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Pure python implementation of WMF parser to extract bitmapped images stored in WMF files
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Kovid Goyal
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269
src/calibre/utils/wmf/parse.py
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269
src/calibre/utils/wmf/parse.py
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#!/usr/bin/env python
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# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
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__license__ = 'GPL v3'
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__copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
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__docformat__ = 'restructuredtext en'
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import sys, struct
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class WMFHeader(object):
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'''
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For header documentation, see
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http://www.skynet.ie/~caolan/publink/libwmf/libwmf/doc/ora-wmf.html
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'''
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def __init__(self, data, log, verbose):
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self.log, self.verbose = log, verbose
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offset = 0
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file_type, header_size, windows_version = struct.unpack_from('<HHH', data)
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offset += 6
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if header_size != 9:
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raise ValueError('Not a WMF file')
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file_size, num_of_objects = struct.unpack_from('<IH', data, offset)
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if file_size * 2 != len(data):
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# file size is in 2-byte units
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raise ValueError('WMF file header specifies incorrect file size')
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offset += 6
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self.records_start_at = header_size * 2
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class DIBHeader(object):
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'''
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See http://en.wikipedia.org/wiki/BMP_file_format
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'''
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def __init__(self, raw):
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hsize = struct.unpack('<I', raw[:4])[0]
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if hsize == 40:
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parts = struct.unpack('<IiiHHIIIIII', raw[:hsize])
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for i, attr in enumerate((
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'header_size', 'width', 'height', 'color_planes',
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'bits_per_pixel', 'compression', 'image_size',
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'hres', 'vres', 'ncols', 'nimpcols'
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)):
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setattr(self, attr, parts[i])
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elif hsize == 12:
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parts = struct.unpack('<IHHHH', raw[:hsize])
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for i, attr in enumerate((
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'header_size', 'width', 'height', 'color_planes',
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'bits_per_pixel')):
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setattr(self, attr, parts[i])
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else:
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raise ValueError('Unsupported DIB header type of size: %d'%hsize)
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self.bitmasks_size = 12 if getattr(self, 'compression', 0) == 3 else 0
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self.color_table_size = 0
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if self.bits_per_pixel != 24:
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# See http://support.microsoft.com/kb/q81498/
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# for all the gory Micro and soft details
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self.color_table_size = getattr(self, 'ncols', 0) * 4
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class WMF(object):
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def __init__(self, log=None, verbose=0):
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if log is None:
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from calibre.utils.logging import default_log as log
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self.log = log
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self.verbose = verbose
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self.map_mode = None
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self.window_origin = None
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self.window_extent = None
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self.bitmaps = []
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self.function_map = { # {{{
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30: 'SaveDC',
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53: 'RealizePalette',
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55: 'SetPalEntries',
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79: 'StartPage',
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80: 'EndPage',
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82: 'AbortDoc',
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94: 'EndDoc',
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258: 'SetBkMode',
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259: 'SetMapMode',
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260: 'SetROP2',
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261: 'SetRelabs',
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262: 'SetPolyFillMode',
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263: 'SetStretchBltMode',
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264: 'SetTextCharExtra',
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295: 'RestoreDC',
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298: 'InvertRegion',
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299: 'PaintRegion',
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300: 'SelectClipRegion',
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301: 'SelectObject',
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302: 'SetTextAlign',
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313: 'ResizePalette',
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332: 'ResetDc',
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333: 'StartDoc',
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496: 'DeleteObject',
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513: 'SetBkColor',
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521: 'SetTextColor',
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522: 'SetTextJustification',
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523: 'SetWindowOrg',
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524: 'SetWindowExt',
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525: 'SetViewportOrg',
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526: 'SetViewportExt',
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527: 'OffsetWindowOrg',
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529: 'OffsetViewportOrg',
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531: 'LineTo',
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532: 'MoveTo',
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544: 'OffsetClipRgn',
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552: 'FillRegion',
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561: 'SetMapperFlags',
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564: 'SelectPalette',
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1040: 'ScaleWindowExt',
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1042: 'ScaleViewportExt',
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1045: 'ExcludeClipRect',
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1046: 'IntersectClipRect',
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1048: 'Ellipse',
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1049: 'FloodFill',
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1051: 'Rectangle',
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1055: 'SetPixel',
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1065: 'FrameRegion',
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1352: 'ExtFloodFill',
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1564: 'RoundRect',
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1565: 'PatBlt',
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2071: 'Arc',
