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qwt_clipper.cpp
/******************************************************************************
* 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_clipper.h"
#include "qwt_point_polar.h"
#include "qwt_interval.h"
#include "qwt_math.h"
#include <qpolygon.h>
#include <qrect.h>
#include <algorithm>
namespace QwtClip
{
// some templates used for inlining
template< class Point, typename T > class LeftEdge;
template< class Point, typename T > class RightEdge;
template< class Point, typename T > class TopEdge;
template< class Point, typename T > class BottomEdge;
}
template< class Point, typename Value >
class QwtClip::LeftEdge
{
public:
inline LeftEdge( Value x1, Value, Value, Value ):
m_x1( x1 )
{
}
inline bool isInside( const Point& p ) const
{
return p.x() >= m_x1;
}
inline Point intersection( const Point& p1, const Point& p2 ) const
{
double dy = ( p1.y() - p2.y() ) / double( p1.x() - p2.x() );
return Point( m_x1, static_cast< Value >( p2.y() + ( m_x1 - p2.x() ) * dy ) );
}
private:
const Value m_x1;
};
template< class Point, typename Value >
class QwtClip::RightEdge
{
public:
inline RightEdge( Value, Value x2, Value, Value ):
m_x2( x2 )
{
}
inline bool isInside( const Point& p ) const
{
return p.x() <= m_x2;
}
inline Point intersection( const Point& p1, const Point& p2 ) const
{
double dy = ( p1.y() - p2.y() ) / double( p1.x() - p2.x() );
return Point( m_x2, static_cast< Value >( p2.y() + ( m_x2 - p2.x() ) * dy ) );
}
private:
const Value m_x2;
};
template< class Point, typename Value >
class QwtClip::TopEdge
{
public:
inline TopEdge( Value, Value, Value y1, Value ):
m_y1( y1 )
{
}
inline bool isInside( const Point& p ) const
{
return p.y() >= m_y1;
}
inline Point intersection( const Point& p1, const Point& p2 ) const
{
double dx = ( p1.x() - p2.x() ) / double( p1.y() - p2.y() );
return Point( static_cast< Value >( p2.x() + ( m_y1 - p2.y() ) * dx ), m_y1 );
}
private:
const Value m_y1;
};
template< class Point, typename Value >
class QwtClip::BottomEdge
{
public:
inline BottomEdge( Value, Value, Value, Value y2 ):
m_y2( y2 )
{
}
inline bool isInside( const Point& p ) const
{
return p.y() <= m_y2;
}
inline Point intersection( const Point& p1, const Point& p2 ) const
{
double dx = ( p1.x() - p2.x() ) / double( p1.y() - p2.y() );
return Point( static_cast< Value >( p2.x() + ( m_y2 - p2.y() ) * dx ), m_y2 );
}
private:
const Value m_y2;
};
using namespace QwtClip;
template< class Polygon, class Rect, typename T >
class QwtPolygonClipper
{
typedef typename Polygon::value_type Point;
public:
explicit QwtPolygonClipper( const Rect& clipRect ):
m_clipRect( clipRect )
{
}
void clipPolygon( Polygon& points1, bool closePolygon ) const
{
#if 0
if ( m_clipRect.contains( points1.boundingRect() ) )
return polygon;
#endif
Polygon points2;
points2.reserve( qMin( 256, points1.size() ) );
clipEdge< LeftEdge< Point, T > >( closePolygon, points1, points2 );
clipEdge< RightEdge< Point, T > >( closePolygon, points2, points1 );
clipEdge< TopEdge< Point, T > >( closePolygon, points1, points2 );
clipEdge< BottomEdge< Point, T > >( closePolygon, points2, points1 );
}
private:
template< class Edge >
inline void clipEdge( bool closePolygon,
const Polygon& points, Polygon& clippedPoints ) const
