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

#include <qgsclipper.h>

Public Types
enum	Boundary { XMax, XMin, YMax, YMin }

Static Public Member Functions
static void	trimFeature (QVector< double > &x, QVector< double > &y, bool shapeOpen)
static void	trimPolygon (QPolygonF &pts, const QgsRectangle &clipRect)
static const unsigned char *	clippedLineWKB (const 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 QVector< double > &inX, const QVector< double > &inY, QVector< double > &outX, QVector< 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

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 39 of file qgsclipper.h.

Member Enumeration Documentation

enum QgsClipper::Boundary

Enumerator:

XMax
XMin
YMax
YMin

Definition at line 69 of file qgsclipper.h.

Member Function Documentation

void QgsClipper::clipEndBottom	(	const double &	x0,
		const double &	y0,
		double &	x1,
		double &	y1,
		double	yMin
	)

inlinestaticprivate

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
	)

inlinestaticprivate

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
	)

inlinestaticprivate

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
	)

inlinestaticprivate

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
	)

inlinestaticprivate

Definition at line 480 of file qgsclipper.h.

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

Referenced by clippedLineWKB().

const unsigned char * QgsClipper::clippedLineWKB	(	const 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
	)

inlinestaticprivate

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
	)

inlinestaticprivate

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
	)

inlinestaticprivate

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
	)

inlinestaticprivate

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
	)

staticprivate

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 100 of file qgsclipper.cpp.

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

Referenced by clippedLineWKB().

bool QgsClipper::inside	(	const double	x,
		const double	y,
		Boundary	b
	)

inlinestaticprivate

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
	)

inlinestaticprivate

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
	)

inlinestaticprivate

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
	)

inlinestaticprivate

Definition at line 391 of file qgsclipper.h.

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

Referenced by trimPolygonToBoundary().

void QgsClipper::trimFeature	(	QVector< double > &	x,
		QVector< double > &	y,
		bool	shapeOpen
	)

inlinestatic

Definition at line 157 of file qgsclipper.h.

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

void QgsClipper::trimFeatureToBoundary	(	const QVector< double > &	inX,
		const QVector< double > &	inY,
		QVector< double > &	outX,
		QVector< double > &	outY,
		Boundary	b,
		bool	shapeOpen
	)

inlinestaticprivate

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
	)

inlinestatic

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
	)

inlinestaticprivate

Definition at line 263 of file qgsclipper.h.

References inside(), and intersectRect().

Referenced by trimPolygon().

Member Data Documentation

const double QgsClipper::MAX_X = 16000

static

Definition at line 62 of file qgsclipper.h.

Referenced by inside(), and intersect().

const double QgsClipper::MAX_Y = 16000

static

Definition at line 64 of file qgsclipper.h.

Referenced by inside(), and intersect().

const double QgsClipper::MIN_X = -16000

static

Definition at line 63 of file qgsclipper.h.

Referenced by inside(), and intersect().

const double QgsClipper::MIN_Y = -16000

static

Definition at line 65 of file qgsclipper.h.

Referenced by inside(), and intersect().

const double QgsClipper::SMALL_NUM = 1e-12

staticprivate

Definition at line 92 of file qgsclipper.h.

Referenced by intersect(), and intersectRect().

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

/tmp/buildd/qgis-2.2.0+wheezy1/src/core/qgsclipper.h
/tmp/buildd/qgis-2.2.0+wheezy1/src/core/qgsclipper.cpp

Public Types

Static Public Member Functions

Static Public Attributes

Static Private Member Functions

Static Private Attributes

Detailed Description

Member Enumeration Documentation

Member Function Documentation

Member Data Documentation