qt组直方图例子-qwt

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qwt中多组直方图的例子如下：

main.cpp代码 
#include <qapplication.h> 
#include <qmainwindow.h> 
#include <qtoolbar.h>  
#include <qtoolbutton.h> 
#include <qcombobox.h> 
#include "barchart.h"  
  
class MainWindow:public QMainWindow  
{  
public: 
    MainWindow( QWidget * = NULL );  
  
private: 
    BarChart *d_chart;  
};  
  
MainWindow::MainWindow( QWidget *parent ):  
    QMainWindow( parent )  
{  
    d_chart = new BarChart( this ); 
    setCentralWidget( d_chart );  
  
    QToolBar *toolBar = new QToolBar( this ); 
  
    QComboBox *typeBox = new QComboBox( toolBar );  
    typeBox->addItem( "Grouped" ); 
    typeBox->addItem( "Stacked" ); 
    typeBox->setSizePolicy( QSizePolicy::Fixed, QSizePolicy::Fixed ); 
  
    QComboBox *orientationBox = new QComboBox( toolBar );  
    orientationBox->addItem( "Vertical" ); 
    orientationBox->addItem( "Horizontal" ); 
    orientationBox->setSizePolicy( QSizePolicy::Fixed, QSizePolicy::Fixed ); 
  
    QToolButton *btnExport = new QToolButton( toolBar );  
    btnExport->setText( "Export" ); 
    btnExport->setToolButtonStyle( Qt::ToolButtonTextUnderIcon ); 
    connect( btnExport, SIGNAL( clicked() ), d_chart, SLOT( exportChart() ) ); 
  
    toolBar->addWidget( typeBox );  
    toolBar->addWidget( orientationBox );  
    toolBar->addWidget( btnExport );  
    addToolBar( toolBar );  
  
    d_chart->setMode( typeBox->currentIndex() );  
    connect( typeBox, SIGNAL( currentIndexChanged( int ) ),  
             d_chart, SLOT( setMode( int ) ) );  
  
    d_chart->setOrientation( orientationBox->currentIndex() ); 
    connect( orientationBox, SIGNAL( currentIndexChanged(int ) ),  
             d_chart, SLOT( setOrientation( int ) ) );  
}  
  
int main(int argc, char **argv )  
{  
    QApplication a( argc, argv );  
  
    MainWindow mainWindow;  
  
    mainWindow.resize( 600, 400 );  
    mainWindow.show();  
  
    return a.exec(); 
}  

barchart.h代码
#ifndef _BAR_CHART_H_  
  
#include <qwt_plot.h>  
  
/**
*QwtPlotMultiBarChart显示一系列样本数据,每个样本由一组集合数据组成。
* 每一个数据都可以显示成一个直方图，当然每一组形成的直方图，既可以并排显示，也可以累加显示。
* 每一个集合的直方图，都可以用QwtColumnSymbol修饰
*/ 
class QwtPlotMultiBarChart; 
  
class BarChart:public QwtPlot  
{  
    Q_OBJECT  
  
public: 
    BarChart( QWidget * = NULL );  
  
public Q_SLOTS: 
    void setMode(int );  
    void setOrientation(int );  
    void exportChart(); 
  
private: 
    void populate(); 
  
    QwtPlotMultiBarChart *d_barChartItem;  
};  
  
#endif  

barchat.cpp代码

#include "barchart.h"  
#include <qwt_plot_renderer.h> 
#include <qwt_plot_canvas.h> 
#include <qwt_plot_multi_barchart.h> 
#include <qwt_column_symbol.h> 
#include <qwt_plot_layout.h> 
#include <qwt_legend.h> 
#include <qwt_scale_draw.h> 
  
BarChart::BarChart( QWidget *parent ):  
    QwtPlot( parent )  
{  
    setAutoFillBackground( true );  
  
    setPalette( Qt::white );  
    canvas()->setPalette( QColor( "LemonChiffon" ) );  
  
    setTitle( "Bar Chart" ); 
  
    setAxisTitle( QwtPlot::yLeft, "Whatever" );  
    setAxisTitle( QwtPlot::xBottom, "Whatever" );  
  
