]> git.tdb.fi Git - ttf2png.git/blobdiff - ttf2png.c
Add support for generating distance field textures
[ttf2png.git] / ttf2png.c
index 3685b5a106d9e3f9641051b13df4dfaa8ac5aeb1..a634b2b9def92998add21bd3e7ecfebf077db243 100644 (file)
--- a/ttf2png.c
+++ b/ttf2png.c
@@ -28,34 +28,63 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 typedef struct sImage
 {
        unsigned w, h;
-       char     *data;
+       unsigned char *data;
 } Image;
 
 typedef struct sGlyph
 {
+       unsigned index;
        unsigned code;
-       Image    image;
+       Image image;
        unsigned x, y;
-       int      offset_x;
-       int      offset_y;
-       int      advance;
+       int offset_x;
+       int offset_y;
+       int advance;
 } Glyph;
 
+typedef struct sKerning
+{
+       unsigned left_code;
+       unsigned right_code;
+       int distance;
+} Kerning;
+
 typedef struct sFont
 {
        unsigned size;
-       int      ascent;
-       int      descent;
+       int ascent;
+       int descent;
        unsigned n_glyphs;
-       Glyph    *glyphs;
-       Image    image;
+       Glyph *glyphs;
+       unsigned n_kerning;
+       Kerning *kerning;
+       Image image;
 } Font;
 
+typedef struct sRange
+{
+       unsigned first;
+       unsigned last;
+} Range;
+
+typedef int bool;
+
+void usage(void);
+int convert_numeric_option(char, int);
+void convert_code_point_range(char, Range *);
+unsigned str_to_code_point(const char *, char **);
+void convert_size(char, unsigned *, unsigned *);
+void sort_and_compact_ranges(Range *, unsigned *);
+int range_cmp(const void *, const void *);
 unsigned round_to_pot(unsigned);
-void usage();
-void init_font(Font *, FT_Face, unsigned, unsigned, int);
-void render_grid(Font *, unsigned, unsigned, unsigned, int);
-void render_packed(Font *);
+void *alloc_image_data(size_t, size_t);
+int init_font(Font *, FT_Face, const Range *, unsigned, bool, unsigned);
+int init_glyphs(Font *, FT_Face, const Range *, bool, unsigned);
+int copy_bitmap(const FT_Bitmap *, Image *);
+void propagate_distance(unsigned short *, int);
+int create_distance_field(const FT_Bitmap *, Image *, unsigned, unsigned);
+int render_grid(Font *, unsigned, unsigned, unsigned, bool, bool);
+int render_packed(Font *, unsigned, unsigned, bool);
 int save_defs(const char *, const Font *);
 int save_png(const char *, const Image *, char);
 
@@ -64,23 +93,27 @@ char verbose = 0;
 int main(int argc, char **argv)
 {
        char *fn;
-       int  begin = 0;
-       int  end = 255;
-       int  size = 10;
-       int  cpl = 0;
-       int  cellw = 0;
-       int  cellh = 0;
-       char autohinter = 0;
-       char seq = 0;
-       char alpha = 0;
-       char invert = 0;
-       char pack = 0;
+       Range *ranges = NULL;
+       unsigned n_ranges = 0;
+       unsigned size = 10;
+       unsigned cpl = 0;
+       unsigned cellw = 0;
+       unsigned cellh = 0;
+       bool autohinter = 0;
+       bool seq = 0;
+       bool alpha = 0;
+       bool invert = 0;
+       bool pack = 0;
+       unsigned margin = 0;
+       unsigned padding = 1;
+       bool npot = 0;
+       unsigned distfield = 0;
 
        FT_Library freetype;
-       FT_Face    face;
+       FT_Face face;
 
-       int  err;
-       int  i;
+       int err;
+       int i;
 
        char *out_fn = "font.png";
        char *def_fn = NULL;
@@ -93,63 +126,22 @@ int main(int argc, char **argv)
                return 1;
        }
 
