On 4/20/2018 5:52 AM, Henri Menke wrote:
Dear list,
I'm trying to determine the kerning between two letters (here A and V). For the
sake of this example I'm inserting negative kerning of -400/1000 em. However,
when I examine the kern in the kerning callback this massive enhancement of the
negative kern doesn't show up but I only see the kerning from the font itself.
How can I access the user-defined kerns? MWE is below.
no real answer but there is nreal need to go nuts in your code
local function show_kerns(head)
local glyph = node.id("glyph")
for item in node.traverse(head) do
if item.id == glyph then
local char = item.char
if char == 65 then
local font = item.font
print(font,char)
local next = item.next
if next.id == glyph then
local nextchar = next.char
local nextfont = next.font
local data = fonts.hashes.identifiers[font]
local kern =
fonts.handlers.otf.getkern(data,char,nextchar)
print(kern)
end
end
end
end
end
that said, what you could do is the loop over the to be packed list (so
later) and then look for a left math node and then start looking at the
characters and kerns
function foo(head)
local glyph = node.id("glyph")
local math = node.id("math")
local current = head
while current do
if current.id == math then
current = current.next
while current do
if current.id == math then
break
elseif current.id == glyph then
local char = current.char
if char == 0x1D434 then
local font = current.font
local next = current.next
if next.id == glyph then
local nextchar = next.char
if char == 0x1D449 then
local nextfont = next.font
local data = fonts.hashes.identifiers[font]
local kern =
fonts.handlers.otf.getkern(data,char,nextchar)
print(char,nextchar,kern)
end
end
current = next
else
current = current.next
end
else
current = current.next
end
end
end
current = current.next
end
end
depending on the macro package that you need to look at math unicodes
and even then you might not see a print because there is already a kern
keep in mind that this kind of hackery is macro package dependent so
your plain test might work out different elsewhere (i haven't tested it
as i operate in a different environment)
Cheers, Henri
---
\input luaotfload.sty
\directlua{
local function show_kerns(head)
for item in node.traverse(head) do
if item.id == node.id("glyph") and item.char == 65 then
% Get current char and font
local nut = node.direct.todirect(item)
local char = node.direct.getchar(nut)
local font = node.direct.getfont(nut)
print(font)
% Get next char and font
local next = node.next(item)
local nextnut = node.direct.todirect(next)
local nextchar = node.direct.getchar(nextnut)
local nextfont = node.direct.getfont(nextnut)
% Determine the kern
local data = fonts.hashes.identifiers[font]
local kern = fonts.handlers.otf.getkern(data,char,nextchar)
print(kern)
end
end
end
%
luatexbase.add_to_callback("kerning",
function(head)
show_kerns(head)
node.kerning(head)
end,
"show_kerns")
}
\directlua{
fonts.handlers.otf.addfeature{
name = "ktest",
type = "kern",
data = { ["A"] = { ["V"] = -400 } } % make them overlap for the example
}
}
\font\test="Latin Modern Roman:+ktest"\test
AV
\bye
--
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