git.sesse.net Git - qscale/blob - libqscale.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <malloc.h>
   4
   5 #include "libqscale.h"
   6
   7 qscale_img *qscale_load_jpeg(const char *filename)
   8 {
   9         FILE *file = fopen(filename, "rb");
  10         qscale_img *img;
  11         if (file == NULL) {
  12                 return NULL;
  13         }
  14
  15         img = qscale_load_jpeg_from_stdio(file);
  16
  17         fclose(file);
  18         return img;
  19 }
  20
  21 qscale_img *qscale_load_jpeg_from_stdio(FILE *file)
  22 {
  23         qscale_img *img = (qscale_img *)malloc(sizeof(qscale_img));
  24         if (img == NULL) {
  25                 return NULL;
  26         }
  27
  28         img->data_y = img->data_cb = img->data_cr = NULL;
  29
  30         /* FIXME: Better error handling here (ie., return NULL). */
  31         struct jpeg_decompress_struct dinfo;
  32         struct jpeg_error_mgr jerr;
  33         dinfo.err = jpeg_std_error(&jerr);
  34         jpeg_create_decompress(&dinfo);
  35         jpeg_stdio_src(&dinfo, stdin);
  36         jpeg_read_header(&dinfo, TRUE);
  37         dinfo.raw_data_out = TRUE;
  38         jpeg_start_decompress(&dinfo);
  39
  40         /* We do not handle anything but YCbCr images (yet?). */
  41         if (dinfo.num_components != 3) {
  42                 qscale_destroy(img);
  43                 return NULL;
  44         }
  45
  46         img->width = dinfo.image_width;
  47         img->height = dinfo.image_height;
  48
  49         img->w0 = dinfo.image_width * dinfo.comp_info[0].h_samp_factor / dinfo.max_h_samp_factor;
  50         img->h0 = dinfo.image_height * dinfo.comp_info[0].v_samp_factor / dinfo.max_v_samp_factor;
  51
  52         img->w1 = dinfo.image_width * dinfo.comp_info[1].h_samp_factor / dinfo.max_h_samp_factor;
  53         img->h1 = dinfo.image_height * dinfo.comp_info[1].v_samp_factor / dinfo.max_v_samp_factor;
  54
  55         img->w2 = dinfo.image_width * dinfo.comp_info[2].h_samp_factor / dinfo.max_h_samp_factor;
  56         img->h2 = dinfo.image_height * dinfo.comp_info[2].v_samp_factor / dinfo.max_v_samp_factor;
  57
  58         img->data_y  = (JSAMPLE*)memalign(16, dinfo.comp_info[0].height_in_blocks * dinfo.comp_info[0].width_in_blocks * DCTSIZE * DCTSIZE);
  59         img->data_cb = (JSAMPLE*)memalign(16, dinfo.comp_info[1].height_in_blocks * dinfo.comp_info[1].width_in_blocks * DCTSIZE * DCTSIZE);
  60         img->data_cr = (JSAMPLE*)memalign(16, dinfo.comp_info[2].height_in_blocks * dinfo.comp_info[2].width_in_blocks * DCTSIZE * DCTSIZE);
  61
  62         if (img->data_y == NULL || img->data_cb == NULL || img->data_cr == NULL) {
  63                 qscale_destroy(img);
  64                 return NULL;
  65         }
  66
  67         int total_lines = 0, blocks = 0;
  68         while (total_lines < dinfo.comp_info[0].height_in_blocks * DCTSIZE) {
  69                 unsigned max_lines = dinfo.max_v_samp_factor * DCTSIZE;
  70
  71                 JSAMPROW y_row_ptrs[max_lines];
  72                 JSAMPROW cb_row_ptrs[max_lines];
  73                 JSAMPROW cr_row_ptrs[max_lines];
  74                 JSAMPROW* ptrs[] = { y_row_ptrs, cb_row_ptrs, cr_row_ptrs };
  75
  76                 int i;
  77                 for (i = 0; i < max_lines; ++i) {
  78                         y_row_ptrs[i]  = img->data_y  + (i+blocks*DCTSIZE*dinfo.comp_info[0].v_samp_factor) * dinfo.comp_info[0].width_in_blocks * DCTSIZE;
  79                         cb_row_ptrs[i] = img->data_cb + (i+blocks*DCTSIZE*dinfo.comp_info[1].v_samp_factor) * dinfo.comp_info[1].width_in_blocks * DCTSIZE;
  80                         cr_row_ptrs[i] = img->data_cr + (i+blocks*DCTSIZE*dinfo.comp_info[2].v_samp_factor) * dinfo.comp_info[2].width_in_blocks * DCTSIZE;
  81                 }
  82
  83                 total_lines += max_lines;
  84                 ++blocks;
  85
  86                 if (jpeg_read_raw_data(&dinfo, ptrs, max_lines) == 0)
  87                         break;
  88         }
  89
  90         jpeg_destroy_decompress(&dinfo);
  91         return img;
  92 }
  93
  94 void qscale_destroy(qscale_img *img)
  95 {
  96         free(img->data_y);
  97         free(img->data_cb);
  98         free(img->data_cr);
  99         free(img);
 100 }