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2074: 'Pie',
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2096: 'Chord',
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3379: 'SetDibToDev',
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247: 'CreatePalette',
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248: 'CreateBrush',
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322: 'DibCreatePatternBrush',
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496: 'DeleteObject',
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505: 'CreatePatternBrush',
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762: 'CreatePenIndirect',
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763: 'CreateFontIndirect',
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764: 'CreateBrushIndirect',
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765: 'CreateBitmapIndirect',
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804: 'Polygon',
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805: 'Polyline',
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1078: 'AnimatePalette',
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1313: 'TextOut',
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1336: 'PolyPolygon',
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1574: 'Escape',
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1583: 'DrawText',
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1790: 'CreateBitmap',
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1791: 'CreateRegion',
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2338: 'BitBlt',
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2368: 'DibBitblt',
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2610: 'ExtTextOut',
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2851: 'StretchBlt',
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2881: 'DibStretchBlt',
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3907: 'StretchDIBits'
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} # }}}
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def __call__(self, stream_or_data):
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data = stream_or_data
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if hasattr(data, 'read'):
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data = data.read()
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self.log.filter_level = self.log.DEBUG
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self.header = WMFHeader(data, self.log, self.verbose)
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offset = self.header.records_start_at
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hsize = struct.calcsize('<IH')
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self.records = []
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while offset < len(data)-6:
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size, func = struct.unpack_from('<IH', data, offset)
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size *= 2 # Convert to bytes
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offset += hsize
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params = ''
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delta = size - hsize
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if delta > 0:
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params = data[offset:offset+delta]
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offset += delta
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func = self.function_map.get(func, func)
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if self.verbose > 3:
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self.log.debug('WMF Record:', size, func)
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self.records.append((func, params))
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for rec in self.records:
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f = getattr(self, rec[0], None)
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if callable(f):
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f(rec[1])
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elif self.verbose > 2:
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self.log.debug('Ignoring record:', rec[0])
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self.has_raster_image = len(self.bitmaps) > 0
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def SetMapMode(self, params):
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if len(params) == 2:
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self.map_mode = struct.unpack('<H', params)[0]
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else:
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self.log.warn('Invalid SetMapMode param')
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def SetWindowOrg(self, params):
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if len(params) == 4:
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self.window_origin = struct.unpack('<HH', params)
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elif len(params) == 8:
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self.window_origin = struct.unpack('<II', params)
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elif len(params) == 16:
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self.window_origin = struct.unpack('<LL', params)
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else:
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self.log.warn('Invalid SetWindowOrg param', repr(params))
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def SetWindowExt(self, params):
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if len(params) == 4:
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self.window_extent = struct.unpack('<HH', params)
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elif len(params) == 8:
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self.window_extent = struct.unpack('<II', params)
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elif len(params) == 16:
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self.window_extent = struct.unpack('<LL', params)
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else:
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self.log.warn('Invalid SetWindowExt param', repr(params))
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def DibStretchBlt(self, raw):
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offset = 0
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fmt = '<IHHHHHHHH'
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raster_op, src_height, src_width, y_src, x_src, dest_height, \
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dest_width, y_dest, x_dest = struct.unpack_from('<IHHHHHHHH', raw, offset)
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offset += struct.calcsize(fmt)
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bmp_data = raw[offset:]
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bmp = self.create_bmp_from_dib(bmp_data)
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self.bitmaps.append(bmp)
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def create_bmp_from_dib(self, raw):
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size = len(raw) + 14
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dh = DIBHeader(raw)
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pixel_array_offset = dh.header_size + dh.bitmasks_size + \
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dh.color_table_size
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parts = ['BM', struct.pack('<I', size), '\0'*4, struct.pack('<I',
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pixel_array_offset)]
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return ''.join(parts) + raw
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def to_png(self):
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bmps = list(sorted(self.bitmaps, key=lambda x: len(x)))
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bmp = bmps[-1]
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from calibre.utils.magick import Image
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img = Image()
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img.load(bmp)
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return img.export('png')
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def wmf_unwrap(wmf_data):
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'''
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Return the largest embedded raster image in the WMF.
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The returned data is in PNG format.
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'''
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w = WMF()
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w(wmf_data)
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if not w.has_raster_image:
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raise ValueError('No raster image found in the WMF')
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return w.to_png()
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if __name__ == '__main__':
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wmf = WMF(verbose=4)
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wmf(open(sys.argv[-1], 'rb'))
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open('/t/test.bmp', 'wb').write(wmf.bitmaps[0])
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