python-pdfminer 20110515+dfsg-1 / usr / share / pyshared / pdfminer / pdfinterp.py

#!/usr/bin/env python2
import sys
import re
try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO
from cmapdb import CMapDB, CMap
from psparser import PSException, PSTypeError, PSEOF
from psparser import PSKeyword, literal_name, keyword_name
from psparser import PSStackParser
from psparser import LIT, KWD, STRICT
from pdftypes import PDFException, PDFStream, PDFObjRef
from pdftypes import resolve1
from pdftypes import int_value, float_value, num_value
from pdftypes import str_value, list_value, dict_value, stream_value
from pdffont import PDFFontError
from pdffont import PDFType1Font, PDFTrueTypeFont, PDFType3Font
from pdffont import PDFCIDFont
from pdfparser import PDFDocument, PDFParser
from pdfparser import PDFPasswordIncorrect
from pdfcolor import PDFColorSpace
from pdfcolor import PREDEFINED_COLORSPACE
from pdfcolor import LITERAL_DEVICE_GRAY, LITERAL_DEVICE_RGB
from pdfcolor import LITERAL_DEVICE_CMYK
from utils import choplist
from utils import mult_matrix, MATRIX_IDENTITY


##  Exceptions
##
class PDFResourceError(PDFException): pass
class PDFInterpreterError(PDFException): pass


##  Constants
##
LITERAL_PDF = LIT('PDF')
LITERAL_TEXT = LIT('Text')
LITERAL_FONT = LIT('Font')
LITERAL_FORM = LIT('Form')
LITERAL_IMAGE = LIT('Image')


##  PDFTextState
##
class PDFTextState(object):

    def __init__(self):
        self.font = None
        self.fontsize = 0
        self.charspace = 0
        self.wordspace = 0
        self.scaling = 100
        self.leading = 0
        self.render = 0
        self.rise = 0
        self.reset()
        # self.matrix is set
        # self.linematrix is set
        return

    def __repr__(self):
        return ('<PDFTextState: font=%r, fontsize=%r, charspace=%r, wordspace=%r, '
                ' scaling=%r, leading=%r, render=%r, rise=%r, '
                ' matrix=%r, linematrix=%r>' %
                (self.font, self.fontsize, self.charspace, self.wordspace,
                 self.scaling, self.leading, self.render, self.rise,
                 self.matrix, self.linematrix))

    def copy(self):
        obj = PDFTextState()
        obj.font = self.font
        obj.fontsize = self.fontsize
        obj.charspace = self.charspace
        obj.wordspace = self.wordspace
        obj.scaling = self.scaling
        obj.leading = self.leading
        obj.render = self.render
        obj.rise = self.rise
        obj.matrix = self.matrix
        obj.linematrix = self.linematrix
        return obj

    def reset(self):
        self.matrix = MATRIX_IDENTITY
        self.linematrix = (0, 0)
        return


##  PDFGraphicState
##
class PDFGraphicState(object):

    def __init__(self):
        self.linewidth = 0
        self.linecap = None
        self.linejoin = None
        self.miterlimit = None
        self.dash = None
        self.intent = None
        self.flatness = None
        return

    def copy(self):
        obj = PDFGraphicState()
        obj.linewidth = self.linewidth
        obj.linecap = self.linecap
        obj.linejoin = self.linejoin
        obj.miterlimit = self.miterlimit
        obj.dash = self.dash
        obj.intent = self.intent
        obj.flatness = self.flatness
        return obj

    def __repr__(self):
        return ('<PDFGraphicState: linewidth=%r, linecap=%r, linejoin=%r, '
                ' miterlimit=%r, dash=%r, intent=%r, flatness=%r>' %
                (self.linewidth, self.linecap, self.linejoin,
                 self.miterlimit, self.dash, self.intent, self.flatness))

##  Resource Manager
##
class PDFResourceManager(object):

    """Repository of shared resources.
    
