RE: 仮想ボディと外枠の関係性

Kida-san,

  *   I agree. I did not realize that there are fonts that do not follow 880:120 (If all had followed, it can be an option of the default location).
As far as I know the Hiragino Mincho fonts have a relative distance between the Japanese EM body and the Latin baseline position at y = 0 different from that of Adobe’s fonts, though most of CFF-based Japanese fonts follow the Adobe convention.

However, from purely typographic viewpoints, the relative distance cannot be standardized, and it is natural that the type designer should decide it, if the BASE table can be set in font and text engines work appropriately referencing the information.

1.       Upper side of the body

2.       Mean height of the body (i.e. centerline).

3.       Bottom side of the body


  *   Which do you think is a better default? Bin-sensei mentioned that any default would be fine, but it’s probably better to specify something rather than leave it in chaos.
The default should be 2, though 1 and 3 also must be selectable options, because it is necessary for all the three Japanese baseline positions may be used to do the so-called “異級数揃え” (alignment of glyphs of different sizes)  especially in display lines.

>> Usually, the position of the Latin baseline relative to the Japanese body is set by the designer of the Latin font (and stored in the BASE table), but if it’s not available in font, it should go through half the heigh of the capital letters.

  *   This part was unclear to me. Do you mean that when you align a Japanese font and a Latin font, they should be aligned using the the center of the Japanese characters and the center of the capital letters in the Latin font?
It is the method that we can choose in the case a Latin font doesn’t have the information about the relative ideographic EM box position information in the BASE table.

To say ideally, the ideal relative distance between the Japanese EM body and the Latin baseline (y = 0) can be set only by the designer of a Latin font. The information is stored in the BASE table, or if it’s not in the table, the position of the horizontal center line of the Japanese EM body and half the Cap. height of the Latin font should be aligned. In the case of a Japanese font, if the information is not in the BASE table, it should be in the OS/2 table. Anyway, if the relative positioning information between the Latin baseline and the Japanese EM body is known, once the y position of a Japanese line or of the bodies of the Japanese glyphs contained in the line is set, the y position of the Latin glyphs in the font can be calculated automatically.

Regards,

--Taro