themespec.c

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/***********************************************************************
 Freeciv - Copyright (C) 2005 - The Freeciv Project
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
***********************************************************************/
 
/***********************************************************************
  Functions for handling the themespec files which describe
  the files and contents of themes.
  original author: David Pfitzner <dwp@mso.anu.edu.au>
***********************************************************************/
 
#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif
 
#include <stdio.h>
#include <stdlib.h> /* exit */
#include <string.h>
 
/* utility */
#include "capability.h"
#include "fcintl.h"
#include "log.h"
#include "registry.h"
#include "string_vector.h"
 
/* common */
#include "game.h"
 
/* client */
#include "citydlg_common.h"
#include "client_main.h" /* for client_state() */
 
/* gui-sdl2 */
#include "dialogs.h"
#include "gui_tilespec.h"
#include "mapview.h"
#include "sprite.h"
 
#include "themespec.h"
 
#define THEMESPEC_SDL2_CAPSTR "+Freeciv-sdl2-3.3-themespec-Devel-2023-Jun-07 duplicates_ok"
/*
 * Themespec capabilities acceptable to this program:
 *
 * +Freeciv-3.3-sdl2-themespec  -  basic format for Freeciv versions 3.3.x;
 *                                 required
 *
 * duplicates_ok  -  we can handle existence of duplicate tags
 *                   (lattermost tag which appears is used; themes which
 *                   have duplicates should specify "+duplicates_ok")
 */
 
#define SPEC_SDL2_CAPSTR "+Freeciv-sdl2-3.3-spec-Devel-2023-Jun-10"
/*
 * Individual spec file capabilities acceptable to this program:
 *
 * +Freeciv-3.3-sdl2-spec  -  basic format for Freeciv versions 3.3.x; required
 */
 
#define THEMESPEC_SUFFIX ".themespec"
 
#if 0
/* TODO: may be useful for theme sprites, too */
struct named_sprites {
   ....
};
#endif /* 0 */
 
struct specfile {
  struct sprite *big_sprite;
  char *file_name;
};
 
#define SPECLIST_TAG specfile
#define SPECLIST_TYPE struct specfile
#include "speclist.h"
 
#define specfile_list_iterate(list, pitem) \
    TYPED_LIST_ITERATE(struct specfile, list, pitem)
#define specfile_list_iterate_end  LIST_ITERATE_END
 
/*
 * Information about an individual sprite. All fields except 'sprite' are
 * filled at the time of the scan of the specfile. 'Sprite' is
 * set/cleared on demand in theme_load_sprite/theme_unload_sprite.
 */
struct small_sprite {
  int ref_count;
 
  /* The sprite is in this file. */
  char *file;
 
  /* Or, the sprite is in this file at the location. */
  struct specfile *sf;
  int x, y, width, height;
 
  /* A little more (optional) data. */
  int hot_x, hot_y;
 
  struct sprite *sprite;
};
 
#define SPECLIST_TAG small_sprite
#define SPECLIST_TYPE struct small_sprite
#include "speclist.h"
 
#define small_sprite_list_iterate(list, pitem)                              \
  TYPED_LIST_ITERATE(struct small_sprite, list, pitem)
#define small_sprite_list_iterate_end LIST_ITERATE_END
 
#define SPECHASH_TAG small_sprite
#define SPECHASH_IKEY_TYPE char *
#define SPECHASH_IDATA_TYPE struct small_sprite *
#define SPECHASH_IKEY_VAL genhash_str_val_func
#define SPECHASH_IKEY_COMP genhash_str_comp_func
#define SPECHASH_IKEY_COPY genhash_str_copy_func
#define SPECHASH_IKEY_FREE genhash_str_free_func
#include "spechash.h"
#define small_sprite_hash_iterate(hash, tag_name, pitem)                    \
  TYPED_HASH_ITERATE(const char *, struct small_sprite *, hash,             \
                     tag_name, pitem)
#define small_sprite_hash_iterate_end HASH_ITERATE_END
 
struct theme {
  char name[512];
  int priority;
 
  char *font_filename;
  int default_font_size;
 
  struct specfile_list *specfiles;
  struct small_sprite_list *small_sprites;
 
  /*
   * This hash table maps themespec tags to struct small_sprites.
   */
  struct small_sprite_hash *sprite_hash;
 
/*  struct named_sprites sprites;*/
 
  struct theme_background_system *background_system;
  struct theme_color_system *color_system;
};
 
struct theme *active_theme = NULL;
 
 
/************************************************************************/
const char *theme_get_name(const struct theme *t)
{
  return t->name;
}
 
/************************************************************************/
const char *theme_font_filename(const struct theme *t)
{
  return t->font_filename;
}
 
/************************************************************************/
int theme_default_font_size(const struct theme *t)
{
  return t->default_font_size;
}
 
/************************************************************************/
static struct theme *theme_new(void)
{
  struct theme *t = fc_calloc(1, sizeof(*t));
 
  t->specfiles = specfile_list_new();
  t->small_sprites = small_sprite_list_new();
 
  return t;
}
 
/************************************************************************/
const char **get_theme_list(void)
{
  static const char **themes = NULL;
 
  if (!themes) {
    /* Note: this means you must restart the client after installing a new
       theme. */
    struct strvec *list = fileinfolist(get_data_dirs(), THEMESPEC_SUFFIX);
    int count = 0;
 
    themes = fc_malloc((1 + strvec_size(list)) * sizeof(*themes));
    strvec_iterate(list, file) {
      struct theme *t = theme_read_toplevel(file);
 
      if (t) {
        themes[count++] = fc_strdup(file);
        theme_free(t);
      }
    } strvec_iterate_end;
    themes[count] = NULL;
    strvec_destroy(list);
  }
 
  return themes;
}
 
/************************************************************************/
static char *themespec_fullname(const char *theme_name)
{
  if (theme_name) {
    char fname[strlen(theme_name) + strlen(THEMESPEC_SUFFIX) + 1], *dname;
 
    fc_snprintf(fname, sizeof(fname),
                "%s%s", theme_name, THEMESPEC_SUFFIX);
 
    dname = fname;
 
    if (dname) {
      return fc_strdup(dname);
    }
  }
 
  return NULL;
}
 
/************************************************************************/
static bool check_themespec_capabilities(struct section_file *file,
                                         const char *which,
                                         const char *us_capstr,
                                         const char *filename)
{
  const char *file_capstr = secfile_lookup_str(file, "%s.options", which);
 
  if (NULL == file_capstr) {
    log_debug("\"%s\": %s file doesn't have capability string",
              filename, which);
    return FALSE;
  }
 
  if (!has_capabilities(us_capstr, file_capstr)) {
    log_debug("\"%s\": %s file appears incompatible:", filename, which);
    log_debug("  datafile options: %s", file_capstr);
    log_debug("  supported options: %s", us_capstr);
 
    return FALSE;
  }
 
  if (!has_capabilities(file_capstr, us_capstr)) {
    log_debug("\"%s\": %s file requires option(s)"
              " that client doesn't support:", filename, which);
    log_debug("  datafile options: %s", file_capstr);
    log_debug("  supported options: %s", us_capstr);
 
    return FALSE;
  }
 
  return TRUE;
}
 
/************************************************************************/
static void theme_free_toplevel(struct theme *t)
{
  if (t->font_filename) {
    free(t->font_filename);
    t->font_filename = NULL;
  }
 
  t->default_font_size = 0;
 
  if (t->background_system) {
    theme_background_system_free(t->background_system);
    t->background_system = NULL;
  }
 
  if (t->color_system) {
    theme_color_system_free(t->color_system);
    t->color_system = NULL;
  }
}
 
/************************************************************************/
void theme_free(struct theme *ftheme)
{
  if (ftheme != NULL) {
    theme_free_sprites(ftheme);
    theme_free_toplevel(ftheme);
    specfile_list_destroy(ftheme->specfiles);
    small_sprite_list_destroy(ftheme->small_sprites);
    free(ftheme);
  }
}
 
/************************************************************************/
void themespec_try_read(const char *theme_name)
{
  if (!(active_theme = theme_read_toplevel(theme_name))) {
    struct strvec *list = fileinfolist(get_data_dirs(), THEMESPEC_SUFFIX);
 
    strvec_iterate(list, file) {
      struct theme *t = theme_read_toplevel(file);
 
      if (t) {
        if (active_theme == NULL || t->priority > active_theme->priority) {
          active_theme = t;
        } else {
          theme_free(t);
        }
      }
    } strvec_iterate_end;
    strvec_destroy(list);
 
    if (active_theme == NULL) {
      log_fatal(_("No usable default theme found, aborting!"));
 
      exit(EXIT_FAILURE);
    }
 
    log_verbose("Trying theme \"%s\".", active_theme->name);
  }
 
  /*  sz_strlcpy(GUI_SDL_OPTION(default_theme_name),
                 theme_get_name(theme)); */
}
 
/************************************************************************/
void themespec_reread(const char *new_theme_name)
{
  struct tile *center_tile;
  enum client_states state = client_state();
  const char *name = new_theme_name ? new_theme_name : active_theme->name;
  char theme_name[strlen(name) + 1], old_name[strlen(active_theme->name) + 1];
 
  /* Make local copies since these values may be freed down below */
  sz_strlcpy(theme_name, name);
  sz_strlcpy(old_name, active_theme->name);
 
  log_normal(_("Loading theme \"%s\"."), theme_name);
 
  /* Step 0:  Record old data.
   *
   * We record the current mapcanvas center, etc.
   */
  center_tile = get_center_tile_mapcanvas();
 
  /* Step 1:  Cleanup.
   *
   * We free all old data in preparation for re-reading it.
   */
  theme_free_sprites(active_theme);
  theme_free_toplevel(active_theme);
 
  /* Step 2:  Read.
   *
   * We read in the new theme. This should be pretty straightforward.
   */
  if (!(active_theme = theme_read_toplevel(theme_name))) {
    if (!(active_theme = theme_read_toplevel(old_name))) {
      /* Always fails. */
      fc_assert_exit_msg(NULL != active_theme,
                         "Failed to re-read the currently loaded theme.");
    }
  }
  /* sz_strlcpy(GUI_SDL_OPTION(default_theme_name), theme->name); */
 
  theme_load_sprites(active_theme);
 
  /* Step 3: Setup
   *
   * This is a seriously sticky problem. On startup, we build a hash
   * from all the sprite data. Then, when we connect to a server, the
   * server sends us ruleset data a piece at a time and we use this data
   * to assemble the sprite structures. But if we change while connected
   *  we have to reassemble all of these. This should just involve
   * calling themespec_setup_*** on everything. But how do we tell what
   * "everything" is?
   *
   * The below code just does things straightforwardly, by setting up
   * each possible sprite again. Hopefully it catches everything, and
   * doesn't mess up too badly if we change themes while not connected
   * to a server.
   */
  if (state < C_S_RUNNING) {
    /* The ruleset data is not sent until this point. */
    return;
  }
 
  /* Step 4:  Draw.
   *
   * Do any necessary redraws.
   */
  popdown_all_game_dialogs();
  generate_citydlg_dimensions();
/*  theme_changed();*/
  can_slide = FALSE;
  center_tile_mapcanvas(center_tile);
  /* update_map_canvas_visible() forces a full redraw. Otherwise with fast
   * drawing we might not get one. Of course this is slower. */
  update_map_canvas_visible();
  can_slide = TRUE;
}
 
/************************************************************************/
static struct sprite *load_sdl2_gfx_file(const char *gfx_filename)
{
  const char **gfx_fileexts = gfx_fileextensions(), *gfx_fileext;
  struct sprite *s;
 
  /* Try out all supported file extensions to find one that works. */
  while ((gfx_fileext = *gfx_fileexts++)) {
    const char *real_full_name;
    char full_name[strlen(gfx_filename) + strlen(".")
                   + strlen(gfx_fileext) + 1];
 
    sprintf(full_name, "%s.%s", gfx_filename, gfx_fileext);
    if ((real_full_name = fileinfoname(get_data_dirs(), full_name))) {
      log_debug("trying to load gfx file \"%s\".", real_full_name);
      s = load_gfxfile(real_full_name, FALSE);
      if (s) {
        return s;
      }
    }
  }
 
  log_error("Could not load gfx file \"%s\".", gfx_filename);
 