-       while((i = getopt(argc, argv, "r:s:l:c:o:atvh?ed:pi")) != -1)
+       while((i = getopt(argc, argv, "r:s:l:c:o:atvh?ed:pim:n:gf:")) != -1)
        {
-               char *ptr;
-               int  temp;
                switch(i)
                {
                case 'r':
-                       if(!strcmp(optarg, "all"))
-                       {
-                               begin = 0;
-                               end = 0x110000;
-                       }
-                       else
-                       {
-                               if(!isdigit(optarg[0]))
-                                       temp = -1;
-                               else
-                               {
-                                       temp = strtol(optarg, &ptr, 0);
-                                       if(ptr[0]!=',' || !isdigit(ptr[1]))
-                                               temp = -1;
-                               }
-                               if(temp<0)
-                               {
-                                       printf("Not a valid range: %s\n", optarg);
-                                       exit(1);
-                               }
-                               else
-                               {
-                                       begin = temp;
-                                       end = strtol(ptr+1, NULL, 0);
-                               }
-                       }
+                       ranges = (Range *)realloc(ranges, (++n_ranges)*sizeof(Range));
+                       convert_code_point_range('r', &ranges[n_ranges-1]);
                        break;
                case 's':
-                       size = strtol(optarg, NULL, 0);
+                       size = convert_numeric_option('s', 1);
                        break;
                case 'l':
-                       cpl = strtol(optarg, NULL, 0);
+                       cpl = convert_numeric_option('l', 1);
                        break;
                case 'c':
-                       if(!strcmp(optarg, "auto"))
-                       {
-                               cellw = 0;
-                               cellh = 0;
-                       }
-                       else if(!strcmp(optarg, "autorect"))
-                       {
-                               cellw = 0;
-                               cellh = 1;
-                       }
-                       else
-                       {
-                               cellw = strtol(optarg, &ptr, 0);
-                               if(ptr[0]=='x' && isdigit(ptr[1]))
-                                       cellh = strtol(ptr+1, NULL, 0);
-                       }
+                       convert_size('c', &cellw, &cellh);
                        break;
                case 'o':
                        out_fn = optarg;
@@ -179,6 +171,18 @@ int main(int argc, char **argv)
                case 'i':
                        invert = 1;
                        break;
+               case 'm':
+                       margin = convert_numeric_option('m', 0);
+                       break;
+               case 'n':
+                       padding = convert_numeric_option('n', 0);
+                       break;
+               case 'g':
+                       npot = 1;
+                       break;
+               case 'f':
+                       distfield = convert_numeric_option('f', 1);
+                       break;
                }
        }
        if(!strcmp(out_fn, "-"))
@@ -215,32 +219,59 @@ int main(int argc, char **argv)
                printf("Glyphs:    %ld\n", face->num_glyphs);
        }
 
-       err = FT_Set_Pixel_Sizes(face, 0, size);
+       err = FT_Set_Pixel_Sizes(face, 0, (distfield ? size*distfield : size));
        if(err)
        {
                fprintf(stderr, "Couldn't set size\n");
                return 1;
        }
 
+       if(!n_ranges)
+       {
+               ranges = malloc(sizeof(Range));
+               ranges[0].first = 0;
+               ranges[0].last = 255;
+               n_ranges = 1;
+       }
+       else
+               sort_and_compact_ranges(ranges, &n_ranges);
+
        font.size = size;
-       init_font(&font, face, begin, end, autohinter);
+       err = init_font(&font, face, ranges, n_ranges, autohinter, distfield);
+       if(err)
+               return 1;
+
+       if(!font.n_glyphs)
+       {
+               fprintf(stderr, "No glyphs found in the requested range\n");
+               return 1;
+       }
+
        if(pack)
-               render_packed(&font);
+               err = render_packed(&font, margin, padding, npot);
        else
-               render_grid(&font, cellw, cellh, cpl, seq);
-       if(invert)
+               err = render_grid(&font, cellw, cellh, cpl, seq, npot);
+       if(err)
+               return 1;
+
+       if(invert || distfield)
        {
-               for(i=0; i<font.image.w*font.image.h; ++i)
+               for(i=0; (unsigned)i<font.image.w*font.image.h; ++i)
                        font.image.data[i] = 255-font.image.data[i];
        }
-       save_png(out_fn, &font.image, alpha);
+       err = save_png(out_fn, &font.image, (alpha && !distfield));
+       if(err)
+               return 1;
+
        if(def_fn)
                save_defs(def_fn, &font);
 
-       for(i=0; i<font.n_glyphs; ++i)
+       for(i=0; (unsigned)i<font.n_glyphs; ++i)
                free(font.glyphs[i].image.data);
        free(font.glyphs);
+       free(font.kerning);
        free(font.image.data);
+       free(ranges);
 
        FT_Done_Face(face);
        FT_Done_FreeType(freetype);
@@ -248,6 +279,195 @@ int main(int argc, char **argv)
        return 0;
 }
 
+void usage(void)
+{
+       printf("ttf2png 1.1 - True Type Font to PNG converter\n"
+               "Copyright (c) 2004-2018  Mikko Rasa, Mikkosoft Productions\n"
+               "Distributed under the GNU General Public License\n\n");
+
+       printf("Usage: ttf2png [options] <TTF file>\n\n");
+
+       printf("Accepted options (default values in [brackets])\n"
+               "  -r  Range of code points to convert [0,255]\n"
+               "  -s  Font size to use, in pixels [10]\n"
+               "  -l  Number of glyphs to put in one line [auto]\n"
+               "  -c  Glyph cell size, in pixels (grid mode only) [auto]\n"
+               "  -o  Output file name (or - for stdout) [font.png]\n");
+       printf("  -a  Force autohinter\n"
+               "  -t  Render glyphs to alpha channel\n"
+               "  -i  Invert colors of the glyphs\n"
+               "  -v  Increase the level of verbosity\n"
+               "  -e  Use cells in sequence, without gaps (grid mode only)\n"
+               "  -p  Pack the glyphs tightly instead of in a grid\n"
+               "  -m  Margin around image edges (packed mode only) [0]\n"
+               "  -n  Padding between glyphs (packed mode only) [1]\n"
+               "  -g  Allow non-power-of-two result\n"
+               "  -f  Create a distance field texture\n"
+               "  -d  File name for writing glyph definitions\n"
+               "  -h  Print this message\n");
+}
+
+int convert_numeric_option(char opt, int min_value)
+{
+       int value;
+       char *ptr;
+
+       value = strtol(optarg, &ptr, 0);
+       if(value<min_value || *ptr)
+       {
+               printf("Invalid option argument in -%c %s\n", opt, optarg);
+               exit(1);
+       }
+
+       return value;
+}
+
+void convert_code_point_range(char opt, Range *range)
+{
+       int value;
+       char *ptr;
+
+       if(!strcmp(optarg, "all"))
+       {
+               range->first = 0;
+               range->last = 0x10FFFF;
+               return;
+       }
+
+       value = str_to_code_point(optarg, &ptr);
+       if(value>0 && *ptr==',')
+       {
+               range->first = value;
+               value = str_to_code_point(ptr+1, &ptr);
+               if(value>0 && !*ptr)
+               {
+                       range->last = value;
+                       return;
+               }
+       }
+
+       printf("Invalid option argument in -%c %s\n", opt, optarg);
+       exit(1);
+}
+
+unsigned str_to_code_point(const char *nptr, char **endptr)
+{
+       if(nptr[0]=='U' && nptr[1]=='+')
+               return strtoul(nptr+2, endptr, 16);
+       else if(nptr[0]&0x80)
+       {
+               unsigned bytes;
+               unsigned code;
+               unsigned i;
+
+               if(endptr)
+                       *endptr = (char *)nptr;
+
+               for(bytes=1; (bytes<4 && (nptr[0]&(0x80>>bytes))); ++bytes)
+                       if((nptr[bytes]&0xC0)!=0x80)
+                               return 0;
+               if(bytes<2)
+                       return 0;
+
+               code = nptr[0]&(0x3F>>bytes);
+               for(i=1; i<bytes; ++i)
+                       code = (code<<6)|(nptr[i]&0x3F);
+
+               if(endptr)
+                       *endptr = (char *)nptr+bytes;
+
+               return code;
+       }
+       else if(isdigit(nptr[0]))
+               return strtoul(nptr, endptr, 0);
+       else
+       {
+               if(endptr)
+                       *endptr = (char *)nptr+1;
+               return *nptr;
+       }
+}
+
+void convert_size(char opt, unsigned *width, unsigned *height)
+{
+       int value;
+       char *ptr;
+
+       if(!strcmp(optarg, "auto"))
+       {
+               *width = 0;
+               *height = 0;
+               return;
+       }
+       else if(!strcmp(optarg, "autorect"))
+       {
+               *width = 0;
+               *height = 1;
+               return;
+       }
+
+       value = strtol(optarg, &ptr, 0);
+       if(value>0)
+       {
+               *width = value;
+               if(*ptr=='x')
+               {
+                       value = strtol(ptr+1, &ptr, 0);
+                       if(value>0 && !*ptr)
+                       {
+                               *height = value;
+                               return;
+                       }
+               }
+               else if(!*ptr)
+               {
+                       *height = *width;
+                       return;
+               }
+       }
+
+       printf("Invalid option argument in -%c %s\n", opt, optarg);
+       exit(1);
+}
+
+void sort_and_compact_ranges(Range *ranges, unsigned *n_ranges)
+{
+       unsigned i, j;
+
+       if(!*n_ranges)
+               return;
+
+       qsort(ranges, *n_ranges, sizeof(Range), &range_cmp);
+       for(i=0, j=1; j<*n_ranges; ++j)
+       {
+               if(ranges[i].last+1>=ranges[j].first)
+               {
+                       if(ranges[j].last>ranges[i].last)
+                               ranges[i].last = ranges[j].last;
+               }
+               else
+               {
+                       ++i;
+                       if(i!=j)
+                               ranges[i] = ranges[j];
+               }
+       }
+
+       *n_ranges = i+1;
+}
+
+int range_cmp(const void *p1, const void *p2)
+{
+       const Range *r1 = (const Range *)p1;
+       const Range *r2 = (const Range *)p2;
+       if(r1->first!=r2->first)
+               return (r1->first<r2->first ? -1 : 1);
+       else if(r1->last!=r2->last)
+               return (r1->last<r2->last ? -1 : 1);
+       else
+               return 0;
+}
+
 unsigned round_to_pot(unsigned n)
 {
        n -= 1;
@@ -260,35 +480,38 @@ unsigned round_to_pot(unsigned n)
        return n+1;
 }
 
