Qwt直方图例子注释

来源：互联网发布：淘宝借贷逾期编辑：程序博客网时间：2024/04/26 07:38

qwt帮助文档还是很多的，学习挺耗时，现将单个直方图显示的例子，注释一遍。

方便理解，后期可以直接使用了。效果如下：

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 *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( orientationBox );  
    toolBar->addWidget( btnExport );  
    addToolBar( toolBar );  
  
    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>  
#include <qstringlist.h> 
  
class DistroChartItem; 
  
class BarChart:public QwtPlot  
{  
    Q_OBJECT  
  
public: 
    BarChart( QWidget * = NULL );  
  
public Q_SLOTS: 
    void setOrientation(int );  
    void exportChart(); 
  
private: 
    void populate(); 
  
    DistroChartItem *d_barChartItem;//自定义直方图类 
    QStringList d_distros;//改变方向重置标题用 
};  
  
#endif  

barchart.cpp代码
#include "barchart.h"  
#include <qwt_plot_renderer.h> 
#include <qwt_plot_canvas.h> 
#include <qwt_plot_barchart.h> 
#include <qwt_column_symbol.h> 
#include <qwt_plot_layout.h> 
#include <qwt_legend.h> 
#include <qwt_scale_draw.h> 
  
class DistroScaleDraw:public QwtScaleDraw  
{  
public: 
    DistroScaleDraw( Qt::Orientation orientation, const QStringList &labels ):  
        d_labels( labels )  
    {  
        setTickLength( QwtScaleDiv::MinorTick, 0 );  
        setTickLength( QwtScaleDiv::MediumTick, 0 );  
        setTickLength( QwtScaleDiv::MajorTick, 2 );  
  
        enableComponent( QwtScaleDraw::Backbone, false );  
  
        if ( orientation == Qt::Vertical ) 
        {  
            setLabelRotation( -60.0 );  
        }  
        else 
        {  
            setLabelRotation( -20.0 );  
        }  
  
        setLabelAlignment( Qt::AlignLeft | Qt::AlignVCenter ); 
    }  
  
    //刻度标签值  
    virtual QwtText label(double value ) const  
    {  
        QwtText lbl;  
  
        constint index = qRound( value );//四舍五入 
        if ( index >= 0 && index <= d_labels.size() ) 
        {  
            lbl = d_labels[ index ];  
        }  
        return lbl; 
    }  
  
private: 
    const QStringList d_labels; 
};  
  
//直方图 
//QwtPlotBarChart将一系列数据显示为bar 
class DistroChartItem:public QwtPlotBarChart  
{  
public: 
    DistroChartItem():  
        QwtPlotBarChart( "Page Hits" ) 
    {  
        setLegendMode( QwtPlotBarChart::LegendBarTitles );//显示所有bar各自的标题，而QwtPlotBarChart::LegendChartTitle 显示这个表的标题 
        setLegendIconSize( QSize( 10, 14 ) );  
    }  
  
    //分配颜色和标题给bar，并更新  
    void addDistro(const QString &distro, const QColor &color )  
    {  
        d_colors += color;  
        d_distros += distro;  
        itemChanged();//Update the legend of the parent plot. 
    }  
  
    //自定义每个Bar  
    virtual QwtColumnSymbol *specialSymbol( 
        int index,const QPointF& ) const  
    {  
  
  
        QwtColumnSymbol *symbol = new QwtColumnSymbol( QwtColumnSymbol::Box );  
        symbol->setLineWidth( 1 );  
        symbol->setFrameStyle( QwtColumnSymbol::Plain );//Raised 
  
        QColor c( Qt::white );  
        if ( index >= 0 && index < d_colors.size() ) 
            c = d_colors[ index ];  
  
        symbol->setPalette( c );  
      
        return symbol; 
    }  
    //自定义每个bar的标题  
    virtual QwtText barTitle(int sampleIndex ) const  
    {  
        QwtText title;  
        if ( sampleIndex >= 0 && sampleIndex < d_distros.size() ) 
            title = d_distros[ sampleIndex ];  
  
        return title; 
    }  
  
private: 
    QList<QColor> d_colors;  
    QList<QString> d_distros;  
};  
  
