Qt 柱状图

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1.官网下载qcustomplot .cpp,qcustomplot.h文件

2.将上述两个文件放在自己的工作目录下

3.将上述两个文件引入CMakeLists.txt中如（qcustomplot .cpp,qcustomplot.h放置的位置和main.cpp在同一目录下）：

set(SOURCE_FILES
      main.cpp
      qcustomplot.h
      qcustomplot.cpp
      )
4.创建一个帮助类,其中包含以下方法

void CMainForm::setupBarChartDemo(QCustomPlot *customPlot)
{

     //this->setFixedSize(1920,1080);
     std::string demoName = "Bar Chart Demo";
     QLinearGradient gradient(0, 0, 0, 400);
     gradient.setColorAt(0, QColor(90, 90, 90));
     gradient.setColorAt(0.38, QColor(105, 105, 105));
     gradient.setColorAt(1, QColor(70, 70, 70));
     customPlot->setBackground(QBrush(gradient));

     // create empty bar chart objects:
     QCPBars *regen = new QCPBars(customPlot->xAxis, customPlot->yAxis);
     QCPBars *nuclear = new QCPBars(customPlot->xAxis, customPlot->yAxis);
     QCPBars *fossil = new QCPBars(customPlot->xAxis, customPlot->yAxis);
     regen->setAntialiased(false); // gives more crisp, pixel aligned bar borders
     nuclear->setAntialiased(false);
     fossil->setAntialiased(false);
     regen->setStackingGap(1);
     nuclear->setStackingGap(1);
     fossil->setStackingGap(1);
     fossil->setName("Fossil fuels");
     fossil->setPen(QPen(QColor(111, 9, 176).lighter(170)));
     fossil->setBrush(QColor(111, 9, 176));
     nuclear->setName("Nuclear");
     nuclear->setPen(QPen(QColor(250, 170, 20).lighter(150)));
     nuclear->setBrush(QColor(250, 170, 20));
     regen->setName("Regenerative");
     regen->setPen(QPen(QColor(0, 168, 140).lighter(130)));
     regen->setBrush(QColor(0, 168, 140));
     // stack bars on top of each other:
     nuclear->moveAbove(fossil);
     regen->moveAbove(nuclear);

     // prepare x axis with country labels:
     QVector<double> ticks;
     QVector<QString> labels;
     ticks << 1 << 2 << 3 << 4 << 5 << 6 << 7;
     labels << "USA" << "Japan" << "Germany" << "France" << "UK" << "Italy" << "Canada";
     QSharedPointer<QCPAxisTickerText> textTicker(new QCPAxisTickerText);
     textTicker->addTicks(ticks, labels);
     customPlot->xAxis->setTicker(textTicker);
     customPlot->xAxis->setTickLabelRotation(60);
     customPlot->xAxis->setSubTicks(false);
     customPlot->xAxis->setTickLength(0, 4);
     customPlot->xAxis->setRange(0, 8);
     customPlot->xAxis->setBasePen(QPen(Qt::white));
     customPlot->xAxis->setTickPen(QPen(Qt::white));
     customPlot->xAxis->grid()->setVisible(true);
     customPlot->xAxis->grid()->setPen(QPen(QColor(130, 130, 130), 0, Qt::DotLine));
     customPlot->xAxis->setTickLabelColor(Qt::white);
     customPlot->xAxis->setLabelColor(Qt::white);

     // prepare y axis:
     customPlot->yAxis->setRange(0, 12.1);//set y
     customPlot->yAxis->setPadding(5); // a bit more space to the left border
     customPlot->yAxis->setLabel("Power Consumption in\nKilowatts per Capita (2007)");
     customPlot->yAxis->setBasePen(QPen(Qt::white));
     customPlot->yAxis->setTickPen(QPen(Qt::white));
     customPlot->yAxis->setSubTickPen(QPen(Qt::white));
     customPlot->yAxis->grid()->setSubGridVisible(true);
     customPlot->yAxis->setTickLabelColor(Qt::white);
     customPlot->yAxis->setLabelColor(Qt::white);
     customPlot->yAxis->grid()->setPen(QPen(QColor(130, 130, 130), 0, Qt::SolidLine));
     customPlot->yAxis->grid()->setSubGridPen(QPen(QColor(130, 130, 130), 0, Qt::DotLine));

     // Add data:
     QVector<double> fossilData, nuclearData, regenData;
     fossilData  << 0.86*10.5 << 0.83*5.5 << 0.84*5.5 << 0.52*5.8 << 0.89*5.2 << 0.90*4.2 << 0.67*11.2;
     nuclearData << 0.08*10.5 << 0.12*5.5 << 0.12*5.5 << 0.40*5.8 << 0.09*5.2 << 0.00*4.2 << 0.07*11.2;
     regenData   << 0.06*10.5 << 0.05*5.5 << 0.04*5.5 << 0.06*5.8 << 0.02*5.2 << 0.07*4.2 << 0.25*11.2;
     fossil->setData(ticks, fossilData);
     nuclear->setData(ticks, nuclearData);
     regen->setData(ticks, regenData);

     // setup legend:
     customPlot->legend->setVisible(true);
     customPlot->axisRect()->insetLayout()->setInsetAlignment(0, Qt::AlignTop|Qt::AlignHCenter);
     customPlot->legend->setBrush(QColor(255, 255, 255, 100));
     customPlot->legend->setBorderPen(Qt::NoPen);
    QFont legendFont = font();
    legendFont.setPointSize(10);
    customPlot->legend->setFont(legendFont);
    customPlot->setInteractions(QCP::iRangeDrag | QCP::iRangeZoom);
}

5.在main.cpp中创建QCustomPlot类，然后调用帮助类中的以上函数（要设置QCustomPlot对象的宽和高）即可完成简单的柱状图