  return NULL;
}
 
/************************************************************************/
static void theme_ensure_big_sprite(struct specfile *sf)
{
  struct section_file *file;
  const char *gfx_filename;
 
  if (sf->big_sprite) {
    /* Looks like it's already loaded. */
    return;
  }
 
  /* Otherwise load it. The big sprite will sometimes be freed and will have
   * to be reloaded, but most of the time it's just loaded once, the small
   * sprites are extracted, and then it's freed. */
  if (!(file = secfile_load(sf->file_name, TRUE))) {
    log_fatal(_("Could not open '%s':\n%s"), sf->file_name, secfile_error());
    exit(EXIT_FAILURE);
  }
 
  if (!check_themespec_capabilities(file, "spec",
                                    SPEC_SDL2_CAPSTR, sf->file_name)) {
    exit(EXIT_FAILURE);
  }
 
  gfx_filename = secfile_lookup_str(file, "file.gfx");
 
  sf->big_sprite = load_sdl2_gfx_file(gfx_filename);
 
  if (!sf->big_sprite) {
    log_fatal("Could not load gfx file for the spec file \"%s\".",
              sf->file_name);
    exit(EXIT_FAILURE);
  }
 
  /* We don't check unused fields here as most fields are only read
   * at the specs scanning time. */
  /*  secfile_check_unused(file); */
 
  secfile_destroy(file);
}
 
/************************************************************************/
static void scan_specfile(struct theme *t, struct specfile *sf,
                          bool duplicates_ok)
{
  struct section_file *file;
  struct section_list *sections;
  int i;
 
  if (!(file = secfile_load(sf->file_name, TRUE))) {
    log_fatal(_("Could not open '%s':\n%s"), sf->file_name, secfile_error());
    exit(EXIT_FAILURE);
  }
  if (!check_themespec_capabilities(file, "spec",
                                    SPEC_SDL2_CAPSTR, sf->file_name)) {
    exit(EXIT_FAILURE);
  }
 
  /* Currently unused */
  (void) secfile_entry_by_path(file, "info.artists");
 
  /* This isn't used during the scan, only when the gfx is really loaded */
  (void) secfile_entry_by_path(file, "file.gfx");
 
  sections = secfile_sections_by_name_prefix(file, "grid_");
 
  if (NULL != sections) {
    section_list_iterate(sections, psection) {
      int j, k;
      int x_top_left, y_top_left, dx, dy;
      int pixel_border;
      const char *gridname = section_name(psection);
 
      pixel_border = secfile_lookup_int_default(file, 0, "%s.pixel_border",
                                                gridname);
 
      if (!secfile_lookup_int(file, &x_top_left, "%s.x_top_left", gridname)
          || !secfile_lookup_int(file, &y_top_left,
                                 "%s.y_top_left", gridname)
          || !secfile_lookup_int(file, &dx, "%s.dx", gridname)
          || !secfile_lookup_int(file, &dy, "%s.dy", gridname)) {
        log_error("Grid \"%s\" invalid: %s", gridname, secfile_error());
        continue;
      }
 
      j = -1;
      while (NULL != secfile_entry_lookup(file, "%s.tiles%d.tag",
                                          gridname, ++j)) {
        struct small_sprite *ss;
        int row, column;
        int x1, y1;
        const char **tags;
        size_t num_tags;
        int hot_x, hot_y;
 
        if (!secfile_lookup_int(file, &row, "%s.tiles%d.row", gridname, j)
            || !secfile_lookup_int(file, &column,
                                   "%s.tiles%d.column", gridname, j)
            || !(tags = secfile_lookup_str_vec(file, &num_tags,
                                               "%s.tiles%d.tag",
                                               gridname, j))) {
          log_error("Small sprite \"%s.tiles%d\" invalid: %s",
                    gridname, j, secfile_error());
          continue;
        }
        hot_x = secfile_lookup_int_default(file, 0, "%s.tiles%d.hot_x",
                                           gridname, j);
        hot_y = secfile_lookup_int_default(file, 0, "%s.tiles%d.hot_y",
                                           gridname, j);
 
