398 lines
12 KiB
Python
398 lines
12 KiB
Python
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"""
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Miscellaneous Routines.
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"""
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import struct
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# from sys import maxint as INF #doesn't work anymore under Python3,
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# but PDF still uses 32 bits ints
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INF = (1<<31) - 1
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import six #Python 2+3 compatibility
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if six.PY3:
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import chardet # For str encoding detection in Py3
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unicode = str
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def make_compat_bytes(in_str):
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"In Py2, does nothing. In Py3, converts to bytes, encoding to unicode."
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assert isinstance(in_str, str), str(type(in_str))
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if six.PY2:
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return in_str
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else:
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return in_str.encode()
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def make_compat_str(in_str):
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"In Py2, does nothing. In Py3, converts to string, guessing encoding."
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assert isinstance(in_str, (bytes, str, unicode)), str(type(in_str))
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if six.PY3 and isinstance(in_str, bytes):
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enc = chardet.detect(in_str)
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in_str = in_str.decode(enc['encoding'])
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return in_str
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def compatible_encode_method(bytesorstring, encoding='utf-8', erraction='ignore'):
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"When Py2 str.encode is called, it often means bytes.encode in Py3. This does either."
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if six.PY2:
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assert isinstance(bytesorstring, (str, unicode)), str(type(bytesorstring))
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return bytesorstring.encode(encoding, erraction)
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if six.PY3:
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if isinstance(bytesorstring, str): return bytesorstring
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assert isinstance(bytesorstring, bytes), str(type(bytesorstring))
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return bytesorstring.decode(encoding, erraction)
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## PNG Predictor
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##
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def apply_png_predictor(pred, colors, columns, bitspercomponent, data):
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if bitspercomponent != 8:
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# unsupported
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raise ValueError("Unsupported `bitspercomponent': %d" %
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bitspercomponent)
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nbytes = colors * columns * bitspercomponent // 8
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i = 0
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buf = b''
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line0 = b'\x00' * columns
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for i in range(0, len(data), nbytes+1):
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ft = data[i]
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if six.PY2:
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ft = six.byte2int(ft)
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i += 1
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line1 = data[i:i+nbytes]
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line2 = b''
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if ft == 0:
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# PNG none
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line2 += line1
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elif ft == 1:
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# PNG sub (UNTESTED)
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c = 0
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for b in line1:
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if six.PY2:
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b = six.byte2int(b)
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c = (c+b) & 255
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line2 += six.int2byte(c)
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elif ft == 2:
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# PNG up
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for (a, b) in zip(line0, line1):
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if six.PY2:
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a, b = six.byte2int(a), six.byte2int(b)
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c = (a+b) & 255
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line2 += six.int2byte(c)
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elif ft == 3:
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# PNG average (UNTESTED)
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c = 0
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for (a, b) in zip(line0, line1):
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if six.PY2:
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a, b = six.byte2int(a), six.byte2int(b)
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c = ((c+a+b)//2) & 255
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line2 += six.int2byte(c)
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else:
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# unsupported
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raise ValueError("Unsupported predictor value: %d" % ft)
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buf += line2
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line0 = line2
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return buf
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## Matrix operations
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##
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MATRIX_IDENTITY = (1, 0, 0, 1, 0, 0)
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def mult_matrix(m1, m0):
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(a1, b1, c1, d1, e1, f1) = m1
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(a0, b0, c0, d0, e0, f0) = m0
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"""Returns the multiplication of two matrices."""
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return (a0*a1+c0*b1, b0*a1+d0*b1,
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a0*c1+c0*d1, b0*c1+d0*d1,
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a0*e1+c0*f1+e0, b0*e1+d0*f1+f0)
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def translate_matrix(m, v):
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"""Translates a matrix by (x, y)."""
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(a, b, c, d, e, f) = m
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(x, y) = v
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return (a, b, c, d, x*a+y*c+e, x*b+y*d+f)
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def apply_matrix_pt(m, v):
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(a, b, c, d, e, f) = m
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(x, y) = v
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"""Applies a matrix to a point."""
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return (a*x+c*y+e, b*x+d*y+f)
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def apply_matrix_norm(m, v):
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"""Equivalent to apply_matrix_pt(M, (p,q)) - apply_matrix_pt(M, (0,0))"""
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(a, b, c, d, e, f) = m
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(p, q) = v
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return (a*p+c*q, b*p+d*q)
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## Utility functions
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##
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# isnumber
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def isnumber(x):
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return isinstance(x, (six.integer_types, float))
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# uniq
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def uniq(objs):
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"""Eliminates duplicated elements."""
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done = set()
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for obj in objs:
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if obj in done:
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continue
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done.add(obj)
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yield obj
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return
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# fsplit
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def fsplit(pred, objs):
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"""Split a list into two classes according to the predicate."""
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t = []
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f = []
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for obj in objs:
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if pred(obj):
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t.append(obj)
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else:
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f.append(obj)
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return (t, f)
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# drange
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def drange(v0, v1, d):
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"""Returns a discrete range."""