-void usage()
+void *alloc_image_data(size_t a, size_t b)
 {
-       printf("ttf2png - True Type Font to PNG converter\n"
-               "Copyright (c) 2004-2008  Mikko Rasa, Mikkosoft Productions\n"
-               "Distributed under the GNU General Public License\n\n"
-               "Usage: ttf2png [options] <TTF file>\n\n"
-               "Accepted options (default values in [brackets])\n"
-               "  -r  Range of characters to convert in the format low,high [0,255]\n"
-               "  -s  Font size to use, in pixels [10]\n"
-               "  -l  Number of characters to put in one line [auto]\n"
-               "  -c  Character cell size, in pixels [auto]\n"
-               "  -o  Output file name (or - for stdout) [font.png]\n"
-               "  -a  Force autohinter\n"
-               "  -t  Render font to alpha channel\n"
-               "  -i  Invert colors of the glyphs\n"
-               "  -v  Increase the level of verbosity\n"
-               "  -e  Use cells in sequence, rather than by code\n"
-               "  -p  Pack the glyphs tightly instead of in a grid\n"
-               "  -d  Write a definition to the given file\n"
-               "  -h  Print this message\n");
+       void *ptr;
+
+       /* Carry out the multiplication manually so we can check for overflow. */
+       while(b>1)
+       {
+               size_t c = a;
+               a *= 2;
+               if(b&1)
+                       a += c;
+               if(a<c)
+               {
+                       fprintf(stderr, "Cannot allocate %lu kbytes of memory for image\n", (unsigned long)(c/1024*b));
+                       return NULL;
+               }
+               b /= 2;
+       }
+       ptr = malloc(a);
+       if(!ptr)
+               fprintf(stderr, "Cannot allocate %lu kbytes of memory for image\n", (unsigned long)(a/1024*b));
+       return ptr;
 }
 
-void init_font(Font *font, FT_Face face, unsigned first, unsigned last, int autohinter)
+int init_font(Font *font, FT_Face face, const Range *ranges, unsigned n_ranges, bool autohinter, unsigned distfield)
 {
-       unsigned i;
+       unsigned i, j;
        unsigned size = 0;
+       int scale = (distfield>0 ? distfield : 1);
 
-       font->ascent = (face->size->metrics.ascender+63)>>6;
-       font->descent = (face->size->metrics.descender+63)>>6;
+       font->ascent = (face->size->metrics.ascender/scale+63)/64;
+       font->descent = (face->size->metrics.descender/scale-63)/64;
 
        if(verbose>=1)
        {
@@ -298,13 +521,58 @@ void init_font(Font *font, FT_Face face, unsigned first, unsigned last, int auto
 
        font->n_glyphs = 0;
        font->glyphs = NULL;
-       for(i=first; i<=last; ++i)
+       for(i=0; i<n_ranges; ++i)
+               if(init_glyphs(font, face, &ranges[i], autohinter, distfield))
+                       return -1;
+
+       if(verbose>=1)
+               printf("Loaded %u glyphs\n", font->n_glyphs);
+
+       font->n_kerning = 0;
+       font->kerning = NULL;
+       for(i=0; i<font->n_glyphs; ++i) for(j=0; j<font->n_glyphs; ++j)
+               if(j!=i)
+               {
+                       FT_Vector kerning;
+                       FT_Get_Kerning(face, font->glyphs[i].index, font->glyphs[j].index, FT_KERNING_DEFAULT, &kerning);
+
+                       /* FreeType documentation says that vertical kerning is practically
+                       never used, so we ignore it. */
+                       if(kerning.x)
+                       {
+                               Kerning *kern;
+
+                               if(font->n_kerning>=size)
+                               {
+                                       size += 16;
+                                       font->kerning = (Kerning *)realloc(font->kerning, size*sizeof(Kerning));
+                               }
+
+                               kern = &font->kerning[font->n_kerning++];
+                               kern->left_code = font->glyphs[i].code;
+                               kern->right_code = font->glyphs[j].code;
+                               kern->distance = (kerning.x/scale+32)/64;
+                       }
+               }
+
+       if(verbose>=1)
+               printf("Loaded %d kerning pairs\n", font->n_kerning);
+
+       return 0;
+}
+
+int init_glyphs(Font *font, FT_Face face, const Range *range, bool autohinter, unsigned distfield)
+{
+       unsigned i, j;
+       unsigned size = font->n_glyphs;
+       int scale = (distfield>0 ? distfield : 1);
+
+       for(i=range->first; i<=range->last; ++i)
        {
-               unsigned  n;
+               unsigned n;
                FT_Bitmap *bmp = &face->glyph->bitmap;
-               int       x, y;
-               int       flags = 0;
-               Glyph     *glyph;
+               int flags = 0;
+               Glyph *glyph;
 
                n = FT_Get_Char_Index(face, i);
                if(!n)
@@ -313,14 +581,32 @@ void init_font(Font *font, FT_Face face, unsigned first, unsigned last, int auto
                if(autohinter)
                        flags |= FT_LOAD_FORCE_AUTOHINT;
                FT_Load_Glyph(face, n, flags);
-               FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL);
+               FT_Render_Glyph(face->glyph, (distfield ? FT_RENDER_MODE_MONO : FT_RENDER_MODE_NORMAL));
 
                if(verbose>=2)
-                       printf("  Char %u: glyph %u, size %dx%d\n", i, n, bmp->width, bmp->rows);
+               {
+                       printf("  Code point U+%04X", i);
+                       if(i>=0x20 && i<0x7F)
+                               printf(" (%c)", i);
+                       else if(i>=0xA0 && i<=0x10FFFF)
+                       {
+                               char utf8[5];
+                               unsigned bytes;
+
+                               for(bytes=2; i>>(1+bytes*5); ++bytes) ;
+                               for(j=0; j<bytes; ++j)
+                                       utf8[j] = 0x80 | ((i>>((bytes-j-1)*6))&0x3F);
+                               utf8[0] |= 0xF0<<(4-bytes);
+                               utf8[j] = 0;
+
+                               printf(" (%s)", utf8);
+                       }
+                       printf(": glyph %u, size %dx%d\n", n, bmp->width/scale, bmp->rows/scale);
+               }
 