        /* there must be at least 1 because of the while(): */
        fc_assert_action(num_tags > 0, continue);
 
        x1 = x_top_left + (dx + pixel_border) * column;
        y1 = y_top_left + (dy + pixel_border) * row;
 
        ss = fc_malloc(sizeof(*ss));
        ss->ref_count = 0;
        ss->file = NULL;
        ss->x = x1;
        ss->y = y1;
        ss->width = dx;
        ss->height = dy;
        ss->sf = sf;
        ss->sprite = NULL;
        ss->hot_x = hot_x;
        ss->hot_y = hot_y;
 
        small_sprite_list_prepend(t->small_sprites, ss);
 
        if (!duplicates_ok) {
          for (k = 0; k < num_tags; k++) {
            if (!small_sprite_hash_insert(t->sprite_hash, tags[k], ss)) {
              log_error("warning: already have a sprite for \"%s\".",
                        tags[k]);
            }
          }
        } else {
          for (k = 0; k < num_tags; k++) {
            (void) small_sprite_hash_replace(t->sprite_hash, tags[k], ss);
          }
        }
 
        FC_FREE(tags);
      }
    } section_list_iterate_end;
    section_list_destroy(sections);
  }
 
  /* Load "extra" sprites.  Each sprite is one file. */
  i = -1;
  while (NULL != secfile_lookup_str(file, "extra.sprites%d.tag", ++i)) {
    struct small_sprite *ss;
    const char **tags;
    const char *filename;
    size_t num_tags, k;
    int hot_x, hot_y;
 
    if (!(tags = secfile_lookup_str_vec(file, &num_tags,
                                        "extra.sprites%d.tag", i))
        || !(filename = secfile_lookup_str(file,
                                           "extra.sprites%d.file", i))) {
      log_error("Small sprite \"extra.sprites%d\" invalid: %s",
                i, secfile_error());
      continue;
    }
 
    hot_x = secfile_lookup_int_default(file, 0, "extra.sprites%d.hot_x", i);
    hot_y = secfile_lookup_int_default(file, 0, "extra.sprites%d.hot_y", i);
 
    ss = fc_malloc(sizeof(*ss));
    ss->ref_count = 0;
    ss->file = fc_strdup(filename);
    ss->sf = NULL;
    ss->sprite = NULL;
    ss->hot_x = hot_x;
    ss->hot_y = hot_y;
 
    small_sprite_list_prepend(t->small_sprites, ss);
 
    if (!duplicates_ok) {
      for (k = 0; k < num_tags; k++) {
        if (!small_sprite_hash_insert(t->sprite_hash, tags[k], ss)) {
          log_error("warning: already have a sprite for \"%s\".", tags[k]);
        }
      }
    } else {
      for (k = 0; k < num_tags; k++) {
        (void) small_sprite_hash_replace(t->sprite_hash, tags[k], ss);
      }
    }
    FC_FREE(tags);
  }
 
  secfile_check_unused(file);
  secfile_destroy(file);
}
 
/************************************************************************/
char *themespec_gfx_filename(const char *gfx_filename)
{
  const char  *gfx_current_fileext;
  const char **gfx_fileexts = gfx_fileextensions();
 
  while ((gfx_current_fileext = *gfx_fileexts++)) {
    const char *real_full_name;
    char *full_name =
      fc_malloc(strlen(gfx_filename) + strlen(".")
                + strlen(gfx_current_fileext) + 1);
 
    sprintf(full_name, "%s.%s", gfx_filename, gfx_current_fileext);
    real_full_name = fileinfoname(get_data_dirs(), full_name);
    FC_FREE(full_name);
    if (real_full_name) {
      return fc_strdup(real_full_name);
    }
  }
 
  log_fatal("Couldn't find a supported gfx file extension for \"%s\".",
            gfx_filename);
 
  exit(EXIT_FAILURE);
  return NULL;
}
 
/************************************************************************/
struct theme *theme_read_toplevel(const char *theme_name)
{
  struct section_file *file;
  char *fname;
  int i;
  size_t num_spec_files;
  const char **spec_filenames;
  const char *file_capstr;
  bool duplicates_ok;
  struct theme *t = theme_new();
  const char *langname;
  const char *filename, *t_fontname;
  const char *lang;
 
