Question

我想在ChartView QML-Object中创建自己的特定图表。我的期望是通过在c ++中指定例如QCategoryAxis而不是在qml中调用此函数来获得充分的灵活性。

首先，我不太确定是否有可能像我希望的那样...... 而对于我非常简单的例子，我得到了一些我无法解决的错误。

如果有人可以帮助我，我会很高兴，因为两周以来我一直在努力使用这个QML / C ++组合。

diabchart.h

    #ifndef DIABCHART_H
    #define DIABCHART_H

    #include <QtCharts/QChartView>
    #include <QtCharts/QCategoryAxis>
    #include <QObject>

    QT_CHARTS_USE_NAMESPACE

    class DiabChart : public QObject
    {
        Q_OBJECT

    public:
        explicit DiabChart(QObject *parent = 0);
    public slots:
        Q_INVOKABLE QCategoryAxis* getCategoryAxisY();

    };

diabchart.cpp

#include "diabchart.h"
#include <QtCharts/QChartView>

QT_CHARTS_USE_NAMESPACE

DiabChart::DiabChart(QObject *parent)
    : QObject(parent)
{

}

QCategoryAxis* DiabChart::getCategoryAxisY()
{
    // Y-Axis (Bloodsugar)
    QCategoryAxis *axisY = new QCategoryAxis();
    axisY->append("critical", 50);
    axisY->append("low", 70);
    axisY->append("normal", 160);
    axisY->append("high", 250);
    axisY->append("extremly high", 450);
    axisY->setRange(0, 450);
    return axisY;
}
#endif // DIABCHART_H

的main.cpp

#include <QQmlApplicationEngine>
#include <QtCharts/QChartView>
#include <QApplication>

#include "diabchart.h"

QT_CHARTS_USE_NAMESPACE

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    qmlRegisterType<DiabChart>("DiabChart", 1, 0, "DiabChart");


    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    return app.exec();
}

main.qml

import QtQuick 2.7
import QtQuick.Controls 1.4
import QtCharts 2.0
import DiabChart 1.0

ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    DiabChart{
        id: xyz
    }

   ChartView{
        title: "Line"
        anchors.fill: parent
        antialiasing: true

        //axes: xyz.getCategoryAxisY()
        //Leads to: Error: Unknown method return type: QCategoryAxis*

        //axes: getCategoryAxisY()
        //Leads to: ReferenceError: getCategoryAxisY is not defined

        //axes: DiabChart.getCategoryAxisY()
        //Leads to: TypeError: Property 'getCategoryAxisY' of object [object Object] is not a function

        ValueAxis{
            id: vlaueAxisX
            min: 0
            max: 24
            tickCount: 12
            labelFormat: "%2.0f:00"
        }

        LineSeries {
            axisX: vlaueAxisX
            axisY: yAxis
            name: "LineSeries"
            XYPoint { id: zero; x: 0; y: 192.6}
            XYPoint { id: first; x: 7; y: 89 }
            XYPoint { x: 9; y: 100 }
            XYPoint { x: 12; y: 50 }
            XYPoint { x: 14; y: 250 }
            XYPoint { x: 18; y: 140 }
            XYPoint { x: 21; y: 80 }
            XYPoint { id: last; x: 23.5; y: 200 }
            XYPoint { id: twentyfour; x: 24; y: 192.6}
        }
    }
}

Answer 1

所以，答案是返回QAbstractAxis*。

为了能够在QML中使用C ++类型，源代码中的某处应该至少有Q_DECLARE_METATYPE()个类型。由于Qt本身以AbstractAxis QML类型运行（从图表API的qt文档中可以看出），因此已经为QAbstractAxis*完成了。但是QCategoryAxis*可能没有注册。

在QtCharts的c ++函数中定义qml对象（ChartView）

1 个答案: