BresenhamLine.py

"""This function takes a roi segment and gives the coordinate of its points.

Given two points coordinates, this function returns the coordinate of all the pixels
belonging to segment that connects the points.
"""

import numpy as np


class BresenhamLine:
    def __init__(self, x, y, x2, y2):
        # """Brensenham line algorithm"""
        self.x   =  x.astype(np.int)
        self.x2  =  x2.astype(np.int)
        self.y   =  y.astype(np.int)
        self.y2  =  y2.astype(np.int)

        steep = 0
        coords = []
        dx = abs(x2 - x)
        dy = abs(y2 - y)
        if (x2 - x) > 0:
            sx = 1
        else:
            sx = -1
            dy = abs(y2 - y)
        if (y2 - y) > 0:
            sy = 1
        else:
            sy = -1
        if dy > dx:
            steep = 1
            x, y    =  y, x
            dx, dy  =  dy, dx
            sx, sy  =  sy, sx
        d = (2 * dy) - dx
        for i in range(0, dx.astype(np.int)):
            if steep:
                coords.append((y, x))
            else:
                coords.append((x, y))
            while d >= 0:
                y  +=  sy
                d  -=  (2 * dx)
            x  +=  sx
            d  += (2 * dy)
        coords.append((x2, y2))

        self.coords  =  coords