-               if(bmp->pixel_mode!=FT_PIXEL_MODE_GRAY)
+               if(bmp->pixel_mode!=FT_PIXEL_MODE_GRAY && bmp->pixel_mode!=FT_PIXEL_MODE_MONO)
                {
-                       fprintf(stderr, "Warning: Glyph %u skipped, not grayscale\n", n);
+                       fprintf(stderr, "Warning: Glyph %u skipped, incompatible pixel mode\n", n);
                        continue;
                }
 
@@ -331,37 +617,182 @@ void init_font(Font *font, FT_Face face, unsigned first, unsigned last, int auto
                }
 
                glyph = &font->glyphs[font->n_glyphs++];
+               glyph->index = n;
                glyph->code = i;
-               glyph->image.w = bmp->width;
-               glyph->image.h = bmp->rows;
-               glyph->image.data = (char *)malloc(bmp->width*bmp->rows);
-               glyph->offset_x = face->glyph->bitmap_left;
-               glyph->offset_y = face->glyph->bitmap_top-bmp->rows;
-               glyph->advance = (int)(face->glyph->advance.x+32)/64;
-
-               if(bmp->pitch<0)
+               glyph->offset_x = (int)(face->glyph->bitmap_left+scale/2)/scale;
+               glyph->offset_y = (int)(face->glyph->bitmap_top-bmp->rows+scale/2)/scale;
+               glyph->advance = (int)(face->glyph->advance.x/scale+32)/64;
+
+               /* Copy the glyph image since FreeType uses a global buffer, which would
+               be overwritten by the next glyph.  Negative pitch means the scanlines
+               start from the bottom. */
+               if(distfield)
                {
-                       for(y=0; y<bmp->rows; ++y) for(x=0; x<bmp->width; ++x)
-                               glyph->image.data[x+(glyph->image.h-1-y)*glyph->image.w] = bmp->buffer[x-y*bmp->pitch];
+                       unsigned margin = 3;
+
+                       glyph->offset_x -= margin;
+                       glyph->offset_y -= margin;
+                       create_distance_field(bmp, &glyph->image, distfield, margin);
                }
                else
                {
-                       for(y=0; y<bmp->rows; ++y) for(x=0; x<bmp->width; ++x)
-                               glyph->image.data[x+y*glyph->image.w] = bmp->buffer[x+y*bmp->pitch];
+                       if(copy_bitmap(bmp, &glyph->image))
+                               return -1;
                }
        }
 
-       if(verbose>=1)
-               printf("Loaded %u glyphs\n", font->n_glyphs);
+       return 0;
 }
 
