question

Error: Cannot assign to non-existent property "setScale"

This is my class.

C++ header

#include <QObject>
#include <QtQuick>

class Scene : public QQuickPaintedItem
{
Q_OBJECT
Q_PROPERTY(int scale READ scale WRITE setScale)
public:
Scene();
void scaleChanged(int _val);

int scale() const;
void setScale(const int &scale);

protected:
int m_scale;

};

C++ source

#include "Scene.h"

void Scene::scaleChanged(int _val)
{
m_scale = _val;
qDebug()<<_val;
update();
}

int Scene::scale() const
{
return m_scale;
}

void Scene::setScale(const int &scale)
{
m_scale = scale;
qDebug()<<scale;
}

Qml file

 Rectangle {
    id: drawArea
    color: "#ffffff"
    Scene {
        id: drawScene
        anchors.fill: parent
        anchors.centerIn: parent
        scale: 1
    }
}

Slider {
    id: slider
    value: 1
    onMoved: drawScene.setScale = value
}

I trying use slider to change scale at Paint, but get error qrc:/Page1Form.ui.qml:64: Error: Cannot assign to non-existent property "setScale" F

Answer 1

drawScene.setScale should be drawScene.scale : the property is named scale . setScale is its setter.

scaleChanged should be a signal and you have to add it of your property (with NOTIFY ). It will be emitted when the value of scale has changed.

Q_PROPERTY(int scale READ scale WRITE setScale NOTIFY scaleChanged)
signals:
void scaleChanged(int val);

slots:
void debugScale(int val);

And then:

QObject::connect(this, &Scene::valueChanged,
                     this, &Scene::debugScale);

void Scene::debugScale(int val)
{
qDebug()<<_val;
update();
}