LCOV - app.info - media/libjpeg/jcprepct.c

LCOV - code coverage report
| Current view: | directory - media/libjpeg - jcprepct.c (source / functions) |  | Found | Hit | Coverage |
| Test: | app.info | Lines: | 118 | 45 | 38.1 %
| Date: | 2012-06-02 | Functions: | 6 | 3 | 50.0 %

           1                 : /*
           2                 :  * jcprepct.c
           3                 :  *
           4                 :  * Copyright (C) 1994-1996, Thomas G. Lane.
           5                 :  * This file is part of the Independent JPEG Group's software.
           6                 :  * For conditions of distribution and use, see the accompanying README file.
           7                 :  *
           8                 :  * This file contains the compression preprocessing controller.
           9                 :  * This controller manages the color conversion, downsampling,
          10                 :  * and edge expansion steps.
          11                 :  *
          12                 :  * Most of the complexity here is associated with buffering input rows
          13                 :  * as required by the downsampler.  See the comments at the head of
          14                 :  * jcsample.c for the downsampler's needs.
          15                 :  */
          16                 :
          17                 : #define JPEG_INTERNALS
          18                 : #include "jinclude.h"
          19                 : #include "jpeglib.h"
          20                 :
          21                 :
          22                 : /* At present, jcsample.c can request context rows only for smoothing.
          23                 :  * In the future, we might also need context rows for CCIR601 sampling
          24                 :  * or other more-complex downsampling procedures.  The code to support
          25                 :  * context rows should be compiled only if needed.
          26                 :  */
          27                 : #ifdef INPUT_SMOOTHING_SUPPORTED
          28                 : #define CONTEXT_ROWS_SUPPORTED
          29                 : #endif
          30                 :
          31                 :
          32                 : /*
          33                 :  * For the simple (no-context-row) case, we just need to buffer one
          34                 :  * row group's worth of pixels for the downsampling step.  At the bottom of
          35                 :  * the image, we pad to a full row group by replicating the last pixel row.
          36                 :  * The downsampler's last output row is then replicated if needed to pad
          37                 :  * out to a full iMCU row.
          38                 :  *
          39                 :  * When providing context rows, we must buffer three row groups' worth of
          40                 :  * pixels.  Three row groups are physically allocated, but the row pointer
          41                 :  * arrays are made five row groups high, with the extra pointers above and
          42                 :  * below "wrapping around" to point to the last and first real row groups.
          43                 :  * This allows the downsampler to access the proper context rows.
          44                 :  * At the top and bottom of the image, we create dummy context rows by
          45                 :  * copying the first or last real pixel row.  This copying could be avoided
          46                 :  * by pointer hacking as is done in jdmainct.c, but it doesn't seem worth the
          47                 :  * trouble on the compression side.
          48                 :  */
          49                 :
          50                 :
          51                 : /* Private buffer controller object */
          52                 :
          53                 : typedef struct {
          54                 :   struct jpeg_c_prep_controller pub; /* public fields */
          55                 :
          56                 :   /* Downsampling input buffer.  This buffer holds color-converted data
          57                 :    * until we have enough to do a downsample step.
          58                 :    */
          59                 :   JSAMPARRAY color_buf[MAX_COMPONENTS];
          60                 :
          61                 :   JDIMENSION rows_to_go;        /* counts rows remaining in source image */
          62                 :   int next_buf_row;             /* index of next row to store in color_buf */
          63                 :
          64                 : #ifdef CONTEXT_ROWS_SUPPORTED   /* only needed for context case */
          65                 :   int this_row_group;           /* starting row index of group to process */
          66                 :   int next_buf_stop;            /* downsample when we reach this index */
          67                 : #endif
          68                 : } my_prep_controller;
          69                 :
          70                 : typedef my_prep_controller * my_prep_ptr;
          71                 :
          72                 :
          73                 : /*
          74                 :  * Initialize for a processing pass.
          75                 :  */
          76                 :
          77                 : METHODDEF(void)
          78               3 : start_pass_prep (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
          79                 : {
          80               3 :   my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
          81                 :
          82               3 :   if (pass_mode != JBUF_PASS_THRU)
          83               0 :     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
          84                 :
          85                 :   /* Initialize total-height counter for detecting bottom of image */
          86               3 :   prep->rows_to_go = cinfo->image_height;
          87                 :   /* Mark the conversion buffer empty */
          88               3 :   prep->next_buf_row = 0;
          89                 : #ifdef CONTEXT_ROWS_SUPPORTED
          90                 :   /* Preset additional state variables for context mode.
