Qwt源码解读之QwtSystemClock类和QwtSamplingThread类

QwtSystemClock类提供了一个高分辨率的时钟功能（依赖于特定的系统）。

代码分析：

class QWT_EXPORT QwtSystemClock{public:    QwtSystemClock();    virtual ~QwtSystemClock();    bool isNull() const;    void start();    double restart();    double elapsed() const;    static double precision();private:    class PrivateData;    PrivateData *d_data;};

QwtSystemClock类在QwtSamplingThread类里被用作了采样时钟。

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QwtSamplingThread类：定期采集样品的线程，继承自QThread。

QwtSamplingThread自身也是一个抽象基类。

代码分析

class QWT_EXPORT QwtSamplingThread: public QThread{    Q_OBJECTpublic:    virtual ~QwtSamplingThread();    double interval() const;    double elapsed() const;public Q_SLOTS:    void setInterval( double interval );    void stop();protected:    explicit QwtSamplingThread( QObject *parent = NULL );    virtual void run();    /*!       Collect a sample       \param elapsed Time since the thread was started in miliseconds     */    virtual void sample( double elapsed ) = 0; // 需重新实现private:    class PrivateData;    PrivateData *d_data;