QGIS API Documentation 3.40.0-Bratislava (b56115d8743)
Loading...
Searching...
No Matches
Public Types | Static Public Member Functions | Static Public Attributes | List of all members
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 ,
  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

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
leftx-coordinate of left side of rectangle
rightx-coordinate of right side of rectangle
bottomy-coordinate of bottom side of rectangle
topy-coordinate of top side of rectangle
x0x-coordinate of start of line
y0y-coordinate of start of line
x1x-coordinate of end of line
y1y-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
curvethe linestring
clipExtentclipping 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
curvethe linestring
clipExtentclipping 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
ptspolygon as 2D coordinates
clipRectclipping 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: