Some questions about the Opentype Designer

[_Bin_]

Hi,
I have some questions that I wanted to ask:

1. What is the meaning of the number next to subtable? (Subtable 3 (x/y) - I don't know the meaning of this x/y). Why sometimes x < y, sometimes x = y?
2. How can I find out the existing kerning value of one character? For example, I type "Va" then "Và" and notice that "Và" doesn't have a kerning value, and I want to set the kerning value of "Và" so it can be exactly like "Va", but I can't find "Va" kerning value in the opentype designer.
3. This question is not exactly FontCreator-related, but I don't understand some terms, for example what is lookups? Where can I find documents or tutorials about these terms?

Thank you so much in advance.

[Bhikkhu Pesala]

1. It is probably not anything you need to concern yourself with yet. FontCreator will add subtables if one is not enough. (From the user manual: 5.4.3.4.2.8 Subtable: Sometimes lookup tables are very large and it's better to break them up into several smaller tables: for this the keyword subtable can be used. Subtables are most commonly used in kerning tables that contain a lot of kerning pairs. We recommend a subtable for every 16,000 kerning pairs.
2. To use the same kerning values for Va and Vá you should create kerning classes. The Autokern wizard could do this for you automatically. I think it's more educational to create one's own kerning classes and retain full control over what goes where. Open the Class Manager, type "a" and Ctrl + Click to select all variants of a: a, à, á, ä ã, etc., adding them to a class, which you might name as "a_lowercase" (for example). Create another kerning class for all variations of V (and W if you like): V, Ṿ, Ṽ, W, Ẃ, Ẁ, Ẅ Ŵ, etc. Now create one kerning pair for @V_Uppercase @a_lowercase. Kerning Pairs (using groups, which are now called "classes.")
3. A lookup is a list of substitutions used by a feature. For example, a feature for OldStyle Figures would use a lookup like this. If the user enables OldStyle Figures, the lookup table will be used to replace each digit with its OldStyle version. A kerning feature need a long lookup table, or several subtables, to lookup kerning pair values.

Code: Select all

lookup OldStyleFigures {
  sub zero -> zero.onum;
  sub one -> one.onum;
  sub two -> two.onum;
  sub three -> three.onum;
  sub four -> four.onum;
  sub five -> five.onum;
  sub six -> six.onum;
  sub seven -> seven.onum;
  sub eight -> eight.onum;
  sub nine -> nine.onum;
}

[_Bin_]

Thank you for your fast reply!

1. Yes I know about subtables, but I don't understand the numbers next to it. For example: Subtable 4 (7085/68952) -> I don't understand 7085/68952 meaning.
2. I knew how to add kerning classes too, but I want to ask if there is any way that I can view all kerning values of one character?
3. Oh I see, thank you. I want to ask about others terms too, and maybe an online document that can explain them.

Sorry for bothering you If that's all you can help then it's okay, I'm grateful. Thank you!

[Erwin Denissen]

1. Yes I know about subtables, but I don't understand the numbers next to it. For example: Subtable 4 (7085/68952) -> I don't understand 7085/68952 meaning.

The left value is the number of items within the lookup or subtable. The value on the right is the total number of "flat items". If no classes are used, then the numbers should be equal.

2. I knew how to add kerning classes too, but I want to ask if there is any way that I can view all kerning values of one character?

Pair positioning (and kerning) always use a pair, so I don't understand the question. Maybe it helps if you click the Code Editor toolbar button which is above the lookup/subtables.

3. Oh I see, thank you. I want to ask about others terms too, and maybe an online document that can explain them.

We expect to provide more documentation (especially related to OpenType features) later this year.