#include "mainwindow.h"

 #include <QApplication>

 #include"plotlines.h"

 int main(int argc, char *argv[])

 {

     QApplication a(argc, argv);

 //    MainWindow w;//这里的主窗口我们没有使用，当然也可以在主窗口中显示曲线

 //    w.show();

     PlotLines line;

     line.show();

     return a.exec();

 }  

 #ifndef PLOTLINES_H

 #define PLOTLINES_H

 #define QWT_DLL

 #include<qwt_plot.h>

 #include <qwt_plot_layout.h>

 #include <qwt_plot_canvas.h>

 #include <qwt_plot_renderer.h>

 #include <qwt_plot_grid.h>

 #include <qwt_plot_histogram.h>

 #include <qwt_plot_curve.h>

 #include <qwt_plot_zoomer.h>

 #include <qwt_plot_panner.h>

 #include <qwt_plot_magnifier.h>

 #include <qwt_legend.h>

 #include <qwt_legend_label.h>

 #include <qwt_column_symbol.h>

 #include <qwt_series_data.h>

 #include <qpen.h>

 #include <qwt_symbol.h>

 #include <qwt_picker_machine.h>

 class PlotLines : public QwtPlot

 {

     Q_OBJECT

 public:

     explicit PlotLines(QWidget *parent = );

 private Q_SLOTS:

     void showItem(const QVariant &itemInfo, bool on);//点击图例，显示相应的曲线

 };  

 #endif // PLOTLINES_H  

 #include "plotlines.h"  

 PlotLines::PlotLines(QWidget *parent) :

     QwtPlot(parent)

 {

     setTitle("图的标题");

 //---------设置画布---------//

     QwtPlotCanvas *canvas=new QwtPlotCanvas();

     canvas->setPalette(Qt::white);

     canvas->setBorderRadius();

     setCanvas( canvas );

     plotLayout()->setAlignCanvasToScales( true );  

     //-----------设置x，y坐标和范围--------------//

     setAxisTitle( QwtPlot::yLeft, "ylabel" );

     setAxisTitle( QwtPlot::xBottom, "xlabel" );

     setAxisScale(QwtPlot::yLeft,0.0,10.0);

     setAxisScale(QwtPlot::xBottom,0.0,10.0);  

     //----------------设置栅格线-------------------//

     QwtPlotGrid *grid = new QwtPlotGrid;

     grid->enableX( true );//设置网格线

     grid->enableY( true );

     grid->setMajorPen( Qt::black, , Qt::DotLine );

     grid->attach( this );  

     //-----------------开始画图----------------------//

     QwtPlotCurve *curve=new QwtPlotCurve("curve");

    // curve->setTitle( "信道"+QString( "%1 " ).arg( i+1));

     curve->setPen(Qt::blue,);//设置曲线颜色 粗细

     curve->setRenderHint(QwtPlotItem::RenderAntialiased,true);//线条光滑化  

     QwtSymbol *symbol = new QwtSymbol( QwtSymbol::Ellipse,

     QBrush( Qt::yellow ), QPen( Qt::red,  ), QSize( , ) );//设置样本点的颜色、大小

     curve->setSymbol( symbol );//添加样本点形状  

     QPolygonF points1, points2;//输入节点数据QPointF(x,y)

     points1<<QPointF(,)<<QPointF(,)<<QPointF(,)<<QPointF(,)<<QPointF(,)<<QPointF(,)<<QPointF(,);

     points2<<QPointF(,)<<QPointF(,)<<QPointF(,)<<QPointF(,)<<QPointF(,)<<QPointF(,)<<QPointF(,);

     curve->setSamples(points1);

     curve->attach( this );

     curve->setLegendAttribute(curve->LegendShowLine);//显示图例的标志，这里显示线的颜色。  

     //曲线2的形状采用默认，即不单独设置画笔的颜色、样本点的显示

     QwtPlotCurve *curve2=new QwtPlotCurve("curve2");

     curve2->setSamples(points2);

     curve2->attach( this );

     curve2->setLegendAttribute(curve->LegendShowLine);  

 //--------------设置图例可以被点击来确定是否显示曲线-----------------------//

     QwtLegend *legend = new QwtLegend;

     legend->setDefaultItemMode( QwtLegendData::Checkable );//图例可被点击

     insertLegend( legend, QwtPlot::RightLegend );

     connect( legend, SIGNAL( checked( const QVariant &, bool, int ) ),

         SLOT( showItem( const QVariant &, bool ) ) );//点击图例操作  

     QwtPlotItemList items = itemList( QwtPlotItem::Rtti_PlotCurve );//获取画了多少条曲线,如果为获取其他形状，注意改变参数

    //  qDebug()<<items;

     for ( int i = ; i < items.size(); i++ )

     {

         if ( i ==  )

         {

             const QVariant itemInfo = itemToInfo( items[i] );

             QwtLegendLabel *legendLabel =

                 qobject_cast<QwtLegendLabel *>( legend->legendWidget( itemInfo ) );

             if ( legendLabel )

                 legendLabel->setChecked( true );//

             items[i]->setVisible( true );

         }

         else

         {

             items[i]->setVisible( false );

         }

     }

     this->resize(,);

     this->replot();

     setAutoReplot( true );//设置自动重画，相当于更新

 }

 //点击图例，显示相应的曲线

 void PlotLines::showItem(const QVariant &itemInfo, bool on)

 {

     QwtPlotItem *plotItem = infoToItem( itemInfo );

     if ( plotItem )

         plotItem->setVisible( on );

 }