modules/gemfont.c

   1 // This file is part of Deark.
   2 // Copyright (C) 2016 Jason Summers
   3 // See the file COPYING for terms of use.
   4
   5 // GEM bitmap font
   6
   7 #include <deark-config.h>
   8 #include <deark-private.h>
   9 DE_DECLARE_MODULE(de_module_gemfont);
  10
  11 typedef struct localctx_struct {
  12         struct de_bitmap_font *font;
  13         i64 face_size;
  14         i64 first_index, last_index;
  15         i64 max_char_cell_width;
  16         i64 char_offset_table_pos;
  17         i64 font_data_pos;
  18         i64 form_width_bytes;
  19         i64 form_height_pixels;
  20         u8 byte_swap_flag;
  21         de_finfo *fi;
  22 } lctx;
  23
  24 static int do_characters(deark *c, lctx *d)
  25 {
  26         i64 i;
  27         i64 row;
  28         i64 n;
  29         struct de_bitmap_font_char *ch;
  30         i64 char_startpos;
  31         u8 *font_data = NULL;
  32         i64 form_nbytes;
  33         int retval = 0;
  34
  35         de_dbg(c, "reading characters");
  36         de_dbg_indent(c, 1);
  37
  38         form_nbytes = d->form_width_bytes * d->form_height_pixels;
  39         if(d->font_data_pos + form_nbytes > c->infile->len) {
  40                 de_err(c, "Font data goes beyond end of file");
  41                 goto done;
  42         }
  43         font_data = de_malloc(c, form_nbytes);
  44         de_read(font_data, d->font_data_pos, form_nbytes);
  45
  46         for(i=0; i<d->font->num_chars; i++) {
  47                 ch = &d->font->char_array[i];
  48                 char_startpos = de_getu16le(d->char_offset_table_pos + 2*i);
  49                 n = de_getu16le(d->char_offset_table_pos + 2*(i+1));
  50                 ch->width = (int)(n - char_startpos);
  51                 ch->height = d->font->nominal_height;
  52                 ch->codepoint_nonunicode = (i32)(d->first_index+i);
  53                 de_dbg2(c, "char[%d] #%d offset=%d width=%d", (int)i, (int)ch->codepoint_nonunicode,
  54                          (int)char_startpos, ch->width);
  55                 if(ch->width<1 || ch->width>d->max_char_cell_width || ch->width>512) continue;
  56
  57                 ch->rowspan = (ch->width+7)/8;
  58                 ch->bitmap = de_malloc(c, ch->height * ch->rowspan);
  59
  60                 for(row=0; row<ch->height; row++) {
  61                         de_copy_bits(font_data + row*d->form_width_bytes, char_startpos,
  62                                 ch->bitmap + row*ch->rowspan, 0, (i64)ch->width);
  63                 }
  64
  65                 if(ch->width > d->font->nominal_width) {
  66                         // Track the maximum character width.
  67                         d->font->nominal_width = ch->width;
  68                 }
  69         }
  70         retval = 1;
  71
  72 done:
  73         de_dbg_indent(c, -1);
  74         de_free(c, font_data);
  75         return retval;
  76 }
  77
  78 static void do_face_name(deark *c, lctx *d)
  79 {
  80         de_ucstring *name = NULL;
  81
  82         name = ucstring_create(c);
  83         dbuf_read_to_ucstring(c->infile, 4, 32, name, DE_CONVFLAG_STOP_AT_NUL,
  84                 DE_ENCODING_ASCII);
  85         de_dbg(c, "face name: \"%s\"", ucstring_getpsz_d(name));
  86         if(!c->filenames_from_file) goto done;
  87
  88         ucstring_strip_trailing_spaces(name);
  89         ucstring_printf(name, DE_ENCODING_LATIN1, "-%d", (int)d->face_size);
  90         d->fi = de_finfo_create(c);
  91         de_finfo_set_name_from_ucstring(c, d->fi, name, 0);
  92
  93 done:
  94         ucstring_destroy(name);
  95 }
  96
  97 static int do_header(deark *c, lctx *d)
  98 {
  99         unsigned int font_flags;
 100         i64 max_char_width;
 101         i64 n;
 102
 103         de_dbg(c, "header at %d", 0);
 104         de_dbg_indent(c, 1);
 105
 106         n = de_getu16le(0);
 107         de_dbg(c, "face ID: %d", (int)n);
 108
 109         d->face_size = de_getu16le(2);
 110         de_dbg(c, "point size: %d", (int)d->face_size);
 111
 112         do_face_name(c, d); // Offset 4-35
 113
 114         d->first_index = de_getu16le(36);
 115         d->last_index = de_getu16le(38);
 116         de_dbg(c, "first char: %d, last char: %d", (int)d->first_index, (int)d->last_index);
 117         d->font->num_chars = d->last_index - d->first_index + 1;
