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Qt开发技术：QCharts（四）QCharts面积图介绍、Demo以及代码详解

若该文为原创文章，未经允许不得转载
原博主博客地址：https://blog.csdn.net/qq21497936
原博主博客导航：https://blog.csdn.net/qq21497936/article/details/102478062
本文章博客地址：https://blog.csdn.net/qq21497936/article/details/108240696
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前言

红胖子，来也！
按照顺序，本章为面积图。

补充

QCharts所有的图表都依赖《Qt开发技术：QCharts（一）QCharts基本介绍以及图表框架详解》中的QChart、QChartView、QLegend、QValueAxis。

Demo

Demo下载地址

当前为v1.1.0版本
CSDN：https://download.csdn.net/download/qq21497936/12753524
QQ群：1047134658（点击“文件”搜索“qChartsTools”，群内与博文同步更新）

面积图

概述

面积图是使用QAreaSeries类或AreaSeries QML类型实现的。默认情况下，X轴被用作一个边界和QLineSeries或线列作为另一个。但是，可以使用QLineSeries或LineSeries作为两个边界。

QAreaSeries（面积图类）

概述

QAreaSeries类在面积图中显示数据。
面积序列用于显示定量数据。它是基于一系列线，用颜色强调边界线之间的区域。由于区域序列基于行序列，QAreaSeries构造函数需要一个QLineSeries实例，该实例定义区域的上边界。默认情况下，使用绘图区域底部作为下边界绘制面积图。下边界可以由另一条线指定，而不是绘图区域的底部。在这种情况下，QAReaSeries应该用两个QLineSeries实例初始化。
注意：当下边界值大于上边界值时，术语上下边界可能会产生误导。重点是这两条边界线之间的区域将被填充。

下面的代码片段说明了如何创建基本面积图：

_pLineSeries = new QLineSeries;
_pLineSeries2 = new QLineSeries;
_pLineSeries3 = new QLineSeries;
_pLineSeries4 = new QLineSeries;
// 方式一：逐一添加，大批量数据较慢
_pLineSeries->append(0, qrand()%11);
_pLineSeries->append(1, qrand()%11);
_pLineSeries->append(2, qrand()%11);
_pLineSeries->append(3, qrand()%11);
_pLineSeries->append(4, qrand()%11);
_pLineSeries->append(5, qrand()%11);
_pLineSeries->append(6, qrand()%11);
_pLineSeries->append(7, qrand()%11);
_pLineSeries->append(8, qrand()%11);
_pLineSeries->append(9, qrand()%11);
_pLineSeries->append(10, qrand()%11);
_pLineSeries->setName("通道1");
_pLineSeries->setPen(QPen(QColor(qrand()%256, qrand()%256, qrand()%256), 2));
// 通用：将数据插入到图表中
_pAreaSeries = new QAreaSeries();
_pAreaSeries->setName("面积1");
_pLineSeries->setPointsVisible(true);
_pLineSeries->setPointLabelsFormat("(@xPoint,@yPoint)");
_pAreaSeries->setUpperSeries(_pLineSeries);
_pChart->addSeries(_pAreaSeries);

效率更高的方式为：

// 方式二：逐一添加，大批量数据插入
QList list;
list.append(_pLineSeries);
list.append(_pLineSeries2);
list.append(_pLineSeries3);
list.append(_pLineSeries4);
for(int index = 0; index < 4; index++)
{
    QList listPointF;
    for(int index = 0; index < 11; index++)
    {
        listPointF << QPointF(index, qrand()%11);
    }
    list.at(index)->append(listPointF);
    list.at(index)->setName(QString("通道%1").arg(index+1));
    list.at(index)->setPen(QPen(QColor(qrand()%256, qrand()%256, qrand()%256), 2));
}
// 通用：将数据插入到图表中
_pAreaSeries = new QAreaSeries();
_pAreaSeries->setName("面积1");
_pLineSeries->setPointsVisible(true);
_pLineSeries->setPointLabelsFormat("(@xPoint,@yPoint)");
_pAreaSeries->setUpperSeries(_pLineSeries);
_pChart->addSeries(_pAreaSeries);

_pAreaSeries2 = new QAreaSeries();
_pAreaSeries2->setName("面积2");
_pAreaSeries2->setUpperSeries(_pLineSeries2);
_pChart->addSeries(_pAreaSeries2);

_pAreaSeries3 = new QAreaSeries();
_pAreaSeries3->setName("面积3");
_pAreaSeries3->setUpperSeries(_pLineSeries3);
_pAreaSeries3->setLowerSeries(_pLineSeries2);
_pChart->addSeries(_pAreaSeries3);
_pAreaSeries4 = new QAreaSeries();
_pAreaSeries4->setName("面积4");
_pAreaSeries4->setUpperSeries(_pLineSeries4);
_pAreaSeries4->setLowerSeries(_pLineSeries3);
_pChart->addSeries(_pAreaSeries4);

本文章博客地址：https://blog.csdn.net/qq21497936/article/details/108240696

Demo核心代码解析

建立QChart显示框架

AreaChartWidget::AreaChartWidget(QWidget *parent) :
    QWidget(parent),
    _pChartView(0),
    _pChart(0),
    _pXValueAxis(0),
    _pYValueAxis(0),
    _pLegend(0),
    _pLineSeries(0),
    _pLineSeries2(0),
    _pLineSeries3(0),
    _pLineSeries4(0),
    _pAreaSeries(0),
    _pAreaSeries2(0),
    _pAreaSeries3(0),
    _pAreaSeries4(0)
{
    _pChartView = new QChartView(this);
    _pChart = new QChart();
    initData();
}

初始化数据

void AreaChartWidget::initData()
{
    _pLineSeries = new QLineSeries;
    _pLineSeries2 = new QLineSeries;
    _pLineSeries3 = new QLineSeries;
    _pLineSeries4 = new QLineSeries;
    // 方式一：逐一添加，大批量数据较慢
    _pLineSeries->append(0, qrand()%11);
    _pLineSeries->append(1, qrand()%11);
    _pLineSeries->append(2, qrand()%11);
    _pLineSeries->append(3, qrand()%11);
    _pLineSeries->append(4, qrand()%11);
    _pLineSeries->append(5, qrand()%11);
    _pLineSeries->append(6, qrand()%11);
    _pLineSeries->append(7, qrand()%11);
    _pLineSeries->append(8, qrand()%11);
    _pLineSeries->append(9, qrand()%11);
    _pLineSeries->append(10, qrand()%11);
    _pLineSeries->setName("通道1");
    _pLineSeries->setPen(QPen(QColor(qrand()%256, qrand()%256, qrand()%256), 2));
    // 通用：将数据插入到图表中
    _pAreaSeries = new QAreaSeries();
    _pAreaSeries->setName("面积1");
    _pLineSeries->setPointsVisible(true);
    _pLineSeries->setPointLabelsFormat("(@xPoint,@yPoint)");
    _pAreaSeries->setUpperSeries(_pLineSeries);
    _pChart->addSeries(_pAreaSeries);

    // 方式二：逐一添加，大批量数据插入
    QList list;
    list.append(_pLineSeries);
    list.append(_pLineSeries2);
    list.append(_pLineSeries3);
    list.append(_pLineSeries4);
    for(int index = 1; index < 4; index++)
    {
        QList listPointF;
        for(int index = 0; index < 11; index++)
        {
            listPointF << QPointF(index, qrand()%11);
        }
        list.at(index)->append(listPointF);
        list.at(index)->setName(QString("通道%1").arg(index+1));
        list.at(index)->setPen(QPen(QColor(qrand()%256, qrand()%256, qrand()%256), 2));
    }
    // 通用：将数据插入到图表中
    _pAreaSeries2 = new QAreaSeries();
    _pAreaSeries2->setName("面积2");
    _pAreaSeries2->setUpperSeries(_pLineSeries2);
    _pChart->addSeries(_pAreaSeries2);

