532 lines
19 KiB
C++
532 lines
19 KiB
C++
// * jdmaster.c
|
|
// *
|
|
// * Copyright (C) 1991-1995, 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 master control logic for the JPEG decompressor.
|
|
// * These routines are concerned with selecting the modules to be executed
|
|
// * and with determining the number of passes and the work to be done in each
|
|
// * pass.
|
|
|
|
|
|
|
|
#define JPEG_INTERNALS
|
|
#include "JINCLUDE.h"
|
|
#include "JPEGLIB.h"
|
|
|
|
|
|
// Private state
|
|
|
|
typedef struct {
|
|
struct jpeg_decomp_master pub; // public fields
|
|
|
|
int pass_number; // # of passes completed
|
|
|
|
boolean using_merged_upsample; // TRUE if using merged upsample/cconvert
|
|
|
|
// Saved references to initialized quantizer modules,
|
|
// * in case we need to switch modes.
|
|
struct jpeg_color_quantizer * quantizer_1pass;
|
|
struct jpeg_color_quantizer * quantizer_2pass;
|
|
} my_decomp_master;
|
|
|
|
typedef my_decomp_master * my_master_ptr;
|
|
|
|
|
|
// * Determine whether merged upsample/color conversion should be used.
|
|
// * CRUCIAL: this must match the actual capabilities of jdmerge.c!
|
|
|
|
LOCAL boolean
|
|
use_merged_upsample (j_decompress_ptr cinfo)
|
|
{
|
|
#ifdef UPSAMPLE_MERGING_SUPPORTED
|
|
// Merging is the equivalent of plain box-filter upsampling
|
|
if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
|
|
return FALSE;
|
|
// jdmerge.c only supports YCC=>RGB color conversion
|
|
if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
|
|
cinfo->out_color_space != JCS_RGB ||
|
|
cinfo->out_color_components != RGB_PIXELSIZE)
|
|
return FALSE;
|
|
// and it only handles 2h1v or 2h2v sampling ratios
|
|
if (cinfo->comp_info[0].h_samp_factor != 2 ||
|
|
cinfo->comp_info[1].h_samp_factor != 1 ||
|
|
cinfo->comp_info[2].h_samp_factor != 1 ||
|
|
cinfo->comp_info[0].v_samp_factor > 2 ||
|
|
cinfo->comp_info[1].v_samp_factor != 1 ||
|
|
cinfo->comp_info[2].v_samp_factor != 1)
|
|
return FALSE;
|
|
// furthermore, it doesn't work if we've scaled the IDCTs differently
|
|
if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
|
|
cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
|
|
cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
|
|
return FALSE;
|
|
// ??? also need to test for upsample-time rescaling, when & if supported
|
|
return TRUE; // by golly, it'll work...
|
|
#else
|
|
return FALSE;
|
|
#endif
|
|
}
|
|
|
|
|
|
// * Compute output image dimensions and related values.
|
|
// * NOTE: this is exported for possible use by application.
|
|
// * Hence it mustn't do anything that can't be done twice.
|
|
// * Also note that it may be called before the master module is initialized!
|
|
|
|
GLOBAL void
|
|
jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
|
|
// Do computations that are needed before master selection phase
|
|
{
|
|
int ci;
|
|
jpeg_component_info *compptr;
|
|
|
|
// Prevent application from calling me at wrong times
|
|
if (cinfo->global_state != DSTATE_READY)
|
|
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
|
|
|
|
#ifdef IDCT_SCALING_SUPPORTED
|
|
|
|
// Compute actual output image dimensions and DCT scaling choices.
|
|
if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
|
|
// Provide 1/8 scaling
|
|
cinfo->output_width = (JDIMENSION)
|
|
jdiv_round_up((LONG) cinfo->image_width, 8L);
|
|
cinfo->output_height = (JDIMENSION)
|
|
jdiv_round_up((LONG) cinfo->image_height, 8L);
|
|
cinfo->min_DCT_scaled_size = 1;
|
|
} else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
|
|
// Provide 1/4 scaling
|
|
cinfo->output_width = (JDIMENSION)
|
|
jdiv_round_up((LONG) cinfo->image_width, 4L);
|
|
cinfo->output_height = (JDIMENSION)
|
|
jdiv_round_up((LONG) cinfo->image_height, 4L);
|
|
cinfo->min_DCT_scaled_size = 2;
|
|
} else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
|
|
// Provide 1/2 scaling
|
|
cinfo->output_width = (JDIMENSION)
|
|
jdiv_round_up((LONG) cinfo->image_width, 2L);
|
|
cinfo->output_height = (JDIMENSION)
|
|
jdiv_round_up((LONG) cinfo->image_height, 2L);
|
|
cinfo->min_DCT_scaled_size = 4;
|
|
} else {
|
|
// Provide 1/1 scaling
|
|
cinfo->output_width = cinfo->image_width;
|
|
cinfo->output_height = cinfo->image_height;
|
|
cinfo->min_DCT_scaled_size = DCTSIZE;
|
|
}
|
|
// In selecting the actual DCT scaling for each component, we try to
|
|
// * scale up the chroma components via IDCT scaling rather than upsampling.
|
|
// * This saves time if the upsampler gets to use 1:1 scaling.
|
|
// * Note this code assumes that the supported DCT scalings are powers of 2.
|
|
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
|
|
ci++, compptr++) {
|
|
int ssize = cinfo->min_DCT_scaled_size;
|
|
while (ssize < DCTSIZE &&
|
|
(compptr->h_samp_factor * ssize * 2 <=
|
|
cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
|
|
(compptr->v_samp_factor * ssize * 2 <=
|
|
cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {
|
|
ssize = ssize * 2;
|
|
}
|
|
compptr->DCT_scaled_size = ssize;
|
|
}
|
|
|
|
// Recompute downsampled dimensions of components;
|
|
// * application needs to know these if using raw downsampled data.
|
|
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
|
|
ci++, compptr++) {
|
|
// Size in samples, after IDCT scaling
|
|
compptr->downsampled_width = (JDIMENSION)
|
|
jdiv_round_up((LONG) cinfo->image_width *
|
|
(LONG) (compptr->h_samp_factor * compptr->DCT_scaled_size),
|
|
(LONG) (cinfo->max_h_samp_factor * DCTSIZE));
|
|
compptr->downsampled_height = (JDIMENSION)
|
|
jdiv_round_up((LONG) cinfo->image_height *
|
|
(LONG) (compptr->v_samp_factor * compptr->DCT_scaled_size),
|
|
(LONG) (cinfo->max_v_samp_factor * DCTSIZE));
|
|
}
|
|
|
|
#else // !IDCT_SCALING_SUPPORTED
|
|
|
|
// Hardwire it to "no scaling"
|
|
cinfo->output_width = cinfo->image_width;
|
|
cinfo->output_height = cinfo->image_height;
|
|
// jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
|
|
// * and has computed unscaled downsampled_width and downsampled_height.
|
|
|
|
#endif // IDCT_SCALING_SUPPORTED
|
|
|
|
// Report number of components in selected colorspace.
|
|
// Probably this should be in the color conversion module...
|
|
switch (cinfo->out_color_space) {
|
|
case JCS_GRAYSCALE:
|
|
cinfo->out_color_components = 1;
|
|
break;
|
|
case JCS_RGB:
|
|
#if RGB_PIXELSIZE != 3
|
|
cinfo->out_color_components = RGB_PIXELSIZE;
|
|
break;
|
|
#endif // else share code with YCbCr
|
|
case JCS_YCbCr:
|
|
cinfo->out_color_components = 3;
|
|
break;
|
|
case JCS_CMYK:
|
|
case JCS_YCCK:
|
|
cinfo->out_color_components = 4;
|
|
break;
|
|
default: // else must be same colorspace as in file
|
|
cinfo->out_color_components = cinfo->num_components;
|
|
break;
|
|
}
|
|
cinfo->output_components = (cinfo->quantize_colors ? 1 :
|
|
cinfo->out_color_components);
|
|
|
|
// See if upsampler will want to emit more than one row at a time
|
|
if (use_merged_upsample(cinfo))
|
|
cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
|
|
else
|
|
cinfo->rec_outbuf_height = 1;
|
|
}
|
|
|
|
|
|
// * Several decompression processes need to range-limit values to the range
|
|
// * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
|
|
// * due to noise introduced by quantization, roundoff error, etc. These
|
|
// * processes are inner loops and need to be as fast as possible. On most
|
|
// * machines, particularly CPUs with pipelines or instruction prefetch,
|
|
// * a (subscript-check-less) C table lookup
|
|
// * x = sample_range_limit[x];
|
|
// * is faster than explicit tests
|
|
// * if (x < 0) x = 0;
|
|
// * else if (x > MAXJSAMPLE) x = MAXJSAMPLE;
|
|
// * These processes all use a common table prepared by the routine below.
|
|
// *
|
|
// * For most steps we can mathematically guarantee that the initial value
|
|
// * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
|
|
// * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial
|
|
// * limiting step (just after the IDCT), a wildly out-of-range value is
|
|
// * possible if the input data is corrupt. To avoid any chance of indexing
|
|
// * off the end of memory and getting a bad-pointer trap, we perform the
|
|
// * post-IDCT limiting thus:
|
|
// * x = range_limit[x & MASK];
|
|
// * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
|
|
// * samples. Under normal circumstances this is more than enough range and
|
|
// * a correct output will be generated; with bogus input data the mask will
|
|
// * cause wraparound, and we will safely generate a bogus-but-in-range output.
|
|
// * For the post-IDCT step, we want to convert the data from signed to unsigned
|
|
// * representation by adding CENTERJSAMPLE at the same time that we limit it.
|
|
// * So the post-IDCT limiting table ends up looking like this:
|
|
// * CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
|
|
// * MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
|
|
// * 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
|
|
// * 0,1,...,CENTERJSAMPLE-1
|
|
// * Negative inputs select values from the upper half of the table after
|
|
// * masking.
|
|
// *
|
|
// * We can save some space by overlapping the start of the post-IDCT table
|
|
// * with the simpler range limiting table. The post-IDCT table begins at
|
|
// * sample_range_limit + CENTERJSAMPLE.
|
|
// *
|
|
// * Note that the table is allocated in near data space on PCs; it's small
|
|
// * enough and used often enough to justify this.
|
|
|
|
LOCAL void
|
|
prepare_range_limit_table (j_decompress_ptr cinfo)
|
|
// Allocate and fill in the sample_range_limit table
|
|
{
|
|
JSAMPLE * table;
|
|
int i;
|
|
|
|
table = (JSAMPLE *)
|
|
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
|
|
(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
|
|
table += (MAXJSAMPLE+1); // allow negative subscripts of simple table
|
|
cinfo->sample_range_limit = table;
|
|
// First segment of "simple" table: limit[x] = 0 for x < 0
|
|
MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
|
|
// Main part of "simple" table: limit[x] = x
|
|
for (i = 0; i <= MAXJSAMPLE; i++)
|
|
table[i] = (JSAMPLE) i;
|
|
table += CENTERJSAMPLE; // Point to where post-IDCT table starts
|
|
// End of simple table, rest of first half of post-IDCT table
|
|
for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
|
|
table[i] = MAXJSAMPLE;
|
|
// Second half of post-IDCT table
|
|
MEMZERO(table + (2 * (MAXJSAMPLE+1)),
|
|
(2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
|
|
MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
|
|
cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
|
|
}
|
|
|
|
|
|
// * Master selection of decompression modules.
