tor-browser

jctrans.c (15276B)

---

/*
* jctrans.c
*
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1995-1998, Thomas G. Lane.
* Modified 2000-2009 by Guido Vollbeding.
* libjpeg-turbo Modifications:
* Copyright (C) 2020, 2022, D. R. Commander.
* For conditions of distribution and use, see the accompanying README.ijg
* file.
*
* This file contains library routines for transcoding compression,
* that is, writing raw DCT coefficient arrays to an output JPEG file.
* The routines in jcapimin.c will also be needed by a transcoder.
*/

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jpegapicomp.h"


/* Forward declarations */
LOCAL(void) transencode_master_selection(j_compress_ptr cinfo,
                                        jvirt_barray_ptr *coef_arrays);
LOCAL(void) transencode_coef_controller(j_compress_ptr cinfo,
                                       jvirt_barray_ptr *coef_arrays);


/*
* Compression initialization for writing raw-coefficient data.
* Before calling this, all parameters and a data destination must be set up.
* Call jpeg_finish_compress() to actually write the data.
*
* The number of passed virtual arrays must match cinfo->num_components.
* Note that the virtual arrays need not be filled or even realized at
* the time write_coefficients is called; indeed, if the virtual arrays
* were requested from this compression object's memory manager, they
* typically will be realized during this routine and filled afterwards.
*/

GLOBAL(void)
jpeg_write_coefficients(j_compress_ptr cinfo, jvirt_barray_ptr *coef_arrays)
{
 if (cinfo->master->lossless)
   ERREXIT(cinfo, JERR_NOTIMPL);

 if (cinfo->global_state != CSTATE_START)
   ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 /* Mark all tables to be written */
 jpeg_suppress_tables(cinfo, FALSE);
 /* (Re)initialize error mgr and destination modules */
 (*cinfo->err->reset_error_mgr) ((j_common_ptr)cinfo);
 (*cinfo->dest->init_destination) (cinfo);
 /* Perform master selection of active modules */
 transencode_master_selection(cinfo, coef_arrays);
 /* Wait for jpeg_finish_compress() call */
 cinfo->next_scanline = 0;     /* so jpeg_write_marker works */
 cinfo->global_state = CSTATE_WRCOEFS;
}


/*
* Initialize the compression object with default parameters,
* then copy from the source object all parameters needed for lossless
* transcoding.  Parameters that can be varied without loss (such as
* scan script and Huffman optimization) are left in their default states.
*/

GLOBAL(void)
jpeg_copy_critical_parameters(j_decompress_ptr srcinfo, j_compress_ptr dstinfo)
{
 JQUANT_TBL **qtblptr;
 jpeg_component_info *incomp, *outcomp;
 JQUANT_TBL *c_quant, *slot_quant;
 int tblno, ci, coefi;

 if (srcinfo->master->lossless)
   ERREXIT(dstinfo, JERR_NOTIMPL);