{
clippedPoints.clear();
if ( points.size() < 2 )
{
if ( points.size() == 1 )
clippedPoints += points[0];
return;
}
const Edge edge( m_clipRect.x(), m_clipRect.x() + m_clipRect.width(),
m_clipRect.y(), m_clipRect.y() + m_clipRect.height() );
if ( !closePolygon )
{
const Point& p1 = points.first();
if ( edge.isInside( p1 ) )
clippedPoints += p1;
}
else
{
const Point& p1 = points.first();
const Point& p2 = points.last();
if ( edge.isInside( p1 ) )
{
if ( !edge.isInside( p2 ) )
clippedPoints += edge.intersection( p1, p2 );
clippedPoints += p1;
}
else if ( edge.isInside( p2 ) )
{
clippedPoints += edge.intersection( p1, p2 );
}
}
const uint nPoints = points.size();
const Point* p = points.constData();
for ( uint i = 1; i < nPoints; i++ )
{
const Point& p1 = p[i];
const Point& p2 = p[i - 1];
if ( edge.isInside( p1 ) )
{
if ( !edge.isInside( p2 ) )
clippedPoints += edge.intersection( p1, p2 );
clippedPoints += p1;
}
else if ( edge.isInside( p2 ) )
{
clippedPoints += edge.intersection( p1, p2 );
}
}
}
const Rect m_clipRect;
};
class QwtCircleClipper
{
public:
explicit QwtCircleClipper( const QRectF& r );
QVector< QwtInterval > clipCircle( const QPointF&, double radius ) const;
private:
enum Edge
{
Left,
Top,
Right,
Bottom,
NEdges
};
QVector< QPointF > cuttingPoints(
Edge, const QPointF& pos, double radius ) const;
double toAngle( const QPointF&, const QPointF& ) const;
const QRectF m_rect;
};
QwtCircleClipper::QwtCircleClipper( const QRectF& r )
: m_rect( r )
{
}
QVector< QwtInterval > QwtCircleClipper::clipCircle(
const QPointF& pos, double radius ) const
{
// using QVarLengthArray TODO ...
QVector< QPointF > points;
for ( int edge = 0; edge < NEdges; edge++ )
points += cuttingPoints( static_cast< Edge >( edge ), pos, radius );
QVector< QwtInterval > intv;
if ( points.size() <= 0 )
{
QRectF cRect( 0, 0, 2 * radius, 2 * radius );
cRect.moveCenter( pos );
if ( m_rect.contains( cRect ) )
intv += QwtInterval( 0.0, 2 * M_PI );
}
else
{
QVector< double > angles;
angles.reserve( points.size() );
for ( int i = 0; i < points.size(); i++ )
angles += toAngle( pos, points[i] );
std::sort( angles.begin(), angles.end() );
const int in = m_rect.contains( qwtPolar2Pos( pos, radius,
angles[0] + ( angles[1] - angles[0] ) / 2 ) );
intv.reserve( angles.size() / 2 );
if ( in )
{
for ( int i = 0; i < angles.size() - 1; i += 2 )
intv += QwtInterval( angles[i], angles[i + 1] );
}
else
{
for ( int i = 1; i < angles.size() - 1; i += 2 )
intv += QwtInterval( angles[i], angles[i + 1] );
intv += QwtInterval( angles.last(), angles.first() );
}
}
return intv;
}
double QwtCircleClipper::toAngle(
const QPointF& from, const QPointF& to ) const
{
if ( from.x() == to.x() )
return from.y() <= to.y() ? M_PI / 2.0 : 3 * M_PI / 2.0;
const double m = qAbs( ( to.y() - from.y() ) / ( to.x() - from.x() ) );
double angle = std::atan( m );
if ( to.x() > from.x() )
{
if ( to.y() > from.y() )
angle = 2 * M_PI - angle;
}
else
{
if ( to.y() > from.y() )
angle = M_PI + angle;
else
angle = M_PI - angle;
}
return angle;
}
QVector< QPointF > QwtCircleClipper::cuttingPoints(
Edge edge, const QPointF& pos, double radius ) const
{
QVector< QPointF > points;
if ( edge == Left || edge == Right )
{
const double x = ( edge == Left ) ? m_rect.left() : m_rect.right();
