Hi Hans (and anyone else interested in synctex),
On Fri, Dec 8, 2023 at 11:38 (-0400), Jim wrote:
> Hi Hans,
> On Fri, Dec 8, 2023 at 15:03 (+0100), Hans Hagen wrote:
>> On 12/7/2023 7:23 PM, Jim wrote:
>>> Hi,
>>> In mtx-synctex.lua, inside
>>> local function findlocation(filename,page,xpos,ypos,tolerance)
>>> there is the following code:
>>> for s=1,tolerance,max(tolerance//10,1) do
>>> locate( s, 0) if fi ~= 0 then tl = s ; goto done end
>>> locate(-s, 0) if fi ~= 0 then tl = s ; goto done end
>>> locate( s, s) if fi ~= 0 then tl = s ; goto done end
>>> locate( s,-s) if fi ~= 0 then tl = s ; goto done end
>>> locate(-s, s) if fi ~= 0 then tl = s ; goto done end
>>> locate(-s,-s) if fi ~= 0 then tl = s ; goto done end
>>> end
>>> Is the omission of the
>>> locate(0, s) ...
>>> and
>>> locate(0, -s) ...
>>> cases intentional, or is that an oversight?
>>> If intentional, can someone explain the rationale to me?
>> it's too long ago to remember the reason ... did you test with and without?
> I did not. Yet.
> But on your suggestion, I will give it a try and get back to you.
I modified mtx-synctex.lua as follows:
% diff /usr/local/context/tex/texmf-context/scripts/context/lua/mtx-synctex.lua
mtx-synctex-jd.lua
279a280
> -- JD added (0, +/-s) cases for testing
282a284,285
> locate( 0, s) if fi ~= 0 then tl = s ; goto done end
> locate( 0,-s) if fi ~= 0 then tl = s ; goto done end
and then wrote the following quick and dirty shell script to create log
files for comparison:
---------------------------------------------------------------------
#! /bin/zsh
# File: compare-my-synctex-version
# Author: Jim Diamond
# Created: 2023/12/08 13:27:23
#
# Purpose: Run some tests to compare ConTeXt's mtx-synctex-lua to
# my own version, vis-a-vis the backward-search
# functionality.
#
# Notes: Assumes $1 is a valid ConTeXt synctex file,
# $2 is a valid page within that file, and
# $3, if present, is a valid
DEFAULT_TOLERANCE=300
if [[ $# < 2 || $# > 3 || ! -r $1 ]]
then
echo >&2 "Usage: $0 <synctex file> <page> [tolerance]"
echo >&2 " tolerance default is $DEFAULT_TOLERANCE."
exit 1
fi
st_file=$1
page=$2
if [[ $3 != "" ]]
then
tolerance=$3
else
tolerance=$DEFAULT_TOLERANCE
fi
x_vals=`seq 100 50 550`
y_vals=`seq 100 50 700`
old_results=${st_file}_page_${page}_tol_${tolerance}_using_current.out
new_results=${st_file}_page_${page}_tol_${tolerance}_using_new.out
if [[ -e $old_results || -e $new_results ]]
then
printf >&2 "$0: at least one of\n\t%s\nor\n\t%s\nexists; quitting.\n" \
$old_results $new_results
exit 1
fi
# Get rid of the extra newline from mtxrun as done below.
for x in $=x_vals
do
for y in $=y_vals
do
printf "%3d, %3d: " $x $y
out=`mtxrun --script synctex --goto --direct \
--page=$page --x=$x --y=$y --tolerance=$tolerance $st_file`
echo $out
done
done | tee $old_results
echo
for x in $=x_vals
do
for y in $=y_vals
do
printf "%3d, %3d: " $x $y
out=`mtxrun --script mtx-synctex-jd.lua --goto --direct \
--page=$page --x=$x --y=$y --tolerance=$tolerance $st_file`
echo $out
done
done | tee $new_results
---------------------------------------------------------------------
and ran it on one page of one synctex file for a few different values of
tolerance (300, 200, 100 and 50). To briefly summarize, the modified
script found a small number of matches that the original script didn't,
occasionally the line number was different (almost always by 1, but a few
times more), and the tolerance returned by this test version was also <= the
tolerance returned by the current version.
Admittedly, with the other two directions added in, a more extensive test
(a total of a bit under 14 minutes CPU time on a Ryzen 4700U) showed the
new version is about 0.5% slower, so there is a very minor downside. (I'd
happily spend the extra matches for the minuscule amount of CPU time, but
others may not.)
Cheers.
Jim
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