1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/libs/libjpeg/jcprepct.c	Thu Sep 08 06:28:38 2011 +0300
     1.3 @@ -0,0 +1,354 @@
     1.4 +/*
     1.5 + * jcprepct.c
     1.6 + *
     1.7 + * Copyright (C) 1994-1996, Thomas G. Lane.
     1.8 + * This file is part of the Independent JPEG Group's software.
     1.9 + * For conditions of distribution and use, see the accompanying README file.
    1.10 + *
    1.11 + * This file contains the compression preprocessing controller.
    1.12 + * This controller manages the color conversion, downsampling,
    1.13 + * and edge expansion steps.
    1.14 + *
    1.15 + * Most of the complexity here is associated with buffering input rows
    1.16 + * as required by the downsampler.  See the comments at the head of
    1.17 + * jcsample.c for the downsampler's needs.
    1.18 + */
    1.19 +
    1.20 +#define JPEG_INTERNALS
    1.21 +#include "jinclude.h"
    1.22 +#include "jpeglib.h"
    1.23 +
    1.24 +
    1.25 +/* At present, jcsample.c can request context rows only for smoothing.
    1.26 + * In the future, we might also need context rows for CCIR601 sampling
    1.27 + * or other more-complex downsampling procedures.  The code to support
    1.28 + * context rows should be compiled only if needed.
    1.29 + */
    1.30 +#ifdef INPUT_SMOOTHING_SUPPORTED
    1.31 +#define CONTEXT_ROWS_SUPPORTED
    1.32 +#endif
    1.33 +
    1.34 +
    1.35 +/*
    1.36 + * For the simple (no-context-row) case, we just need to buffer one
    1.37 + * row group's worth of pixels for the downsampling step.  At the bottom of
    1.38 + * the image, we pad to a full row group by replicating the last pixel row.
    1.39 + * The downsampler's last output row is then replicated if needed to pad
    1.40 + * out to a full iMCU row.
    1.41 + *
    1.42 + * When providing context rows, we must buffer three row groups' worth of
    1.43 + * pixels.  Three row groups are physically allocated, but the row pointer
    1.44 + * arrays are made five row groups high, with the extra pointers above and
    1.45 + * below "wrapping around" to point to the last and first real row groups.
    1.46 + * This allows the downsampler to access the proper context rows.
    1.47 + * At the top and bottom of the image, we create dummy context rows by
    1.48 + * copying the first or last real pixel row.  This copying could be avoided
    1.49 + * by pointer hacking as is done in jdmainct.c, but it doesn't seem worth the
    1.50 + * trouble on the compression side.
    1.51 + */
    1.52 +
    1.53 +
    1.54 +/* Private buffer controller object */
    1.55 +
    1.56 +typedef struct {
    1.57 +  struct jpeg_c_prep_controller pub; /* public fields */
    1.58 +
    1.59 +  /* Downsampling input buffer.  This buffer holds color-converted data
    1.60 +   * until we have enough to do a downsample step.
    1.61 +   */
    1.62 +  JSAMPARRAY color_buf[MAX_COMPONENTS];
    1.63 +
    1.64 +  JDIMENSION rows_to_go;	/* counts rows remaining in source image */
    1.65 +  int next_buf_row;		/* index of next row to store in color_buf */
    1.66 +
    1.67 +#ifdef CONTEXT_ROWS_SUPPORTED	/* only needed for context case */
    1.68 +  int this_row_group;		/* starting row index of group to process */
    1.69 +  int next_buf_stop;		/* downsample when we reach this index */
    1.70 +#endif
    1.71 +} my_prep_controller;
    1.72 +
    1.73 +typedef my_prep_controller * my_prep_ptr;
    1.74 +
    1.75 +
    1.76 +/*
    1.77 + * Initialize for a processing pass.
    1.78 + */
    1.79 +
    1.80 +METHODDEF(void)
    1.81 +start_pass_prep (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
    1.82 +{
    1.83 +  my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
    1.84 +
    1.85 +  if (pass_mode != JBUF_PASS_THRU)
    1.86 +    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    1.87 +
    1.88 +  /* Initialize total-height counter for detecting bottom of image */
    1.89 +  prep->rows_to_go = cinfo->image_height;
    1.90 +  /* Mark the conversion buffer empty */
    1.91 +  prep->next_buf_row = 0;
    1.92 +#ifdef CONTEXT_ROWS_SUPPORTED
    1.93 +  /* Preset additional state variables for context mode.
