Re: [Freetype] using a Stroker to make a glyph border pixmap

[David Turner]

Hello George,

George Ogata wrote:
> Hi,
>
> if my understanding is correct, the Stroker functions should enable me
> to obtain a border of a glyph.  I've only found a couple of stroker
> examples, and documentation seems rather scant.  It seems using
> FT_Glyph_Stroke is the simplest way, but I can't understand why this
> simple test program doesn't print out the border; it just prints the
> normal glyph instead. Can someone tell me what I'm doing wrong?
>
> Thanks.

You're not doing anything wrong, it's simply that the stroker is still
buggy (experimental).

Well, to be honest, I *just* commited the 'last' fixes to the CVS 
Repository. May I encourage you to test the current code and report
your results here ?

Regards,

- David Turner
- The FreeType Project  (www.freetype.org)

> //////////////////////////////////////////////////
>
> #include <stdlib.h>
> #include <stdio.h>
>
> #include <ft2build.h>
> #include FT_FREETYPE_H
> #include FT_STROKER_H
>
> /* Error checking facility */
> const char *error_string(FT_Error error) {
> #undef __FTERRORS_H__
> #define FT_ERRORDEF( e, v, s )  { e, s },
> #define FT_ERROR_START_LIST     {
> #define FT_ERROR_END_LIST       { 0, 0 } };
>   static const struct ErrorRecord {
>     int          err_code;
>     const char*  err_msg;
>   } ft_errors[] = 
> #include FT_ERRORS_H
>
>   const struct ErrorRecord *p;
>   for (p = ft_errors; p->err_msg; ++p)
>     if (p->err_code == error)
>       return p->err_msg;
>   return "??";
> }
> #define CHECK(func, arglist)                                            \
>   do {                                                                  \
>     if ((error = func arglist)) {                                       \
>       fprintf(stderr, "%d: %s failed (%d): %s\n", __LINE__, #func, error, 
> error_string(error)); \
>       done(EXIT_FAILURE);                                               \
>     }                                                                   \
>   } while (0)
>
> /* FT resources */
> FT_Library lib;
> FT_Face face;
> FT_Glyph glyph;
> FT_Stroker stroker;
>
> /* Free everything and exit. */
> void done(int status) {
>   if (stroker)
>     FT_Stroker_Done(stroker);
>   if (glyph)
>     FT_Done_Glyph(glyph);
>   if (face)
>     FT_Done_Face(face);
>   if (lib)
>     FT_Done_FreeType(lib);
>   exit(status);
> }
>
> void print_bitmap(FT_Bitmap *map) {
>   int s, r, c;
>   s = map->pitch > 0 ? 0 : (map->rows - 1) * -map->pitch;
>   printf("pitch=%d size=%dx%d\n", map->pitch, map->rows, map->width);
>   for (r = 0; r < map->rows; ++r, s += map->pitch) {
>     for (c = 0; c < map->width; ++c) {
>       if (map->buffer[s+c])
>         printf("#");
>       else
>         printf(" ");
>     }
>     printf("\n");
>   }
> }
>
> int main(int argc, char **argv) {
>   FT_Error error;
>   FT_Vector origin = {0, 0};
>
>   if (argc != 2) {
>     printf("usage: %s FONTFILE", argv[0]);
>     return EXIT_FAILURE;
>   }
>
>   // init library and load char
>   CHECK( FT_Init_FreeType, (&lib) );
>   CHECK( FT_New_Face, (lib, argv[1], 0, &face) );
>   CHECK( FT_Set_Pixel_Sizes, (face, 40, 0) );
>   CHECK( FT_Load_Char, (face, 'A', FT_LOAD_DEFAULT) );
>   CHECK( FT_Get_Glyph, (face->glyph, &glyph) );
>
>   // make stroker
>   CHECK( FT_Stroker_New, (face->memory, &stroker) );
>   FT_Stroker_Set, (stroker,
>                    32,
>                    FT_STROKER_LINECAP_ROUND,
>                    FT_STROKER_LINEJOIN_ROUND,
>                    0);
>
>   // make bitmap
>   CHECK( FT_Glyph_Stroke, (&glyph, stroker, 1) );
>   CHECK( FT_Glyph_To_Bitmap, (&glyph, FT_RENDER_MODE_NORMAL, &origin, 1) );
>
>   print_bitmap(&((FT_BitmapGlyph)glyph)->bitmap);
>   done(EXIT_SUCCESS);
>   return 0;  // not reached
> }
>
>
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