    ResourceManager facilitates reuse of shared resources
    such as fonts and images so that large objects are not
    allocated multiple times.
    """
    debug = 0

    def __init__(self, caching=True):
        self.caching = caching
        self._cached_fonts = {}
        return

    def get_procset(self, procs):
        for proc in procs:
            if proc is LITERAL_PDF:
                pass
            elif proc is LITERAL_TEXT:
                pass
            else:
                #raise PDFResourceError('ProcSet %r is not supported.' % proc)
                pass
        return

    def get_cmap(self, cmapname, strict=False):
        try:
            return CMapDB.get_cmap(cmapname)
        except CMapDB.CMapNotFound:
            if strict: raise
            return CMap()

    def get_font(self, objid, spec):
        if objid and objid in self._cached_fonts:
            font = self._cached_fonts[objid]
        else:
            if 2 <= self.debug:
                print >>sys.stderr, 'get_font: create: objid=%r, spec=%r' % (objid, spec)
            if STRICT:
                if spec['Type'] is not LITERAL_FONT:
                    raise PDFFontError('Type is not /Font')
            # Create a Font object.
            if 'Subtype' in spec:
                subtype = literal_name(spec['Subtype'])
            else:
                if STRICT:
                    raise PDFFontError('Font Subtype is not specified.')
                subtype = 'Type1'
            if subtype in ('Type1', 'MMType1'):
                # Type1 Font
                font = PDFType1Font(self, spec)
            elif subtype == 'TrueType':
                # TrueType Font
                font = PDFTrueTypeFont(self, spec)
            elif subtype == 'Type3':
                # Type3 Font
                font = PDFType3Font(self, spec)
            elif subtype in ('CIDFontType0', 'CIDFontType2'):
                # CID Font
                font = PDFCIDFont(self, spec)
            elif subtype == 'Type0':
                # Type0 Font
                dfonts = list_value(spec['DescendantFonts'])
                assert dfonts
                subspec = dict_value(dfonts[0]).copy()
                for k in ('Encoding', 'ToUnicode'):
                    if k in spec:
                        subspec[k] = resolve1(spec[k])
                font = self.get_font(None, subspec)
            else:
                if STRICT:
                    raise PDFFontError('Invalid Font spec: %r' % spec)
                font = PDFType1Font(self, spec) # this is so wrong!
            if objid and self.caching:
                self._cached_fonts[objid] = font
        return font


##  PDFContentParser
##
class PDFContentParser(PSStackParser):

    def __init__(self, streams):
        self.streams = streams
        self.istream = 0
        PSStackParser.__init__(self, None)
        return

    def fillfp(self):
        if not self.fp:
            if self.istream < len(self.streams):
                strm = stream_value(self.streams[self.istream])
                self.istream += 1
            else:
                raise PSEOF('Unexpected EOF, file truncated?')
            self.fp = StringIO(strm.get_data())
        return

    def seek(self, pos):
        self.fillfp()
        PSStackParser.seek(self, pos)
        return

    def fillbuf(self):
        if self.charpos < len(self.buf): return
        while 1:
            self.fillfp()
            self.bufpos = self.fp.tell()
            self.buf = self.fp.read(self.BUFSIZ)
            if self.buf: break
            self.fp = None
        self.charpos = 0
        return

    def get_inline_data(self, pos, target='EI'):
        self.seek(pos)
        i = 0
        data = ''
        while i <= len(target):
            self.fillbuf()
            if i:
                c = self.buf[self.charpos]
                data += c
                self.charpos += 1
                if len(target) <= i and c.isspace():
                    i += 1
                elif i < len(target) and c == target[i]:
                    i += 1
                else:
                    i = 0
            else:
                try:
                    j = self.buf.index(target[0], self.charpos)
                    #print 'found', (0, self.buf[j:j+10])
                    data += self.buf[self.charpos:j+1]
                    self.charpos = j+1
                    i = 1
                except ValueError:
                    data += self.buf[self.charpos:]
                    self.charpos = len(self.buf)
        data = data[:-(len(target)+1)] # strip the last part
        data = re.sub(r'(\x0d\x0a|[\x0d\x0a])$', '', data)
        return (pos, data)

    def flush(self):
        self.add_results(*self.popall())
        return

    KEYWORD_BI = KWD('BI')
    KEYWORD_ID = KWD('ID')
    KEYWORD_EI = KWD('EI')
    def do_keyword(self, pos, token):
        if token is self.KEYWORD_BI:
            # inline image within a content stream
            self.start_type(pos, 'inline')
        elif token is self.KEYWORD_ID:
            try:
                (_, objs) = self.end_type('inline')
                if len(objs) % 2 != 0:
                    raise PSTypeError('Invalid dictionary construct: %r' % objs)
                d = dict( (literal_name(k), v) for (k,v) in choplist(2, objs) )
                (pos, data) = self.get_inline_data(pos+len('ID '))
                obj = PDFStream(d, data)
                self.push((pos, obj))
                self.push((pos, self.KEYWORD_EI))
            except PSTypeError:
                if STRICT: raise
        else:
            self.push((pos, token))
        return


