OpenCV  3.0.0
Open Source Computer Vision
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cv::LineIterator Class Reference

Line iterator. More...

#include "imgproc.hpp"

Public Member Functions

 LineIterator (const Mat &img, Point pt1, Point pt2, int connectivity=8, bool leftToRight=false)
 intializes the iterator More...
ucharoperator* ()
 returns pointer to the current pixel More...
LineIteratoroperator++ ()
 prefix increment operator (++it). shifts iterator to the next pixel More...
LineIterator operator++ (int)
 postfix increment operator (it++). shifts iterator to the next pixel More...
Point pos () const
 returns coordinates of the current pixel More...

Public Attributes

int count
int elemSize
int err
int minusDelta
int minusStep
int plusDelta
int plusStep
const ucharptr0
int step

Detailed Description

Line iterator.

The class is used to iterate over all the pixels on the raster line segment connecting two specified points.

The class LineIterator is used to get each pixel of a raster line. It can be treated as versatile implementation of the Bresenham algorithm where you can stop at each pixel and do some extra processing, for example, grab pixel values along the line or draw a line with an effect (for example, with XOR operation).

The number of pixels along the line is stored in LineIterator::count. The method LineIterator::pos returns the current position in the image:

// grabs pixels along the line (pt1, pt2)
// from 8-bit 3-channel image to the buffer
LineIterator it(img, pt1, pt2, 8);
LineIterator it2 = it;
vector<Vec3b> buf(it.count);
for(int i = 0; i < it.count; i++, ++it)
buf[i] = *(const Vec3b)*it;
// alternative way of iterating through the line
for(int i = 0; i < it2.count; i++, ++it2)
Vec3b val =<Vec3b>(it2.pos());
CV_Assert(buf[i] == val);

Constructor & Destructor Documentation

cv::LineIterator::LineIterator ( const Mat img,
Point  pt1,
Point  pt2,
int  connectivity = 8,
bool  leftToRight = false 

intializes the iterator

creates iterators for the line connecting pt1 and pt2 the line will be clipped on the image boundaries the line is 8-connected or 4-connected If leftToRight=true, then the iteration is always done from the left-most point to the right most, not to depend on the ordering of pt1 and pt2 parameters

Member Function Documentation

uchar* cv::LineIterator::operator* ( )

returns pointer to the current pixel

LineIterator& cv::LineIterator::operator++ ( )

prefix increment operator (++it). shifts iterator to the next pixel

LineIterator cv::LineIterator::operator++ ( int  )

postfix increment operator (it++). shifts iterator to the next pixel

Point cv::LineIterator::pos ( ) const

returns coordinates of the current pixel

Member Data Documentation

int cv::LineIterator::count
int cv::LineIterator::elemSize
int cv::LineIterator::err
int cv::LineIterator::minusDelta
int cv::LineIterator::minusStep
int cv::LineIterator::plusDelta
int cv::LineIterator::plusStep
uchar* cv::LineIterator::ptr
const uchar* cv::LineIterator::ptr0
int cv::LineIterator::step

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