|
|
// * This is done once at jpeg_start_decompress time. We determine
|
|
// * which modules will be used and give them appropriate initialization calls.
|
|
// * We also initialize the decompressor input side to begin consuming data.
|
|
// *
|
|
// * Since jpeg_read_header has finished, we know what is in the SOF
|
|
// * and (first) SOS markers. We also have all the application parameter
|
|
// * settings.
|
|
|
|
LOCAL void
|
|
master_selection (j_decompress_ptr cinfo)
|
|
{
|
|
my_master_ptr master = (my_master_ptr) cinfo->master;
|
|
boolean use_c_buffer;
|
|
LONG samplesperrow;
|
|
JDIMENSION jd_samplesperrow;
|
|
|
|
// Initialize dimensions and other stuff
|
|
jpeg_calc_output_dimensions(cinfo);
|
|
prepare_range_limit_table(cinfo);
|
|
|
|
// Width of an output scanline must be representable as JDIMENSION.
|
|
samplesperrow = (LONG) cinfo->output_width * (LONG) cinfo->out_color_components;
|
|
jd_samplesperrow = (JDIMENSION) samplesperrow;
|
|
if ((LONG) jd_samplesperrow != samplesperrow)
|
|
ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
|
|
|
|
// Initialize my private state
|
|
master->pass_number = 0;
|
|
master->using_merged_upsample = use_merged_upsample(cinfo);
|
|
|
|
// Color quantizer selection
|
|
master->quantizer_1pass = NULL;
|
|
master->quantizer_2pass = NULL;
|
|
// No mode changes if not using buffered-image mode.
|
|
if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
|
|
cinfo->enable_1pass_quant = FALSE;
|
|
cinfo->enable_external_quant = FALSE;
|
|
cinfo->enable_2pass_quant = FALSE;
|
|
}
|
|
if (cinfo->quantize_colors) {
|
|
if (cinfo->raw_data_out)
|
|
ERREXIT(cinfo, JERR_NOTIMPL);
|
|
// 2-pass quantizer only works in 3-component color space.
|
|
if (cinfo->out_color_components != 3) {
|
|
cinfo->enable_1pass_quant = TRUE;
|
|
cinfo->enable_external_quant = FALSE;
|
|
cinfo->enable_2pass_quant = FALSE;
|
|
cinfo->colormap = NULL;
|
|
} else if (cinfo->colormap != NULL) {
|
|
cinfo->enable_external_quant = TRUE;
|
|
} else if (cinfo->two_pass_quantize) {
|
|
cinfo->enable_2pass_quant = TRUE;
|
|
} else {
|
|
cinfo->enable_1pass_quant = TRUE;
|
|
}
|
|
|
|
if (cinfo->enable_1pass_quant) {
|
|
#ifdef QUANT_1PASS_SUPPORTED
|
|
jinit_1pass_quantizer(cinfo);
|
|
master->quantizer_1pass = cinfo->cquantize;
|
|
#else
|
|
ERREXIT(cinfo, JERR_NOT_COMPILED);
|
|
#endif
|
|
}
|
|
|
|
// We use the 2-pass code to map to external colormaps.
|
|
if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
|
|
#ifdef QUANT_2PASS_SUPPORTED
|
|
jinit_2pass_quantizer(cinfo);
|
|
master->quantizer_2pass = cinfo->cquantize;
|
|
#else
|
|
ERREXIT(cinfo, JERR_NOT_COMPILED);
|
|
#endif
|
|
}
|
|
// If both quantizers are initialized, the 2-pass one is left active;
|
|
// * this is necessary for starting with quantization to an external map.