    1.94 +   * These aren't used in non-context mode, so we needn't test which mode.
    1.95 +   */
    1.96 +  prep->this_row_group = 0;
    1.97 +  /* Set next_buf_stop to stop after two row groups have been read in. */
    1.98 +  prep->next_buf_stop = 2 * cinfo->max_v_samp_factor;
    1.99 +#endif
   1.100 +}
   1.101 +
   1.102 +
   1.103 +/*
   1.104 + * Expand an image vertically from height input_rows to height output_rows,
   1.105 + * by duplicating the bottom row.
   1.106 + */
   1.107 +
   1.108 +LOCAL(void)
   1.109 +expand_bottom_edge (JSAMPARRAY image_data, JDIMENSION num_cols,
   1.110 +		    int input_rows, int output_rows)
   1.111 +{
   1.112 +  register int row;
   1.113 +
   1.114 +  for (row = input_rows; row < output_rows; row++) {
   1.115 +    jcopy_sample_rows(image_data, input_rows-1, image_data, row,
   1.116 +		      1, num_cols);
   1.117 +  }
   1.118 +}
   1.119 +
   1.120 +
   1.121 +/*
   1.122 + * Process some data in the simple no-context case.
   1.123 + *
   1.124 + * Preprocessor output data is counted in "row groups".  A row group
   1.125 + * is defined to be v_samp_factor sample rows of each component.
   1.126 + * Downsampling will produce this much data from each max_v_samp_factor
   1.127 + * input rows.
   1.128 + */
   1.129 +
   1.130 +METHODDEF(void)
   1.131 +pre_process_data (j_compress_ptr cinfo,
   1.132 +		  JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
   1.133 +		  JDIMENSION in_rows_avail,
   1.134 +		  JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr,
   1.135 +		  JDIMENSION out_row_groups_avail)
   1.136 +{
   1.137 +  my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
   1.138 +  int numrows, ci;
   1.139 +  JDIMENSION inrows;
   1.140 +  jpeg_component_info * compptr;
   1.141 +
   1.142 +  while (*in_row_ctr < in_rows_avail &&
   1.143 +	 *out_row_group_ctr < out_row_groups_avail) {
   1.144 +    /* Do color conversion to fill the conversion buffer. */
   1.145 +    inrows = in_rows_avail - *in_row_ctr;
   1.146 +    numrows = cinfo->max_v_samp_factor - prep->next_buf_row;
   1.147 +    numrows = (int) MIN((JDIMENSION) numrows, inrows);
   1.148 +    (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr,
   1.149 +				       prep->color_buf,
   1.150 +				       (JDIMENSION) prep->next_buf_row,
   1.151 +				       numrows);
   1.152 +    *in_row_ctr += numrows;
   1.153 +    prep->next_buf_row += numrows;
   1.154 +    prep->rows_to_go -= numrows;
   1.155 +    /* If at bottom of image, pad to fill the conversion buffer. */
   1.156 +    if (prep->rows_to_go == 0 &&
   1.157 +	prep->next_buf_row < cinfo->max_v_samp_factor) {
   1.158 +      for (ci = 0; ci < cinfo->num_components; ci++) {
   1.159 +	expand_bottom_edge(prep->color_buf[ci], cinfo->image_width,
   1.160 +			   prep->next_buf_row, cinfo->max_v_samp_factor);
   1.161 +      }
   1.162 +      prep->next_buf_row = cinfo->max_v_samp_factor;
   1.163 +    }
   1.164 +    /* If we've filled the conversion buffer, empty it. */
   1.165 +    if (prep->next_buf_row == cinfo->max_v_samp_factor) {
   1.166 +      (*cinfo->downsample->downsample) (cinfo,
   1.167 +					prep->color_buf, (JDIMENSION) 0,
   1.168 +					output_buf, *out_row_group_ctr);
   1.169 +      prep->next_buf_row = 0;
   1.170 +      (*out_row_group_ctr)++;
   1.171 +    }
   1.172 +    /* If at bottom of image, pad the output to a full iMCU height.
   1.173 +     * Note we assume the caller is providing a one-iMCU-height output buffer!