-void render_grid(Font *font, unsigned cellw, unsigned cellh, unsigned cpl, int seq)
+int copy_bitmap(const FT_Bitmap *bmp, Image *image)
+{
+       unsigned x, y;
+       unsigned char *src;
+       unsigned char *dst;
+
+       image->w = bmp->width;
+       image->h = bmp->rows;
+       if(!image->w || !image->h)
+       {
+               image->data = NULL;
+               return 0;
+       }
+
+       image->data = (unsigned char *)malloc(image->w*image->h);
+       if(!image->data)
+       {
+               fprintf(stderr, "Cannot allocate %d bytes of memory for glyph\n", image->w*image->h);
+               return -1;
+       }
+
+       if(bmp->pitch<0)
+               src = bmp->buffer+(bmp->rows-1)*-bmp->pitch;
+       else
+               src = bmp->buffer;
+       dst = image->data;
+
+       for(y=0; y<bmp->rows; ++y)
+       {
+               if(bmp->pixel_mode==FT_PIXEL_MODE_MONO)
+               {
+                       for(x=0; x<bmp->width; ++x)
+                               dst[x] = ((src[x/8]&(0x80>>(x%8))) ? 0xFF : 0x00);
+               }
+               else
+               {
+                       for(x=0; x<bmp->width; ++x)
+                               dst[x] = src[x];
+               }
+
+               src += bmp->pitch;
+               dst += image->w;
+       }
+
+       return 0;
+}
+
+void propagate_distance(unsigned short *pixel, int offset)
+{
+       unsigned short *neighbor = pixel+offset;
+       if((*neighbor^*pixel)&0x8000)
+               *neighbor = (*neighbor&0x8000)+1;
+       else if((*neighbor&0x7FFF)>(*pixel&0x7FFF))
+               *neighbor = *pixel+2;
+}
+
+int create_distance_field(const FT_Bitmap *bmp, Image *image, unsigned scale, unsigned margin)
+{
+       unsigned x, y;
+       Image base_image;
+       unsigned short *distance_map;
+       unsigned map_w;
+       unsigned map_h;
+       unsigned offset;
+
+       if(!bmp->width || !bmp->rows)
+       {
+               image->w = 0;
+               image->h = 0;
+               image->data = NULL;
+               return 0;
+       }
+
+       if(copy_bitmap(bmp, &base_image))
+               return -1;
+
+       map_w = base_image.w+2*margin*scale+scale-1;
+       map_w -= map_w%scale;
+       map_h = base_image.h+2*margin*scale+scale-1;
+       map_h -= map_h%scale;
+       distance_map = (unsigned short *)malloc(map_w*map_h*sizeof(unsigned short));
+       if(!distance_map)
+       {
+               fprintf(stderr, "Cannot allocate %d bytes of memory for distance map\n", map_w*map_h);
+               free(base_image.data);
+               return -1;
+       }
+
+       image->w = map_w/scale;
+       image->h = map_h/scale;
+       image->data = (unsigned char *)malloc(image->w*image->h);
+       if(!image->data)
+       {
+               fprintf(stderr, "Cannot allocate %d bytes of memory for glyph\n", image->w*image->h);
+               free(base_image.data);
+               free(distance_map);
+               return -1;
+       }
+
+       for(x=0; x<map_w*map_h; ++x)
+               distance_map[x] = 0x7FFF;
+
+       offset = margin*scale*(map_w+1);
+       for(y=0; y<base_image.h; ++y) for(x=0; x<base_image.w; ++x)
+               distance_map[offset+x+y*map_w] |= (base_image.data[x+y*base_image.w]&0x80)<<8;
+
+       for(y=0; y<map_h; ++y)
+       {
+               for(x=0; x+1<map_w; ++x)
+                       propagate_distance(distance_map+x+y*map_w, 1);
+               for(x=map_w-1; x>0; --x)
+                       propagate_distance(distance_map+x+y*map_w, -1);
+       }
+
+       for(x=0; x<map_w; ++x)
+       {
+               for(y=0; y+1<map_h; ++y)
+                       propagate_distance(distance_map+x+y*map_w, map_w);
+               for(y=map_h-1; y>0; --y)
+                       propagate_distance(distance_map+x+y*map_w, -map_w);
+       }
+
+       offset = scale/2*(map_w+1);
+       for(y=0; y<image->h; ++y) for(x=0; x<image->w; ++x)
+       {
+               unsigned short pixel = distance_map[offset+(x+y*map_w)*scale];
+               unsigned short dist = (pixel&0x7FFF)*0x7F/(margin*scale*2+1);
+               if(dist>0x7F)
+                       dist = 0x7F;
+               if(pixel&0x8000)
+                       image->data[x+y*image->w] = 0x80+dist;
+               else
+                       image->data[x+y*image->w] = 0x7F-dist;
+       }
+
+       free(distance_map);
+       free(base_image.data);
+
+       return 0;
+}
+
+int render_grid(Font *font, unsigned cellw, unsigned cellh, unsigned cpl, bool seq, bool npot)
 {
        unsigned i;
-       int      top = 0, bot = 0;
+       int top = 0, bot = 0;
        unsigned first, last;
        unsigned maxw = 0, maxh = 0;
 
+       /* Find extremes of the glyph images. */
        for(i=0; i<font->n_glyphs; ++i)
        {
                int y;
@@ -379,6 +810,7 @@ void render_grid(Font *font, unsigned cellw, unsigned cellh, unsigned cpl, int s
 
        if(cellw==0)
        {
+               /* Establish a large enough cell to hold all glyphs in the range. */
                int square = (cellh==cellw);
                cellw = maxw;
                cellh = top-bot;
@@ -396,12 +828,14 @@ void render_grid(Font *font, unsigned cellw, unsigned cellh, unsigned cpl, int s
                printf("Max size:  %u x %u\n", maxw, maxh);
                printf("Y range:   [%d %d]\n", bot, top);
                printf("Cell size: %u x %u\n", cellw, cellh);
-               if(maxw>cellw || top-bot>cellh)
+               if(maxw>cellw || (unsigned)(top-bot)>cellh)
                        fprintf(stderr, "Warning: character size exceeds cell size\n");
        }
 
        if(cpl==0)
        {
+               /* Determine number of characters per line, trying to fit all the glyphs
+               in a square image. */
                for(i=1;; i<<=1)
                {
                        cpl = i/cellw;
@@ -415,16 +849,25 @@ void render_grid(Font *font, unsigned cellw, unsigned cellh, unsigned cpl, int s
                first -= first%cpl;
        last = font->glyphs[font->n_glyphs-1].code;
 
-       font->image.w = round_to_pot(cpl*cellw);
-       font->image.h = round_to_pot((last-first+cpl)/cpl*cellh);
+       font->image.w = cpl*cellw;
+       if(!npot)
+               font->image.w = round_to_pot(font->image.w);
+       if(seq)
+               font->image.h = (font->n_glyphs+cpl-1)/cpl*cellh;
+       else
+               font->image.h = (last-first+cpl)/cpl*cellh;
+       if(!npot)
+               font->image.h = round_to_pot(font->image.h);
 
