20200511-01 基于 QCustomPlot 移植到 QML 上(qt.514)

朴灿烈づ我的快乐病毒、 2023-03-13 05:24 15阅读 0赞

[源码下载][Link 1]

# 一：要点说明 #

### 1. replot() 界面刷新（需要单独调用) ###

replot() 这个函数的作用是用于刷新显示界面，根据文档显示，刷新的方式总共有 4 中：

rpImmediateRefresh 立即全局更新（先立即重绘表格，然后调用 QWidget::repaint() 重绘整个 widget
    
    rpQueuedRefresh 依次更新（先立即重绘表格，然后调用 QWidget::update() 进行更新，避免多次 repaint() 消耗资源)
    
    rpRefreshHint （默认)取决于 hint 是否被设置为 QCP::phImmediaRefresh，可以查看 setPlottingHints)
    
    rpQueuedReplot 整个更新事件循环进行，以避免没有意义的重复更新

所以在作者使用中，采用 300ms 执行一次 replot(QCustomPlot::RefreshPriority::rpQueuedReplot) 进行界面更新

在测试中，IMX6UL, 500M CPU 资源占用率（不是特别高，没有单独计算仅在个人写的APP上为40-50之间波动)

### 2. 清除函数 ###

似乎没有找到单独可以调用的函数，所以使用 setData() 函数代替

void clear_all()
    
    {
    
    //getPlot() 就是用来获取 QCustomPlot 指针
    
    getPlot()->graph(0)->setData(QVector<double>(), QVector<double>());
    
    getPlot()->replot();
    
    }

### 3. 单独加点 ###

void append_data(const double& key, const double& val)
    
    {
    
    getPlot()->graph(0)->addData(key, val);
    
    }

### 4. QQuickPaintItem ###

提供了在 QML 上绘制的 QPainter API，可以将 QWidget 或者自定义控件绘制到 QML 界面上，需要实现 paint() , 如果需要在控件上实现其他功能，比如鼠标功能，可以具体查看 QQuickItem 类中的虚拟函数定义

--------------------

# 二：源码 （代码格式参考网上信息) #

//ProFile
    #需要添加
    QT += quick qml printsupport core
    
    //main.cpp
    QApplication app(argc, argv); //使用这个来代替 QCoreApplication 等默认创建的 application
    qmlRegisterType <QCustomLine> ("DataModel", 1, 0, "ChartModel_Test");
    
    //main.qml
    注意使用 ApplicationWindow{} 来代替 Window()

// qcustomchart.h 
    #include <QtQuick>
    
    class QCustomPlot;
    class QCPAbstractPlottable;
    
    class QCustomChart : public QQuickPaintedItem
    {
    Q_OBJECT
    public:
    explicit QCustomChart(QQuickItem *parent = nullptr);
    virtual ~QCustomChart();
    
    void paint(QPainter *painter) override;
    virtual void initChartUI(){};
    
    QCustomPlot *getPlot();
    
    protected:
    
    virtual void mousePressEvent( QMouseEvent* event ) override;
    virtual void mouseReleaseEvent( QMouseEvent* event ) override;
    virtual void mouseMoveEvent( QMouseEvent* event ) override;
    virtual void mouseDoubleClickEvent( QMouseEvent* event ) override;
    virtual void wheelEvent( QWheelEvent *event ) override;
    
    void routeMouseEvents( QMouseEvent* event );
    void routeWheelEvents( QWheelEvent* event );
    
    public slots:
    void onChartViewReplot(); 
    void updateChartViewSize();  
    private: 
        QCustomPlot* mCustomPlot {nullptr}; 
    };
    
    //qcustomchart.cpp
    #include "qcustomchart.h"
    #include "qcustomplot.h"
    #include <QDebug>
    
    QCustomChart::QCustomChart(QQuickItem *parent) : QQuickPaintedItem(parent),
    mCustomPlot(new QCustomPlot())
    {
    setFlag(QQuickItem::ItemHasContents, true);
    setAcceptedMouseButtons(Qt::AllButtons);
    setAcceptHoverEvents(true);
    
    connect(this, &QQuickPaintedItem::widthChanged, this, &QCustomChart::updateChartViewSize);
    connect(this, &QQuickPaintedItem::heightChanged, this, &QCustomChart::updateChartViewSize);
    
    }
    
    QCustomChart::~QCustomChart()
    {
    delete mCustomPlot;
    }
    
    void QCustomChart::paint(QPainter *painter)
    {
    /// add active check
    if (!painter->isActive())
    return;
    QPixmap    picture( boundingRect().size().toSize() );
    QCPPainter qcpPainter( &picture );
    mCustomPlot->toPainter(&qcpPainter);
    painter->drawPixmap(QPoint(), picture);
    }
    
    QCustomPlot *QCustomChart::getPlot()
    {
    return mCustomPlot;
    }
    
    
    
    void QCustomChart::mousePressEvent(QMouseEvent *event)
    {
    routeMouseEvents(event);
    }
    
    void QCustomChart::mouseReleaseEvent(QMouseEvent *event)
    {
    routeMouseEvents(event);
    }
    
    void QCustomChart::mouseMoveEvent(QMouseEvent *event)
    {
    routeMouseEvents(event);
    }
    
    void QCustomChart::mouseDoubleClickEvent(QMouseEvent *event)
    {
    routeMouseEvents(event);
    }
    
    void QCustomChart::wheelEvent(QWheelEvent *event)
    {
    routeWheelEvents( event );
    }
    
    
    void QCustomChart::updateChartViewSize()
    {
    mCustomPlot->setGeometry(0, 0, (int)width(), (int)height());
    mCustomPlot->setViewport(QRect(0, 0, (int)width(), (int)height()));
    }
    
    void QCustomChart::onChartViewReplot()
    {
    update();
    }
    
    void QCustomChart::routeMouseEvents(QMouseEvent *event)
    {
    QMouseEvent* newEvent = new QMouseEvent(event->type(), event->localPos(), event->button(), event->buttons(), event->modifiers());
    QCoreApplication::postEvent(mCustomPlot, newEvent);
    }
    
    void QCustomChart::routeWheelEvents(QWheelEvent *event)
    {
    QWheelEvent* newEvent = new QWheelEvent(event->pos(), event->delta(), event->buttons(), event->modifiers(), event->orientation());
    QCoreApplication::postEvent(mCustomPlot, newEvent);
    }

//qcustomline.h
    #include "qcustomchart.h"
    
    class QCustomLine : public QCustomChart
    {
    Q_OBJECT
    public:
    explicit QCustomLine(QQuickItem *parent = nullptr);
    virtual ~QCustomLine();
    Q_INVOKABLE void initChart();
    
    Q_INVOKABLE void appendData(const double &key, const double &value);
    Q_INVOKABLE void replace(const QVector<double> &keys, const QVector<double> &values);
    Q_INVOKABLE void clearAll();
    Q_INVOKABLE void setXYRange(int x_s, int x_e, int y_s, int y_e);
    virtual void timerEvent(QTimerEvent *event) override;
    
    Q_INVOKABLE void append_test();
    Q_INVOKABLE void replace_test();
    Q_INVOKABLE void updateUI();
    
    };
    //qcustomline.cpp
    #include "qcustomline.h"
    #include "qcustomplot.h"
    
    QCustomLine::QCustomLine(QQuickItem *parent) : QCustomChart(parent)
    {
    
    }
    
    QCustomLine::~QCustomLine()
    {
    
    }
    
    void QCustomLine::initChart()
    {
    updateChartViewSize();
    
    getPlot()->addGraph();
    getPlot()->graph(0)->setPen( QPen(Qt::red));
    getPlot()->xAxis->setLabel( "t1" );
    getPlot()->yAxis->setLabel( "S1" );
    getPlot()->xAxis->setRange( 0, 1000 );
    getPlot()->yAxis->setRange( 0, 10 );
    getPlot()->setInteractions( QCP::iRangeDrag | QCP::iRangeZoom );
    
    startTimer(1000);
    
    connect(getPlot(), &QCustomPlot::afterReplot, this, &QCustomLine::onChartViewReplot);
    
    //    getPlot()->replot();
    }
    
    void QCustomLine::appendData(const double &key, const double &value)
    {
    getPlot()->graph(0)->addData(key, value);
    }
    
    void QCustomLine::replace(const QVector<double> &keys, const QVector<double> &values)
    {
    getPlot()->graph(0)->setData(keys, values);
    getPlot()->replot();
    }
    
    void QCustomLine::clearAll()
    {
    getPlot()->graph(0)->setData(QVector<double>(), QVector<double>());
    getPlot()->replot();
    }
    
    void QCustomLine::setXYRange(int x_s, int x_e, int y_s, int y_e)
    {
    getPlot()->xAxis->setRange(x_s, x_e);
    getPlot()->yAxis->setRange(y_s, y_e);
    getPlot()->replot();
    }
    
    void QCustomLine::timerEvent(QTimerEvent */*event*/)
    {
    static double t, U;
    U = ((double)rand() / RAND_MAX) * 5;
    getPlot()->graph(0)->addData(t++, U);
    getPlot()->replot();
    }
    
    void QCustomLine::append_test()
    {
    static double t, U;
    U = ((double)rand() / RAND_MAX) * 5;
    appendData(t++, U);
    }
    
    void QCustomLine::replace_test()
    {
    QVector<double> tX;
    QVector<double> tY;
    tX << 1 << 3 << 4;
    tY << 1 << 5 << 1;
    replace(tX, tY);
    }
    
    void QCustomLine::updateUI()
    {
    getPlot()->replot(QCustomPlot::RefreshPriority::rpQueuedReplot);
    }

--------------------

# 异常记录： #

### 1） 如下异常提示 ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI0ODkwOTUz_size_16_color_FFFFFF_t_70][]

如果出现这种异常提示：

QPainter::begin: Paint device returned engine = 0, type: 2

QPainter::setRenderHint: Painter must be active to set rendering hints

请检查，

一：QML 是否已经用 ApplicationWindow 代替 Window 控件

二：在使用中，作者是通过 loader 加载的控件，并且在启动之后默认调用了 replot() 根本原因在于时间差，paint device 并没有准备好，所以可以略微延时执行，在构造函数中不要调用 replot()

### 2）在嵌入式等资源受限设备中出现，异常不知原因内存溢出死机情况 ###

很有可能是由于过快过多的图表刷新导致，内存资源耗尽导致程序嗝屁，建议跟新界面刷新策略，比如降低界面刷新的频率，去掉没有意义的界面刷新步骤

[Link 1]: https://download.csdn.net/download/qq_24890953/12408941
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI0ODkwOTUz_size_16_color_FFFFFF_t_70]: /images/20230312/b5c49c2edc7641f5899f3e6fd6478aad.png