Qt中直方图的使用-qwt例子
1、直方图效果图如下
2、main.cpp代码 如下：
#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();
}
3、barchart.h文件如下：
#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
4、barchat.cpp代码如下：
#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;
const int 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 )
{
const struct
{
const char *distro;
const int 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" );
}