Re: [ft] Help finding glyphs in TTF files

[Michael Franklin]

Well, I my test text is "1234abcdEFGH".  But what I see on my screen is "NOPQ~ 
??bcde".  Looking at an ASCII table I can see that what I want and what I see 
are off by 29.  


Mike


________________________________
From: Wojciech Mamrak <address@hidden>
To: suzuki toshiya <address@hidden> 
Cc: Michael Franklin <address@hidden>; "address@hidden" <address@hidden> 
Sent: Sunday, March 31, 2013 1:02 AM
Subject: Re: [ft] Help finding glyphs in TTF files


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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