          91                 :    * These aren't used in non-context mode, so we needn't test which mode.
          92                 :    */
          93               3 :   prep->this_row_group = 0;
          94                 :   /* Set next_buf_stop to stop after two row groups have been read in. */
          95               3 :   prep->next_buf_stop = 2 * cinfo->max_v_samp_factor;
          96                 : #endif
          97               3 : }
          98                 :
          99                 :
         100                 : /*
         101                 :  * Expand an image vertically from height input_rows to height output_rows,
         102                 :  * by duplicating the bottom row.
         103                 :  */
         104                 :
         105                 : LOCAL(void)
         106               0 : expand_bottom_edge (JSAMPARRAY image_data, JDIMENSION num_cols,
         107                 :                     int input_rows, int output_rows)
         108                 : {
         109                 :   register int row;
         110                 :
         111               0 :   for (row = input_rows; row < output_rows; row++) {
         112               0 :     jcopy_sample_rows(image_data, input_rows-1, image_data, row,
         113                 :                       1, num_cols);
         114                 :   }
         115               0 : }
         116                 :
         117                 :
         118                 : /*
         119                 :  * Process some data in the simple no-context case.
         120                 :  *
         121                 :  * Preprocessor output data is counted in "row groups".  A row group
         122                 :  * is defined to be v_samp_factor sample rows of each component.
         123                 :  * Downsampling will produce this much data from each max_v_samp_factor
         124                 :  * input rows.
         125                 :  */
         126                 :
         127                 : METHODDEF(void)
         128             159 : pre_process_data (j_compress_ptr cinfo,
         129                 :                   JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
         130                 :                   JDIMENSION in_rows_avail,
         131                 :                   JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr,
         132                 :                   JDIMENSION out_row_groups_avail)
         133                 : {
         134             159 :   my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
         135                 :   int numrows, ci;
         136                 :   JDIMENSION inrows;
         137                 :   jpeg_component_info * compptr;
         138                 :
         139             606 :   while (*in_row_ctr < in_rows_avail &&
         140             144 :          *out_row_group_ctr < out_row_groups_avail) {
         141                 :     /* Do color conversion to fill the conversion buffer. */
         142             144 :     inrows = in_rows_avail - *in_row_ctr;
         143             144 :     numrows = cinfo->max_v_samp_factor - prep->next_buf_row;
         144             144 :     numrows = (int) MIN((JDIMENSION) numrows, inrows);
         145             288 :     (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr,
         146                 :                                        prep->color_buf,
         147             144 :                                        (JDIMENSION) prep->next_buf_row,
         148                 :                                        numrows);
         149             144 :     *in_row_ctr += numrows;
         150             144 :     prep->next_buf_row += numrows;
         151             144 :     prep->rows_to_go -= numrows;
         152                 :     /* If at bottom of image, pad to fill the conversion buffer. */
         153             147 :     if (prep->rows_to_go == 0 &&
         154               3 :         prep->next_buf_row < cinfo->max_v_samp_factor) {
         155               0 :       for (ci = 0; ci < cinfo->num_components; ci++) {
         156               0 :         expand_bottom_edge(prep->color_buf[ci], cinfo->image_width,
         157                 :                            prep->next_buf_row, cinfo->max_v_samp_factor);
         158                 :       }
         159               0 :       prep->next_buf_row = cinfo->max_v_samp_factor;
         160                 :     }
         161                 :     /* If we've filled the conversion buffer, empty it. */
         162             144 :     if (prep->next_buf_row == cinfo->max_v_samp_factor) {
         163             144 :       (*cinfo->downsample->downsample) (cinfo,
         164                 :                                         prep->color_buf, (JDIMENSION) 0,
         165                 :                                         output_buf, *out_row_group_ctr);
         166             144 :       prep->next_buf_row = 0;
         167             144 :       (*out_row_group_ctr)++;
         168                 :     }
         169                 :     /* If at bottom of image, pad the output to a full iMCU height.
         170                 :      * Note we assume the caller is providing a one-iMCU-height output buffer!