   1.174 +     */
   1.175 +    if (prep->rows_to_go == 0 &&
   1.176 +	*out_row_group_ctr < out_row_groups_avail) {
   1.177 +      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
   1.178 +	   ci++, compptr++) {
   1.179 +	expand_bottom_edge(output_buf[ci],
   1.180 +			   compptr->width_in_blocks * DCTSIZE,
   1.181 +			   (int) (*out_row_group_ctr * compptr->v_samp_factor),
   1.182 +			   (int) (out_row_groups_avail * compptr->v_samp_factor));
   1.183 +      }
   1.184 +      *out_row_group_ctr = out_row_groups_avail;
   1.185 +      break;			/* can exit outer loop without test */
   1.186 +    }
   1.187 +  }
   1.188 +}
   1.189 +
   1.190 +
   1.191 +#ifdef CONTEXT_ROWS_SUPPORTED
   1.192 +
   1.193 +/*
   1.194 + * Process some data in the context case.
   1.195 + */
   1.196 +
   1.197 +METHODDEF(void)
   1.198 +pre_process_context (j_compress_ptr cinfo,
   1.199 +		     JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
   1.200 +		     JDIMENSION in_rows_avail,
   1.201 +		     JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr,
   1.202 +		     JDIMENSION out_row_groups_avail)
   1.203 +{
   1.204 +  my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
   1.205 +  int numrows, ci;
   1.206 +  int buf_height = cinfo->max_v_samp_factor * 3;
   1.207 +  JDIMENSION inrows;
   1.208 +
   1.209 +  while (*out_row_group_ctr < out_row_groups_avail) {
   1.210 +    if (*in_row_ctr < in_rows_avail) {
   1.211 +      /* Do color conversion to fill the conversion buffer. */
   1.212 +      inrows = in_rows_avail - *in_row_ctr;
   1.213 +      numrows = prep->next_buf_stop - prep->next_buf_row;
   1.214 +      numrows = (int) MIN((JDIMENSION) numrows, inrows);
   1.215 +      (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr,
   1.216 +					 prep->color_buf,
   1.217 +					 (JDIMENSION) prep->next_buf_row,
   1.218 +					 numrows);
   1.219 +      /* Pad at top of image, if first time through */
   1.220 +      if (prep->rows_to_go == cinfo->image_height) {
   1.221 +	for (ci = 0; ci < cinfo->num_components; ci++) {
   1.222 +	  int row;
   1.223 +	  for (row = 1; row <= cinfo->max_v_samp_factor; row++) {
   1.224 +	    jcopy_sample_rows(prep->color_buf[ci], 0,
   1.225 +			      prep->color_buf[ci], -row,
   1.226 +			      1, cinfo->image_width);
   1.227 +	  }
   1.228 +	}
   1.229 +      }
   1.230 +      *in_row_ctr += numrows;
   1.231 +      prep->next_buf_row += numrows;
   1.232 +      prep->rows_to_go -= numrows;
   1.233 +    } else {
   1.234 +      /* Return for more data, unless we are at the bottom of the image. */
   1.235 +      if (prep->rows_to_go != 0)
   1.236 +	break;
   1.237 +      /* When at bottom of image, pad to fill the conversion buffer. */
   1.238 +      if (prep->next_buf_row < prep->next_buf_stop) {
   1.239 +	for (ci = 0; ci < cinfo->num_components; ci++) {
   1.240 +	  expand_bottom_edge(prep->color_buf[ci], cinfo->image_width,
   1.241 +			     prep->next_buf_row, prep->next_buf_stop);
   1.242 +	}
   1.243 +	prep->next_buf_row = prep->next_buf_stop;
   1.244 +      }
   1.245 +    }
   1.246 +    /* If we've gotten enough data, downsample a row group. */
   1.247 +    if (prep->next_buf_row == prep->next_buf_stop) {
   1.248 +      (*cinfo->downsample->downsample) (cinfo,
   1.249 +					prep->color_buf,
   1.250 +					(JDIMENSION) prep->this_row_group,
   1.251 +					output_buf, *out_row_group_ctr);
   1.252 +      (*out_row_group_ctr)++;
   1.253 +      /* Advance pointers with wraparound as necessary. */
   1.254 +      prep->this_row_group += cinfo->max_v_samp_factor;
   1.255 +      if (prep->this_row_group >= buf_height)
   1.256 +	prep->this_row_group = 0;
   1.257 +      if (prep->next_buf_row >= buf_height)
   1.258 +	prep->next_buf_row = 0;
   1.259 +      prep->next_buf_stop = prep->next_buf_row + cinfo->max_v_samp_factor;
   1.260 +    }
   1.261 +  }
   1.262 +}
   1.263 +
   1.264 +
   1.265 +/*
   1.266 + * Create the wrapped-around downsampling input buffer needed for context mode.
