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Save work on streams.

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Michael R Sweet 2021-05-06 16:07:58 -04:00
parent d2a0484d93
commit c61d6ad686
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GPG Key ID: 999559A027815955
4 changed files with 120 additions and 3 deletions
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4
pdfio-object.c
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@ -197,10 +197,12 @@ _pdfioObjLoad(pdfio_obj_t *obj) // I - Object
//
pdfio_stream_t * // O - Stream or `NULL` on error
pdfioObjOpenStream(pdfio_obj_t *obj) // I - Object
pdfioObjOpenStream(pdfio_obj_t *obj, // I - Object
bool decode) // I - Decode/decompress data?
{
// TODO: Implement me
(void)obj;
(void)decode;
return (NULL);
}

2
pdfio-private.h
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@ -224,7 +224,9 @@ extern bool _pdfioFileWrite(pdfio_file_t *pdf, const void *buffer, size_t bytes
extern void _pdfioObjDelete(pdfio_obj_t *obj) PDFIO_INTERNAL;
extern bool _pdfioObjLoad(pdfio_obj_t *obj) PDFIO_INTERNAL;
extern pdfio_stream_t *_pdfioStreamCreate(pdfio_obj_t *obj, pdfio_filter_t compression) PDFIO_INTERNAL;
extern void _pdfioStreamDelete(pdfio_stream_t *st) PDFIO_INTERNAL;
extern pdfio_stream_t *_pdfioStreamOpen(pdfio_obj_t *obj, bool decode) PDFIO_INTERNAL;
extern bool _pdfioStringIsAllocated(pdfio_file_t *pdf, const char *s) PDFIO_INTERNAL;

104
pdfio-stream.c
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@ -27,6 +27,25 @@ pdfioStreamClose(pdfio_stream_t *st) // I - Stream
}
//
// '_pdfioStreamCreate()' - Create a stream for writing.
//
// Note: pdfioObjCreateStream handles writing the object and its dictionary.
//
pdfio_stream_t * // O - Stream or `NULL` on error
_pdfioStreamCreate(
pdfio_obj_t *obj, // I - Object
pdfio_filter_t compression) // I - Compression to apply
{
// TODO: Implement me
(void)obj;
(void)compression;
return (NULL);
}
//
// 'pdfioStreamConsume()' - Consume bytes from the stream.
//
@ -76,6 +95,91 @@ pdfioStreamGetToken(
}
//
// '_pdfioStreamOpen()' - Create a stream for reading.
//
// Note: pdfioObjOpenStream handles loading the object's dictionary and
// getting the start of the stream data.
//
pdfio_stream_t * // O - Stream or `NULL` on error
_pdfioStreamOpen(pdfio_obj_t *obj, // I - Object
bool decode) // I - Decode/decompress the stream?
{
pdfio_stream_t *st; // Stream
// Allocate a new stream object...
if ((st = (pdfio_stream_t *)calloc(1, sizeof(pdfio_stream_t))) == NULL)
{
_pdfioFileError(obj->pdf, "Unable to allocate memory for a stream.");
return (NULL);
}
st->pdf = obj->pdf;
st->obj = obj;
_pdfioFileSeek(st->pdf, obj->stream_offset, SEEK_SET);
if (decode)
{
// Try to decode/decompress the contents of this object...
pdfio_dict_t *dict = pdfioObjGetDict(obj);
// Object dictionary
const char *filter = pdfioDictGetName(dict, "Filter");
// Filter value
if (!filter)
{
// No single filter name, do we have a compound filter?
if (pdfioDictGetArray(dict, "Filter"))
{
// TODO: Implement compound filters...
_pdfioFileError(st->pdf, "Unsupported compound stream filter.");
free(st);
return (NULL);
}
// No filter, read as-is...
st->filter = PDFIO_FILTER_NONE;
}
else if (!strcmp(filter, "FlateDecode"))
{
// Flate compression
int bpc = (int)pdfioDictGetNumber(dict, "BitsPerComponent");
// Bits per component
int colors = (int)pdfioDictGetNumber(dict, "Colors");
// Number of colors
int columns = (int)pdfioDictGetNumber(dict, "Columns");
// Number of columns
int predictor = (int)pdfioDictGetNumber(dict, "Predictor");
// Predictory value, if any
st->filter = PDFIO_FILTER_FLATE;
}
else if (!strcmp(filter, "LZWDecode"))
{
// LZW compression
st->filter = PDFIO_FILTER_LZW;
}
else
{
// Something else we don't support
_pdfioFileError(st->pdf, "Unsupported stream filter '/%s'.", filter);
free(st);
return (NULL);
}
}
else
{
// Just return the stream data as-is...
st->filter = PDFIO_FILTER_NONE;
}
return (st);
}
//
// 'pdfioStreamPeek()' - Peek at data in a stream.
//

13
pdfio.h
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@ -58,7 +58,16 @@ typedef bool (*pdfio_error_cb_t)(pdfio_file_t *pdf, const char *message, void *d
typedef enum pdfio_filter_e // Compression/decompression filters for streams
{
PDFIO_FILTER_NONE, // No filter
PDFIO_FILTER_FLATE // Flate filter
PDFIO_FILTER_ASCIIHEX, // ASCIIHexDecode filter (reading only)
PDFIO_FILTER_ASCII85, // ASCII85Decode filter (reading only)
PDFIO_FILTER_CCITTFAX, // CCITTFaxDecode filter
PDFIO_FILTER_CRYPT, // Encryption filter
PDFIO_FILTER_DCT, // DCTDecode (JPEG) filter
PDFIO_FILTER_FLATE, // FlateDecode filter
PDFIO_FILTER_JBIG2, // JBIG2Decode filter
PDFIO_FILTER_JPX, // JPXDecode filter (reading only)
PDFIO_FILTER_LZW, // LZWDecode filter (reading only)
PDFIO_FILTER_RUNLENGTH, // RunLengthDecode filter (reading only)
} pdfio_filter_t;
typedef struct _pdfio_obj_s pdfio_obj_t;// Numbered object in PDF file
typedef struct pdfio_rect_s // PDF rectangle
@ -157,7 +166,7 @@ extern pdfio_dict_t *pdfioObjGetDict(pdfio_obj_t *obj) PDFIO_PUBLIC;
extern unsigned short pdfioObjGetGeneration(pdfio_obj_t *obj) PDFIO_PUBLIC;
extern size_t pdfioObjGetNumber(pdfio_obj_t *obj) PDFIO_PUBLIC;
extern const char *pdfioObjGetType(pdfio_obj_t *obj) PDFIO_PUBLIC;
extern pdfio_stream_t *pdfioObjOpenStream(pdfio_obj_t *obj) PDFIO_PUBLIC;
extern pdfio_stream_t *pdfioObjOpenStream(pdfio_obj_t *obj, bool decode) PDFIO_PUBLIC;
extern pdfio_obj_t *pdfioPageCopy(pdfio_file_t *pdf, pdfio_obj_t *src) PDFIO_PUBLIC;