    d_barChartItem = new QwtPlotMultiBarChart( "Bar Chart " ); 
    d_barChartItem->setLayoutPolicy( QwtPlotMultiBarChart::AutoAdjustSamples   ); 
    d_barChartItem->setSpacing( 20 );//spacing 是两个样本之间的距离（两个直方图之间的距离，或者每组直方图之间的距离 
    d_barChartItem->setMargin( 3);// margin 最外层的直方图与画布的边框矩形之间的距离 
  
    d_barChartItem->attach( this );  
  
    insertLegend( new QwtLegend() );//插入描述符 
  
    populate();  
    setOrientation( 0 );  
  
    setAutoReplot( true );  
}  
  
void BarChart::populate() 
{  
    staticconst char *colors[] = { "DarkOrchid", "SteelBlue", "Gold" };  
  
    constint numSamples = 5;  
    constint numBars = sizeof( colors ) / sizeof( colors[0] ); 
  
    QList<QwtText> titles;  
    for (int i = 0; i < numBars; i++ ) 
    {  
        QString title("Bar %1"); 
        titles += title.arg( i );  
    }  
    d_barChartItem->setBarTitles( titles );//统一设置直方图的标题，这些标题是给legend用的 
    d_barChartItem->setLegendIconSize( QSize( 10, 14 ) ); 
  
    for (int i = 0; i < numBars; i++ ) 
    {  
        QwtColumnSymbol *symbol = new QwtColumnSymbol( QwtColumnSymbol::Box );  
        symbol->setLineWidth( 1 );//设置这个Box的边框宽度 
        symbol->setFrameStyle( QwtColumnSymbol::Plain  );//或者Raised 和NoFrame 
        symbol->setPalette( QPalette( colors[i] ) );  
  
        d_barChartItem->setSymbol( i, symbol );//每一组内部的直方图设置 
    }  
      
    QVector< QVector<double> > series;//二维数据 
    for (int i = 0; i < numSamples; i++ )//所有样本（直方图组） 
    {  
        QVector<double> values; 
        for (int j = 0; j < numBars; j++ )//每组内的直方图赋值 
            values += ( 2 + qrand() % 8 );  
  
        series += values;  
    }  
  
    d_barChartItem->setSamples( series );  
}  
//设置直方图显示方式 
void BarChart::setMode(int mode )  
{  
    if ( mode == 0 ) 
    {  
        d_barChartItem->setStyle( QwtPlotMultiBarChart::Grouped ); 
    }  
    else 
    {  
        d_barChartItem->setStyle( QwtPlotMultiBarChart::Stacked ); 
    }  
}  
//设置直方图显示方向和坐标轴变化 
void BarChart::setOrientation(int orientation )  
{  
    QwtPlot::Axis axis1, axis2;  
  
    if ( orientation == 0 ) 
    {  
        axis1 = QwtPlot::xBottom;  
        axis2 = QwtPlot::yLeft;  
  
        d_barChartItem->setOrientation( Qt::Vertical ); 
    }  
    else 
    {  
        axis1 = QwtPlot::yLeft;  
        axis2 = QwtPlot::xBottom;  
  
        d_barChartItem->setOrientation( Qt::Horizontal ); 
    }  
    //设置x轴刻度  
    setAxisScale( axis1, 0, d_barChartItem->dataSize() - 1, 1.0 ); 
    //设置y周刻度自动调整  
    setAxisAutoScale( axis2 );  
  
    //Backbone = the line where the ticks are located.    Ticks    Labels  
    //重新绘制坐标轴刻度  
    QwtScaleDraw *scaleDraw1 = axisScaleDraw( axis1 ); 
    scaleDraw1->enableComponent( QwtScaleDraw::Backbone,false );  
    scaleDraw1->enableComponent( QwtScaleDraw::Ticks, false );  
    QwtScaleDraw *scaleDraw2 = axisScaleDraw( axis2 ); 
  
    scaleDraw2->enableComponent( QwtScaleDraw::Backbone,true );  
    scaleDraw2->enableComponent( QwtScaleDraw::Ticks, true );  
    scaleDraw2->enableComponent( QwtScaleDraw::Labels ,true );  
  
  
  
  
    plotLayout()->setAlignCanvasToScale( axis1, true );  
    plotLayout()->setAlignCanvasToScale( axis2, false );  
  
    plotLayout()->setCanvasMargin( 0 );  
    updateCanvasMargins();  
  
    replot();  
}  
  
void BarChart::exportChart() 
{  
    QwtPlotRenderer renderer;  
    renderer.exportTo( this, "barchart.pdf" );  
}  

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