   1.267 + */
   1.268 +
   1.269 +LOCAL(void)
   1.270 +create_context_buffer (j_compress_ptr cinfo)
   1.271 +{
   1.272 +  my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
   1.273 +  int rgroup_height = cinfo->max_v_samp_factor;
   1.274 +  int ci, i;
   1.275 +  jpeg_component_info * compptr;
   1.276 +  JSAMPARRAY true_buffer, fake_buffer;
   1.277 +
   1.278 +  /* Grab enough space for fake row pointers for all the components;
   1.279 +   * we need five row groups' worth of pointers for each component.
   1.280 +   */
   1.281 +  fake_buffer = (JSAMPARRAY)
   1.282 +    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.283 +				(cinfo->num_components * 5 * rgroup_height) *
   1.284 +				SIZEOF(JSAMPROW));
   1.285 +
   1.286 +  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
   1.287 +       ci++, compptr++) {
   1.288 +    /* Allocate the actual buffer space (3 row groups) for this component.
   1.289 +     * We make the buffer wide enough to allow the downsampler to edge-expand
   1.290 +     * horizontally within the buffer, if it so chooses.
   1.291 +     */
   1.292 +    true_buffer = (*cinfo->mem->alloc_sarray)
   1.293 +      ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.294 +       (JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE *
   1.295 +		      cinfo->max_h_samp_factor) / compptr->h_samp_factor),
   1.296 +       (JDIMENSION) (3 * rgroup_height));
   1.297 +    /* Copy true buffer row pointers into the middle of the fake row array */
   1.298 +    MEMCOPY(fake_buffer + rgroup_height, true_buffer,
   1.299 +	    3 * rgroup_height * SIZEOF(JSAMPROW));
   1.300 +    /* Fill in the above and below wraparound pointers */
   1.301 +    for (i = 0; i < rgroup_height; i++) {
   1.302 +      fake_buffer[i] = true_buffer[2 * rgroup_height + i];
   1.303 +      fake_buffer[4 * rgroup_height + i] = true_buffer[i];
   1.304 +    }
   1.305 +    prep->color_buf[ci] = fake_buffer + rgroup_height;
   1.306 +    fake_buffer += 5 * rgroup_height; /* point to space for next component */
   1.307 +  }
   1.308 +}
   1.309 +
   1.310 +#endif /* CONTEXT_ROWS_SUPPORTED */
   1.311 +
   1.312 +
   1.313 +/*
   1.314 + * Initialize preprocessing controller.
   1.315 + */
   1.316 +
   1.317 +GLOBAL(void)
   1.318 +jinit_c_prep_controller (j_compress_ptr cinfo, boolean need_full_buffer)
   1.319 +{
   1.320 +  my_prep_ptr prep;
   1.321 +  int ci;
   1.322 +  jpeg_component_info * compptr;
   1.323 +
   1.324 +  if (need_full_buffer)		/* safety check */
   1.325 +    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
   1.326 +
   1.327 +  prep = (my_prep_ptr)
   1.328 +    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.329 +				SIZEOF(my_prep_controller));
   1.330 +  cinfo->prep = (struct jpeg_c_prep_controller *) prep;
   1.331 +  prep->pub.start_pass = start_pass_prep;
   1.332 +
   1.333 +  /* Allocate the color conversion buffer.
   1.334 +   * We make the buffer wide enough to allow the downsampler to edge-expand
   1.335 +   * horizontally within the buffer, if it so chooses.
   1.336 +   */
   1.337 +  if (cinfo->downsample->need_context_rows) {
   1.338 +    /* Set up to provide context rows */
   1.339 +#ifdef CONTEXT_ROWS_SUPPORTED
   1.340 +    prep->pub.pre_process_data = pre_process_context;
   1.341 +    create_context_buffer(cinfo);
   1.342 +#else
   1.343 +    ERREXIT(cinfo, JERR_NOT_COMPILED);
   1.344 +#endif
   1.345 +  } else {
   1.346 +    /* No context, just make it tall enough for one row group */
   1.347 +    prep->pub.pre_process_data = pre_process_data;
   1.348 +    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
   1.349 +	 ci++, compptr++) {
   1.350 +      prep->color_buf[ci] = (*cinfo->mem->alloc_sarray)
   1.351 +	((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.352 +	 (JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE *
   1.353 +			cinfo->max_h_samp_factor) / compptr->h_samp_factor),
   1.354 +	 (JDIMENSION) cinfo->max_v_samp_factor);
   1.355 +    }
   1.356 +  }
   1.357 +}