Hi,
for a text background graphic I need the character box sizes of a given
string. I managed to collect the needed info (width, height, depth,
kerns), but there is still some flaw in the kerning part.
For example:
"VATo" is printed out (in the shell) as
V 12 11 0
*kerning -85721.088
A 10 11 0
*kerning -64487.424
T 10 11 0
*kerning -64487.424
o 7 7 0
The character stands in the first column, followed by width, height and
depth (in pixel). The "*kerning" line shows the kerning value (in sp) of
the neighbouring character pair. No problem here.
But "A much longer Test graphic VATo"
A 12 11 0
5 0 0
m 13 7 0
*kerning -21233.664
u 8 7 0
c 7 7 0
*kerning -21233.664
h 8 11 0
5 0 0
l 4 11 0
o 7 7 0
n 9 7 0
g 8 7 3
e 7 7 0
r 6 7 0
5 0 0
T 11 11 0
e 7 7 0
s 6 7 0
t 6 10 0
5 0 0
g 8 7 3
r 6 7 0
a 8 7 0
p 9 7 3
h 8 11 0
i 4 10 0
c 7 7 0
5 0 0
V 12 11 0
A 12 11 0
T 11 11 0
o 7 7 0
sees no kerning for "VATo" (although the text is printed with the
correct kerning).
What am I missing? Example code is attached.
Peter
-- http://lua-users.org/wiki/SimpleRound
local function round(num, idp)
local mult = 10^(idp or 0)
return math.floor(num * mult + 0.5) / mult
end
local function topixel(n)
local dimenfactor = 1/49336
return n*dimenfactor
end
function foo_box(text)
local s = text
local tfmdata = fonts.ids[font.current()]
if tfmdata then
local characters = tfmdata.characters
local char = { }
local lastchar
local u,width,height,depth,kerns
for i= 1,string.len(s) do
u = utf.byte(string.sub(s,i,i))
if not char[u] then
width = characters[u].width or 0
height = characters[u].height or 0
depth = characters[u].depth or 0
if lastchar then kerns = characters[lastchar].kerns
if kerns then
kern= kerns[u] or 0
if not(kern==0) then print("*kerning",kern) end
end
else kern = 0
end
char[u] = {
w = round(topixel((width+kern))),
h = round(topixel(height)),
d = round(topixel(depth)) }
end
lastchar = u
print(string.sub(s,i,i),char[u].w,char[u].h,char[u].d)
end
end
end
\registerctxluafile{box}{0.1}
\starttext
\ctxlua{foo_box("A much longer Test graphic VATo")}
\ctxlua{foo_box("VATo")}
\stoptext
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