##  Interpreter
##
class PDFPageInterpreter(object):

    debug = 0

    def __init__(self, rsrcmgr, device):
        self.rsrcmgr = rsrcmgr
        self.device = device
        return

    def dup(self):
        return PDFPageInterpreter(self.rsrcmgr, self.device)

    # init_resources(resources):
    #   Prepare the fonts and XObjects listed in the Resource attribute.
    def init_resources(self, resources):
        self.resources = resources
        self.fontmap = {}
        self.xobjmap = {}
        self.csmap = PREDEFINED_COLORSPACE.copy()
        if not resources: return
        def get_colorspace(spec):
            if isinstance(spec, list):
                name = literal_name(spec[0])
            else:
                name = literal_name(spec)
            if name == 'ICCBased' and isinstance(spec, list) and 2 <= len(spec):
                return PDFColorSpace(name, stream_value(spec[1])['N'])
            elif name == 'DeviceN' and isinstance(spec, list) and 2 <= len(spec):
                return PDFColorSpace(name, len(list_value(spec[1])))
            else:
                return PREDEFINED_COLORSPACE[name]
        for (k,v) in dict_value(resources).iteritems():
            if 2 <= self.debug:
                print >>sys.stderr, 'Resource: %r: %r' % (k,v)
            if k == 'Font':
                for (fontid,spec) in dict_value(v).iteritems():
                    objid = None
                    if isinstance(spec, PDFObjRef):
                        objid = spec.objid
                    spec = dict_value(spec)
                    self.fontmap[fontid] = self.rsrcmgr.get_font(objid, spec)
            elif k == 'ColorSpace':
                for (csid,spec) in dict_value(v).iteritems():
                    self.csmap[csid] = get_colorspace(resolve1(spec))
            elif k == 'ProcSet':
                self.rsrcmgr.get_procset(list_value(v))
            elif k == 'XObject':
                for (xobjid,xobjstrm) in dict_value(v).iteritems():
                    self.xobjmap[xobjid] = xobjstrm
        return

    # init_state(ctm)
    #   Initialize the text and graphic states for rendering a page.
    def init_state(self, ctm):
        # gstack: stack for graphical states.
        self.gstack = []
        self.ctm = ctm
        self.device.set_ctm(self.ctm)
        self.textstate = PDFTextState()
        self.graphicstate = PDFGraphicState()
        self.curpath = []
        # argstack: stack for command arguments.
        self.argstack = []
        # set some global states.
        self.scs = self.ncs = None
        if self.csmap:
            self.scs = self.ncs = self.csmap.values()[0]
        return

    def push(self, obj):
        self.argstack.append(obj)
        return

    def pop(self, n):
        if n == 0: return []
        x = self.argstack[-n:]
        self.argstack = self.argstack[:-n]
        return x

    def get_current_state(self):
        return (self.ctm, self.textstate.copy(), self.graphicstate.copy())

    def set_current_state(self, state):
        (self.ctm, self.textstate, self.graphicstate) = state
        self.device.set_ctm(self.ctm)
        return

    # gsave
    def do_q(self):
        self.gstack.append(self.get_current_state())
        return
    # grestore
    def do_Q(self):
        if self.gstack:
            self.set_current_state(self.gstack.pop())
        return

    # concat-matrix
    def do_cm(self, a1, b1, c1, d1, e1, f1):
        self.ctm = mult_matrix((a1,b1,c1,d1,e1,f1), self.ctm)
        self.device.set_ctm(self.ctm)
        return

    # setlinewidth
    def do_w(self, linewidth):
        self.graphicstate.linewidth = linewidth
        return
    # setlinecap
    def do_J(self, linecap):
        self.graphicstate.linecap = linecap
        return
    # setlinejoin
    def do_j(self, linejoin):
        self.graphicstate.linejoin = linejoin
        return
    # setmiterlimit
    def do_M(self, miterlimit):
        self.graphicstate.miterlimit = miterlimit
        return
    # setdash
    def do_d(self, dash, phase):
        self.graphicstate.dash = (dash, phase)
        return
    # setintent
    def do_ri(self, intent):
        self.graphicstate.intent = intent
        return
    # setflatness
    def do_i(self, flatness):
        self.graphicstate.flatness = flatness
        return
    # load-gstate
    def do_gs(self, name):
        #XXX
        return