-       font->image.data = (char *)malloc(font->image.w*font->image.h);
+       font->image.data = (unsigned char *)alloc_image_data(font->image.w, font->image.h);
+       if(!font->image.data)
+               return -1;
        memset(font->image.data, 255, font->image.w*font->image.h);
 
        for(i=0; i<font->n_glyphs; ++i)
        {
-               Glyph    *glyph;
-               int      ci, cx, cy;
+               Glyph *glyph;
+               unsigned ci, cx, cy;
                unsigned x, y;
 
                glyph = &font->glyphs[i];
@@ -446,61 +889,87 @@ void render_grid(Font *font, unsigned cellw, unsigned cellh, unsigned cpl, int s
 
                for(y=0; y<glyph->image.h; ++y) for(x=0; x<glyph->image.w; ++x)
                {
-                       if(cx+x<0 || cx+x>=font->image.w || cy+y<0 || cy+y>=font->image.h)
+                       if(cx+x>=font->image.w || cy+y>=font->image.h)
                                continue;
                        font->image.data[cx+x+(cy+y)*font->image.w] = 255-glyph->image.data[x+y*glyph->image.w];
                }
        }
+
+       return 0;
 }
 
-void render_packed(Font *font)
+int render_packed(Font *font, unsigned margin, unsigned padding, bool npot)
 {
        unsigned i;
-       unsigned area = 0;
-       char     *used_glyphs;
+       size_t area = 0;
+       char *used_glyphs;
        unsigned *used_pixels;
-       unsigned cx = 0, cy;
+       unsigned cx = margin, cy;
        unsigned used_h = 0;
 
+       /* Compute the total area occupied by glyphs and padding. */
        for(i=0; i<font->n_glyphs; ++i)
-               area += (font->glyphs[i].image.w+1)*(font->glyphs[i].image.h+1);
+       {
+               size_t a = area+(font->glyphs[i].image.w+padding)*(font->glyphs[i].image.h+padding);
+               if(a<area)
+               {
+                       fprintf(stderr, "Overflow in counting total glyph area\n");
+                       return -1;
+               }
+               area = a;
+       }
 
+       /* Find an image size that's no higher than wide, allowing for some
+       imperfections in the packing. */
        for(font->image.w=1;; font->image.w<<=1)
        {
-               font->image.h = (area*5/4)/font->image.w;
+               if(font->image.w<=margin*2)
+                       continue;
+               font->image.h = (area*5/4)/(font->image.w-margin*2)+margin*2;
                if(font->image.h<=font->image.w)
                        break;
        }
-       font->image.h = round_to_pot(font->image.h);
-
-       font->image.data = (char *)malloc(font->image.w*font->image.h);
+       if(!npot)
+               font->image.h = round_to_pot(font->image.h);
+
+       /* Allocate arrays for storing the image and keeping track of used pixels and
+       glyphs.  Since glyphs are rectangular and the image is filled starting from
+       the top, it's enough to track the number of used pixels at the top of each
+       column. */
+       font->image.data = (unsigned char *)alloc_image_data(font->image.w, font->image.h);
+       if(!font->image.data)
+               return -1;
        memset(font->image.data, 255, font->image.w*font->image.h);
        used_pixels = (unsigned *)malloc(font->image.w*sizeof(unsigned));
        memset(used_pixels, 0, font->image.w*sizeof(unsigned));
        used_glyphs = (char *)malloc(font->n_glyphs);
        memset(used_glyphs, 0, font->n_glyphs);
 
-       for(cy=0; cy<font->image.h;)
+       for(cy=margin; cy+margin<font->image.h;)
        {
                unsigned w;
                unsigned x, y;
-               Glyph    *glyph = NULL;
+               Glyph *glyph = NULL;
                unsigned best_score = 0;
                unsigned target_h = 0;
 
-               for(; (cx<font->image.w && used_pixels[cx]>cy); ++cx)
-                       if(used_pixels[cx]-cy-1>target_h)
-                               target_h = used_pixels[cx]-cy-1;
+               /* Find the leftmost free pixel on this row.  Also record the lowest
+               extent of glyphs to the left of the free position. */
+               for(; (cx+margin<font->image.w && used_pixels[cx]>cy); ++cx)
+                       if(used_pixels[cx]-cy-padding>target_h)
+                               target_h = used_pixels[cx]-cy-padding;
 
-               if(cx>=font->image.w)
+               if(cx+margin>=font->image.w)
                {
-                       cx = 0;
+                       cx = margin;
                        ++cy;
                        continue;
                }
 
-               for(w=0; (cx+w<font->image.w && used_pixels[cx+w]<=cy); ++w) ;
+               /* Count the free pixel at this position. */
+               for(w=0; (cx+w+margin<font->image.w && used_pixels[cx+w]<=cy); ++w) ;
 
+               /* Find a suitable glyph to put here. */
                for(i=0; i<font->n_glyphs; ++i)
                {
                        Glyph *g;
@@ -510,7 +979,10 @@ void render_packed(Font *font)
                        {
                                unsigned score;
 
