QgsClipper Class Reference

A class to trim lines and polygons to within a rectangular region. More...

#include <qgsclipper.h>

List of all members.

Public Types
enum	Boundary { XMax, XMin, YMax, YMin }
Static Public Member Functions
static void	trimFeature (std::vector< double > &x, std::vector< double > &y, bool shapeOpen)
static void	trimPolygon (QPolygonF &pts, const QgsRectangle &clipRect)
static unsigned char *	clippedLineWKB (unsigned char *wkb, const QgsRectangle &clipExtent, QPolygonF &line)
	Reads a polyline from WKB and clips it to clipExtent.
Static Public Attributes
static const double	MAX_X = 16000
static const double	MIN_X = -16000
static const double	MAX_Y = 16000
static const double	MIN_Y = -16000
Static Private Member Functions
static void	trimFeatureToBoundary (const std::vector< double > &inX, const std::vector< double > &inY, std::vector< double > &outX, std::vector< double > &outY, Boundary b, bool shapeOpen)
static void	trimPolygonToBoundary (const QPolygonF &inPts, QPolygonF &outPts, const QgsRectangle &rect, Boundary b, double boundaryValue)
static bool	inside (const double x, const double y, Boundary b)
static bool	inside (const QPointF &pt, Boundary b, double val)
static QgsPoint	intersect (const double x1, const double y1, const double x2, const double y2, Boundary b)
static QPointF	intersectRect (const QPointF &pt1, const QPointF &pt2, Boundary b, const QgsRectangle &rect)
static bool	clipLineSegment (double xLeft, double xRight, double yBottom, double yTop, double &x0, double &y0, double &x1, double &y1)
static void	connectSeparatedLines (double x0, double y0, double x1, double y1, const QgsRectangle &clipRect, QPolygonF &pts)
	Connects two lines split by the clip (by inserting points on the clip border)
static void	clipStartTop (double &x0, double &y0, const double &x1, const double &y1, double yMax)
static void	clipStartBottom (double &x0, double &y0, const double &x1, const double &y1, double yMin)
static void	clipStartRight (double &x0, double &y0, const double &x1, const double &y1, double xMax)
static void	clipStartLeft (double &x0, double &y0, const double &x1, const double &y1, double xMin)
static void	clipEndTop (const double &x0, const double &y0, double &x1, double &y1, double yMax)
static void	clipEndBottom (const double &x0, const double &y0, double &x1, double &y1, double yMin)
static void	clipEndRight (const double &x0, const double &y0, double &x1, double &y1, double xMax)
static void	clipEndLeft (const double &x0, const double &y0, double &x1, double &y1, double xMin)
Static Private Attributes
static const double	SMALL_NUM = 1e-12

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Detailed Description

A class to trim lines and polygons to within a rectangular region.

The functions in this class are likely to be called from within a render loop and hence need to as CPU efficient as possible. The main purpose of the functions in this class are to trim lines and polygons to lie within a rectangular region. This is necessary for drawing items to an X11 display which have a limit on the magnitude of the screen coordinates (+/- 32768, i.e. 16 bit integer).

Definition at line 41 of file qgsclipper.h.

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Member Enumeration Documentation

enum QgsClipper::Boundary

Enumerator:

XMax
XMin
YMax
YMin

Definition at line 71 of file qgsclipper.h.

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Member Function Documentation

void QgsClipper::clipEndBottom	(	const double &	x0,
		const double &	y0,
		double &	x1,
		double &	y1,
		double	yMin
	)		[inline, static, private]

Definition at line 461 of file qgsclipper.h.

Referenced by clipLineSegment().

void QgsClipper::clipEndLeft	(	const double &	x0,
		const double &	y0,
		double &	x1,
		double &	y1,
		double	xMin
	)		[inline, static, private]

Definition at line 473 of file qgsclipper.h.

