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269 lines
8.2 KiB
269 lines
8.2 KiB
import struct
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from sys import maxsize as INF
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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(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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while i < len(data):
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pred = data[i]
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i += 1
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line1 = data[i:i+nbytes]
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i += nbytes
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if pred == 0:
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# PNG none
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buf += line1
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elif pred == 1:
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# PNG sub (UNTESTED)
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c = 0
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bufline = []
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for b in line1:
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c = (c+b) & 255
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bufline.append(c)
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buf += bytes(bufline)
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elif pred == 2:
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# PNG up
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bufline = []
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for (a,b) in zip(line0,line1):
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c = (a+b) & 255
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bufline.append(c)
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buf += bytes(bufline)
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elif pred == 3:
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# PNG average (UNTESTED)
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c = 0
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bufline = []
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for (a,b) in zip(line0,line1):
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c = ((c+a+b)//2) & 255
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bufline.append(c)
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buf += bytes(bufline)
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else:
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# unsupported
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raise ValueError(pred)
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line0 = line1
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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(matrix1, matrix2):
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"""Returns the multiplication of two matrices."""
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(a1,b1,c1,d1,e1,f1) = matrix1
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(a0,b0,c0,d0,e0,f0) = matrix2
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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(matrix, point):
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"""Translates a matrix by (x,y)."""
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(a,b,c,d,e,f) = matrix
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(x,y) = point
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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(matrix, point):
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"""Applies a matrix to a point."""
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(a,b,c,d,e,f) = matrix
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(x,y) = point
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return (a*x+c*y+e, b*x+d*y+f)
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def apply_matrix_norm(matrix, norm):
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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) = matrix
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(p,q) = norm
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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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# 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: continue
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done.add(obj)
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yield obj
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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
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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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def trailiter(iterable, skipfirst=False):
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"""Yields (prev_element, element), starting with (None, first_element).
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If skipfirst is True, there will be no (None, item1) element and we'll start
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directly with (item1, item2).
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"""
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it = iter(iterable)
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if skipfirst:
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prev = next(it)
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else:
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prev = None
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for item in it:
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yield prev, item
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prev = item
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# nunpack
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def nunpack(b, default=0):
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"""Unpacks 1 to 4 byte integers (big endian)."""
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if isinstance(b, str):
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b = b.encode('latin-1')
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l = len(b)
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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 b[0]
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elif l == 2:
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return struct.unpack(b'>H', b)[0]
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elif l == 3:
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return struct.unpack(b'>L', b'\x00'+b)[0]
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elif l == 4:
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return struct.unpack(b'>L', b)[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( chr(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('\xfe\xff'):
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return str(s[2:], 'utf-16be', 'ignore')
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else:
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return ''.join( PDFDocEncoding[ord(c)] for c in s )
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def htmlescape(s, encoding='ascii'):
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"""Escapes a string for SGML/XML/HTML"""
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s = s.replace('&','&').replace('>','>').replace('<','<').replace('"','"')
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# Additionally to basic replaces, we also make sure that all characters are convertible to our
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# target encoding. If they're not, they're replaced by XML entities.
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encoded = s.encode(encoding, errors='xmlcharrefreplace')
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return encoded.decode(encoding)
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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(matrix):
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(a,b,c,d,e,f) = matrix
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return '[%.2f,%.2f,%.2f,%.2f, (%.2f,%.2f)]' % (a,b,c,d,e,f)
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def set_debug_logging():
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import logging, sys
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logging.basicConfig(level=logging.DEBUG, stream=sys.stderr)
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class ObjIdRange:
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"A utility class to represent a range of object IDs."
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def __init__(self, start, nobjs):
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self.start = start
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self.nobjs = nobjs
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def __repr__(self):
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return '<ObjIdRange: %d-%d>' % (self.get_start_id(), self.get_end_id())
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def get_start_id(self):
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return self.start
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def get_end_id(self):
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return self.start + self.nobjs - 1
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def get_nobjs(self):
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return self.nobjs
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# create_bmp
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def create_bmp(data, bits, width, height):
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info = struct.pack('<IiiHHIIIIII', 40, width, height, 1, bits, 0, len(data), 0, 0, 0, 0)
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assert len(info) == 40, len(info)
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header = struct.pack('<ccIHHI', 'B', 'M', 14+40+len(data), 0, 0, 14+40)
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assert len(header) == 14, len(header)
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# XXX re-rasterize every line
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return header+info+data
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