calculating bounding box of a string

[Bart De Lathouwer]

Hi all,

 

I'm trying to calculate the bounding box of a string using the method described further down.

Somehow this method is not quite exact. When i draw the string, it's seems to be shorter that calculated.

(I did an example using the gara.ttf file on Win Nt 4 SP 4)

 

Am i using the correct procedure to calculate the bounding box?

 

 

Thanks

Bart De Lathouwer

 

 

 

 

 

 

FT_BBox
ftText::getBoundingRect()
{
 assert(m_face.face);

 

 FT_Error ftErr = 0;
    FT_Pos  origin_x = 0;
 FT_UInt  previous_index = 0;

 

 m_bbox.xMin = 0;
 m_bbox.yMin = 0;
 m_bbox.xMax = 0;
 m_bbox.yMax = 0;

 

 string::iterator i;
 for (i = m_sText.begin(); i < m_sText.end(); i++) {

 

  //------------------------------------------------------------
  FT_UInt glyph_index = FT_Get_Char_Index(m_face.face, *i);

 

  //------------------------------------------------------------
  if (m_bKerning && previous_index && glyph_index) {
   FT_Vector delta = {0,0};
   FT_Get_Kerning(m_face.face, previous_index, glyph_index,
       ft_kerning_default, &delta);
   m_bbox.xMax += delta.x;
  }
  
  //------------------------------------------------------------
  ftErr = FT_Load_Glyph(m_face.face, glyph_index, FT_LOAD_DEFAULT);
  assert(ftErr == 0);

 

  //------------------------------------------------------------
  FT_Glyph  glyph;
  ftErr = FT_Get_Glyph(m_face.face->glyph, &glyph);
  FT_BBox box;
  FT_Glyph_Get_CBox(glyph, 0, &box);

 

  // grow bounding box
  m_bbox.xMax += m_face.face->glyph->advance.x;
  if (box.yMin < m_bbox.yMin)
   m_bbox.yMin = box.yMin;
  if (box.yMax > m_bbox.yMax)
   m_bbox.yMax = box.yMax;

 

  previous_index = glyph_index;
 }

 

 return m_bbox;
}