Referenced by clipLineSegment().

void QgsClipper::clipEndRight	(	const double &	x0,
		const double &	y0,
		double &	x1,
		double &	y1,
		double	xMax
	)		[inline, static, private]

Definition at line 467 of file qgsclipper.h.

Referenced by clipLineSegment().

void QgsClipper::clipEndTop	(	const double &	x0,
		const double &	y0,
		double &	x1,
		double &	y1,
		double	yMax
	)		[inline, static, private]

Definition at line 455 of file qgsclipper.h.

Referenced by clipLineSegment().

bool QgsClipper::clipLineSegment	(	double	xLeft,
		double	xRight,
		double	yBottom,
		double	yTop,
		double &	x0,
		double &	y0,
		double &	x1,
		double &	y1
	)		[inline, static, private]

Definition at line 480 of file qgsclipper.h.

References clipEndBottom(), clipEndLeft(), clipEndRight(), clipEndTop(), clipStartBottom(), clipStartLeft(), clipStartRight(), and clipStartTop().

Referenced by clippedLineWKB().

unsigned char * QgsClipper::clippedLineWKB	(	unsigned char *	wkb,
		const QgsRectangle &	clipExtent,
		QPolygonF &	line
	)		[static]

Reads a polyline from WKB and clips it to clipExtent.

Parameters:

wkb	pointer to the start of the line wkb
clipExtent	clipping bounds
line	out: clipped line coordinates

Definition at line 38 of file qgsclipper.cpp.

References clipLineSegment(), connectSeparatedLines(), QGis::WKBLineString25D, QgsRectangle::xMaximum(), QgsRectangle::xMinimum(), QgsRectangle::yMaximum(), and QgsRectangle::yMinimum().

Referenced by QgsFeatureRendererV2::_getLineString().

void QgsClipper::clipStartBottom	(	double &	x0,
		double &	y0,
		const double &	x1,
		const double &	y1,
		double	yMin
	)		[inline, static, private]

Definition at line 437 of file qgsclipper.h.

Referenced by clipLineSegment().

void QgsClipper::clipStartLeft	(	double &	x0,
		double &	y0,
		const double &	x1,
		const double &	y1,
		double	xMin
	)		[inline, static, private]

Definition at line 449 of file qgsclipper.h.

Referenced by clipLineSegment().

void QgsClipper::clipStartRight	(	double &	x0,
		double &	y0,
		const double &	x1,
		const double &	y1,
		double	xMax
	)		[inline, static, private]

Definition at line 443 of file qgsclipper.h.

Referenced by clipLineSegment().

void QgsClipper::clipStartTop	(	double &	x0,
		double &	y0,
		const double &	x1,
		const double &	y1,
		double	yMax
	)		[inline, static, private]

Definition at line 431 of file qgsclipper.h.

Referenced by clipLineSegment().

void QgsClipper::connectSeparatedLines	(	double	x0,
		double	y0,
		double	x1,
		double	y1,
		const QgsRectangle &	clipRect,
		QPolygonF &	pts
	)		[static, private]

Connects two lines split by the clip (by inserting points on the clip border)

Parameters:

x0	x-coordinate of the first line end
y0	y-coordinate of the first line end
x1	x-coordinate of the second line start
y1	y-coordinate of the second line start
clipRect	clip rectangle
pts,:	in/out array of clipped points

Definition at line 108 of file qgsclipper.cpp.

References doubleNear(), QgsRectangle::xMaximum(), QgsRectangle::xMinimum(), QgsRectangle::yMaximum(), and QgsRectangle::yMinimum().

Referenced by clippedLineWKB().

bool QgsClipper::inside	(	const double	x,
		const double	y,
		Boundary	b
	)		[inline, static, private]

Definition at line 299 of file qgsclipper.h.

References MAX_X, MAX_Y, MIN_X, MIN_Y, XMax, XMin, YMax, and YMin.

Referenced by trimFeatureToBoundary(), and trimPolygonToBoundary().

bool QgsClipper::inside	(	const QPointF &	pt,
		Boundary	b,
		double	val
	)		[inline, static, private]

Definition at line 323 of file qgsclipper.h.

