Module Pdfcodec

module Pdfcodec: sig .. end

Encoding and Decoding PDF Streams

Currently supported:

Decoders: ASCIIHexDecode, ASCII85Decode, FlateDecode, RunLengthDecode, CCITTFaxDecode, LZWDecode, JBIG2 (via jbig2dec)
Encoders: ASCIIHexDecode, ASCII85Decode, FlateDecode, RunLengthDecode, CCITTFaxDecode G3, CCITTFaxDecode G4 (via imagemagick)
Decode predictors: PNG (all), TIFF (8-bit only).

Types

type encoding =

`\|`	`ASCIIHex`
`\|`	`ASCII85`
`\|`	`RunLength`
`\|`	`Flate`
`\|`	`CCITT of int * int`
`\|`	`CCITTG4 of int * int`

Supported encodings.

type predictor =

`\|`	`TIFF2`
`\|`	`PNGNone`
`\|`	`PNGSub`
`\|`	`PNGUp`
`\|`	`PNGAverage`
`\|`	`PNGPaeth`
`\|`	`PNGOptimum`

Predictors.

exception Couldn'tDecodeStream of string

There was bad data.

exception DecodeNotSupported of string

CamlPDF doesn't support this encoding or its predictor.

Encoding

val encode_pdfstream : Pdf.t ->
       encoding ->
       ?im:string ->
       ?only_if_smaller:bool ->
       ?predictor:predictor ->
       ?predictor_columns:int -> Pdf.pdfobject -> unit

Encode a PDF stream with an encoding. im is the path to imagemagick (only for CCITTG4) If only_if_smaller is true, the stream remains uncompressed if compression would make it bigger. predictor and predictor_columns describe any predictor to be used.

Decoding

val decode_pdfstream : ?jbig2dec:string -> Pdf.t -> Pdf.pdfobject -> unit

Given a document and stream, decode. The pdf document is updated with the decoded stream. May raise either of the exceptions above. If jbig2dec is given, JBIG2 streams will be decompressed with it. Otherwise, they are left alone.

val decode_pdfstream_onestage : ?jbig2dec:string -> Pdf.t -> Pdf.pdfobject -> unit

Given a document and stream decode just one stage. May raise either of the exceptions above. If jbig2dec is given, JBIG2 streams will be decompressed with it. Otherwise, they are left alone.

val decode_pdfstream_until_unknown : ?jbig2dec:string -> Pdf.t -> Pdf.pdfobject -> unit

Given a document and stream decode until there's an unknown decoder. May raise Couldn'tDecodeStream. If jbig2dec is given, JBIG2 streams will be decompressed with it. Otherwise, they are left alone.

val decode_from_input : Pdfio.input -> Pdf.pdfobject -> Pdfio.bytes option

Given a Pdfio.input with pointer at the first byte and an inline image stream dictionary, decode the first decoder and its predictor. Return the data, or None if this decoder isn't supported but the data pointer has been left in the right place. The exceptions above can both be raised, in the case of bad data or a completely unknown encoding.

Low level functionality

val flate_level : int Stdlib.ref

Setting this changes globally the FlateDecode compression level. Default 6.

val encode_flate : Pdfio.bytes -> Pdfio.bytes

Encode data in FlateDecode.

val decode_flate : Pdfio.bytes -> Pdfio.bytes

Decode data in FlateDecode.

val encode_ccitt : int -> int -> Pdfio.bytes -> Pdfio.bytes

Encode data in CCITTDecode Group 3.

val encode_ccittg4 : ?im:string -> int -> int -> Pdfio.bytes -> Pdfio.bytes

Encode data in CCITTDecode Group 4. Presently we do this via imagemagick, given by im.

val debug : bool Stdlib.ref

Setting this boolean prints some debug information.