pdf_base.ps

GhostScript的源代码

      pop true
    } {
		% Update Objects from GlobalObjects
      DEBUG { (%Global=>local: ) print dup == } if
      Objects exch GlobalObjects 1 index get lput false
    } ifelse
  } {
    pop false
  } ifelse
} bind def
/oforce /exec load def
/oget		% <array> <index> oget <object>
		% <dict> <key> oget <object>
 { 2 copy get dup xcheck
    { exec dup 4 1 roll put }
    { exch pop exch pop }
   ifelse
 } bind def
% A null value in a dictionary is equivalent to an omitted key;
% we must check for this specially.
/knownoget
 { 2 copy known
    { oget dup null eq { pop false } { true } ifelse }
    { pop pop false }
   ifelse
 } bind def

% PDF 1.1 defines a 'foreign file reference', but not its meaning.
% Per the specification, we convert these to nulls.
/F		% <file#> <object#> <generation#> F <object>
 {		% Some PDF 1.1 files use F as a synonym for f!
   count 3 lt { f } { pop pop pop null } ifelse
 } bind def

/checkgeneration {  % <object#> <generation#> checkgeneration <object#> <OK>
  Generations 2 index lget 1 sub 1 index eq {
    pop true
  } {
    Generations 2 index lget 0 eq {
      (Warning: reference to free object: )
    } {
      (Warning: wrong generation: )
    } ifelse print 1 index =only ( ) print =only ( R) = false
  } ifelse
} bind def
/R {		% <object#> <generation#> R <object>
  1 index unresolved?
    { /resolveR cvx 3 packedarray cvx }
    { checkgeneration { Objects exch lget } { pop null } ifelse }
   ifelse
} bind def

% If we encounter an object definition while reading sequentially,
% we just store it away and keep going.
/objopdict mark
  valueopdict { } forall
  /endobj dup cvx
.dicttomark readonly def
/obj {			% <object#> <generation#> obj <object>
  PDFfile objopdict .pdfrun
} bind def
/endobj {		% <object#> <generation#> <object> endobj <object>
  3 1 roll
		% Read the xref entry if we haven't yet done so.
		% This is only needed for generation # checking.
  1 index unresolved? {
    PDFfile fileposition
    2 index readxrefentry pop
    PDFoffset add PDFfile exch setfileposition
  } if
  checkgeneration {
		% The only global objects we bother to save are
		% (resource) dictionaries.
    1 index dup gcheck exch type /dicttype eq and {
      DEBUG { (%Local=>global: ) print dup == } if
      GlobalObjects 1 index 3 index put
      IsGlobal 1 index 1 put
    } if
    Objects exch 2 index lput
  } {
    pop pop null
  } ifelse
} bind def

% When resolving an object reference, we stop at the endobj.
/resolveopdict mark
  valueopdict { } forall
  /endobj { endobj exit } bind
.dicttomark readonly def
/resolveR		% <object#> <generation#> resolveR <object>
 { DEBUG { (%Resolving: ) print 2 copy 2 array astore == } if
   1 index unresolved?
    { PDFfile fileposition 3 1 roll
      1 index readxrefentry
      3 1 roll checkgeneration
       {		% Stack: savepos objpos obj#
	 exch PDFoffset add PDFfile exch setfileposition
	 PDFfile token pop 2 copy ne
	  { (xref error!\n) print /resolveR cvx /rangecheck signalerror
	  }
	 if pop PDFfile token pop
	 PDFfile token pop /obj ne
	  { (xref error!\n) print /resolveR cvx /rangecheck signalerror
	  }
	 if
	 pdf_run_resolve	% PDFfile resolveopdict .pdfrun
       }
       { Objects exch null lput pop null
       }
      ifelse exch PDFfile exch setfileposition
    }
    { pop Objects exch lget
    }
   ifelse
 } bind def      

% ================================ Streams ================================ %

% We represent a stream by an executable dictionary that contains,
% in addition to the contents of the original stream dictionary:
%	/File - the file or string where the stream contents are stored,
%	  if the stream is not an external one.
%	/FilePosition - iff File is a file, the position in the file
%	  where the contents start.
%	/StreamKey - the key used to decrypt this stream, if any.
% We do the real work of constructing the data stream only when the
% contents are needed.