  fname = themespec_fullname(theme_name);
  if (!fname) {
    log_error("Can't find theme \"%s\".", theme_name);
    theme_free(t);
    return NULL;
  }
  log_verbose("themespec file is \"%s\".", fname);
 
  if (!(file = secfile_load(fname, TRUE))) {
    log_error("Could not open '%s':\n%s", fname, secfile_error());
    FC_FREE(fname);
    theme_free(t);
 
    return NULL;
  }
 
  if (!check_themespec_capabilities(file, "themespec",
                                    THEMESPEC_SDL2_CAPSTR, fname)) {
    secfile_destroy(file);
    FC_FREE(fname);
    theme_free(t);
 
    return NULL;
  }
 
  file_capstr = secfile_lookup_str(file, "themespec.options");
  duplicates_ok = has_capabilities("+duplicates_ok", file_capstr);
 
  (void) secfile_entry_by_path(file, "themespec.name"); /* Currently unused */
 
  sz_strlcpy(t->name, theme_name);
  t->priority = secfile_lookup_int_default(file, 0, "themespec.priority");
 
  langname = setup_langname();
 
  t_fontname = NULL;
  for (i = 0;
       (lang = secfile_lookup_str_default(file, NULL, "themespec.fonts%d.langname", i)) != NULL;
       i++) {
    if (langname != NULL && strstr(langname, lang) != NULL) {
      t_fontname = secfile_lookup_str(file, "themespec.fonts%d.font_file", i);
      /* Don't break the loop, but read all the entries to avoid "unused entry" warnings */
    } else {
      (void) secfile_entry_lookup(file, "themespec.fonts%d.font_file", i);
    }
  }
 
  if (t_fontname == NULL) {
    t_fontname = secfile_lookup_str(file, "themespec.default_font_file");
  } else {
    (void) secfile_entry_lookup(file, "themespec.default_font_file");
  }
 
  if ((filename = fileinfoname(get_data_dirs(), t_fontname))) {
    t->font_filename = fc_strdup(filename);
  } else {
    log_fatal("Could not open font: %s", t_fontname);
    secfile_destroy(file);
    FC_FREE(fname);
    theme_free(t);
 
    return NULL;
  }
  log_debug("theme font file %s", t->font_filename);
 
  t->default_font_size = secfile_lookup_int_default(file, 10, "themespec.default_font_size");
  log_debug("theme default font size %d", t->default_font_size);
 
  spec_filenames = secfile_lookup_str_vec(file, &num_spec_files,
                                          "themespec.files");
  if (NULL == spec_filenames || 0 == num_spec_files) {
    log_error("No theme graphics files specified in \"%s\"", fname);
    secfile_destroy(file);
    FC_FREE(fname);
    theme_free(t);
 
    return NULL;
  }
 
  fc_assert(t->sprite_hash == NULL);
  t->sprite_hash = small_sprite_hash_new();
  for (i = 0; i < num_spec_files; i++) {
    struct specfile *sf = fc_malloc(sizeof(*sf));
 
    log_debug("spec file %s", spec_filenames[i]);
 
    sf->big_sprite = NULL;
    filename = fileinfoname(get_data_dirs(), spec_filenames[i]);
    if (!filename) {
      log_error("Can't find spec file \"%s\".", spec_filenames[i]);
      secfile_destroy(file);
      FC_FREE(fname);
      theme_free(t);
 
      return NULL;
    }
    sf->file_name = fc_strdup(filename);
    scan_specfile(t, sf, duplicates_ok);
 
    specfile_list_prepend(t->specfiles, sf);
  }
  FC_FREE(spec_filenames);
 
  t->background_system = theme_background_system_read(file);
  t->color_system = theme_color_system_read(file);
 
  secfile_check_unused(file);
 
  secfile_destroy(file);
  log_verbose("finished reading \"%s\".", fname);
  FC_FREE(fname);
 
  return t;
}
 
/************************************************************************/
static struct sprite *theme_load_sprite(struct theme *t, const char *tag_name)
{
  /* Lookup information about where the sprite is found. */
  struct small_sprite *ss;
 
  log_debug("theme_load_sprite(tag='%s')", tag_name);
  if (!small_sprite_hash_lookup(t->sprite_hash, tag_name, &ss)) {
    return NULL;
  }
 