    _pAreaSeries3 = new QAreaSeries();
    _pAreaSeries3->setName("面积3");
    _pAreaSeries3->setUpperSeries(_pLineSeries3);
    _pAreaSeries3->setLowerSeries(_pLineSeries2);
    _pChart->addSeries(_pAreaSeries3);

    _pAreaSeries4 = new QAreaSeries();
    _pAreaSeries4->setName("面积4");
    _pAreaSeries4->setUpperSeries(_pLineSeries4);
    _pAreaSeries4->setLowerSeries(_pLineSeries3);
    _pChart->addSeries(_pAreaSeries4);


    // 通用：X轴和Y轴的处理(先插入数据再处理轴,否则不会有轴)
    _pChart->createDefaultAxes();
    _pYValueAxis = dynamic_cast(_pChart->axisY());
//    _pYValueAxis = new QValueAxis(_pChart);
    _pYValueAxis->setRange(0, 10);
    _pYValueAxis->setLinePen(QPen(Qt::black, 1));
    // tick
    _pYValueAxis->setTickCount(5);
    _pYValueAxis->setGridLinePen(QPen(Qt::gray, 1));
    _pYValueAxis->setGridLineVisible(true);
    // subTick
    _pYValueAxis->setMinorTickCount(4);
    _pYValueAxis->setMinorGridLineVisible(true);
    _pYValueAxis->setLabelFormat("%d");
//    _pChart->addAxis(_pYValueAxis, Qt::AlignLeft);

    _pXValueAxis = dynamic_cast(_pChart->axisX());
//    _pXValueAxis = new QValueAxis(_pChart);
    _pXValueAxis->setRange(0, 10);
    _pXValueAxis->setLinePen(QPen(Qt::black, 1));
    // tick
    _pXValueAxis->setTickCount(5);
    _pXValueAxis->setGridLinePen(QPen(Qt::gray, 1));
    _pXValueAxis->setGridLineVisible(true);
    // subTick
    _pXValueAxis->setMinorTickCount(4); // 相反
    _pXValueAxis->setMinorGridLineVisible(true);
    _pXValueAxis->setLabelFormat("%d s");
//    _pChart->addAxis(_pXValueAxis, Qt::AlignBottom);

    // 通用：视图显示设置为图表
    _pChartView->setRubberBand(QChartView::NoRubberBand);   // 不缩放
    _pChartView->setDragMode(QChartView::NoDrag);   // 拽拖：需要自己重写QCharView
    _pChartView->setChart(_pChart);


    // 标识
    _pLegend = _pChart->legend();
    _pLegend->setAlignment(Qt::AlignRight);

    // 平滑
    _pChartView->setRenderHint(QPainter::Antialiasing, true);
    // 阴影
    _pChart->setDropShadowEnabled(true);
}

设置数据线是否显示（标签显示会同步）

void AreaChartWidget::setDataVisible(int index, bool visible)
{
    if(index < 0 || index > 3)
    {
        return;
    }
    QList list;
    list.append(_pAreaSeries);
    list.append(_pAreaSeries2);
    list.append(_pAreaSeries3);
    list.append(_pAreaSeries4);
    list.at(index)->setVisible(visible);
}

设置主题样式

void AreaChartWidget::setTheme(QChart::ChartTheme theme)
{
    _pChart->setTheme(theme);
}

设置动画模式

void AreaChartWidget::setAnimationOptions(QChart::AnimationOption option)
{
    _pChart->setAnimationOptions(option);
}

设置标签显示位置

void AreaChartWidget::setAlignment(Qt::Alignment align)
{
    _pLegend->setAlignment(align);
}

设置标签是否可见

void AreaChartWidget::setLegendVisible(bool visible)
{
    _pLegend->setVisible(visible);
    _pChartView->setRenderHint(QPainter::Antialiasing);
}