 118
 119         max_char_width = de_getu16le(50);
 120         d->max_char_cell_width = de_getu16le(52);
 121         de_dbg(c, "max char width: %d, max char cell width: %d", (int)max_char_width,
 122                 (int)d->max_char_cell_width);
 123
 124         n = de_getu16le(54);
 125         de_dbg(c, "left offset: %d", (int)n);
 126         n = de_getu16le(56);
 127         de_dbg(c, "right offset: %d", (int)n);
 128
 129         n = de_getu16le(62);
 130         de_dbg(c, "lightening mask: 0x%04x", (unsigned int)n);
 131
 132         font_flags = (unsigned int)de_getu16le(66);
 133         d->byte_swap_flag = (font_flags & 0x04) ? 1 : 0;
 134
 135         de_dbg(c, "byte swap flag: %d", (int)d->byte_swap_flag);
 136         if(d->byte_swap_flag) {
 137                 de_warn(c, "This font uses an unsupported byte-swap option, and might not be "
 138                         "decoded correctly.");
 139         }
 140
 141         n = de_getu32le(68);
 142         de_dbg(c, "horiz. offset table offset: %u", (unsigned int)n);
 143
 144         d->char_offset_table_pos = de_getu32le(72);
 145         d->font_data_pos = de_getu32le(76);
 146         de_dbg(c, "char. offset table offset: %d", (int)d->char_offset_table_pos);
 147         de_dbg(c, "font data offset: %d", (int)d->font_data_pos);
 148
 149         d->form_width_bytes = de_getu16le(80);
 150         d->form_height_pixels = de_getu16le(82);
 151         de_dbg(c, "form width: %d bytes", (int)d->form_width_bytes);
 152         de_dbg(c, "form height: %d pixels", (int)d->form_height_pixels);
 153
 154         de_dbg_indent(c, -1);
 155         return 1;
 156 }
 157
 158 static void de_run_gemfont(deark *c, de_module_params *mparams)
 159 {
 160         lctx *d = NULL;
 161         i64 i;
 162         int saved_indent_level;
 163
 164         de_dbg_indent_save(c, &saved_indent_level);
 165         d = de_malloc(c, sizeof(lctx));
 166         d->font = de_create_bitmap_font(c);
 167         d->font->has_nonunicode_codepoints = 1;
 168
 169         if(!do_header(c, d)) goto done;
 170
 171         d->font->nominal_width = 1; // This will be calculated later
 172         d->font->nominal_height = (int)d->form_height_pixels;
 173         if(d->font->nominal_height<1 || d->font->nominal_height>512) goto done;
 174
 175         if(d->font->num_chars<1) goto done;
 176         d->font->char_array = de_mallocarray(c, d->font->num_chars, sizeof(struct de_bitmap_font_char));
 177
 178         if(!do_characters(c, d)) goto done;
 179
 180         de_font_bitmap_font_to_image(c, d->font, d->fi, 0);
 181
 182 done:
 183         de_dbg_indent_restore(c, saved_indent_level);
 184         if(d->font) {
 185                 if(d->font->char_array) {
 186                         for(i=0; i<d->font->num_chars; i++) {
 187                                 de_free(c, d->font->char_array[i].bitmap);
 188                         }
 189                         de_free(c, d->font->char_array);
 190                 }
 191                 de_destroy_bitmap_font(c, d->font);
 192         }
 193         de_finfo_destroy(c, d->fi);
 194         de_free(c, d);
 195 }
 196
 197 // This is a difficult format to reliably identify.
 198 static int de_identify_gemfont(deark *c)
 199 {
 200         int has_usual_lm;
 201         i64 fdoffs, fwidth, fheight, eofd;
 202
 203         if(!de_input_file_has_ext(c, "fnt") &&
 204                 !de_input_file_has_ext(c, "gft"))
 205         {
 206                 return 0;
 207         }
 208
 209         has_usual_lm = !dbuf_memcmp(c->infile, 62, "UUUU", 4);
 210         fdoffs = de_getu32le(76);
 211         if(fdoffs<88) return 0;
 212         fwidth = de_getu16le(80);
 213         fheight = de_getu16le(82);
 214         if(fwidth<1 || fheight<1) return 0;
 215         eofd = fdoffs + fwidth*fheight; // end of font data
 216         if(eofd > c->infile->len) return 0;
 217         if(eofd==c->infile->len && has_usual_lm) return 100;
 218         if(eofd==c->infile->len) return 70;
 219         if(has_usual_lm) return 25;
 220         return 0;
 221 }
 222
 223 void de_module_gemfont(deark *c, struct deark_module_info *mi)
 224 {
 225         mi->id = "gemfont";
 226         mi->desc = "GEM bitmap font";
 227         mi->run_fn = de_run_gemfont;
 228         mi->identify_fn = de_identify_gemfont;
 229 }