pwb_tutorial_04_centering

#!/usr/bin/env bash

## BEGIN_DOC
## This example introduces PWB actions for
## determining screen dimensions and for setting
## centering margins around the content.
##
## The source lines are surveyed to identify
## the longest line.  The longest line value
## is used to set margins that will center the
## just-large-enough content area on the console.
## END_DOC

# 1. Enable the builtin(s)
enable pwb
enable ate

# 2. Create line-printing function
print_line()
{
    local -i index="$1"
    local data_name="$2"
    local -i chars_limit="$3"

    ate get_row "$data_name" "$index"
    local line="${ATE_ARRAY[0]}"

    printf "%-*s" "$chars_limit" "${line:0:$chars_limit}"
}

# 3. Get data
declare ftable
ate declare ftable 1
ate get_array_name ftable
declare -n ftarray="$ATE_VALUE"

#  Diff #1: Note longest file name while adding to the table
#           This could also be done using 'ate walk_rows'
declare -i curlen maxlen=0
for fname in *; do
    ftarray+=( "$fname" )
    curlen="${#fname}"
    (( maxlen = curlen > maxlen ? curlen : maxlen ))
done
ftarray=( * )
unset -n ftarray
ate index_rows ftable

declare -i file_count
ate get_row_count ftable -v file_count

#4 Declare the pwb handle
declare phandle
pwb declare phandle ftable "$file_count" print_line

# Diff #2 Set margins to center the content
pwb get_dimensions
declare -i swide="${PWB_ASSOC[screen_cols]}"
declare -i lrmargin=$(( (swide - maxlen) / 2 ))
pwb set_margins phandle 5 "$lrmargin"

#5 Start the interaction
pwb init
pwb start phandle
pwb restore