Re: [ft] Help finding glyphs in TTF files

[Michael Franklin]

Thanks for your reply.


My text is just a string constant of "1234abcdEFGH".  


With Arial.ttf, FT_Err_Invalid_Opcode is returned.  With Ariali.ttf (Italic) 
FT_Err_ENDF_In_Exec_Stream is returned.  


With
 Verdana.ttf and FreeMono.ttf, no error is returned, but the text "NOPQ~
 ??bcde" is displayed (?? are two characters I don't know how to type in
 this email).  However if I subtract 29 from text[i] the text 
"1234abcdEFGH" is displayed as expected.

Weird isn't it?  Possibly one of my data types is the wrong size?



----- Original Message -----
From: suzuki toshiya <address@hidden>
To: Michael Franklin <address@hidden>
Cc: "address@hidden" <address@hidden>
Sent: Saturday, March 30, 2013 10:09 PM
Subject: Re: [ft] Help finding glyphs in TTF files

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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