學習qml的筆記，Qt Quick核心程式設計的一個例子：

1、實現一個類（從object以及派生類中繼承而來），使用Q_OBJECT巨集。

#ifndef COLORMAKER_H
#define COLORMAKER_H
#include <QObject>
#include <QColor>
class ColorMaker : public QObject
{
    Q_OBJECT
    Q_ENUMS(GenerateAlgorithm)
    Q_PROPERTY(QColor color READ color WRITE setColor NOTIFY colorChanged)
    Q_PROPERTY(QColor timeColor READ timeColor)
public:
    ColorMaker(QObject *parent = 0);
    ~ColorMaker();
    enum GenerateAlgorithm{
        RandomRGB,
        RandomRed,
        RandomGreen,
        RandomBlue,
        LinearIncrease
    };
    QColor color() const;
    void setColor(const QColor & color);
    QColor timeColor() const;
    Q_INVOKABLE GenerateAlgorithm algorithm() const;
    Q_INVOKABLE void setAlgorithm(GenerateAlgorithm algorithm);
signals:
    void colorChanged(const QColor & color);
    void currentTime(const QString &strTime);
public slots:
    void start();
    void stop();
protected:
    void timerEvent(QTimerEvent *e);
private:
    GenerateAlgorithm m_algorithm;
    QColor m_currentColor;
    int m_nColorTimer;
};
#endif // COLORMAKER_H
 

//定時改變顏色、顯示當前時間的一個類的實現

#include <QTimerEvent>
#include <QDateTime>
ColorMaker::ColorMaker(QObject *parent)
    : QObject(parent)
    , m_algorithm(RandomRGB)
    , m_currentColor(Qt::black)
    , m_nColorTimer(0)
{
    qsrand(QDateTime::currentDateTime().toTime_t());
}
ColorMaker::~ColorMaker()
{
}
QColor ColorMaker::color() const
{
    return m_currentColor;
}
void ColorMaker::setColor(const QColor &color)
{
    m_currentColor = color;
    emit colorChanged(m_currentColor);
}
QColor ColorMaker::timeColor() const
{
    QTime time = QTime::currentTime();
    int r = time.hour();
    int g = time.minute()*2;
    int b = time.second()*4;
    return QColor::fromRgb(r, g, b);
}
ColorMaker::GenerateAlgorithm ColorMaker::algorithm() const
{
    return m_algorithm;
}
void ColorMaker::setAlgorithm(GenerateAlgorithm algorithm)
{
    m_algorithm = algorithm;
}
void ColorMaker::start()
{
    if(m_nColorTimer == 0)
    {
        m_nColorTimer = startTimer(1000);
    }
}
void ColorMaker::stop()
{
    if(m_nColorTimer > 0)
    {
        killTimer(m_nColorTimer);
        m_nColorTimer = 0;
    }
}
void ColorMaker::timerEvent(QTimerEvent *e)
{
    if(e->timerId() == m_nColorTimer)
    {
        switch(m_algorithm)
        {
        case RandomRGB:
            m_currentColor.setRgb(qrand() % 255, qrand() % 255, qrand() % 255);
            break;
        case RandomRed:
            m_currentColor.setRed(qrand() % 255);
            break;
        case RandomGreen:
            m_currentColor.setGreen(qrand() % 255);
            break;
        case RandomBlue:
            m_currentColor.setBlue(qrand() % 255);
            break;
        case LinearIncrease:
            {
                int r = m_currentColor.red() + 10;
                int g = m_currentColor.green() + 10;
                int b = m_currentColor.blue() + 10;
                m_currentColor.setRgb(r % 255, g % 255, b % 255);
            }
            break;
        }
        emit colorChanged(m_currentColor);
        emit currentTime(QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss"));
    }
    else
    {
        QObject::timerEvent(e);
    }
}
 

2、在下文建立聯絡之前 將c++類註冊為qml類

#include "colormaker.h"

qmlRegisterType<Colormaker>("qt.Colormaker", 1, 0, "Colormaker");

3、在qml中匯入c++註冊完成的類

import an.qt.ColorMaker 1.0

4、建立例項

Colormaker{
        id:colorMaker;
        color: Qt.green;
    }

qml直接呼叫c++函式

c++中通過傳送訊號---->>qml中接收並處理