|
|
}
|
|
|
|
// Post-processing: in particular, color conversion first
|
|
if (! cinfo->raw_data_out) {
|
|
if (master->using_merged_upsample) {
|
|
#ifdef UPSAMPLE_MERGING_SUPPORTED
|
|
jinit_merged_upsampler(cinfo); // does color conversion too
|
|
#else
|
|
ERREXIT(cinfo, JERR_NOT_COMPILED);
|
|
#endif
|
|
} else {
|
|
jinit_color_deconverter(cinfo);
|
|
jinit_upsampler(cinfo);
|
|
}
|
|
jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
|
|
}
|
|
// Inverse DCT
|
|
jinit_inverse_dct(cinfo);
|
|
// Entropy decoding: either Huffman or arithmetic coding.
|
|
if (cinfo->arith_code) {
|
|
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
|
|
} else {
|
|
if (cinfo->progressive_mode) {
|
|
#ifdef D_PROGRESSIVE_SUPPORTED
|
|
jinit_phuff_decoder(cinfo);
|
|
#else
|
|
ERREXIT(cinfo, JERR_NOT_COMPILED);
|
|
#endif
|
|
} else
|
|
jinit_huff_decoder(cinfo);
|
|
}
|
|
|
|
// Initialize principal buffer controllers.
|
|
use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
|
|
jinit_d_coef_controller(cinfo, use_c_buffer);
|
|
|
|
if (! cinfo->raw_data_out)
|
|
jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
|
|
|
|
// We can now tell the memory manager to allocate virtual arrays.
|
|
(*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
|
|
|
|
// Initialize input side of decompressor to consume first scan.
|
|
(*cinfo->inputctl->start_input_pass) (cinfo);
|
|
|
|
#ifdef D_MULTISCAN_FILES_SUPPORTED
|
|
// If jpeg_start_decompress will read the whole file, initialize
|
|
// * progress monitoring appropriately. The input step is counted
|
|
// * as one pass.
|
|
if (cinfo->progress != NULL && ! cinfo->buffered_image &&
|
|
cinfo->inputctl->has_multiple_scans) {
|
|
int nscans;
|
|
// Estimate number of scans to set pass_limit.
|
|
if (cinfo->progressive_mode) {
|
|
// Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component.
|
|
nscans = 2 + 3 * cinfo->num_components;
|
|
} else {
|
|
// For a nonprogressive multiscan file, estimate 1 scan per component.
|
|
nscans = cinfo->num_components;
|
|
}
|
|
cinfo->progress->pass_counter = 0L;
|
|
cinfo->progress->pass_limit = (LONG) cinfo->total_iMCU_rows * nscans;
|
|
cinfo->progress->completed_passes = 0;
|
|
cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
|
|
// Count the input pass as done
|
|
master->pass_number++;
|
|
}
|
|
#endif // D_MULTISCAN_FILES_SUPPORTED
|
|
}
|
|
|
|
|
|
// * Per-pass setup.
|
|
// * This is called at the beginning of each output pass. We determine which
|
|
// * modules will be active during this pass and give them appropriate
|
|
// * start_pass calls. We also set is_dummy_pass to indicate whether this
|
|
// * is a "real" output pass or a dummy pass for color quantization.
|
|
// * (In the latter case, jdapi.c will crank the pass to completion.)