 /* Safety check to ensure start_compress not called yet. */
 if (dstinfo->global_state != CSTATE_START)
   ERREXIT1(dstinfo, JERR_BAD_STATE, dstinfo->global_state);
 /* Copy fundamental image dimensions */
 dstinfo->image_width = srcinfo->image_width;
 dstinfo->image_height = srcinfo->image_height;
 dstinfo->input_components = srcinfo->num_components;
 dstinfo->in_color_space = srcinfo->jpeg_color_space;
#if JPEG_LIB_VERSION >= 70
 dstinfo->jpeg_width = srcinfo->output_width;
 dstinfo->jpeg_height = srcinfo->output_height;
 dstinfo->min_DCT_h_scaled_size = srcinfo->min_DCT_h_scaled_size;
 dstinfo->min_DCT_v_scaled_size = srcinfo->min_DCT_v_scaled_size;
#endif
 /* Initialize all parameters to default values */
 jpeg_set_defaults(dstinfo);
 /* jpeg_set_defaults may choose wrong colorspace, eg YCbCr if input is RGB.
  * Fix it to get the right header markers for the image colorspace.
  */
 jpeg_set_colorspace(dstinfo, srcinfo->jpeg_color_space);
 dstinfo->data_precision = srcinfo->data_precision;
 dstinfo->CCIR601_sampling = srcinfo->CCIR601_sampling;
 /* Copy the source's quantization tables. */
 for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
   if (srcinfo->quant_tbl_ptrs[tblno] != NULL) {
     qtblptr = &dstinfo->quant_tbl_ptrs[tblno];
     if (*qtblptr == NULL)
       *qtblptr = jpeg_alloc_quant_table((j_common_ptr)dstinfo);
     memcpy((*qtblptr)->quantval, srcinfo->quant_tbl_ptrs[tblno]->quantval,
            sizeof((*qtblptr)->quantval));
     (*qtblptr)->sent_table = FALSE;
   }
 }
 /* Copy the source's per-component info.
  * Note we assume jpeg_set_defaults has allocated the dest comp_info array.
  */
 dstinfo->num_components = srcinfo->num_components;
 if (dstinfo->num_components < 1 || dstinfo->num_components > MAX_COMPONENTS)
   ERREXIT2(dstinfo, JERR_COMPONENT_COUNT, dstinfo->num_components,
            MAX_COMPONENTS);
 for (ci = 0, incomp = srcinfo->comp_info, outcomp = dstinfo->comp_info;
      ci < dstinfo->num_components; ci++, incomp++, outcomp++) {
   outcomp->component_id = incomp->component_id;
   outcomp->h_samp_factor = incomp->h_samp_factor;
   outcomp->v_samp_factor = incomp->v_samp_factor;
   outcomp->quant_tbl_no = incomp->quant_tbl_no;
   /* Make sure saved quantization table for component matches the qtable
    * slot.  If not, the input file re-used this qtable slot.
    * IJG encoder currently cannot duplicate this.
    */
   tblno = outcomp->quant_tbl_no;
   if (tblno < 0 || tblno >= NUM_QUANT_TBLS ||
       srcinfo->quant_tbl_ptrs[tblno] == NULL)
     ERREXIT1(dstinfo, JERR_NO_QUANT_TABLE, tblno);
   slot_quant = srcinfo->quant_tbl_ptrs[tblno];
   c_quant = incomp->quant_table;
   if (c_quant != NULL) {
     for (coefi = 0; coefi < DCTSIZE2; coefi++) {
       if (c_quant->quantval[coefi] != slot_quant->quantval[coefi])
         ERREXIT1(dstinfo, JERR_MISMATCHED_QUANT_TABLE, tblno);
     }
   }
   /* Note: we do not copy the source's Huffman table assignments;
    * instead we rely on jpeg_set_colorspace to have made a suitable choice.
    */
 }
 /* Also copy JFIF version and resolution information, if available.
  * Strictly speaking this isn't "critical" info, but it's nearly
  * always appropriate to copy it if available.  In particular,
  * if the application chooses to copy JFIF 1.02 extension markers from
  * the source file, we need to copy the version to make sure we don't
  * emit a file that has 1.02 extensions but a claimed version of 1.01.
  * We will *not*, however, copy version info from mislabeled "2.01" files.
  */
 if (srcinfo->saw_JFIF_marker) {
   if (srcinfo->JFIF_major_version == 1) {
     dstinfo->JFIF_major_version = srcinfo->JFIF_major_version;
     dstinfo->JFIF_minor_version = srcinfo->JFIF_minor_version;
   }
   dstinfo->density_unit = srcinfo->density_unit;
   dstinfo->X_density = srcinfo->X_density;
   dstinfo->Y_density = srcinfo->Y_density;
 }
}


/*
* Master selection of compression modules for transcoding.
* This substitutes for jcinit.c's initialization of the full compressor.
*/

