lzw support added.

git-svn-id: https://pdfminerr.googlecode.com/svn/trunk/pdfminer@21 1aa58f4a-7d42-0410-adbc-911cccaed67c

TODO

@@ -1,9 +1,9 @@
-TODO:
-  - Code Documentation.
+TODOs:
+  - Documentation.
   - Error handling for invalid type.
+  - PDF Writers.
 
   - Outlines.
   - Named Objects. (pages)
-  - Writers.
-  - Linearized PDF.
-  - Encryption?
+  - Any special treatments for linearized PDFs?
+  - More encryption support? (no way...)

lzw.py

@@ -0,0 +1,97 @@
+#!/usr/bin/env python
+import sys
+stderr = sys.stderr
+
+##  LZWDecoder
+##
+class LZWDecoder:
+  
+  def __init__(self, fp, debug=0):
+    self.fp = fp
+    self.debug = debug
+    self.buff = 0
+    self.bpos = 8
+    self.nbits = 9
+    self.table = None
+    self.prevbuf = None
+    return
+
+  def readbits(self, bits):
+    bits0 = bits
+    v = 0
+    while 1:
+      # the number of remaining bits we can get from the current buffer.
+      r = 8-self.bpos
+      if bits <= r:
+        # |-----8-bits-----|
+        # |-bpos-|-bits-|  |
+        # |      |----r----|
+        v = (v<<bits) | ((self.buff>>(r-bits)) & ((1<<bits)-1))
+        self.bpos += bits
+        break
+      else:
+        # |-----8-bits-----|
+        # |-bpos-|---bits----...
+        # |      |----r----|
+        v = (v<<r) | (self.buff & ((1<<r)-1))
+        bits -= r
+        x = self.fp.read(1)
+        if not x: raise EOFError
+        self.buff = ord(x)
+        self.bpos = 0
+    return v
+
+  def feed(self, code):
+    x = ''
+    if code == 256:
+      self.table = [ chr(c) for c in xrange(256) ] # 0-255
+      self.table.append(None) # 256
+      self.table.append(None) # 257
+      self.prevbuf = ''
+      self.nbits = 9
+    elif code == 257:
+      pass
+    elif not self.prevbuf:
+      x = self.prevbuf = self.table[code]
+    else:
+      if code < len(self.table):
+        x = self.table[code]
+        self.table.append(self.prevbuf+x[0])
+      else:
+        self.table.append(self.prevbuf+self.prevbuf[0])
+        x = self.table[code]
+      l = len(self.table)
+      if l == 511:
+        self.nbits = 10
+      elif l == 1023:
+        self.nbits = 11
+      elif l == 2047:
+        self.nbits = 12
+      self.prevbuf = x
+    return x
+  
+  def run(self):
+    while 1:
+      try:
+        code = self.readbits(self.nbits)
+      except EOFError:
+        break
+      x = self.feed(code)
+      yield x
+      if self.debug:
+        print >>stderr, ('nbits=%d, code=%d, output=%r, table=%r' %
+                         (self.nbits, code, x, self.table[258:]))
+    return
+    
+
+def main(argv):
+  import StringIO
+  input = '\x80\x0b\x60\x50\x22\x0c\x0c\x85\x01'
+  fp = StringIO.StringIO(input)
+  expected = '\x2d\x2d\x2d\x2d\x2d\x41\x2d\x2d\x2d\x42'
+  output = ''.join(LZWDecoder(fp, debug=1).run())
+  print (input, expected, output)
+  print output == expected
+  return 0
+
+if __name__ == '__main__': sys.exit(main(sys.argv))

pdf2txt.py

@@ -83,10 +83,13 @@ class TextItem:
             (self.matrix, self.font, self.size, self.width, self.text))
   
   def dump(self, outfp, codec):
+    def e(x):
+      x = x.replace('&','&amp;').replace('>','&gt;').replace('<','&lt;')
+      return x.encode(codec, 'xmlcharrefreplace')
     (a,b,c,d,tx,ty) = self.matrix
-    outfp.write('<text x="%.3f" y="%.3f" font=%r size="%.3f" width="%.3f">' %
-                (tx, ty, self.font.fontname, self.size, self.width))
-    outfp.write(self.text.encode(codec, 'xmlcharrefreplace'))
+    outfp.write('<text x="%.3f" y="%.3f" font="%s" size="%.3f" width="%.3f">' %
+                (tx, ty, e(self.font.fontname), self.size, self.width))
+    outfp.write(e(self.text))
     outfp.write('</text>\n')
     return
 
@@ -182,10 +185,10 @@ def pdf2txt(outfp, rsrc, fname, pages, codec, debug=0):
 def main(argv):
   import getopt
   def usage():
-    print 'usage: %s [-d] [-c codec] [-p pages] file ...' % argv[0]
+    print 'usage: %s [-d] [-c codec] [-p pages] [-o output] file ...' % argv[0]
     return 100
   try:
-    (opts, args) = getopt.getopt(argv[1:], 'dp:c:')
+    (opts, args) = getopt.getopt(argv[1:], 'dp:c:o:')
   except getopt.GetoptError:
     return usage()
   if not args: return usage()

pdfparser.py

@@ -9,6 +9,7 @@ import md5, struct
 stderr = sys.stderr
 from utils import choplist, nunpack
 from arcfour import Arcfour
+from lzw import LZWDecoder
 from psparser import PSException, PSSyntaxError, PSTypeError, PSEOF, \
      PSLiteral, PSKeyword, PSLiteralTable, PSKeywordTable, \
      literal_name, keyword_name, \
@@ -208,7 +209,11 @@ class PDFStream:
         # will get errors if the document is encrypted.
         data = zlib.decompress(data)
       elif f == LITERAL_LZW_DECODE:
-        raise PDFNotImplementedError('LZWDecode is currently unsupported.')
+        try:
+          from cStringIO import StringIO
+        except ImportError:
+          from StringIO import StringIO
+        data = ''.join(LZWDecoder(StringIO(data)).run())
       elif f == LITERAL_CRYPT:
         raise PDFEncryptionError
       else: