mirror of
https://github.com/wassname/scikit-image.git
synced 2026-07-07 23:10:36 +08:00
Stefan van der Walt
67 lines
1.4 KiB
Cython
67 lines
1.4 KiB
Cython
import numpy as np
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cimport numpy as np
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cimport cython
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cdef extern from "math.h":
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int abs(int i)
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@cython.boundscheck(False)
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@cython.wraparound(False)
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def bresenham(int y, int x, int y2, int x2):
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"""
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Generate line pixel coordinates.
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Parameters
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----------
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y, x : int
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Starting position (row, column).
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y2, x2 : int
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End position (row, column).
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Returns
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-------
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rr, cc : (N,) ndarray of int
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Indices of pixels that belong to the line.
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May be used to directly index into an array, e.g.
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``img[rr, cc] = 1``.
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"""
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cdef np.ndarray[np.int32_t, ndim=1, mode="c"] rr, cc
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cdef int steep = 0
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cdef int dx = abs(x2 - x)
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cdef int dy = abs(y2 - y)
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cdef int sx, sy, d, i
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if (x2 - x) > 0: sx = 1
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else: sx = -1
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if (y2 - y) > 0: sy = 1
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else: sy = -1
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if dy > dx:
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steep = 1
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x,y = y,x
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dx,dy = dy,dx
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sx,sy = sy,sx
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d = (2 * dy) - dx
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rr = np.zeros(int(dx) + 1, dtype=np.int32)
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cc = np.zeros(int(dx) + 1, dtype=np.int32)
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for i in range(dx):
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if steep:
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rr[i] = x
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cc[i] = y
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else:
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rr[i] = y
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cc[i] = x
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while d >= 0:
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y = y + sy
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d = d - (2 * dx)
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x = x + sx
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d = d + (2 * dy)
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rr[dx] = y2
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cc[dx] = x2
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return rr, cc
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