  fc_assert_ret_val(ss->ref_count >= 0, NULL);
 
  if (!ss->sprite) {
    /* If the sprite hasn't been loaded already, then load it. */
    fc_assert_ret_val(ss->ref_count == 0, NULL);
    if (ss->file) {
      ss->sprite = load_sdl2_gfx_file(ss->file);
      if (!ss->sprite) {
        log_fatal("Couldn't load gfx file \"%s\" for sprite '%s'.",
                  ss->file, tag_name);
        exit(EXIT_FAILURE);
      }
    } else {
      int sf_w, sf_h;
 
      theme_ensure_big_sprite(ss->sf);
      get_sprite_dimensions(ss->sf->big_sprite, &sf_w, &sf_h);
      if (ss->x < 0 || ss->x + ss->width > sf_w
          || ss->y < 0 || ss->y + ss->height > sf_h) {
        log_error("Sprite '%s' in file \"%s\" isn't within the image!",
                  tag_name, ss->sf->file_name);
        return NULL;
      }
      ss->sprite =
        crop_sprite(ss->sf->big_sprite, ss->x, ss->y, ss->width, ss->height,
                    NULL, -1, -1, 1.0, FALSE);
    }
  }
 
  /* Track the reference count so we know when to free the sprite. */
  ss->ref_count++;
 
  return ss->sprite;
}
 
/************************************************************************/
static void theme_unload_sprite(struct theme *t, const char *tag_name)
{
  struct small_sprite *ss;
 
  small_sprite_hash_lookup(t->sprite_hash, tag_name, &ss);
  fc_assert_ret(ss);
  fc_assert_ret(ss->ref_count >= 1);
  fc_assert_ret(ss->sprite);
 
  ss->ref_count--;
 
  if (ss->ref_count == 0) {
    /* Nobody's using the sprite anymore, so we should free it.  We know
     * where to find it if we need it again. */
    log_debug("freeing sprite '%s'.", tag_name);
    free_sprite(ss->sprite);
    ss->sprite = NULL;
  }
}
 
/* Not very safe, but convenient: */
#define SET_SPRITE(field, tag)                                    \
  do {                                                            \
    t->sprites.field = theme_load_sprite(t, tag);                 \
    fc_assert_exit_msg(NULL != t->sprites.field,                  \
                       "Sprite tag '%s' missing.", tag);          \
  } while (FALSE)
 
/* Sets sprites.field to tag or (if tag isn't available) to alt */
#define SET_SPRITE_ALT(field, tag, alt)                                     \
  do {                                                                      \
    t->sprites.field = theme_load_sprite(t, tag);                           \
    if (!t->sprites.field) {                                                \
      t->sprites.field = theme_load_sprite(t, alt);                         \
    }                                                                       \
    fc_assert_exit_msg(NULL != t->sprites.field,                            \
                       "Sprite tag '%s' and alternate '%s' are "            \
                       "both missing.", tag, alt);                          \
  } while (FALSE)
 
/* Sets sprites.field to tag, or NULL if not available */
#define SET_SPRITE_OPT(field, tag) \
  t->sprites.field = theme_load_sprite(t, tag)
 
#define SET_SPRITE_ALT_OPT(field, tag, alt)                                 \
  do {                                                                      \
    t->sprites.field = theme_lookup_sprite_tag_alt(t, LOG_VERBOSE, tag, alt,\
                                                   "sprite", #field);       \
  } while (FALSE)
 
/************************************************************************/
static void theme_lookup_sprite_tags(struct theme *t)
{
  /* the 'sprites' structure is currently not used, for now we call some
   * functions in gui_tilespec.c instead */
 
  tilespec_setup_theme();
  tilespec_setup_city_gfx();
  tilespec_setup_city_icons();
}
 
/************************************************************************/
static void theme_finish_loading_sprites(struct theme *t)
{
  specfile_list_iterate(t->specfiles, sf) {
    if (sf->big_sprite) {
      free_sprite(sf->big_sprite);
      sf->big_sprite = NULL;
    }
  } specfile_list_iterate_end;
}
 
