Re: [css-inline] Alignment of Drop Caps

On Thu, May 15, 2014 at 11:16 PM, Dave Cramer <dauwhe@gmail.com> wrote:

>
> The ultimate question, of course, is what to call the subject itself. Are
> they drop caps? Initial caps? Drop initials? Versals? Lettrines?
>

They occur in scripts, such as Thai, that do not have capital letters, so
better to avoid using the term "caps".  I would call them "dropped initial
letters".

Generalizing from what I know about Thai and Latin scripts, the principles
seem to be as follows. A given font and script determine two alignment
points based on the top and bottom of "normal initial" letters in that
script. "Normal initial" implies capital letters for a bicameral script,
and without ascenders, descenders or combining marks.  (The initial letter
depth is typically going to be the point that would be aligned with the
Latin baseline in a line that mixes that script with Latin.) Call these two
alignment points the initial letter top and initial letter bottom.

Then:

- align the initial letter top of the dropped initial with the initial
letter top of the rest of the first line,
- align the initial letter bottom of the dropped initial with the initial
letter bottom of the nth-line
- choose the font size based on these alignments and the number of lines
that the initial letter is being dropped

There are two special cases to handle:

- When you have an abnormal initial glyph cluster that extends above the
normal initial letter top, then it just sticks out above the first line.
 However, in this case you have to pay attention to the positioning of the
baseline of the first line of the paragraph.  Generally you would want the
extra height of the initial letter not to affect the position of the first
baseline unless it would get too close to something above it. Note that the
extra height could be quite substantial with Thai, where you have multiple
levels of diacritics.

- When you have an abnormal initial glyph cluster that extends below the
normal initial letter bottom, there seem to be several reasonable
strategies:

a) Align normally, but indent sufficient additional lines to clear the
bottom of the cluster
b) Align based on the bottom of the bounding box of the drop initial,
increase the number of lines and don't change the font size
c) Align based on the bottom of the bounding box of the drop initial, keep
the number of lines the same, but scale the font

(I would need to do more research to see which of these three strategies is
most common for Thai.)  Liam, is this consistent with what you have seen
for other scripts?  I would guess it's probably correct for Chinese and
Devanagari, but I have no idea how dropped initial letters work in Arabic.

James