'each' now supports format strings %i, %n, %t

Try: ffcast -ws each echo %%%%%n-%t_%i

doc/ffcast.1.pod

@@ -99,7 +99,8 @@ Note I<E<lt>argsE<gt>> to an internal I<E<lt>sub-commandE<gt>> are not
 automatically subject to format string substitution, although sub-commands may
 choose to do format string substitution on their own.
 
-The following format strings are supported:
+The following format strings are supported for all external commands, as well
+as the sub-commands B<png> and B<rec>:
 
 =over 4
 
@@ -147,12 +148,30 @@ Equivalent to B<%wx%h+%x+%y>
 
 Equivalent to B<%wx%h>
 
-=item B<%%>
+=back
+
+The B<each> sub-command supports the following format strings:
+
+=over 4
+
+=item B<%i>
 
-A literal %
+The identifier of the selection
+
+=item B<%n>
+
+This being the I<n>th selection
+
+=item B<%t>
+
+The type of the selection
 
 =back
 
+The format string B<%%> is always substituted for a literal C<%>, whenever
+format string substitution is performed. Therefore, multiple levels of
+escaping may be required when sub-commands are chained.
+
 =head1 GEOMETRY SPECIFICATION
 
 A I<E<lt>geospecE<gt>> specifies a geometry in one of the following forms:
@@ -228,9 +247,10 @@ head 0, using either of:
     ffcast -ww ffcast -i -x 0 -g %g png
 
 Take three individual screenshots of heads 0, 1, 2, one by one. The B<each>
-command runs a command for each user selection consecutively:
+command runs a command for each user selection consecutively; it supports
+several format strings:
 
-    ffcast -x 0,1,2 each png head_%g.png
+    ffcast -x 0,1,2 each png %t_%i-%s.png
 
 =head1 SEE ALSO
 

src/subcmd.bash

@@ -52,18 +52,27 @@ sub_cmdfuncs['%']=run_external_command
 sub_commands['dump']='dump region-related variables in bash code'
 sub_cmdfuncs['dump']=subcmd_dump
 subcmd_dump() {
-    (( ! ${#head_ids[@]} )) || declare -p heads
-    declare -p {root,}{w,h} _{x,y} {x,y}_ offsets_list
+    declare -p {root,}{w,h} _{x,y} {x,y}_ offsets_list \
+        rects heads regions windows
 }
 
 sub_commands['each']='run a sub-command on each selection consecutively'
 sub_cmdfuncs['each']=subcmd_each
 subcmd_each() {
     : 'usage: each [sub-command]'
-    local offsets;
-    for offsets in "${offsets_list[@]}"; do
+    local -A fmtmap_each=(['i']='$i' ['n']='$((n + 1))' ['t']='$t')
+    local -a args
+    local -i n
+    local -- i t
+    for ((n=0; n<${#rects[@]}; ++n)); do
+        local -n ref_rect=${rects[n]}
+        t=${rects[n]%%\[*}; t=${t%s}
+        i=${rects[n]#*\[}; i=${i%\]}
+        substitute_format_strings fmtmap_each args "$@"
+        offsets=$ref_rect
         set_region_vars_by_offsets 1 || continue
-        run_subcmd_or_command "$@"
+        run_subcmd_or_command "${args[@]}"
+        unset -n ref_rect
     done
 }
 
@@ -99,7 +108,7 @@ sub_commands['png']='take a screenshot and save it as a PNG image'
 sub_cmdfuncs['png']=subcmd_png
 subcmd_png() {
     : 'usage: png [filename]'
-    local -a args=()
+    local -a args
     substitute_format_strings fmtmap args "$@"
     : ${args[0]="$(printf '%s-%(%s)T_%dx%d.png' screenshot -1 "$w" "$h")"}
     msg 'saving to file: %s' "${args[-1]}"  # unreliable
@@ -113,7 +122,7 @@ sub_commands['rec']='record a screencast'
 sub_cmdfuncs['rec']=subcmd_rec
 subcmd_rec() {
     : 'usage: rec [-m <n>] [filename.ext]'
-    local -a args=()
+    local -a args
     local -a v=(fatal error info verbose debug)  # ffmpeg loglevels
     local m=1 opt
     OPTIND=1