-                               score = g->image.h+1;
+                               /* Prefer glyphs that would reach exactly as low as the ones left
+                               of here.  This aims to create a straight edge at the bottom for
+                               lining up further glyphs. */
+                               score = g->image.h+padding;
                                if(g->image.h==target_h)
                                        score *= g->image.w;
                                else
@@ -536,28 +1008,37 @@ void render_packed(Font *font)
 
                for(y=0; y<glyph->image.h; ++y) for(x=0; x<glyph->image.w; ++x)
                {
-                       if(cx+x<0 || cx+x>=font->image.w || cy+y<0 || cy+y>=font->image.h)
+                       if(cx+x>=font->image.w || cy+y>=font->image.h)
                                continue;
                        font->image.data[cx+x+(cy+y)*font->image.w] = 255-glyph->image.data[x+y*glyph->image.w];
                }
-               for(x=0; x<glyph->image.w+2; ++x)
+               for(x=0; x<glyph->image.w+2*padding; ++x)
                {
-                       if(cx+x<1 || cx+x>font->image.w)
+                       if(cx+x<padding || cx+x>=font->image.w+padding)
                                continue;
-                       if(used_pixels[cx+x-1]<cy+glyph->image.h+1)
-                               used_pixels[cx+x-1] = cy+glyph->image.h+1;
+                       if(used_pixels[cx+x-padding]<cy+glyph->image.h+padding)
+                               used_pixels[cx+x-padding] = cy+glyph->image.h+padding;
                }
 
-               if(cy+glyph->image.h>used_h)
-                       used_h = cy+glyph->image.h;
+               if(cy+glyph->image.h+margin>used_h)
+                       used_h = cy+glyph->image.h+margin;
        }
 
-       font->image.h = round_to_pot(used_h);
+       /* Trim the image to the actually used size, in case the original estimate
+       was too pessimistic. */
+       font->image.h = used_h;
+       if(!npot)
+               font->image.h = round_to_pot(font->image.h);
+
+       free(used_glyphs);
+       free(used_pixels);
+
+       return 0;
 }
 
 int save_defs(const char *fn, const Font *font)
 {
-       FILE     *out;
+       FILE *out;
        unsigned i;
 
        out = fopen(fn, "w");
@@ -567,11 +1048,22 @@ int save_defs(const char *fn, const Font *font)
                return -1;
        }
 
-       fprintf(out, "%d %d %d %d %d\n", font->image.w, font->image.h, font->size, font->ascent, font->descent);
+       fprintf(out, "# Image/font info:\n");
+       fprintf(out, "# width height size ascent descent\n");
+       fprintf(out, "font %d %d %d %d %d\n", font->image.w, font->image.h, font->size, font->ascent, font->descent);
+       fprintf(out, "\n# Glyph info:\n");
+       fprintf(out, "# code x y width height offset_x offset_y advance\n");
        for(i=0; i<font->n_glyphs; ++i)
        {
                const Glyph *g = &font->glyphs[i];
-               fprintf(out, "%u %u %u %u %u %d %d %d\n", g->code, g->x, g->y, g->image.w, g->image.h, g->offset_x, g->offset_y, g->advance);
+               fprintf(out, "glyph %u %u %u %u %u %d %d %d\n", g->code, g->x, g->y, g->image.w, g->image.h, g->offset_x, g->offset_y, g->advance);
+       }
+       fprintf(out, "\n# Kerning info:\n");
+       fprintf(out, "# left right distance\n");
+       for(i=0; i<font->n_kerning; ++i)
+       {
+               const Kerning *k = &font->kerning[i];
+               fprintf(out, "kern %u %u %d\n", k->left_code, k->right_code, k->distance);
        }
 
        fclose(out);
@@ -581,13 +1073,13 @@ int save_defs(const char *fn, const Font *font)
 
 int save_png(const char *fn, const Image *image, char alpha)
 {
-       FILE       *out;
+       FILE *out;
        png_struct *pngs;
-       png_info   *pngi;
-       png_byte   *rows[image->h];
-       int        i;
-       png_byte   *data2;
-       int        color;
+       png_info *pngi;
+       png_byte **rows;
+       unsigned i;
+       png_byte *data2 = 0;
+       int color;
 
        if(!strcmp(fn, "-"))
                out = stdout;
@@ -616,9 +1108,12 @@ int save_png(const char *fn, const Image *image, char alpha)
        }
 
        png_init_io(pngs, out);
+       rows = (png_byte **)malloc(image->h*sizeof(png_byte *));
        if(alpha)
        {
-               data2 = (png_byte *)malloc(image->w*image->h*2);
+               data2 = (png_byte *)alloc_image_data(image->w*2, image->h);
+               if(!data2)
+                       return -1;
                for(i=0; i<image->w*image->h; ++i)
                {
                        data2[i*2] = 255;
@@ -638,6 +1133,7 @@ int save_png(const char *fn, const Image *image, char alpha)
        png_set_rows(pngs, pngi, rows);
        png_write_png(pngs, pngi, PNG_TRANSFORM_IDENTITY, NULL);
        png_destroy_write_struct(&pngs, &pngi);
+       free(rows);
        if(alpha)
                free(data2);