sigil.py

import json

try:
    import numpy
except ImportError:
    numpy = None

class Sigil(object):
    def __init__(self, ops, origin=None, char=None, angle=0):
        '''Given a list of differential ops, and an optional origin, create a
        Sigil instance. If origin is omitted, it is estimated with ops_origin.

        If part of a SigilDict, char is the character this Sigil represents.'''

        self.origin = origin
        if origin is None:
            self.origin = ops_origin(ops)

        self.scale = ops_scale(ops)

        self.ops = ops
        self.char = char

        self.angle = angle

        x1, x2, y1, y2 = ops_bb(ops)
        if angle == 0:
            self.width = x2 - x1
        elif angle == -90:
            self.width = y2 - y1

    @staticmethod
    def from_abs_ops(ops):
        return Sigil(diff_ops(ops))

    def to_dict(self):
        return {
                'origin': self.origin,
                'ops': self.ops,
                }

    def rotated(self, angle=-90):
        '''Return a copy of the sigil rotated clockwise by the given angle.'''

        if numpy is None:
            raise NotImplementedError('rotated() requires numpy')

        theta = angle * numpy.pi / 180.0

        matrix = numpy.array([[ numpy.cos(theta), numpy.sin(theta)],
                              [-numpy.sin(theta), numpy.cos(theta)]])

        trans_ops = [(list(matrix.dot(coords)), operator)
                for (coords, operator) in self.ops]
        trans_origin = list(matrix.dot(self.origin))

        return Sigil(ops=trans_ops,
                origin=trans_origin,
                char=self.char,
                angle=self.angle + angle)

    def cmp(self, other):
        if len(self.ops) != len(other.ops):
            print 'different lengths ({}, {}). trying prefix'.format(len(self.ops), len(other.ops))

        ans = []
        for ((x1, y1), c1), ((x2, y2), c2) in zip(self.ops, other.ops):
            s = '{:.2g}'.format(max(abs(x1-x2), abs(y1-y2)))
            if c1 != c2:
                s = s+'*'
            ans.append(s)

        return ', '.join(ans)

    def rescale(self, sf):
        self.origin = [x*sf for x in self.origin]

        for (i, op) in enumerate(self.ops):
            self.ops[i] = [[x*sf for x in op[0]], op[1]]

        self.scale = ops_scale(self.ops)

        x1, x2, _, _ = ops_bb(self.ops)
        self.width = x2 - x1

    def __len__(self):
        return len(self.ops)

    def __str__(self):
        ops_str = '[{}]'.format(', '.join(
            '(({:.2f}, {:.2f}), {})'.format(op[0][0], op[0][1], op[1])
            for op in self.ops))
        return 'Sigil({!r}, {})'.format(self.char, ops_str)


class SigilDict(dict):
    @staticmethod
    def from_json(json_file):
        result = SigilDict()

        for k, v in json.load(json_file).items():
            if isinstance(v, dict):
                v = [v]

            result[k] = [Sigil(char=str(k), **params) for params in v]

        return result

    def to_json(self, json_file):
        json.dump({k: [s.to_dict() for s in v] for (k, v) in self.items()},
                json_file, sort_keys=True, indent=4)

def remove_zero_ops(ops, tol=0.01):
    '''Given a list of absolute ops, remove all ops with a length of less than
    tol (0.01 by default).'''

    assert ops[0][1] == 'm'
    px, py = ops[0][0]

    ans = [ops[0]]
    tol = 0.01

    for (x, y), c in ops[1:]:
        n2 = (x-px) ** 2 + (y-py) ** 2

        if n2 > tol ** 2:
            ans.append( ((x, y), c) )
            px, py = x, y

    return ans

def diff_ops(ops):
    '''Convert a list of absolute ops (eg from a PDF) to differential ops,
    by subtracting the coords of the first 'm' op.'''
    assert ops[0][1] == 'm'
    px, py = ops[0][0]

    ans = []

    for (x, y), c in ops[1:]:
        ans.append( ((x-px, y-py), c) )
        px, py = x, y

    return ans

def ops_bb(ops):
    '''Given a differential ops list, determine the bounding box as
    (min x, max x, min y, max y).

    It ignores the points on curve (c) operators, since the line doesn't
    necessarily reach these points.'''

    px, py = 0, 0
    xs, ys = [0], [0]

    for (dx, dy), c in ops:
        px += dx
        py += dy
        if c != 'c':
            xs.append(px)
            ys.append(py)

    return (min(xs), max(xs), min(ys), max(ys))

def ops_origin(ops):
    '''Given a differential ops list, estimate the origin, as a vector from
    the initial position. The origin is the (min x)-(min y) corner of the
    bounding box.'''

    min_x, _, min_y, _ = ops_bb(ops)
    return (min_x, min_y)

def ops_height(ops):
    '''Given a differential ops list, determine the height of the bounding
    box.'''

    _, _, min_y, max_y = ops_bb(ops)
    return max_y - min_y

def ops_scale(ops):
    '''Get an arbitrary number indicating the scale of the sigil,
    given some differential operations.

    Uses sum |dx_i| + |dy_i|.'''

    ans = 0

    for (dx, dy), _ in ops:
        ans += abs(dx) + abs(dy)

    return ans