LOCAL(void)
transencode_master_selection(j_compress_ptr cinfo,
                            jvirt_barray_ptr *coef_arrays)
{
 /* Although we don't actually use input_components for transcoding,
  * jcmaster.c's initial_setup will complain if input_components is 0.
  */
 cinfo->input_components = 1;
 /* Initialize master control (includes parameter checking/processing) */
 jinit_c_master_control(cinfo, TRUE /* transcode only */);

 /* Entropy encoding: either Huffman or arithmetic coding. */
 if (cinfo->arith_code) {
#ifdef C_ARITH_CODING_SUPPORTED
   jinit_arith_encoder(cinfo);
#else
   ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
 } else {
   if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED
     jinit_phuff_encoder(cinfo);
#else
     ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
   } else
     jinit_huff_encoder(cinfo);
 }

 /* We need a special coefficient buffer controller. */
 transencode_coef_controller(cinfo, coef_arrays);

 jinit_marker_writer(cinfo);

 /* We can now tell the memory manager to allocate virtual arrays. */
 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);

 /* Write the datastream header (SOI, JFIF) immediately.
  * Frame and scan headers are postponed till later.
  * This lets application insert special markers after the SOI.
  */
 (*cinfo->marker->write_file_header) (cinfo);
}


/*
* The rest of this file is a special implementation of the coefficient
* buffer controller.  This is similar to jccoefct.c, but it handles only
* output from presupplied virtual arrays.  Furthermore, we generate any
* dummy padding blocks on-the-fly rather than expecting them to be present
* in the arrays.
*/

/* Private buffer controller object */

typedef struct {
 struct jpeg_c_coef_controller pub; /* public fields */

 JDIMENSION iMCU_row_num;      /* iMCU row # within image */
 JDIMENSION mcu_ctr;           /* counts MCUs processed in current row */
 int MCU_vert_offset;          /* counts MCU rows within iMCU row */
 int MCU_rows_per_iMCU_row;    /* number of such rows needed */

 /* Virtual block array for each component. */
 jvirt_barray_ptr *whole_image;

 /* Workspace for constructing dummy blocks at right/bottom edges. */
 JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU];
} my_coef_controller;

typedef my_coef_controller *my_coef_ptr;


LOCAL(void)
start_iMCU_row(j_compress_ptr cinfo)
/* Reset within-iMCU-row counters for a new row */
{
 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;

 /* In an interleaved scan, an MCU row is the same as an iMCU row.
  * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
  * But at the bottom of the image, process only what's left.
  */
 if (cinfo->comps_in_scan > 1) {
   coef->MCU_rows_per_iMCU_row = 1;
 } else {
   if (coef->iMCU_row_num < (cinfo->total_iMCU_rows - 1))
     coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
   else
     coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
 }

 coef->mcu_ctr = 0;
 coef->MCU_vert_offset = 0;
}


/*
* Initialize for a processing pass.
*/

METHODDEF(void)
start_pass_coef(j_compress_ptr cinfo, J_BUF_MODE pass_mode)
{
 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;

 if (pass_mode != JBUF_CRANK_DEST)
   ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

 coef->iMCU_row_num = 0;
 start_iMCU_row(cinfo);
}


/*
* Process some data.
* We process the equivalent of one fully interleaved MCU row ("iMCU" row)
* per call, ie, v_samp_factor block rows for each component in the scan.
* The data is obtained from the virtual arrays and fed to the entropy coder.
* Returns TRUE if the iMCU row is completed, FALSE if suspended.
*
* NB: input_buf is ignored; it is likely to be a NULL pointer.
*/

METHODDEF(boolean)
compress_output(j_compress_ptr cinfo, JSAMPIMAGE input_buf)
{
 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
 JDIMENSION MCU_col_num;       /* index of current MCU within row */
 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
 int blkn, ci, xindex, yindex, yoffset, blockcnt;
 JDIMENSION start_col;
 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
 JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
 JBLOCKROW buffer_ptr;
 jpeg_component_info *compptr;