    # moveto
    def do_m(self, x, y):
        self.curpath.append(('m',x,y))
        return
    # lineto
    def do_l(self, x, y):
        self.curpath.append(('l',x,y))
        return
    # curveto
    def do_c(self, x1, y1, x2, y2, x3, y3):
        self.curpath.append(('c',x1,y1,x2,y2,x3,y3))
        return
    # urveto
    def do_v(self, x2, y2, x3, y3):
        self.curpath.append(('v',x2,y2,x3,y3))
        return
    # rveto
    def do_y(self, x1, y1, x3, y3):
        self.curpath.append(('y',x1,y1,x3,y3))
        return
    # closepath
    def do_h(self):
        self.curpath.append(('h',))
        return
    # rectangle
    def do_re(self, x, y, w, h):
        self.curpath.append(('m',x,y))
        self.curpath.append(('l',x+w,y))
        self.curpath.append(('l',x+w,y+h))
        self.curpath.append(('l',x,y+h))
        self.curpath.append(('h',))
        return

    # stroke
    def do_S(self):
        self.device.paint_path(self.graphicstate, True, False, False, self.curpath)
        self.curpath = []
        return
    # close-and-stroke
    def do_s(self):
        self.do_h()
        self.do_S()
        return
    # fill
    def do_f(self):
        self.device.paint_path(self.graphicstate, False, True, False, self.curpath)
        self.curpath = []
        return
    # fill (obsolete)
    do_F = do_f
    # fill-even-odd
    def do_f_a(self):
        self.device.paint_path(self.graphicstate, False, True, True, self.curpath)
        self.curpath = []
        return
    # fill-and-stroke
    def do_B(self):
        self.device.paint_path(self.graphicstate, True, True, False, self.curpath)
        self.curpath = []
        return
    # fill-and-stroke-even-odd
    def do_B_a(self):
        self.device.paint_path(self.graphicstate, True, True, True, self.curpath)
        self.curpath = []
        return
    # close-fill-and-stroke
    def do_b(self):
        self.do_h()
        self.do_B()
        return
    # close-fill-and-stroke-even-odd
    def do_b_a(self):
        self.do_h()
        self.do_B_a()
        return
    # close-only
    def do_n(self):
        self.curpath = []
        return
    # clip
    def do_W(self): return
    # clip-even-odd
    def do_W_a(self): return

    # setcolorspace-stroking
    def do_CS(self, name):
        self.scs = self.csmap[literal_name(name)]
        return
    # setcolorspace-non-strokine
    def do_cs(self, name):
        self.ncs = self.csmap[literal_name(name)]
        return
    # setgray-stroking
    def do_G(self, gray):
        #self.do_CS(LITERAL_DEVICE_GRAY)
        return
    # setgray-non-stroking
    def do_g(self, gray):
        #self.do_cs(LITERAL_DEVICE_GRAY)
        return
    # setrgb-stroking
    def do_RG(self, r, g, b):
        #self.do_CS(LITERAL_DEVICE_RGB)
        return
    # setrgb-non-stroking
    def do_rg(self, r, g, b):
        #self.do_cs(LITERAL_DEVICE_RGB)
        return
    # setcmyk-stroking
    def do_K(self, c, m, y, k):
        #self.do_CS(LITERAL_DEVICE_CMYK)
        return
    # setcmyk-non-stroking
    def do_k(self, c, m, y, k):
        #self.do_cs(LITERAL_DEVICE_CMYK)
        return

    # setcolor
    def do_SCN(self):
        if self.scs:
            n = self.scs.ncomponents
        else:
            if STRICT:
                raise PDFInterpreterError('No colorspace specified!')
            n = 1
        self.pop(n)
        return
    def do_scn(self):
        if self.ncs:
            n = self.ncs.ncomponents
        else:
            if STRICT:
                raise PDFInterpreterError('No colorspace specified!')
            n = 1
        self.pop(n)
        return
    def do_SC(self):
        self.do_SCN()
        return
    def do_sc(self):
        self.do_scn()
        return