/************************************************************************/
void theme_load_sprites(struct theme *t)
{
  theme_lookup_sprite_tags(t);
  theme_finish_loading_sprites(t);
}
 
/************************************************************************/
struct sprite *theme_lookup_sprite_tag_alt(struct theme *t,
                                           enum log_level level,
                                           const char *tag, const char *alt,
                                           const char *what,
                                           const char *name)
{
  struct sprite *sp;
 
  /* (should get sprite_hash before connection) */
  fc_assert_ret_val_msg(NULL != t->sprite_hash, NULL,
                        "attempt to lookup for %s \"%s\" before "
                        "sprite_hash setup", what, name);
 
  sp = theme_load_sprite(t, tag);
  if (sp) {
    return sp;
  }
 
  sp = theme_load_sprite(t, alt);
  if (sp) {
    log_verbose("Using alternate graphic \"%s\" (instead of \"%s\") "
                "for %s \"%s\".", alt, tag, what, name);
    return sp;
  }
 
  log_base(level, "Don't have graphics tags \"%s\" or \"%s\" for %s \"%s\".",
           tag, alt, what, name);
  if (LOG_FATAL >= level) {
    exit(EXIT_FAILURE);
  }
 
  return NULL;
}
 
#define FULL_TILE_X_OFFSET ((t->normal_tile_width - t->full_tile_width) / 2)
#define FULL_TILE_Y_OFFSET (t->normal_tile_height - t->full_tile_height)
 
#define ADD_SPRITE(s, draw_fog, x_offset, y_offset)                         \
  (fc_assert(s != NULL),                                                    \
   sprs->sprite = s,                                                        \
   sprs->foggable = (draw_fog && t->fogstyle == FOG_AUTO),                  \
   sprs->offset_x = x_offset,                                               \
   sprs->offset_y = y_offset,                                               \
   sprs++)
#define ADD_SPRITE_SIMPLE(s) ADD_SPRITE(s, TRUE, 0, 0)
#define ADD_SPRITE_FULL(s)                                                  \
  ADD_SPRITE(s, TRUE, FULL_TILE_X_OFFSET, FULL_TILE_Y_OFFSET)
 
/************************************************************************/
static void theme_unload_all_sprites(struct theme *t)
{
  if (t->sprite_hash) {
    small_sprite_hash_iterate(t->sprite_hash, tag_name, ss) {
      while (ss->ref_count > 0) {
        theme_unload_sprite(t, tag_name);
      }
    } small_sprite_hash_iterate_end;
  }
}
 
/************************************************************************/
void theme_free_sprites(struct theme *t)
{
  log_debug("theme_free_sprites()");
 
  theme_unload_all_sprites(t);
 
  if (t->sprite_hash) {
    small_sprite_hash_destroy(t->sprite_hash);
    t->sprite_hash = NULL;
  }
 
  small_sprite_list_iterate(t->small_sprites, ss) {
    small_sprite_list_remove(t->small_sprites, ss);
    if (ss->file) {
      FC_FREE(ss->file);
    }
    fc_assert(ss->sprite == NULL);
    FC_FREE(ss);
  } small_sprite_list_iterate_end;
 
  specfile_list_iterate(t->specfiles, sf) {
    specfile_list_remove(t->specfiles, sf);
    FC_FREE(sf->file_name);
    if (sf->big_sprite) {
      free_sprite(sf->big_sprite);
      sf->big_sprite = NULL;
    }
    FC_FREE(sf);
  } specfile_list_iterate_end;
 
#if 0
  /* TODO: may be useful for theme sprites, too */
  sprite_vector_iterate(&t->sprites.****, psprite) {
    free_sprite(*psprite);
  } sprite_vector_iterate_end;
  sprite_vector_free(&t->sprites.****);
#endif /* 0 */
 
  /* the 'sprites' structure is currently not used, for now we call some
   * functions in gui_tilespec.c instead */
 
  tilespec_free_theme();
  tilespec_free_city_gfx();
  tilespec_free_city_icons();
}
 
/************************************************************************/
struct theme_background_system *theme_get_background_system(const struct theme *t)
{
  return t->background_system;
}
 
/************************************************************************/
struct theme_color_system *theme_get_color_system(const struct theme *t)
{
  return t->color_system;
}