BarChart::BarChart( QWidget *parent ):  
    QwtPlot( parent )  
{  
    conststruct   
    {  
        constchar *distro;  
        constint hits;  
        QColor color;  
  
    } pageHits[] =  
    {  
        { "Arch", 1114, QColor("DodgerBlue" ) },  
        { "Debian", 1373, QColor("#d70751" ) },  
        { "Fedora", 1638, QColor("SteelBlue" ) },  
        { "Mageia", 1395, QColor("Indigo" ) },  
        { "Mint", 3874, QColor( 183, 255, 183 ) }, 
        { "openSuSE", 1532, QColor( 115, 186, 37 ) }, 
        { "Puppy", 1059, QColor("LightSkyBlue" ) },  
        { "Ubuntu", 2391, QColor("FireBrick" ) }  
    };  
  
    setAutoFillBackground( true );  
    setPalette( QColor( "Linen" ) ); 
  
    //设置画布  
    QwtPlotCanvas *canvas = new QwtPlotCanvas();  
    canvas->setLineWidth( 2 );  
    canvas->setFrameStyle( QFrame::Box | QFrame::Sunken ); 
    canvas->setBorderRadius( 10 );  
  
    QPalette canvasPalette( QColor( "Plum" ) );  
    canvasPalette.setColor( QPalette::Foreground, QColor("Indigo" ) );  
    canvas->setPalette( canvasPalette );  
  
    setCanvas( canvas );  
  
    setTitle( "DistroWatch Page Hit Ranking, April 2012" ); 
  
    d_barChartItem = new DistroChartItem();  
  
    //数据源  
    QVector< double > samples;  
  
    for ( uint i = 0; i <sizeof( pageHits ) / sizeof( pageHits[ 0 ] ); i++ )  
    {  
        d_distros += pageHits[ i ].distro; //给标题赋值  
        samples += pageHits[ i ].hits;//给数据赋值 
  
        d_barChartItem->addDistro(   
            pageHits[ i ].distro, pageHits[ i ].color );//更新颜色和标题 
    }  
  
    d_barChartItem->setSamples( samples );//更新数据 
  
    d_barChartItem->attach( this );  
  
    insertLegend( new QwtLegend() );  
  
    setOrientation( 0 );  
    setAutoReplot( false );  
}  
  
void BarChart::setOrientation(int o )  
{  
    const Qt::Orientation orientation = 
        ( o == 0 ) ? Qt::Vertical : Qt::Horizontal;  
  
    int axis1 = QwtPlot::xBottom; 
    int axis2 = QwtPlot::yLeft; 
  
    if ( orientation == Qt::Horizontal ) 
        qSwap( axis1, axis2 );  
  
    d_barChartItem->setOrientation( orientation );//直方图方向 
    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( 30);// margin 最外层的直方图与画布的边框矩形之间的距离 
  
    setAxisTitle( axis1, "Distros" ); 
    setAxisMaxMinor( axis1, 3);//设置坐标轴小刻度的最大值 
    setAxisMaxMajor( axis1, 10);//设置坐标轴大刻度的最大值 
    setAxisScaleDraw( axis1, new DistroScaleDraw( orientation, d_distros ) );//需要重新更新标题 
  
  
    setAxisTitle( axis2, "Hits per day ( HPD )" ); 
    setAxisMaxMinor( axis2, 3 );  
  
    QwtScaleDraw *scaleDraw = new QwtScaleDraw();  
    scaleDraw->setTickLength( QwtScaleDiv::MediumTick, 4 ); 
    setAxisScaleDraw( axis2, scaleDraw );  
  
    plotLayout()->setCanvasMargin( 0 );  
    replot();  
}  
  
void BarChart::exportChart() 
{  
    QwtPlotRenderer renderer;  
    renderer.exportTo( this, "distrowatch.pdf" );  
}  

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