         171                 :      */
         172             147 :     if (prep->rows_to_go == 0 &&
         173               3 :         *out_row_group_ctr < out_row_groups_avail) {
         174               0 :       for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
         175               0 :            ci++, compptr++) {
         176               0 :         expand_bottom_edge(output_buf[ci],
         177               0 :                            compptr->width_in_blocks * DCTSIZE,
         178               0 :                            (int) (*out_row_group_ctr * compptr->v_samp_factor),
         179               0 :                            (int) (out_row_groups_avail * compptr->v_samp_factor));
         180                 :       }
         181               0 :       *out_row_group_ctr = out_row_groups_avail;
         182               0 :       break;                    /* can exit outer loop without test */
         183                 :     }
         184                 :   }
         185             159 : }
         186                 :
         187                 :
         188                 : #ifdef CONTEXT_ROWS_SUPPORTED
         189                 :
         190                 : /*
         191                 :  * Process some data in the context case.
         192                 :  */
         193                 :
         194                 : METHODDEF(void)
         195               0 : pre_process_context (j_compress_ptr cinfo,
         196                 :                      JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
         197                 :                      JDIMENSION in_rows_avail,
         198                 :                      JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr,
         199                 :                      JDIMENSION out_row_groups_avail)
         200                 : {
         201               0 :   my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
         202                 :   int numrows, ci;
         203               0 :   int buf_height = cinfo->max_v_samp_factor * 3;
         204                 :   JDIMENSION inrows;
         205                 :
         206               0 :   while (*out_row_group_ctr < out_row_groups_avail) {
         207               0 :     if (*in_row_ctr < in_rows_avail) {
         208                 :       /* Do color conversion to fill the conversion buffer. */
         209               0 :       inrows = in_rows_avail - *in_row_ctr;
         210               0 :       numrows = prep->next_buf_stop - prep->next_buf_row;
         211               0 :       numrows = (int) MIN((JDIMENSION) numrows, inrows);
         212               0 :       (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr,
         213                 :                                          prep->color_buf,
         214               0 :                                          (JDIMENSION) prep->next_buf_row,
         215                 :                                          numrows);
         216                 :       /* Pad at top of image, if first time through */
         217               0 :       if (prep->rows_to_go == cinfo->image_height) {
         218               0 :         for (ci = 0; ci < cinfo->num_components; ci++) {
         219                 :           int row;
         220               0 :           for (row = 1; row <= cinfo->max_v_samp_factor; row++) {
         221               0 :             jcopy_sample_rows(prep->color_buf[ci], 0,
         222                 :                               prep->color_buf[ci], -row,
         223                 :                               1, cinfo->image_width);
         224                 :           }
         225                 :         }
         226                 :       }
         227               0 :       *in_row_ctr += numrows;
         228               0 :       prep->next_buf_row += numrows;
         229               0 :       prep->rows_to_go -= numrows;
         230                 :     } else {
         231                 :       /* Return for more data, unless we are at the bottom of the image. */
         232               0 :       if (prep->rows_to_go != 0)
         233               0 :         break;
         234                 :       /* When at bottom of image, pad to fill the conversion buffer. */
         235               0 :       if (prep->next_buf_row < prep->next_buf_stop) {
         236               0 :         for (ci = 0; ci < cinfo->num_components; ci++) {
         237               0 :           expand_bottom_edge(prep->color_buf[ci], cinfo->image_width,
         238                 :                              prep->next_buf_row, prep->next_buf_stop);
         239                 :         }
         240               0 :         prep->next_buf_row = prep->next_buf_stop;
         241                 :       }
         242                 :     }
         243                 :     /* If we've gotten enough data, downsample a row group. */
         244               0 :     if (prep->next_buf_row == prep->next_buf_stop) {
         245               0 :       (*cinfo->downsample->downsample) (cinfo,
         246                 :                                         prep->color_buf,
         247               0 :                                         (JDIMENSION) prep->this_row_group,
         248                 :                                         output_buf, *out_row_group_ctr);
         249               0 :       (*out_row_group_ctr)++;
         250                 :       /* Advance pointers with wraparound as necessary. */
         251               0 :       prep->this_row_group += cinfo->max_v_samp_factor;
         252               0 :       if (prep->this_row_group >= buf_height)
         253               0 :         prep->this_row_group = 0;
         254               0 :       if (prep->next_buf_row >= buf_height)
         255               0 :         prep->next_buf_row = 0;
         256               0 :       prep->next_buf_stop = prep->next_buf_row + cinfo->max_v_samp_factor;
         257                 :     }
         258                 :   }
         259               0 : }
         260                 :
         261                 :
         262                 : /*
         263                 :  * Create the wrapped-around downsampling input buffer needed for context mode.
