Le 25/06/2011 21:20, Arno Trautmann a écrit :
Hi all,
I'm becoming desparate and I guess it's only a small error I'm making. I
try to (please don't ask why …) to colorize all letters in a document. I
do so by registering the following function in the post_linebreak_filter:
local color_push = node.new(WHAT,COL)
local color_pop = node.new(WHAT,COL)
color_push.cmd = 1
color_pop.cmd = 2
uppercasecolor = function (head)
for line in node.traverse_id(HLIST,head) do
for letter in node.traverse_id(GLYPH,line.head) do
color_push.data = math.random().." .5 .5 rg"
node.insert_before(line.head,letter,node.copy(color_push))
node.insert_after(line.head,letter,node.copy(color_pop))
end
end
return head
end
This works fine /except/ for the first letter of every line except the
first line. So the first line is fine, but for every following line in a
paragraph, the first letter is not colored.
As already remarked by Khaled, you have to do:
line.head = node.insert_before...
The thing is the node is inserted, but the head field of the hlist still
points to the old head, so the new head is ignored.
I also get warnings
LuaTeX warning: pop empty color page stack 0
so it seems that the color_push does not work in that cases?
It is simply ignored, so the color stack is still empty when the first
pop occurs.
But I don't
see what I'm doing wrong …
To understand what mistake I'm making, I tried to use
letter = node.first_glyph(line) [or line.head?]
instead of the for loop, but then letter doesn't seem to be a node at all.
That should be node.first_glyph(line.head) (otherwise you browse over
the list of nodes of which the line is part, not the list of nodes which
is the contents of the line). But anyway node.first_glyph only finds
glyph nodes (id 37) with subtype 1 (real glyphs). It's not quite clear
to me what's the difference between a glyph-character (subtype 0) and a
glyph-glyph (subtype 1), but the function is concerned with the latter only.
Best,
Paul
