qwt_compass_rose.cpp

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/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * 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 "qwt_compass_rose.h"
#include "qwt_point_polar.h"
#include "qwt_painter.h"
#include <qpainter.h>

static QPointF qwtIntersection( 
    QPointF p11, QPointF p12, QPointF p21, QPointF p22 )
{
    const QLineF line1( p11, p12 );
    const QLineF line2( p21, p22 );

    QPointF pos;
    if ( line1.intersect( line2, &pos ) == QLineF::NoIntersection )
        return QPointF();

    return pos;
}

QwtCompassRose::QwtCompassRose()
{
}

QwtCompassRose::~QwtCompassRose()
{
}
    
void QwtCompassRose::setPalette( const QPalette &p )
{
    d_palette = p;
}   
    
const QPalette &QwtCompassRose::palette() const
{
    return d_palette;
}   

class QwtSimpleCompassRose::PrivateData
{
public:
    PrivateData():
        width( 0.2 ),
        numThorns( 8 ),
        numThornLevels( -1 ),
        shrinkFactor( 0.9 )
    {
    }

    double width;
    int numThorns;
    int numThornLevels;
    double shrinkFactor;
};

QwtSimpleCompassRose::QwtSimpleCompassRose(
    int numThorns, int numThornLevels )
{
    d_data = new PrivateData();
    d_data->numThorns = numThorns;
    d_data->numThornLevels = numThornLevels;

    const QColor dark( 128, 128, 255 );
    const QColor light( 192, 255, 255 );

    QPalette palette;
    palette.setColor( QPalette::Dark, dark );
    palette.setColor( QPalette::Light, light );

    setPalette( palette );
}

QwtSimpleCompassRose::~QwtSimpleCompassRose()
{
    delete d_data;
}

void QwtSimpleCompassRose::setShrinkFactor( double factor )
{
    d_data->shrinkFactor = factor;
}

double QwtSimpleCompassRose::shrinkFactor() const
{
    return d_data->shrinkFactor;
}

void QwtSimpleCompassRose::draw( QPainter *painter, const QPointF &center,
    double radius, double north, QPalette::ColorGroup cg ) const
{
    QPalette pal = palette();
    pal.setCurrentColorGroup( cg );

    drawRose( painter, pal, center, radius, north, d_data->width,
        d_data->numThorns, d_data->numThornLevels, d_data->shrinkFactor );
}

void QwtSimpleCompassRose::drawRose(
    QPainter *painter,
    const QPalette &palette,
    const QPointF &center, double radius, double north, double width,
    int numThorns, int numThornLevels, double shrinkFactor )
{
    if ( numThorns < 4 )
        numThorns = 4;

    if ( numThorns % 4 )
        numThorns += 4 - numThorns % 4;

    if ( numThornLevels <= 0 )
        numThornLevels = numThorns / 4;

    if ( shrinkFactor >= 1.0 )
        shrinkFactor = 1.0;

    if ( shrinkFactor <= 0.5 )
        shrinkFactor = 0.5;

    painter->save();

    painter->setPen( Qt::NoPen );

    for ( int j = 1; j <= numThornLevels; j++ )
    {
        double step =  qPow( 2.0, j ) * M_PI / numThorns;
        if ( step > M_PI_2 )
            break;

        double r = radius;
        for ( int k = 0; k < 3; k++ )
        {
            if ( j + k < numThornLevels )
                r *= shrinkFactor;
        }

        double leafWidth = r * width;
        if ( 2.0 * M_PI / step > 32 )
            leafWidth = 16;

        const double origin = qwtRadians( north );
        for ( double angle = origin;
            angle < 2.0 * M_PI + origin; angle += step )
        {
            const QPointF p = qwtPolar2Pos( center, r, angle );
            const QPointF p1 = qwtPolar2Pos( center, leafWidth, angle + M_PI_2 );
            const QPointF p2 = qwtPolar2Pos( center, leafWidth, angle - M_PI_2 );
            const QPointF p3 = qwtPolar2Pos( center, r, angle + step / 2.0 );
            const QPointF p4 = qwtPolar2Pos( center, r, angle - step / 2.0 );

            QPainterPath darkPath;
            darkPath.moveTo( center );
            darkPath.lineTo( p );
            darkPath.lineTo( qwtIntersection( center, p3, p1, p ) );

            painter->setBrush( palette.brush( QPalette::Dark ) );
            painter->drawPath( darkPath );

            QPainterPath lightPath;
            lightPath.moveTo( center );
            lightPath.lineTo( p );
            lightPath.lineTo( qwtIntersection( center, p4, p2, p ) );

            painter->setBrush( palette.brush( QPalette::Light ) );
            painter->drawPath( lightPath );
        }
    }
    painter->restore();
}

void QwtSimpleCompassRose::setWidth( double width )
{
    d_data->width = width;
    if ( d_data->width < 0.03 )
        d_data->width = 0.03;

    if ( d_data->width > 0.4 )
        d_data->width = 0.4;
}

double QwtSimpleCompassRose::width() const
{
    return d_data->width;
}

void QwtSimpleCompassRose::setNumThorns( int numThorns )
{
    if ( numThorns < 4 )
        numThorns = 4;

    if ( numThorns % 4 )
        numThorns += 4 - numThorns % 4;

    d_data->numThorns = numThorns;
}

int QwtSimpleCompassRose::numThorns() const
{
    return d_data->numThorns;
}

void QwtSimpleCompassRose::setNumThornLevels( int numThornLevels )
{
    d_data->numThornLevels = numThornLevels;
}

int QwtSimpleCompassRose::numThornLevels() const
{
    return d_data->numThornLevels;
}