         264                 :  */
         265                 :
         266                 : LOCAL(void)
         267               0 : create_context_buffer (j_compress_ptr cinfo)
         268                 : {
         269               0 :   my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
         270               0 :   int rgroup_height = cinfo->max_v_samp_factor;
         271                 :   int ci, i;
         272                 :   jpeg_component_info * compptr;
         273                 :   JSAMPARRAY true_buffer, fake_buffer;
         274                 :
         275                 :   /* Grab enough space for fake row pointers for all the components;
         276                 :    * we need five row groups' worth of pointers for each component.
         277                 :    */
         278               0 :   fake_buffer = (JSAMPARRAY)
         279               0 :     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
         280               0 :                                 (cinfo->num_components * 5 * rgroup_height) *
         281                 :                                 SIZEOF(JSAMPROW));
         282                 :
         283               0 :   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
         284               0 :        ci++, compptr++) {
         285                 :     /* Allocate the actual buffer space (3 row groups) for this component.
         286                 :      * We make the buffer wide enough to allow the downsampler to edge-expand
         287                 :      * horizontally within the buffer, if it so chooses.
         288                 :      */
         289               0 :     true_buffer = (*cinfo->mem->alloc_sarray)
         290               0 :       ((j_common_ptr) cinfo, JPOOL_IMAGE,
         291               0 :        (JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE *
         292               0 :                       cinfo->max_h_samp_factor) / compptr->h_samp_factor),
         293               0 :        (JDIMENSION) (3 * rgroup_height));
         294                 :     /* Copy true buffer row pointers into the middle of the fake row array */
         295               0 :     MEMCOPY(fake_buffer + rgroup_height, true_buffer,
         296                 :             3 * rgroup_height * SIZEOF(JSAMPROW));
         297                 :     /* Fill in the above and below wraparound pointers */
         298               0 :     for (i = 0; i < rgroup_height; i++) {
         299               0 :       fake_buffer[i] = true_buffer[2 * rgroup_height + i];
         300               0 :       fake_buffer[4 * rgroup_height + i] = true_buffer[i];
         301                 :     }
         302               0 :     prep->color_buf[ci] = fake_buffer + rgroup_height;
         303               0 :     fake_buffer += 5 * rgroup_height; /* point to space for next component */
         304                 :   }
         305               0 : }
         306                 :
         307                 : #endif /* CONTEXT_ROWS_SUPPORTED */
         308                 :
         309                 :
         310                 : /*
         311                 :  * Initialize preprocessing controller.
         312                 :  */
         313                 :
         314                 : GLOBAL(void)
         315               3 : jinit_c_prep_controller (j_compress_ptr cinfo, boolean need_full_buffer)
         316                 : {
         317                 :   my_prep_ptr prep;
         318                 :   int ci;
         319                 :   jpeg_component_info * compptr;
         320                 :
         321               3 :   if (need_full_buffer)         /* safety check */
         322               0 :     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
         323                 :
         324               3 :   prep = (my_prep_ptr)
         325               3 :     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
         326                 :                                 SIZEOF(my_prep_controller));
         327               3 :   cinfo->prep = (struct jpeg_c_prep_controller *) prep;
         328               3 :   prep->pub.start_pass = start_pass_prep;
         329                 :
         330                 :   /* Allocate the color conversion buffer.
         331                 :    * We make the buffer wide enough to allow the downsampler to edge-expand
         332                 :    * horizontally within the buffer, if it so chooses.
         333                 :    */
         334               3 :   if (cinfo->downsample->need_context_rows) {
         335                 :     /* Set up to provide context rows */
         336                 : #ifdef CONTEXT_ROWS_SUPPORTED
         337               0 :     prep->pub.pre_process_data = pre_process_context;
         338               0 :     create_context_buffer(cinfo);
         339                 : #else
         340                 :     ERREXIT(cinfo, JERR_NOT_COMPILED);
         341                 : #endif
         342                 :   } else {
         343                 :     /* No context, just make it tall enough for one row group */
         344               3 :     prep->pub.pre_process_data = pre_process_data;
         345              15 :     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
         346               9 :          ci++, compptr++) {
         347              18 :       prep->color_buf[ci] = (*cinfo->mem->alloc_sarray)
         348              27 :         ((j_common_ptr) cinfo, JPOOL_IMAGE,
         349              18 :          (JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE *
         350              18 :                         cinfo->max_h_samp_factor) / compptr->h_samp_factor),
         351               9 :          (JDIMENSION) cinfo->max_v_samp_factor);
         352                 :     }
         353                 :   }
         354               3 : }

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