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assert v0 < v1, str((v0, v1, d))
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return range(int(v0)//d, int(v1+d)//d)
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# get_bound
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def get_bound(pts):
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"""Compute a minimal rectangle that covers all the points."""
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(x0, y0, x1, y1) = (INF, INF, -INF, -INF)
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for (x, y) in pts:
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x0 = min(x0, x)
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y0 = min(y0, y)
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x1 = max(x1, x)
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y1 = max(y1, y)
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return (x0, y0, x1, y1)
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# pick
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def pick(seq, func, maxobj=None):
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"""Picks the object obj where func(obj) has the highest value."""
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maxscore = None
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for obj in seq:
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score = func(obj)
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if maxscore is None or maxscore < score:
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(maxscore, maxobj) = (score, obj)
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return maxobj
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# choplist
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def choplist(n, seq):
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"""Groups every n elements of the list."""
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r = []
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for x in seq:
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r.append(x)
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if len(r) == n:
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yield tuple(r)
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r = []
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return
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# nunpack
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def nunpack(s, default=0):
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"""Unpacks 1 to 4 or 8 byte integers (big endian)."""
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l = len(s)
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if not l:
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return default
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elif l == 1:
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return ord(s)
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elif l == 2:
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return struct.unpack('>H', s)[0]
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elif l == 3:
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return struct.unpack('>L', b'\x00'+s)[0]
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elif l == 4:
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return struct.unpack('>L', s)[0]
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elif l == 8:
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return struct.unpack('>Q', s)[0]
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else:
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raise TypeError('invalid length: %d' % l)
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# decode_text
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PDFDocEncoding = ''.join(six.unichr(x) for x in (
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0x0000, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0007,
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0x0008, 0x0009, 0x000a, 0x000b, 0x000c, 0x000d, 0x000e, 0x000f,
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0x0010, 0x0011, 0x0012, 0x0013, 0x0014, 0x0015, 0x0017, 0x0017,
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0x02d8, 0x02c7, 0x02c6, 0x02d9, 0x02dd, 0x02db, 0x02da, 0x02dc,
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0x0020, 0x0021, 0x0022, 0x0023, 0x0024, 0x0025, 0x0026, 0x0027,
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0x0028, 0x0029, 0x002a, 0x002b, 0x002c, 0x002d, 0x002e, 0x002f,
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0x0030, 0x0031, 0x0032, 0x0033, 0x0034, 0x0035, 0x0036, 0x0037,
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0x0038, 0x0039, 0x003a, 0x003b, 0x003c, 0x003d, 0x003e, 0x003f,
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0x0040, 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047,
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0x0048, 0x0049, 0x004a, 0x004b, 0x004c, 0x004d, 0x004e, 0x004f,
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0x0050, 0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057,
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0x0058, 0x0059, 0x005a, 0x005b, 0x005c, 0x005d, 0x005e, 0x005f,
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0x0060, 0x0061, 0x0062, 0x0063, 0x0064, 0x0065, 0x0066, 0x0067,
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0x0068, 0x0069, 0x006a, 0x006b, 0x006c, 0x006d, 0x006e, 0x006f,
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0x0070, 0x0071, 0x0072, 0x0073, 0x0074, 0x0075, 0x0076, 0x0077,
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0x0078, 0x0079, 0x007a, 0x007b, 0x007c, 0x007d, 0x007e, 0x0000,
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0x2022, 0x2020, 0x2021, 0x2026, 0x2014, 0x2013, 0x0192, 0x2044,
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0x2039, 0x203a, 0x2212, 0x2030, 0x201e, 0x201c, 0x201d, 0x2018,
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0x2019, 0x201a, 0x2122, 0xfb01, 0xfb02, 0x0141, 0x0152, 0x0160,
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0x0178, 0x017d, 0x0131, 0x0142, 0x0153, 0x0161, 0x017e, 0x0000,
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0x20ac, 0x00a1, 0x00a2, 0x00a3, 0x00a4, 0x00a5, 0x00a6, 0x00a7,
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0x00a8, 0x00a9, 0x00aa, 0x00ab, 0x00ac, 0x0000, 0x00ae, 0x00af,
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0x00b0, 0x00b1, 0x00b2, 0x00b3, 0x00b4, 0x00b5, 0x00b6, 0x00b7,
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0x00b8, 0x00b9, 0x00ba, 0x00bb, 0x00bc, 0x00bd, 0x00be, 0x00bf,
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0x00c0, 0x00c1, 0x00c2, 0x00c3, 0x00c4, 0x00c5, 0x00c6, 0x00c7,
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0x00c8, 0x00c9, 0x00ca, 0x00cb, 0x00cc, 0x00cd, 0x00ce, 0x00cf,
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0x00d0, 0x00d1, 0x00d2, 0x00d3, 0x00d4, 0x00d5, 0x00d6, 0x00d7,
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0x00d8, 0x00d9, 0x00da, 0x00db, 0x00dc, 0x00dd, 0x00de, 0x00df,
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0x00e0, 0x00e1, 0x00e2, 0x00e3, 0x00e4, 0x00e5, 0x00e6, 0x00e7,
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0x00e8, 0x00e9, 0x00ea, 0x00eb, 0x00ec, 0x00ed, 0x00ee, 0x00ef,
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0x00f0, 0x00f1, 0x00f2, 0x00f3, 0x00f4, 0x00f5, 0x00f6, 0x00f7,
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0x00f8, 0x00f9, 0x00fa, 0x00fb, 0x00fc, 0x00fd, 0x00fe, 0x00ff,
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))
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def decode_text(s):
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"""Decodes a PDFDocEncoding string to Unicode."""