|
|
|
|
METHODDEF void
|
|
prepare_for_output_pass (j_decompress_ptr cinfo)
|
|
{
|
|
my_master_ptr master = (my_master_ptr) cinfo->master;
|
|
|
|
if (master->pub.is_dummy_pass) {
|
|
#ifdef QUANT_2PASS_SUPPORTED
|
|
// Final pass of 2-pass quantization
|
|
master->pub.is_dummy_pass = FALSE;
|
|
(*cinfo->cquantize->start_pass) (cinfo, FALSE);
|
|
(*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
|
|
(*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
|
|
#else
|
|
ERREXIT(cinfo, JERR_NOT_COMPILED);
|
|
#endif // QUANT_2PASS_SUPPORTED
|
|
} else {
|
|
if (cinfo->quantize_colors && cinfo->colormap == NULL) {
|
|
// Select new quantization method
|
|
if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
|
|
cinfo->cquantize = master->quantizer_2pass;
|
|
master->pub.is_dummy_pass = TRUE;
|
|
} else if (cinfo->enable_1pass_quant) {
|
|
cinfo->cquantize = master->quantizer_1pass;
|
|
} else {
|
|
ERREXIT(cinfo, JERR_MODE_CHANGE);
|
|
}
|
|
}
|
|
(*cinfo->idct->start_pass) (cinfo);
|
|
(*cinfo->coef->start_output_pass) (cinfo);
|
|
if (! cinfo->raw_data_out) {
|
|
if (! master->using_merged_upsample)
|
|
(*cinfo->cconvert->start_pass) (cinfo);
|
|
(*cinfo->upsample->start_pass) (cinfo);
|
|
if (cinfo->quantize_colors)
|
|
(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
|
|
(*cinfo->post->start_pass) (cinfo,
|
|
(master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
|
|
(*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
|
|
}
|
|
}
|
|
|
|
// Set up progress monitor's pass info if present
|
|
if (cinfo->progress != NULL) {
|
|
cinfo->progress->completed_passes = master->pass_number;
|
|
cinfo->progress->total_passes = master->pass_number +
|
|
(master->pub.is_dummy_pass ? 2 : 1);
|
|
// In buffered-image mode, we assume one more output pass if EOI not
|
|
// * yet reached, but no more passes if EOI has been reached.
|
|
if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
|
|
cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
// * Finish up at end of an output pass.
|
|
|
|
METHODDEF void
|
|
finish_output_pass (j_decompress_ptr cinfo)
|
|
{
|
|
my_master_ptr master = (my_master_ptr) cinfo->master;
|
|
|
|
if (cinfo->quantize_colors)
|
|
(*cinfo->cquantize->finish_pass) (cinfo);
|
|
master->pass_number++;
|
|
}
|
|
|
|
|
|
#ifdef D_MULTISCAN_FILES_SUPPORTED
|
|
|
|
// * Switch to a new external colormap between output passes.
|
|
|
|
GLOBAL void
|
|
jpeg_new_colormap (j_decompress_ptr cinfo)
|
|
{
|
|
my_master_ptr master = (my_master_ptr) cinfo->master;
|
|
|
|
// Prevent application from calling me at wrong times
|
|
if (cinfo->global_state != DSTATE_BUFIMAGE)
|
|
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
|
|
|
|
if (cinfo->quantize_colors && cinfo->enable_external_quant &&
|
|
cinfo->colormap != NULL) {
|
|
// Select 2-pass quantizer for external colormap use
|
|
cinfo->cquantize = master->quantizer_2pass;
|
|
// Notify quantizer of colormap change
|
|
(*cinfo->cquantize->new_color_map) (cinfo);
|
|
master->pub.is_dummy_pass = FALSE; // just in case
|
|
} else
|
|
ERREXIT(cinfo, JERR_MODE_CHANGE);
|
|
}
|
|
|
|
#endif // D_MULTISCAN_FILES_SUPPORTED
|
|
|
|
|
|
// * Initialize master decompression control and select active modules.
|
|
// * This is performed at the start of jpeg_start_decompress.
|
|
|
|
GLOBAL void
|
|
jinit_master_decompress (j_decompress_ptr cinfo)
|
|
{
|
|
my_master_ptr master;
|
|
|
|
master = (my_master_ptr)
|
|
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
|
|
SIZEOF(my_decomp_master));
|
|
cinfo->master = (struct jpeg_decomp_master *) master;
|
|
master->pub.prepare_for_output_pass = prepare_for_output_pass;
|
|
master->pub.finish_output_pass = finish_output_pass;
|
|
|
|
master->pub.is_dummy_pass = FALSE;
|
|
|
|
master_selection(cinfo);
|
|
}
|