% Construct a stream.  The length is not reliable in the face of
% different end-of-line conventions, but it's all we've got.
%
% PDF files are inconsistent about what may fall between the 'stream' keyword
% and the actual stream data, and it appears that no one algorithm can
% detect this reliably.  We used to try to guess whether the file included
% extraneous \r and/or \n characters, but we no longer attempt to do so,
% especially since the PDF 1.2 specification states flatly that the only
% legal terminators following the 'stream' keyword are \n or \r\n, both of
% which are properly skipped and discarded by the token operator.
/stream {	% <dict> stream <modified_dict>
  dup /F known dup PDFsource PDFfile eq or {
    not {
      dup /File PDFfile put
      dup /FilePosition PDFfile fileposition put
      DEBUG { (%FilePosition: ) print dup /FilePosition get == } if
    } if
    PDFfile fileposition 1 index /Length oget add
      PDFfile exch setfileposition
  } {
    pop
	% We're already reading from a stream, which we can't reposition.
	% Capture the sub-stream contents in a string.
    dup /Length oget string PDFsource exch readstring
    not {
      (Unexpected EOF in stream!\n) print
      /stream cvx /rangecheck signalerror
    } if
    1 index exch /File exch put
  } ifelse
  PDFsource token pop
    /endstream ne { /stream cvx /syntaxerror signalerror } if
  cvx
} bind def
/endstream {
  exit
} bind def

% Extract and apply filters.
/filterparms {		% <dict> <DPkey> <Fkey> filterparms
			%   <dict> <parms> <filternames>
  exch 2 index exch .knownget not { null } if
  exch 2 index exch .knownget not { { } } if
  dup type /nametype eq {
    1 array astore
    1 index null ne { exch 1 array astore exch } if
  } if
} bind def
/applyfilters {		% <parms> <source> <filternames> applyfilters <stream>
  2 index null eq {
    { filter }
  } {
    {		% Stack: parms stream filtername
      2 index 0 get dup null eq { pop } { exch } ifelse filter
      exch dup length 1 sub 1 exch getinterval exch
    }
  } ifelse forall exch pop
} bind def

% Resolve a stream dictionary to a PostScript stream.
% Streams with no filters require special handling:
%	- If we are going to interpret their contents, we let endstream
%	  terminate the interpretation loop;
%	- If we are just going to read data from them, we impose
%	  a SubFileDecode filter that reads just the requisite amount of data.
% Note that, in general, resolving a stream repositions PDFfile.
% Clients must save and restore the position of PDFfile themselves.
/resolvestream {	% <streamdict> <readdata?> resolvestream <stream>
  1 index /F .knownget {
		% This stream is stored on an external file.
    (r) file exch
    /FDecodeParms /FFilter filterparms
		% Stack: readdata? dict parms filternames
    4 -1 roll exch
    pdf_decrypt_stream
    apply_filters
  } {
    exch dup /FilePosition .knownget {
      1 index /File get exch setfileposition
    } if
		% Stack: readdata? dict
    /DecodeParms /Filter filterparms
		% Stack: readdata? dict parms filternames
    2 index /File get exch
		% Stack: readdata? dict parms file/string filternames
    pdf_decrypt_stream		% add decryption if needed
    dup length 0 eq {
		% All the PDF filters have EOD markers, but in this case
		% there is no specified filter.
      pop exch pop
		% Stack: readdata? dict file/string
      2 index {
		% We're going to read data; use a SubFileDecode filter.
	1 index /Length oget () /SubFileDecode filter
      } {
	dup type /filetype ne {
		% Use a SubFileDecode filter to read from a string.
	  0 () SubFileDecode filter
	} if
      } ifelse
    } {
      applyfilters
    } ifelse
  } ifelse
		% Stack: readdata? dict file
  exch pop exch pop
} bind def

% ============================ Name/number trees ============================ %

/nameoget {		% <nametree> <key> nameoget <obj|null>
  exch /Names exch .treeget
} bind def

/numoget {		% <numtree> <key> numoget <obj|null>
  exch /Nums exch .treeget
} bind def

/.treeget {		% <key> <leafkey> <tree> .treeget <obj|null>
  dup /Kids knownoget {
    exch pop .branchget
  } {
    exch get .leafget
  } ifelse
} bind def

/.branchget {		%  <key> <leafkey> <kids> .branchget <obj|null>
  dup length 0 eq {
    pop pop pop null
  } {
    dup length -1 bitshift 2 copy oget
			% Stack: key leafkey kids mid kids[mid]
    dup /Limits oget aload pop
			% Stack: key leafkey kids mid kids[mid] min max
    6 index lt {
      pop pop
      1 add 1 index length 1 index sub getinterval .branchget
    } {
      5 index gt {
	pop
	0 exch getinterval .branchget
      } {
	exch pop exch pop .treeget
      } ifelse
    } ifelse
  } ifelse
} bind def

/.leafget {		% <key> <pairs> .leafget <obj|null>
  dup length 2 eq {
    dup 0 get 2 index eq { 1 oget } { pop null } ifelse
    exch pop
  } {
    dup length -1 bitshift -2 and 2 copy oget
			% Stack: key pairs mid pairs[mid]
    3 index gt { 0 exch } { 1 index length 1 index sub } ifelse
    getinterval .leafget
  } ifelse
} bind def

end			% pdfdict
.setglobal