Re: [ft] Help finding glyphs in TTF files

[Wojciech Mamrak]

Hi,

how did you come up with that -29? :)

regards

2013/3/30 suzuki toshiya <address@hidden>

Hi,

What kind of text[] is passed to FT_Load_Char()?
And what kind of the error is returned?

Regards,
mpsuzuki

Michael Franklin wrote:
>
> Hello,
>
> First of all, let me say thanks for FreeType.  I was thrilled when text first appeared (clean and crisp) on my embedded system for the fist time even if it wasn't the text I hoped for.  And I'm hoping you can help me with that.
>
> I'm creating an embedded system using a Cortex-M4 processor and the Sourcery Codebench Lite (GCC 4.7.2) toolchain.
>
> I'm trying to do a simple glyph to bitmap rendering as demonstrated in the FreeType Tutorial 1.  I have successfully displayed glyphs from Verdana.ttf (stolen from my Windows 8 computer) and FreeMono.ttf (stolen from my Mint Linux computer).  However, with both of these fonts, I can't get the correct glyphs unless I subtract 29 from the character code as shown below.
>
> error = FT_Load_Char(face, text[i] - 29, FT_LOAD_RENDER);   //this works
> error = FT_Load_Char(face, text[i], FT_LOAD_RENDER);   //this doesn't work
>
> Verdana.ttf reports 1 charmap (platform: 0, encoding: 1) and Mono.ttf reports 0 charmaps, which also seems strange.
>
> I also tried a few other fonts (Arial.ttf from my Windows 8 computer and a few others), but they all return various errors after calling FT_Load_Char.  Sometimes FT_Err_Invalid_Opcode and sometimes FT_Err_ENDF_In_Exec_Stream depending on the file.
>
> At first I suspected my disk I/O routines, but these have all been working well in my libpng port, so I'm fairly confident they are working well.  Also,  FT_New_Face doesn't give me any errors.
>
> Here's my source code.  Please let me know if you have any suggestions.
>
> Thanks.
>
> DrawText(const Point& p, const uint8_t size, const File& file, const Color& color, const char* text, ...)
> {
>     FT_Library library;
>
>     FT_Error error = FT_Init_FreeType(&library);
>     if (error)
>     {
>         printf("FT_Init_FreeType failed\r]n");
>         return;
>     }
>
>     printf("FT_Init_FreeType finished\r\n");
>
>     FT_Face face;
>     error = FT_New_Face( library, "/arialbi.ttf", 0, &face );
>     if ( error == FT_Err_Unknown_File_Format )
>     {
>         printf("FT_New_Face failed\r\n");
>         //... the font file could be opened and read, but it appears
>         //... that its font format is unsupported
>     }
>     else if ( error )
>     {
>         printf("FT_New_Face failed 2: %d\r\n", error);
>         //... another error code means that the font file could not
>         //... be opened or read, or simply that it is broken...
>     }
>     else
>     {
>         printf("FT_New_Face finished\r\n");
>
>         printf("%d charmaps exist\r\n", face->num_charmaps);
>         for (int n = 0; n < face->num_charmaps; n++ )
>         {
>             FT_CharMap charmap = face->charmaps[n];
>             printf("charmap: %d, %d\r\n", charmap->platform_id, charmap->encoding_id);
>         }
>
>         error = FT_Set_Char_Size(
>             face,      // handle to face object
>             0,         // char_width in 1/64th of points
>             size << 6, // char_height in 1/64th of points
>             72,        // horizontal device resolution in dots per inch
>             72);       // vertical device resolution
>
>         if (error)
>         {
>             printf("FT_Set_Char_Size failed\r\n");
>         }
>         else
>         {
>             printf("FT_Set_Char_Size finished\r\n");
>
>             int i = 0;
>             int16_t x = 200;
>             int16_t y = 200;
>             while (text[i] != '\0')
>             {
>                 error = FT_Load_Char(face, text[i] - 29, FT_LOAD_RENDER);
>                 if (error)
>                 {
>                     printf("Missing Glyph for char %c: %d\r\n", text[i], error);
>                 }
>                 else
>                 {
>                     printf("FT_Load_Char[%c] succeeded\r\n", text[i]);
>                     FT_Draw_Bitmap(&face->glyph->bitmap, face->glyph->bitmap_left + x, y - face->glyph->bitmap_top);
>
>                     //Move cursor to position for next character
>                     x += (face->glyph->advance.x >> 6);  //int 1/64th units, so shift by 6
>                     y += (face->glyph->advance.y >> 6);
>
>                     printf("%d,%d\r\n", x, y);
>                 }
>
>                 i++;
>             }
>         }
>
>         error = FT_Done_Face(face);
>         if (error)
>         {
>             printf("FT_Done_Face failed\r\n");
>         }
>     }
>
>     error = FT_Done_FreeType(library);
>     if (error)
>     {
>         printf("FT_Done_FreeType failed\r\n");
>     }
> }
>
> void FT_Draw_Bitmap( FT_Bitmap*  bitmap, FT_Int x, FT_Int y)
> {
>     FT_Int  i, j, p, q;
>     FT_Int  x_max = x + bitmap->width;
>     FT_Int  y_max = y + bitmap->rows;
>
>     for ( i = x, p = 0; i < x_max; i++, p++ )
>     {
>         for ( j = y, q = 0; j < y_max; j++, q++ )
>         {
>             uint8_t alpha = bitmap->buffer[q * bitmap->width + p];
>             SetPixel({i, j}, Color(alpha, alpha, alpha));
>         }
>     }
> }
>
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