www.pudn.com > imgport.rar > jctrans.c, change:2008-11-05,size:14767b


/* 
 * jctrans.c 
 * 
 * Copyright (C) 1995-1998, 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 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" 
 
 
/* Forward declarations */ 
LOCAL(void) transencode_master_selection 
	JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays)); 
LOCAL(void) transencode_coef_controller 
	JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays)); 
 
#if defined(__VISAGECPP__) 
/* Visual Age fixups for multiple declarations */ 
#  define start_pass_coef   start_pass_coef2 /* already in jccoeft.c */ 
#  define compress_output   compress_output2 /* already in jccoeft.c */ 
#endif 
 
 
/* 
 * 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->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; 
 
  /* 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; 
  /* 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); 
      MEMCOPY((*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) { 
    ERREXIT(cinfo, JERR_ARITH_NOTIMPL); 
  } 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; 
} 
 
 
/* 
 * 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; 
 
  /* 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 FAR *) buffer, C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); 
  for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) { 
    coef->dummy_buffer[i] = buffer + i; 
  } 
} 
 
#if defined(__VISAGECPP__) 
#  ifdef start_pass_coef2 
#   undef start_pass_coef2 
#  endif 
#  ifdef compress_output2 
#    undef compress_output2 
#  endif 
#endif