    # sharing-name
    def do_sh(self, name): return

    # begin-text
    def do_BT(self):
        self.textstate.reset()
        return
    # end-text
    def do_ET(self):
        return

    # begin-compat
    def do_BX(self): return
    # end-compat
    def do_EX(self): return

    # marked content operators
    def do_MP(self, tag):
        self.device.do_tag(tag)
        return
    def do_DP(self, tag, props):
        self.device.do_tag(tag, props)
        return
    def do_BMC(self, tag):
        self.device.begin_tag(tag)
        return
    def do_BDC(self, tag, props):
        self.device.begin_tag(tag, props)
        return
    def do_EMC(self):
        self.device.end_tag()
        return

    # setcharspace
    def do_Tc(self, space):
        self.textstate.charspace = space
        return
    # setwordspace
    def do_Tw(self, space):
        self.textstate.wordspace = space
        return
    # textscale
    def do_Tz(self, scale):
        self.textstate.scaling = scale
        return
    # setleading
    def do_TL(self, leading):
        self.textstate.leading = -leading
        return
    # selectfont
    def do_Tf(self, fontid, fontsize):
        try:
            self.textstate.font = self.fontmap[literal_name(fontid)]
        except KeyError:
            raise
            if STRICT:
                raise PDFInterpreterError('Undefined Font id: %r' % fontid)
            return
        self.textstate.fontsize = fontsize
        return
    # setrendering
    def do_Tr(self, render):
        self.textstate.render = render
        return
    # settextrise
    def do_Ts(self, rise):
        self.textstate.rise = rise
        return

    # text-move
    def do_Td(self, tx, ty):
        (a,b,c,d,e,f) = self.textstate.matrix
        self.textstate.matrix = (a,b,c,d,tx*a+ty*c+e,tx*b+ty*d+f)
        self.textstate.linematrix = (0, 0)
        #print >>sys.stderr, 'Td(%r,%r): %r' % (tx,ty,self.textstate)
        return
    # text-move
    def do_TD(self, tx, ty):
        (a,b,c,d,e,f) = self.textstate.matrix
        self.textstate.matrix = (a,b,c,d,tx*a+ty*c+e,tx*b+ty*d+f)
        self.textstate.leading = ty
        self.textstate.linematrix = (0, 0)
        #print >>sys.stderr, 'TD(%r,%r): %r' % (tx,ty,self.textstate)
        return
    # textmatrix
    def do_Tm(self, a,b,c,d,e,f):
        self.textstate.matrix = (a,b,c,d,e,f)
        self.textstate.linematrix = (0, 0)
        return
    # nextline
    def do_T_a(self):
        (a,b,c,d,e,f) = self.textstate.matrix
        self.textstate.matrix = (a,b,c,d,self.textstate.leading*c+e,self.textstate.leading*d+f)
        self.textstate.linematrix = (0, 0)
        return

    # show-pos
    def do_TJ(self, seq):
        #print >>sys.stderr, 'TJ(%r): %r' % (seq,self.textstate)
        if self.textstate.font is None:
            if STRICT:
                raise PDFInterpreterError('No font specified!')
            return
        self.device.render_string(self.textstate, seq)
        return
    # show
    def do_Tj(self, s):
        self.do_TJ([s])
        return
    # quote
    def do__q(self, s):
        self.do_T_a()
        self.do_TJ([s])
        return
    # doublequote
    def do__w(self, aw, ac, s):
        self.do_Tw(aw)
        self.do_Tc(ac)
        self.do_TJ([s])
        return

    # inline image
    def do_BI(self): # never called
        return
    def do_ID(self): # never called
        return
    def do_EI(self, obj):
        if 'W' in obj and 'H' in obj:
            iobjid = str(id(obj))
            self.device.begin_figure(iobjid, (0,0,1,1), MATRIX_IDENTITY)
            self.device.render_image(iobjid, obj)
            self.device.end_figure(iobjid)
        return