设置是否绘制平滑

void AreaChartWidget::setAntialiasing(bool antialiasing)
{
    _pChartView->setRenderHint(QPainter::Antialiasing, antialiasing);
}

设置是否有阴影

void AreaChartWidget::setShadow(bool shadow)
{
    _pChart->setDropShadowEnabled(shadow);
}

是否显示数据点（新增）

void AreaChartWidget::setPointVisible(bool visible)
{
    _pAreaSeries->setPointsVisible(visible);
    _pAreaSeries2->setPointsVisible(visible);
    _pAreaSeries3->setPointsVisible(visible);
    _pAreaSeries4->setPointsVisible(visible);
}

是否显示数据点坐标（新增）

void AreaChartWidget::setPointLabelVisible(bool visible)
{
    _pAreaSeries->setPointLabelsFormat("(@xPoint,@yPoint)");
    _pAreaSeries->setPointLabelsVisible(visible);
    _pAreaSeries2->setPointLabelsFormat("(@xPoint,@yPoint)");
    _pAreaSeries2->setPointLabelsVisible(visible);
    _pAreaSeries3->setPointLabelsFormat("(@xPoint,@yPoint)");
    _pAreaSeries3->setPointLabelsVisible(visible);
    _pAreaSeries4->setPointLabelsFormat("(@xPoint,@yPoint)");
    _pAreaSeries4->setPointLabelsVisible(visible);
}

重置随机数据

void AreaChartWidget::resetData()
{
    _pChart->removeAllSeries();
    _pLineSeries = new QLineSeries;
    _pLineSeries2 = new QLineSeries;
    _pLineSeries3 = new QLineSeries;
    _pLineSeries4 = new QLineSeries;

    QList list;
    list.append(_pLineSeries);
    list.append(_pLineSeries2);
    list.append(_pLineSeries3);
    list.append(_pLineSeries4);
    for(int index = 0; index < 4; index++)
    {
        QList listPointF;
        for(int index = 0; index < 11; index++)
        {
            listPointF << QPointF(index, qrand()%11);
        }
        list.at(index)->append(listPointF);
        list.at(index)->setName(QString("通道%1").arg(index+1));
        list.at(index)->setPen(QPen(QColor(qrand()%256, qrand()%256, qrand()%256), 2));
    }

    _pAreaSeries = new QAreaSeries();
    _pAreaSeries->setName("面积1");
    _pAreaSeries->setUpperSeries(_pLineSeries);

    _pAreaSeries2 = new QAreaSeries();
    _pAreaSeries->setName("面积2");
    _pAreaSeries2->setUpperSeries(_pLineSeries2);
    _pChart->addSeries(_pAreaSeries2);

    _pAreaSeries3 = new QAreaSeries();
    _pAreaSeries3->setName("面积3");
    _pAreaSeries3->setUpperSeries(_pLineSeries3);
    _pAreaSeries3->setLowerSeries(_pLineSeries2);
    _pChart->addSeries(_pAreaSeries3);

    _pAreaSeries4 = new QAreaSeries();
    _pAreaSeries4->setName("面积4");
    _pAreaSeries4->setUpperSeries(_pLineSeries3);
    _pAreaSeries4->setLowerSeries(_pLineSeries4);
    _pChart->addSeries(_pAreaSeries4);

    _pChart->addSeries(_pAreaSeries);
    resetColor();
}

初始化颜色

void AreaChartWidget::resetColor()
{
    QList list;
    list.append(_pLineSeries);
    list.append(_pLineSeries2);
    list.append(_pLineSeries3);
    list.append(_pLineSeries4);
    for(int index = 0; index < list.size(); index++)
    {
        list.at(index)->setColor(QColor(qrand()%256, qrand()%256, qrand()%256));
    }
}

工程模板：对应版本号v1.1.0

对应版本号v1.1.0
增加面积图
对折线图、曲线图和面积图增加数据点显示、数据点标签显示