QgsClipper Class Reference

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

#include <qgsclipper.h>

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

Static Public Member Functions
static QgsConstWkbPtr	clippedLineWKB (QgsConstWkbPtr &wkb, const QgsRectangle &clipExtent, QPolygonF &line)
	Reads a polyline from WKB and clips it to clipExtent. More...
static void	trimFeature (QVector< double > &x, QVector< double > &y, bool shapeOpen)
	Trims the given feature to a rectangular box. More...
static void	trimPolygon (QPolygonF &pts, const QgsRectangle &clipRect)

Static Public Attributes
static const double	MAX_X = 16000
static const double	MAX_Y = 16000
static const double	MIN_X = -16000
static const double	MIN_Y = -16000

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 40 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

Definition at line 70 of file qgsclipper.h.

Member Function Documentation

clippedLineWKB()

QgsConstWkbPtr QgsClipper::clippedLineWKB ( QgsConstWkbPtr &  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 41 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 160 of file qgsclipper.h.

trimPolygon()

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

inlinestatic

Definition at line 181 of file qgsclipper.h.

Member Data Documentation

MAX_X

const double QgsClipper::MAX_X = 16000

static

Definition at line 63 of file qgsclipper.h.

MAX_Y

const double QgsClipper::MAX_Y = 16000

static

Definition at line 65 of file qgsclipper.h.

MIN_X

const double QgsClipper::MIN_X = -16000

static

Definition at line 64 of file qgsclipper.h.

MIN_Y

const double QgsClipper::MIN_Y = -16000

static

Definition at line 66 of file qgsclipper.h.

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

• /tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsclipper.h
• /tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsclipper.cpp