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 780 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 264 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 285 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 299 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-3.34.0+99sid/src/core/qgsclipper.h
/build/qgis-3.34.0+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