Once you click on a personality in Character Viewer (Emoji & Symbols), a big preview is displayed within the element column and it contains grid traces to point out how the character is specified by some kind of bounding field. I’m making an attempt to determine precisely what every grid line represents.
I constructed an iOS app that attracts varied font metrics to attempt to determine it out. My greatest guess is:
- Backside line: ?
- Dotted line: baseline – perhaps it is the peak of the preview space – (ascent – descent) / 2
- High line: ?
- Left and proper: the character’s typographic bounds with the character centered horizontally
For the underside line, having a look at ⏁ (DENTISTRY SYMBOL LIGHT DOWN AND HORIZONTAL WITH CIRCLE) U+23C1:
Is it the font’s descent? I do not assume so, the glyph sits straight atop the underside line in Character Viewer with the circle resting on the baseline. Drawing the descent reveals that’s even decrease so the character doesn’t relaxation on it there may be additional padding between the glyph and descent.
For the highest line, having a look at T (LATIN CAPITAL LETTER T) U+0054:
Is it cap peak? No, cap peak sits straight atop the T but Character Viewer exhibits some area between the glyph and information line.
Ascent? No, ascent is way increased up with an excessive amount of padding between the road and glyph.
Typographic bounds? No, it sits straight atop the glyph.
Numerous fascinating characters have differing positions, like:
- 〓 (GETA MARK) U+3013
- Å (LATIN CAPITAL LETTER A WITH RING ABOVE) U+00C5