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if s.startswith(b'\xfe\xff'):
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return six.text_type(s[2:], 'utf-16be', 'ignore')
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else:
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return ''.join(PDFDocEncoding[c] for c in s)
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# enc
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def enc(x, codec='ascii'):
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"""Encodes a string for SGML/XML/HTML"""
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if six.PY3 and isinstance(x, bytes):
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return ''
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x = x.replace('&', '&').replace('>', '>').replace('<', '<').replace('"', '"')
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if codec:
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x = x.encode(codec, 'xmlcharrefreplace')
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return x
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def bbox2str(bbox):
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(x0, y0, x1, y1) = bbox
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return '%.3f,%.3f,%.3f,%.3f' % (x0, y0, x1, y1)
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def matrix2str(m):
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(a, b, c, d, e, f) = m
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return '[%.2f,%.2f,%.2f,%.2f, (%.2f,%.2f)]' % (a, b, c, d, e, f)
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def vecBetweenBoxes(obj1, obj2):
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"""A distance function between two TextBoxes.
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Consider the bounding rectangle for obj1 and obj2.
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Return vector between 2 boxes boundaries if they don't overlap, otherwise returns vector betweeen boxes centers
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+------+..........+ (x1, y1)
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| obj1 | :
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+------+www+------+
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: | obj2 |
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(x0, y0) +..........+------+
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"""
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(x0, y0) = (min(obj1.x0, obj2.x0), min(obj1.y0, obj2.y0))
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(x1, y1) = (max(obj1.x1, obj2.x1), max(obj1.y1, obj2.y1))
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(ow, oh) = (x1-x0, y1-y0)
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(iw, ih) = (ow-obj1.width-obj2.width, oh-obj1.height-obj2.height)
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if iw<0 and ih<0:
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# if one is inside another we compute euclidean distance
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(xc1, yc1) = ( (obj1.x0+obj1.x1)/2, (obj1.y0+obj1.y1)/2 )
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(xc2, yc2) = ( (obj2.x0+obj2.x1)/2, (obj2.y0+obj2.y1)/2 )
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return (xc1-xc2, yc1-yc2)
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else:
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return (max(0, iw), max(0, ih))
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## Plane
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##
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## A set-like data structure for objects placed on a plane.
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## Can efficiently find objects in a certain rectangular area.
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## It maintains two parallel lists of objects, each of
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## which is sorted by its x or y coordinate.
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##
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class Plane(object):
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def __init__(self, bbox, gridsize=50):
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self._seq = [] # preserve the object order.
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self._objs = set()
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self._grid = {}
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self.gridsize = gridsize
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(self.x0, self.y0, self.x1, self.y1) = bbox
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return
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def __repr__(self):
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return ('<Plane objs=%r>' % list(self))
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def __iter__(self):
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return ( obj for obj in self._seq if obj in self._objs )
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def __len__(self):
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return len(self._objs)
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def __contains__(self, obj):
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return obj in self._objs
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def _getrange(self, bbox):
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(x0, y0, x1, y1) = bbox
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if (x1 <= self.x0 or self.x1 <= x0 or
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y1 <= self.y0 or self.y1 <= y0): return
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x0 = max(self.x0, x0)
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y0 = max(self.y0, y0)
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x1 = min(self.x1, x1)
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y1 = min(self.y1, y1)
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for y in drange(y0, y1, self.gridsize):
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for x in drange(x0, x1, self.gridsize):
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yield (x, y)
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return
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# extend(objs)
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def extend(self, objs):
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for obj in objs:
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self.add(obj)
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return
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# add(obj): place an object.
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def add(self, obj):
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for k in self._getrange((obj.x0, obj.y0, obj.x1, obj.y1)):
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if k not in self._grid:
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r = []
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self._grid[k] = r
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else:
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r = self._grid[k]
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r.append(obj)
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self._seq.append(obj)
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self._objs.add(obj)
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return
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# remove(obj): displace an object.
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def remove(self, obj):
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for k in self._getrange((obj.x0, obj.y0, obj.x1, obj.y1)):
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try:
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self._grid[k].remove(obj)
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except (KeyError, ValueError):
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pass
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self._objs.remove(obj)
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return
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# find(): finds objects that are in a certain area.
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def find(self, bbox):
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(x0, y0, x1, y1) = bbox
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done = set()
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for k in self._getrange(bbox):
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if k not in self._grid:
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continue
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for obj in self._grid[k]:
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if obj in done:
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continue
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done.add(obj)
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if (obj.x1 <= x0 or x1 <= obj.x0 or
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obj.y1 <= y0 or y1 <= obj.y0):
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continue
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yield obj
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return
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