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src/Source/LibTIFF4/tif_jpeg.c  view on Meta::CPAN

std_skip_input_data(j_decompress_ptr cinfo, long num_bytes)
{
	JPEGState* sp = (JPEGState*) cinfo;

	if (num_bytes > 0) {
		if ((size_t)num_bytes > sp->src.bytes_in_buffer) {
			/* oops, buffer overrun */
			(void) std_fill_input_buffer(cinfo);
		} else {
			sp->src.next_input_byte += (size_t) num_bytes;
			sp->src.bytes_in_buffer -= (size_t) num_bytes;
		}
	}
}

static void
std_term_source(j_decompress_ptr cinfo)
{
	/* No work necessary here */
	(void) cinfo;
}

static void
TIFFjpeg_data_src(JPEGState* sp, TIFF* tif)
{
	(void) tif;
	sp->cinfo.d.src = &sp->src;
	sp->src.init_source = std_init_source;
	sp->src.fill_input_buffer = std_fill_input_buffer;
	sp->src.skip_input_data = std_skip_input_data;
	sp->src.resync_to_restart = jpeg_resync_to_restart;
	sp->src.term_source = std_term_source;
	sp->src.bytes_in_buffer = 0;		/* for safety */
	sp->src.next_input_byte = NULL;
}

/*
 * Alternate source manager for reading from JPEGTables.
 * We can share all the code except for the init routine.
 */

static void
tables_init_source(j_decompress_ptr cinfo)
{
	JPEGState* sp = (JPEGState*) cinfo;

	sp->src.next_input_byte = (const JOCTET*) sp->jpegtables;
	sp->src.bytes_in_buffer = (size_t) sp->jpegtables_length;
}

static void
TIFFjpeg_tables_src(JPEGState* sp, TIFF* tif)
{
	TIFFjpeg_data_src(sp, tif);
	sp->src.init_source = tables_init_source;
}

/*
 * Allocate downsampled-data buffers needed for downsampled I/O.
 * We use values computed in jpeg_start_compress or jpeg_start_decompress.
 * We use libjpeg's allocator so that buffers will be released automatically
 * when done with strip/tile.
 * This is also a handy place to compute samplesperclump, bytesperline.
 */
static int
alloc_downsampled_buffers(TIFF* tif, jpeg_component_info* comp_info,
			  int num_components)
{
	JPEGState* sp = JState(tif);
	int ci;
	jpeg_component_info* compptr;
	JSAMPARRAY buf;
	int samples_per_clump = 0;

	for (ci = 0, compptr = comp_info; ci < num_components;
	     ci++, compptr++) {
		samples_per_clump += compptr->h_samp_factor *
			compptr->v_samp_factor;
		buf = TIFFjpeg_alloc_sarray(sp, JPOOL_IMAGE,
				compptr->width_in_blocks * DCTSIZE,
				(JDIMENSION) (compptr->v_samp_factor*DCTSIZE));
		if (buf == NULL)
			return (0);
		sp->ds_buffer[ci] = buf;
	}
	sp->samplesperclump = samples_per_clump;
	return (1);
}


/*
 * JPEG Decoding.
 */

#ifdef CHECK_JPEG_YCBCR_SUBSAMPLING

#define JPEG_MARKER_SOF0 0xC0
#define JPEG_MARKER_SOF1 0xC1
#define JPEG_MARKER_SOF2 0xC2
#define JPEG_MARKER_SOF9 0xC9
#define JPEG_MARKER_SOF10 0xCA
#define JPEG_MARKER_DHT 0xC4
#define JPEG_MARKER_SOI 0xD8
#define JPEG_MARKER_SOS 0xDA
#define JPEG_MARKER_DQT 0xDB
#define JPEG_MARKER_DRI 0xDD
#define JPEG_MARKER_APP0 0xE0
#define JPEG_MARKER_COM 0xFE
struct JPEGFixupTagsSubsamplingData
{
	TIFF* tif;
	void* buffer;
	uint32 buffersize;
	uint8* buffercurrentbyte;
	uint32 bufferbytesleft;
	uint64 fileoffset;
	uint64 filebytesleft;
	uint8 filepositioned;
};
static void JPEGFixupTagsSubsampling(TIFF* tif);
static int JPEGFixupTagsSubsamplingSec(struct JPEGFixupTagsSubsamplingData* data);