Subscript and Superscript - Position Adjustment in Italic/oblique/slanted Styles

Position Adjustment in Italic/oblique/slanted Styles

Another subtle adjustment that is most often forgotten in renderers, is controlling the direction of movement for superscripts and subscripts, when they don't lie on the baseline. It should notably take into account the current font's style for italics, notably its slanting direction; most renderers only adjust the position vertically, and forget to shift it horizontally as well. This creates collision with surrounding letters in the same italic size. One can see an example of such collision on the right side when rendered in HTML. To avoid such problem, it is often necessary to insert a small positive horizontal margin (or a thin space) (on the left side of the first the superscript character), or a negative margin (or a tiny backspace) before the subscript. It is more critical with glyphs from fonts in "Oblique" styles that are more slanted than those from fonts in Italic style, and some fonts reverse the direction of slanting, so there's no general solution except when the renderer takes into account the font metrics properties that provides the angle of slanting,

But more generally, the same problem occurs as well between spans of normal glyphs (non-subperscript and non-subscripts) when slanting styles are mixed.