 /* Align the virtual buffers for the components used in this scan. */
 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
   compptr = cinfo->cur_comp_info[ci];
   buffer[ci] = (*cinfo->mem->access_virt_barray)
     ((j_common_ptr)cinfo, coef->whole_image[compptr->component_index],
      coef->iMCU_row_num * compptr->v_samp_factor,
      (JDIMENSION)compptr->v_samp_factor, FALSE);
 }

 /* Loop to process one whole iMCU row */
 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
      yoffset++) {
   for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
        MCU_col_num++) {
     /* Construct list of pointers to DCT blocks belonging to this MCU */
     blkn = 0;                 /* index of current DCT block within MCU */
     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
       compptr = cinfo->cur_comp_info[ci];
       start_col = MCU_col_num * compptr->MCU_width;
       blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width :
                                                 compptr->last_col_width;
       for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
         if (coef->iMCU_row_num < last_iMCU_row ||
             yindex + yoffset < compptr->last_row_height) {
           /* Fill in pointers to real blocks in this row */
           buffer_ptr = buffer[ci][yindex + yoffset] + start_col;
           for (xindex = 0; xindex < blockcnt; xindex++)
             MCU_buffer[blkn++] = buffer_ptr++;
         } else {
           /* At bottom of image, need a whole row of dummy blocks */
           xindex = 0;
         }
         /* Fill in any dummy blocks needed in this row.
          * Dummy blocks are filled in the same way as in jccoefct.c:
          * all zeroes in the AC entries, DC entries equal to previous
          * block's DC value.  The init routine has already zeroed the
          * AC entries, so we need only set the DC entries correctly.
          */
         for (; xindex < compptr->MCU_width; xindex++) {
           MCU_buffer[blkn] = coef->dummy_buffer[blkn];
           MCU_buffer[blkn][0][0] = MCU_buffer[blkn - 1][0][0];
           blkn++;
         }
       }
     }
     /* Try to write the MCU. */
     if (!(*cinfo->entropy->encode_mcu) (cinfo, MCU_buffer)) {
       /* Suspension forced; update state counters and exit */
       coef->MCU_vert_offset = yoffset;
       coef->mcu_ctr = MCU_col_num;
       return FALSE;
     }
   }
   /* Completed an MCU row, but perhaps not an iMCU row */
   coef->mcu_ctr = 0;
 }
 /* Completed the iMCU row, advance counters for next one */
 coef->iMCU_row_num++;
 start_iMCU_row(cinfo);
 return TRUE;
}


METHODDEF(boolean)
compress_output_12(j_compress_ptr cinfo, J12SAMPIMAGE input_buf)
{
 return compress_output(cinfo, (JSAMPIMAGE)input_buf);
}


/*
* Initialize coefficient buffer controller.
*
* Each passed coefficient array must be the right size for that
* coefficient: width_in_blocks wide and height_in_blocks high,
* with unitheight at least v_samp_factor.
*/

LOCAL(void)
transencode_coef_controller(j_compress_ptr cinfo,
                           jvirt_barray_ptr *coef_arrays)
{
 my_coef_ptr coef;
 JBLOCKROW buffer;
 int i;

 coef = (my_coef_ptr)
   (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
                               sizeof(my_coef_controller));
 cinfo->coef = (struct jpeg_c_coef_controller *)coef;
 coef->pub.start_pass = start_pass_coef;
 coef->pub.compress_data = compress_output;
 coef->pub.compress_data_12 = compress_output_12;

 /* Save pointer to virtual arrays */
 coef->whole_image = coef_arrays;

 /* Allocate and pre-zero space for dummy DCT blocks. */
 buffer = (JBLOCKROW)
   (*cinfo->mem->alloc_large) ((j_common_ptr)cinfo, JPOOL_IMAGE,
                               C_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
 jzero_far((void *)buffer, C_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
 for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
   coef->dummy_buffer[i] = buffer + i;
 }
}