References XMax, XMin, YMax, and YMin.

QgsPoint QgsClipper::intersect	(	const double	x1,
		const double	y1,
		const double	x2,
		const double	y2,
		Boundary	b
	)		[inline, static, private]

Definition at line 344 of file qgsclipper.h.

References MAX_X, MAX_Y, MIN_X, MIN_Y, QgsPoint::set(), SMALL_NUM, XMax, XMin, YMax, and YMin.

Referenced by trimFeatureToBoundary().

QPointF QgsClipper::intersectRect	(	const QPointF &	pt1,
		const QPointF &	pt2,
		Boundary	b,
		const QgsRectangle &	rect
	)		[inline, static, private]

Definition at line 391 of file qgsclipper.h.

References doubleNear(), SMALL_NUM, XMax, QgsRectangle::xMaximum(), XMin, QgsRectangle::xMinimum(), YMax, QgsRectangle::yMaximum(), YMin, and QgsRectangle::yMinimum().

Referenced by trimPolygonToBoundary().

void QgsClipper::trimFeature	(	std::vector< double > &	x,
		std::vector< double > &	y,
		bool	shapeOpen
	)		[inline, static]

Definition at line 157 of file qgsclipper.h.

References trimFeatureToBoundary(), XMax, XMin, YMax, and YMin.

Referenced by QgsVectorLayer::drawLineString(), and QgsVectorLayer::drawPolygon().

void QgsClipper::trimFeatureToBoundary	(	const std::vector< double > &	inX,
		const std::vector< double > &	inY,
		std::vector< double > &	outX,
		std::vector< double > &	outY,
		Boundary	b,
		bool	shapeOpen
	)		[inline, static, private]

Definition at line 197 of file qgsclipper.h.

References inside(), intersect(), QgsPoint::x(), and QgsPoint::y().

Referenced by trimFeature().

void QgsClipper::trimPolygon	(	QPolygonF &	pts,
		const QgsRectangle &	clipRect
	)		[inline, static]

Definition at line 178 of file qgsclipper.h.

References trimPolygonToBoundary(), XMax, QgsRectangle::xMaximum(), XMin, QgsRectangle::xMinimum(), YMax, QgsRectangle::yMaximum(), YMin, and QgsRectangle::yMinimum().

Referenced by QgsFeatureRendererV2::_getPolygon().

void QgsClipper::trimPolygonToBoundary	(	const QPolygonF &	inPts,
		QPolygonF &	outPts,
		const QgsRectangle &	rect,
		Boundary	b,
		double	boundaryValue
	)		[inline, static, private]

Definition at line 263 of file qgsclipper.h.

References inside(), and intersectRect().

Referenced by trimPolygon().

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Member Data Documentation

const double QgsClipper::MAX_X = 16000 [static]

Definition at line 64 of file qgsclipper.h.

Referenced by QgsVectorLayer::drawFeature(), QgsVectorLayer::drawLineString(), QgsVectorLayer::drawPolygon(), inside(), and intersect().

const double QgsClipper::MAX_Y = 16000 [static]

Definition at line 66 of file qgsclipper.h.

Referenced by QgsVectorLayer::drawFeature(), QgsVectorLayer::drawLineString(), QgsVectorLayer::drawPolygon(), inside(), and intersect().

const double QgsClipper::MIN_X = -16000 [static]

Definition at line 65 of file qgsclipper.h.

Referenced by inside(), and intersect().

const double QgsClipper::MIN_Y = -16000 [static]

Definition at line 67 of file qgsclipper.h.

Referenced by inside(), and intersect().

const double QgsClipper::SMALL_NUM = 1e-12 [static, private]

Definition at line 92 of file qgsclipper.h.

Referenced by intersect(), and intersectRect().

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The documentation for this class was generated from the following files:

• src/core/qgsclipper.h
• src/core/qgsclipper.cpp