font->driver->text_extents (font, &code, 1, &metrics);
LGLYPH_SET_LBEARING (glyph, metrics.lbearing);
LGLYPH_SET_RBEARING (glyph, metrics.rbearing);
font->driver->text_extents (font, &code, 1, &metrics);
LGLYPH_SET_LBEARING (glyph, metrics.lbearing);
LGLYPH_SET_RBEARING (glyph, metrics.rbearing);