    # invoke an XObject
    def do_Do(self, xobjid):
        xobjid = literal_name(xobjid)
        try:
            xobj = stream_value(self.xobjmap[xobjid])
        except KeyError:
            if STRICT:
                raise PDFInterpreterError('Undefined xobject id: %r' % xobjid)
            return
        if 1 <= self.debug:
            print >>sys.stderr, 'Processing xobj: %r' % xobj
        subtype = xobj.get('Subtype')
        if subtype is LITERAL_FORM and 'BBox' in xobj:
            interpreter = self.dup()
            bbox = list_value(xobj['BBox'])
            matrix = list_value(xobj.get('Matrix', MATRIX_IDENTITY))
            # According to PDF reference 1.7 section 4.9.1, XObjects in 
            # earlier PDFs (prior to v1.2) use the page's Resources entry
            # instead of having their own Resources entry.
            resources = dict_value(xobj.get('Resources')) or self.resources.copy()
            self.device.begin_figure(xobjid, bbox, matrix)
            interpreter.render_contents(resources, [xobj], ctm=mult_matrix(matrix, self.ctm))
            self.device.end_figure(xobjid)
        elif subtype is LITERAL_IMAGE and 'Width' in xobj and 'Height' in xobj:
            self.device.begin_figure(xobjid, (0,0,1,1), MATRIX_IDENTITY)
            self.device.render_image(xobjid, xobj)
            self.device.end_figure(xobjid)
        else:
            # unsupported xobject type.
            pass
        return

    def process_page(self, page):
        if 1 <= self.debug:
            print >>sys.stderr, 'Processing page: %r' % page
        (x0,y0,x1,y1) = page.mediabox
        if page.rotate == 90:
            ctm = (0,-1,1,0, -y0,x1)
        elif page.rotate == 180:
            ctm = (-1,0,0,-1, x1,y1)
        elif page.rotate == 270:
            ctm = (0,1,-1,0, y1,-x0)
        else:
            ctm = (1,0,0,1, -x0,-y0)
        self.device.begin_page(page, ctm)
        self.render_contents(page.resources, page.contents, ctm=ctm)
        self.device.end_page(page)
        return

    # render_contents(resources, streams, ctm)
    #   Render the content streams.
    #   This method may be called recursively.
    def render_contents(self, resources, streams, ctm=MATRIX_IDENTITY):
        if 1 <= self.debug:
            print >>sys.stderr, ('render_contents: resources=%r, streams=%r, ctm=%r' %
                             (resources, streams, ctm))
        self.init_resources(resources)
        self.init_state(ctm)
        self.execute(list_value(streams))
        return

    def execute(self, streams):
        try:
            parser = PDFContentParser(streams)
        except PSEOF:
            # empty page
            return
        while 1:
            try:
                (_,obj) = parser.nextobject()
            except PSEOF:
                break
            if isinstance(obj, PSKeyword):
                name = keyword_name(obj)
                method = 'do_%s' % name.replace('*','_a').replace('"','_w').replace("'",'_q')
                if hasattr(self, method):
                    func = getattr(self, method)
                    nargs = func.func_code.co_argcount-1
                    if nargs:
                        args = self.pop(nargs)
                        if 2 <= self.debug:
                            print >>sys.stderr, 'exec: %s %r' % (name, args)
                        if len(args) == nargs:
                            func(*args)
                    else:
                        if 2 <= self.debug:
                            print >>sys.stderr, 'exec: %s' % (name)
                        func()
                else:
                    if STRICT:
                        raise PDFInterpreterError('Unknown operator: %r' % name)
            else:
                self.push(obj)
        return


##  process_pdf
##
class PDFTextExtractionNotAllowed(PDFInterpreterError): pass

def process_pdf(rsrcmgr, device, fp, pagenos=None, maxpages=0, password='',
                caching=True, check_extractable=True):
    # Create a PDF parser object associated with the file object.
    parser = PDFParser(fp)
    # Create a PDF document object that stores the document structure.
    doc = PDFDocument(caching=caching)
    # Connect the parser and document objects.
    parser.set_document(doc)
    doc.set_parser(parser)
    # Supply the document password for initialization.
    # (If no password is set, give an empty string.)
    doc.initialize(password)
    # Check if the document allows text extraction. If not, abort.
    if check_extractable and not doc.is_extractable:
        raise PDFTextExtractionNotAllowed('Text extraction is not allowed: %r' % fp)
    # Create a PDF interpreter object.
    interpreter = PDFPageInterpreter(rsrcmgr, device)
    # Process each page contained in the document.
    for (pageno,page) in enumerate(doc.get_pages()):
        if pagenos and (pageno not in pagenos): continue
        interpreter.process_page(page)
        if maxpages and maxpages <= pageno+1: break
    return