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

#include <qgsclipper.h>

Public Types
enum	Boundary { XMax , XMin , YMax , YMin , ZMax , ZMin }
	A handy way to refer to the four boundaries. More...

Static Public Member Functions
static bool	clipLineSegment (double left, double right, double bottom, double top, double &x0, double &y0, double &x1, double &y1)
	Clips a line segment to a rectangle.

static void	clipped3dLine (const QVector< double > &xIn, const QVector< double > &yIn, const QVector< double > &zIn, QVector< double > &x, QVector< double > &y, QVector< double > &z, const QgsBox3D &clipExtent)
	Takes a line with 3D coordinates and clips it to clipExtent.

static QPolygonF	clippedLine (const QgsCurve &curve, const QgsRectangle &clipExtent)
	Takes a linestring and clips it to clipExtent.

static QPolygonF	clippedLine (const QPolygonF &curve, const QgsRectangle &clipExtent)
	Takes a 2D curve and clips it to clipExtent.

static void	trimFeature (QVector< double > &x, QVector< double > &y, bool shapeOpen)
	Trims the given feature to a rectangular box.

static void	trimPolygon (QPolygonF &pts, const QgsRectangle &clipRect)
	Trims the given polygon to a rectangular box, by modifying the given polygon in place.

static void	trimPolygon (QVector< double > &x, QVector< double > &y, QVector< double > &z, const QgsBox3D &clipRect)
	Trims a polygon consisting of the specified x, y and z values to a pseudo 3D box, by modifying the arrays in place.

Static Public Attributes
static const double	MAX_X = 16000
	Maximum X-coordinate of the rectangular box used for clipping.

static const double	MAX_Y = 16000
	Maximum Y-coordinate of the rectangular box used for clipping.

static const double	MIN_X = -16000
	Minimum X-coordinate of the rectangular box used for clipping.

static const double	MIN_Y = -16000
	Minimum Y-coordinate of the rectangular box used for clipping.

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 50 of file qgsclipper.h.

Member Enumeration Documentation

◆ Boundary

enum QgsClipper::Boundary

A handy way to refer to the four boundaries.

Enumerator
XMax
XMin
YMax
YMin
ZMax	Maximum Z. Since QGIS 3.26
ZMin	Minimum Z. Since QGIS 3.26

Definition at line 82 of file qgsclipper.h.

Member Function Documentation

◆ clipLineSegment()

bool QgsClipper::clipLineSegment	(	double	left,
		double	right,
		double	bottom,
		double	top,
		double &	x0,
		double &	y0,
		double &	x1,
		double &	y1
	)

inlinestatic

Clips a line segment to a rectangle.

An implementation of the 'Fast clipping' algorithm (Sobkow et al. 1987, Computers & Graphics Vol.11, 4, p.459-467).

Parameters

left	x-coordinate of left side of rectangle
right	x-coordinate of right side of rectangle
bottom	y-coordinate of bottom side of rectangle
top	y-coordinate of top side of rectangle
x0	x-coordinate of start of line
y0	y-coordinate of start of line
x1	x-coordinate of end of line
y1	y-coordinate of end of line

Returns: true if line was clipped.

Since: QGIS 3.26

Definition at line 776 of file qgsclipper.h.

◆ clipped3dLine()

void QgsClipper::clipped3dLine	(	const QVector< double > &	xIn,
		const QVector< double > &	yIn,
		const QVector< double > &	zIn,
		QVector< double > &	x,
		QVector< double > &	y,
		QVector< double > &	z,
		const QgsBox3D &	clipExtent
	)

static

Takes a line with 3D coordinates and clips it to clipExtent.

Note: Not available in Python bindings

Since: QGIS 3.26

Definition at line 40 of file qgsclipper.cpp.

◆ clippedLine() [1/2]

QPolygonF QgsClipper::clippedLine	(	const QgsCurve &	curve,
		const QgsRectangle &	clipExtent
	)

static

Takes a linestring and clips it to clipExtent.

Parameters

curve	the linestring
clipExtent	clipping bounds

Returns: clipped line coordinates

Definition at line 110 of file qgsclipper.cpp.

◆ clippedLine() [2/2]

QPolygonF QgsClipper::clippedLine	(	const QPolygonF &	curve,
		const QgsRectangle &	clipExtent
	)

static

Takes a 2D curve and clips it to clipExtent.

Parameters

curve	the linestring
clipExtent	clipping bounds

Returns: clipped line coordinates

Since: QGIS 3.16

Definition at line 115 of file qgsclipper.cpp.

◆ trimFeature()

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

inlinestatic

Trims the given feature to a rectangular box.

Returns the trimmed feature in x and y. The shapeOpen parameter determines whether the function treats the points as a closed shape (polygon), or as an open shape (linestring).

Note: not available in Python bindings on android

Definition at line 260 of file qgsclipper.h.

◆ trimPolygon() [1/2]

void QgsClipper::trimPolygon	(	QPolygonF &	pts,
		const QgsRectangle &	clipRect
	)

inlinestatic

Trims the given polygon to a rectangular box, by modifying the given polygon in place.

Parameters

pts	polygon as 2D coordinates
clipRect	clipping rectangle

Definition at line 281 of file qgsclipper.h.

◆ trimPolygon() [2/2]

void QgsClipper::trimPolygon	(	QVector< double > &	x,
		QVector< double > &	y,
		QVector< double > &	z,
		const QgsBox3D &	clipRect
	)

inlinestatic

Trims a polygon consisting of the specified x, y and z values to a pseudo 3D box, by modifying the arrays in place.

Note: Not available in Python bindings

Since: QGIS 3.26

Definition at line 295 of file qgsclipper.h.

Member Data Documentation

◆ MAX_X

const double QgsClipper::MAX_X = 16000

static

Maximum X-coordinate of the rectangular box used for clipping.

Definition at line 72 of file qgsclipper.h.

◆ MAX_Y

const double QgsClipper::MAX_Y = 16000

static

Maximum Y-coordinate of the rectangular box used for clipping.

Definition at line 76 of file qgsclipper.h.

◆ MIN_X

const double QgsClipper::MIN_X = -16000

static

Minimum X-coordinate of the rectangular box used for clipping.

Definition at line 74 of file qgsclipper.h.

◆ MIN_Y

const double QgsClipper::MIN_Y = -16000

static

Minimum Y-coordinate of the rectangular box used for clipping.

Definition at line 78 of file qgsclipper.h.

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

/build/qgis-3.39.0+git20240920+d85f3c2a281+99sid/src/core/qgsclipper.h
/build/qgis-3.39.0+git20240920+d85f3c2a281+99sid/src/core/qgsclipper.cpp

Public Types

Static Public Member Functions

Static Public Attributes

Detailed Description

Member Enumeration Documentation

◆ Boundary

Member Function Documentation

◆ clipLineSegment()

◆ clipped3dLine()

◆ clippedLine() [1/2]

◆ clippedLine() [2/2]

◆ trimFeature()

◆ trimPolygon() [1/2]

◆ trimPolygon() [2/2]

Member Data Documentation

◆ MAX_X

◆ MAX_Y

◆ MIN_X

◆ MIN_Y