Released version 6.1.3

examples/scatterplot/main.cpp

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+#include <qapplication.h>
+#include "mainwindow.h"
+
+int main( int argc, char **argv )
+{
+    QApplication a( argc, argv );
+
+    MainWindow w;
+    w.resize( 800, 600 );
+    w.show();
+
+    return a.exec();
+}

examples/scatterplot/mainwindow.cpp

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+#include "mainwindow.h"
+#include "plot.h"
+#include <qmath.h>
+
+static double randomValue()
+{
+    // a number between [ 0.0, 1.0 ]
+    return ( qrand() % 100000 ) / 100000.0;
+}
+
+MainWindow::MainWindow()
+{
+    d_plot = new Plot( this );
+    d_plot->setTitle( "Scatter Plot" );
+    setCentralWidget( d_plot );
+
+    // a million points
+    setSamples( 100000 );
+}
+
+void MainWindow::setSamples( int numPoints )
+{
+    QPolygonF samples;
+
+    for ( int i = 0; i < numPoints; i++ )
+    {
+        const double x = randomValue() * 24.0 + 1.0;
+        const double y = ::log( 10.0 * ( x - 1.0 ) + 1.0 ) 
+            * ( randomValue() * 0.5 + 0.9 );
+
+        samples += QPointF( x, y );
+    }
+
+    d_plot->setSamples( samples );
+}

examples/scatterplot/mainwindow.h

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+#ifndef _MAINWINDOW_H_
+#define _MAINWINDOW_H_ 1
+
+#include <qmainwindow.h>
+
+class Plot;
+
+class MainWindow: public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    MainWindow();
+
+private:
+    void setSamples( int samples );
+
+private:
+    Plot *d_plot;
+};
+
+#endif

examples/scatterplot/plot.cpp

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+#include "plot.h"
+#include <qwt_plot_magnifier.h>
+#include <qwt_plot_panner.h>
+#include <qwt_plot_picker.h>
+#include <qwt_picker_machine.h>
+#include <qwt_plot_curve.h>
+
+class DistancePicker: public QwtPlotPicker
+{
+public:
+    DistancePicker( QWidget *canvas ):
+        QwtPlotPicker( canvas )
+    {
+        setTrackerMode( QwtPicker::ActiveOnly );
+        setStateMachine( new QwtPickerDragLineMachine() );
+        setRubberBand( QwtPlotPicker::PolygonRubberBand );
+    }
+
+    virtual QwtText trackerTextF( const QPointF &pos ) const
+    {
+        QwtText text;
+
+        const QPolygon points = selection();
+        if ( !points.isEmpty() )
+        {
+            QString num;
+            num.setNum( QLineF( pos, invTransform( points[0] ) ).length() );
+
+            QColor bg( Qt::white );
+            bg.setAlpha( 200 );
+
+            text.setBackgroundBrush( QBrush( bg ) );
+            text.setText( num );
+        }
+        return text;
+    }
+};
+
+Plot::Plot( QWidget *parent ):
+    QwtPlot( parent ),
+    d_curve( NULL )
+{
+    canvas()->setStyleSheet(
+        "border: 2px solid Black;"
+        "border-radius: 15px;"
+        "background-color: qlineargradient( x1: 0, y1: 0, x2: 0, y2: 1,"
+            "stop: 0 LemonChiffon, stop: 1 PaleGoldenrod );"
+    );
+
+    // attach curve
+    d_curve = new QwtPlotCurve( "Scattered Points" );
+    d_curve->setPen( QColor( "Purple" ) );
+
+    // when using QwtPlotCurve::ImageBuffer simple dots can be
+    // rendered in parallel on multicore systems.
+    d_curve->setRenderThreadCount( 0 ); // 0: use QThread::idealThreadCount()
+
+    d_curve->attach( this );
+
+    setSymbol( NULL );
+
+    // panning with the left mouse button
+    (void )new QwtPlotPanner( canvas() );
+
+    // zoom in/out with the wheel
+    QwtPlotMagnifier *magnifier = new QwtPlotMagnifier( canvas() );
+    magnifier->setMouseButton( Qt::NoButton );
+
+    // distanve measurement with the right mouse button
+    DistancePicker *picker = new DistancePicker( canvas() );
+    picker->setMousePattern( QwtPlotPicker::MouseSelect1, Qt::RightButton );
+    picker->setRubberBandPen( QPen( Qt::blue ) );
+}
+
+void Plot::setSymbol( QwtSymbol *symbol )
+{
+    d_curve->setSymbol( symbol );
+
+    if ( symbol == NULL )
+    {
+        d_curve->setStyle( QwtPlotCurve::Dots );
+    }
+}
+
+void Plot::setSamples( const QVector<QPointF> &samples )
+{
+    d_curve->setPaintAttribute( 
+        QwtPlotCurve::ImageBuffer, samples.size() > 1000 );
+
+    d_curve->setSamples( samples );
+}

examples/scatterplot/plot.h

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+#ifndef _PLOT_H_
+#define _PLOT_H_ 1
+
+#include <qwt_plot.h>
+
+class QwtPlotCurve;
+class QwtSymbol;
+
+class Plot : public QwtPlot
+{
+    Q_OBJECT
+
+public:
+    Plot( QWidget *parent = NULL );
+
+    void setSymbol( QwtSymbol * );
+    void setSamples( const QVector<QPointF> &samples );
+
+private:
+    QwtPlotCurve *d_curve;
+};
+
+#endif // _PLOT_H_

examples/scatterplot/scatterplot.pro

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+################################################################
+# Qwt Widget Library
+# Copyright (C) 1997   Josef Wilgen
+# Copyright (C) 2002   Uwe Rathmann
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the Qwt License, Version 1.0
+################################################################
+
+include( $${PWD}/../examples.pri )
+
+TARGET       = scatterplot
+
+HEADERS = \
+    mainwindow.h \
+    plot.h
+
+SOURCES = \
+    main.cpp \
+    mainwindow.cpp \
+    plot.cpp
+