if ( qAbs( pos.x() - x ) < radius )
{
const double off = std::sqrt( qwtSqr( radius ) - qwtSqr( pos.x() - x ) );
const double m_y1 = pos.y() + off;
if ( m_y1 >= m_rect.top() && m_y1 <= m_rect.bottom() )
points += QPointF( x, m_y1 );
const double m_y2 = pos.y() - off;
if ( m_y2 >= m_rect.top() && m_y2 <= m_rect.bottom() )
points += QPointF( x, m_y2 );
}
}
else
{
const double y = ( edge == Top ) ? m_rect.top() : m_rect.bottom();
if ( qAbs( pos.y() - y ) < radius )
{
const double off = std::sqrt( qwtSqr( radius ) - qwtSqr( pos.y() - y ) );
const double x1 = pos.x() + off;
if ( x1 >= m_rect.left() && x1 <= m_rect.right() )
points += QPointF( x1, y );
const double m_x2 = pos.x() - off;
if ( m_x2 >= m_rect.left() && m_x2 <= m_rect.right() )
points += QPointF( m_x2, y );
}
}
return points;
}
void QwtClipper::clipPolygon(
const QRectF& clipRect, QPolygon& polygon, bool closePolygon )
{
const int minX = qCeil( clipRect.left() );
const int maxX = qFloor( clipRect.right() );
const int minY = qCeil( clipRect.top() );
const int maxY = qFloor( clipRect.bottom() );
const QRect r( minX, minY, maxX - minX, maxY - minY );
QwtPolygonClipper< QPolygon, QRect, int > clipper( r );
clipper.clipPolygon( polygon, closePolygon );
}
void QwtClipper::clipPolygon(
const QRect& clipRect, QPolygon& polygon, bool closePolygon )
{
QwtPolygonClipper< QPolygon, QRect, int > clipper( clipRect );
clipper.clipPolygon( polygon, closePolygon );
}
void QwtClipper::clipPolygonF(
const QRectF& clipRect, QPolygonF& polygon, bool closePolygon )
{
QwtPolygonClipper< QPolygonF, QRectF, double > clipper( clipRect );
clipper.clipPolygon( polygon, closePolygon );
}
QPolygon QwtClipper::clippedPolygon(
const QRectF& clipRect, const QPolygon& polygon, bool closePolygon )
{
QPolygon points( polygon );
clipPolygon( clipRect, points, closePolygon );
return points;
}
QPolygon QwtClipper::clippedPolygon(
const QRect& clipRect, const QPolygon& polygon, bool closePolygon )
{
QPolygon points( polygon );
clipPolygon( clipRect, points, closePolygon );
return points;
}
QPolygonF QwtClipper::clippedPolygonF(
const QRectF& clipRect, const QPolygonF& polygon, bool closePolygon )
{
QPolygonF points( polygon );
clipPolygonF( clipRect, points, closePolygon );
return points;
}
QVector< QwtInterval > QwtClipper::clipCircle( const QRectF& clipRect,
const QPointF& center, double radius )
{
QwtCircleClipper clipper( clipRect );
return clipper.clipCircle( center, radius );
}
QVector
Definition qwt_clipper.h:23
QwtInterval
A class representing an interval.
Definition qwt_interval.h:23
QwtClipper::clipPolygon
QWT_EXPORT void clipPolygon(const QRect &, QPolygon &, bool closePolygon=false)
Definition qwt_clipper.cpp:390
QwtClipper::clippedPolygonF
QWT_EXPORT QPolygonF clippedPolygonF(const QRectF &, const QPolygonF &, bool closePolygon=false)
Definition qwt_clipper.cpp:455
QwtClipper::clipPolygonF
QWT_EXPORT void clipPolygonF(const QRectF &, QPolygonF &, bool closePolygon=false)
Definition qwt_clipper.cpp:404
QwtClipper::clipCircle
QWT_EXPORT QVector< QwtInterval > clipCircle(const QRectF &, const QPointF &, double radius)
Definition qwt_clipper.cpp:477
QwtClipper::clippedPolygon
QWT_EXPORT QPolygon clippedPolygon(const QRect &, const QPolygon &, bool closePolygon=false)
Definition qwt_clipper.cpp:437