Re: [Devel] bug? Rendering glyphs twice

[David Turner]

Hello Gustavo,

Gustavo J A M Carneiro a écrit :
> 
>         I'm not sure, but this could be a bug in freetype. My program renders 
> a
> text using freetype this way:
>         1- A list o outline glyphs is obtained with their rendering positions.
> This list of glyphs and positions forms a text line;
>         2- The rendering position of text line is adjusted to achieve
> alignment;
>         3- Finally, the list of glyphs is rendered to a pixel buffer. The
> original outline glyphs are preserved, because I convert them to bitmaps
> with:
>   error = FT_Glyph_To_Bitmap(&glyph, ft_render_mode_normal, NULL, 0);
> 
>         I keep the outline glyphs around and later, when I need to render the
> same text again, I use the same glyphs. Unfortunately, at the second and
> subsequent renders the glyphs are rendered at wrong positions. A
> attached two screenshots of the results of first and second rendering.
> 
>         This seems like a bug in freetype (btw, I using freetype 2.0.4), but 
> it
> seems like a common programming error I'd appreciate a hint on what I
> may be doing wrong. Thanks.
>

It's difficult to tell wether this is a FreeType or programming error.
Could you try creating your bitmaps a bit differently, as in:

  FT_Glyph  glyph_copy;

  error = FT_Glyph_Copy( glyph, &glyph_copy );
  if (error) ...

  error = FT_Glyph_To_Bitmap( &glyph_copy, ft_render_mode_normal, NULL, 0 );
  FT_Done_Glyph( glyph_copy );
  if (error) ...

and also try:

  FT_Glyph  glyph_copy;

  error = FT_Glyph_Copy( glyph, &glyph_copy );
  if (error) ...

  error = FT_Glyph_To_Bitmap( &glyph_copy, ft_render_mode_normal, NULL, 1 );
  if (error) ...

to see if this makes a difference. Normally, FT_Glyph_To_Bitmap shouldn't
change the content of the original glyph, which is why I'm surprised by
your results..

Regards,

- David


 
> --
> Gustavo João Alves Marques Carneiro <address@hidden>
> 
>   
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>                          Name: ft2_2nd_render.png
>    ft2_2nd_render.png    Type: PNG Image (image/png)
>                      Encoding: base64