src/jcstest.c

/*
 * jcstest.c
 *
 * Copyright (C) 2011, 2025, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 */

/* This program demonstrates how to check for the colorspace extension
   capabilities of libjpeg-turbo at both compile time and run time. */

#include <stdio.h>
#include "jpeglib.h"
#include "jerror.h"
#include <setjmp.h>

#ifndef JCS_EXTENSIONS
#define JCS_EXT_RGB  6
#endif
#if !defined(JCS_EXTENSIONS) || !defined(JCS_ALPHA_EXTENSIONS)
#define JCS_EXT_RGBA  12
#endif

static char lasterror[JMSG_LENGTH_MAX] = "No error";

typedef struct _error_mgr {
  struct jpeg_error_mgr pub;
  jmp_buf jb;
} error_mgr;

static void my_error_exit(j_common_ptr cinfo)
{
  error_mgr *myerr = (error_mgr *)cinfo->err;
  (*cinfo->err->output_message) (cinfo);
  longjmp(myerr->jb, 1);
}

static void my_output_message(j_common_ptr cinfo)
{
  (*cinfo->err->format_message) (cinfo, lasterror);
}

int main(void)
{
  int jcs_valid = -1, jcs_alpha_valid = -1;
  struct jpeg_compress_struct cinfo;
  error_mgr jerr;

  printf("libjpeg-turbo colorspace extensions:\n");
#if JCS_EXTENSIONS
  printf("  Present at compile time\n");
#else
  printf("  Not present at compile time\n");
#endif

  cinfo.err = jpeg_std_error(&jerr.pub);
  jerr.pub.error_exit = my_error_exit;
  jerr.pub.output_message = my_output_message;

  if (setjmp(jerr.jb)) {
    /* this will execute if libjpeg has an error */
    jcs_valid = 0;
    goto done;
  }

  jpeg_create_compress(&cinfo);
  cinfo.input_components = 3;
  jpeg_set_defaults(&cinfo);
  cinfo.in_color_space = JCS_EXT_RGB;
  jpeg_default_colorspace(&cinfo);
  jcs_valid = 1;

done:
  if (jcs_valid)
    printf("  Working properly\n");
  else
    printf("  Not working properly.  Error returned was:\n    %s\n",
           lasterror);

  printf("libjpeg-turbo alpha colorspace extensions:\n");
#if JCS_ALPHA_EXTENSIONS
  printf("  Present at compile time\n");
#else
  printf("  Not present at compile time\n");
#endif

  if (setjmp(jerr.jb)) {
    /* this will execute if libjpeg has an error */
    jcs_alpha_valid = 0;
    goto done2;
  }

  cinfo.in_color_space = JCS_EXT_RGBA;
  jpeg_default_colorspace(&cinfo);
  jcs_alpha_valid = 1;

done2:
  if (jcs_alpha_valid)
    printf("  Working properly\n");
  else
    printf("  Not working properly.  Error returned was:\n    %s\n",
           lasterror);

  jpeg_destroy_compress(&cinfo);
  return 0;
}