mirror of
https://github.com/aaronsgiles/JPEGView.git
synced 2024-06-01 03:41:27 +00:00
1 line
8.8 KiB
C
1 line
8.8 KiB
C
|
/*
* jdpostct.c
*
* Copyright (C) 1994, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains the decompression postprocessing controller.
* This controller manages the upsampling, color conversion, and color
* quantization/reduction steps; specifically, it controls the buffering
* between upsample/color conversion and color quantization/reduction.
*
* If no color quantization/reduction is required, then this module has no
* work to do, and it just hands off to the upsample/color conversion code.
* An integrated upsample/convert/quantize process would replace this module
* entirely.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Private buffer controller object */
typedef struct {
struct jpeg_d_post_controller pub; /* public fields */
/* Color quantization source buffer: this holds output data from
* the upsample/color conversion step to be passed to the quantizer.
* For two-pass color quantization, we need a full-image buffer;
* for one-pass operation, a strip buffer is sufficient.
*/
jvirt_sarray_ptr virtual; /* virtual array, or NULL if one-pass */
JSAMPARRAY buffer; /* strip buffer, or current strip of virtual */
JDIMENSION strip_height; /* buffer size in rows */
/* for two-pass mode only: */
JDIMENSION starting_row; /* row # of first row in current strip */
JDIMENSION next_row; /* index of next row to fill/empty in strip */
} my_post_controller;
typedef my_post_controller * my_post_ptr;
/* Forward declarations */
METHODDEF void post_process_1pass
JPP((j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
JDIMENSION in_row_groups_avail,
JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
JDIMENSION out_rows_avail));
#ifdef QUANT_2PASS_SUPPORTED
METHODDEF void post_process_prepass
JPP((j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
JDIMENSION in_row_groups_avail,
JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
JDIMENSION out_rows_avail));
METHODDEF void post_process_2pass
JPP((j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
JDIMENSION in_row_groups_avail,
JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
JDIMENSION out_rows_avail));
#endif
/*
* Initialize for a processing pass.
*/
METHODDEF void
start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
{
my_post_ptr post = (my_post_ptr) cinfo->post;
switch (pass_mode) {
case JBUF_PASS_THRU:
if (cinfo->quantize_colors) {
/* Single-pass processing with color quantization. */
post->pub.post_process_data = post_process_1pass;
} else {
/* For single-pass processing without color quantization,
* I have no work to do; just call the upsampler directly.
*/
post->pub.post_process_data = cinfo->upsample->upsample;
}
break;
#ifdef QUANT_2PASS_SUPPORTED
case JBUF_SAVE_AND_PASS:
/* First pass of 2-pass quantization */
if (post->virtual == NULL)
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
post->pub.post_process_data = post_process_prepass;
break;
case JBUF_CRANK_DEST:
/* Second pass of 2-pass quantization */
if (post->virtual == NULL)
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
post->pub.post_process_data = post_process_2pass;
break;
#endif /* QUANT_2PASS_SUPPORTED */
default:
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
break;
}
post->starting_row = post->next_row = 0;
}
/*
* Process some data in the one-pass (strip buffer) case.
* This is used for color precision reduction as well as one-pass quantization.
*/
METHODDEF void
post_process_1pass (j_decompress_ptr cinfo,
JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
JDIMENSION in_row_groups_avail,
JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
JDIMENSION out_rows_avail)
{
my_post_ptr post = (my_post_ptr) cinfo->post;
JDIMENSION num_rows,
|