Support arbitrary command line via format string

This really is the way to be free, for everyone. Thanks to the simple command line partition mechanism, this is implemented as a natural extension to the original syntax, in a completely backward compatible manner. This new syntax in fact supersedes the old syntax, but the old syntax is more convenient, and is for now preserved. Also worth mentioning, is that the cast command line is now executed via `exec', since there is no command name verification for the format string syntax. Without `exec', internal functions would be accessible as the command name, which is undesirable.
ropery · Oct 20, 2011 · 4c28261 · 4c28261
1 parent dbd2654
commit 4c28261
Showing 1 changed file with 117 additions and 63 deletions.
diff --git a/ffcast.bash b/ffcast.bash
@@ -21,12 +21,9 @@ shopt -s extglob
 
 readonly progname=ffcast progver='@VERSION@'
 readonly cast_cmd_pattern='@(ffmpeg|byzanz-record|recordmydesktop)'
-declare -a cast_args x11grab_opts
-declare -a cast_cmdline=(ffmpeg -v 1 -r 25 -- -vcodec libx264 \
-    "$(printf '%s-%(%Y%m%d-%H%M%S)T.mkv' "$progname" -1)")
-declare -- cast_cmd=${cast_cmdline[0]}
 declare -- region_select_action
-declare -i borderless=1 mod16=0 print_geometry_only=0 verbosity=0
+declare -i borderless=1 mod16=0 print_geometry_only=0 use_format_string=0
+declare -i verbosity=0
 
 #---
 # Functions
@@ -85,6 +82,48 @@ error() {
     _msg 'error: ' "$@"
 } >&2
 
+format_to_string() {
+    local fmt=$1 str c
+    printf %s "$fmt" | {
+    while IFS= read -r -n 1 -d '' c; do
+        if [[ $c == '%' ]]; then
+            IFS= read -r -n 1 -d '' c || :
+            case $c in
+                '%')
+                    str+=%
+                    ;;
+                'd')
+                    str+=$DISPLAY
+                    ;;
+                'h')
+                    str+=$h
+                    ;;
+                'w')
+                    str+=$w
+                    ;;
+                'x')
+                    str+=$_x
+                    ;;
+                'y')
+                    str+=$_y
+                    ;;
+                'X')
+                    str+=$x_
+                    ;;
+                'Y')
+                    str+=$y_
+                    ;;
+                *)
+                    str+=%$c
+                    ;;
+            esac
+        else
+            str+=$c
+        fi
+    done
+    printf %s "$str"; }
+}
+
 list_cast_cmds() {
     local -a cmds
     IFS='|' read -a cmds <<< "${cast_cmd_pattern:2: -1}"
@@ -229,9 +268,9 @@ xwininfo_get_corners() {
 usage() {
     cat <<EOF
 $progname $progver
-Usage: ${0##*/} [arguments] [ffmpeg command]
+Usage: ${0##*/} [arguments] [[%] command line]
 
-  Arguments:
+  arguments:
     -s           select a rectangular region by mouse
     -w           select a window by mouse click
     -b           include window borders hereafter
@@ -257,12 +296,6 @@ cat <<EOF
   Any number of selections are supported, e.g., -sw is valid.
   All selected regions are combined by union.
 
-  FFmpeg command is run as given, with x11grab input options inserted,
-  either replacing the first instance of '--' or, if no '--' is given,
-  after 'ffmpeg'.  You can give any valid ffmpeg command line, e.g.,
-
-    ${0##*/} -s ffmpeg -r 25 -- -f alsa -i hw:0 -vcodec libx264 cast.mkv
-
   <geospec> is usually not used.  It is intended as a way to use external
   region selection commands.  For example,
 
@@ -274,6 +307,25 @@ cat <<EOF
                  (x2,y2) = (right,bottom) offset of the region
   - wxh+x+y      (wxh) = dimensions of the region
                  (+x+y) = (+left+top) offset of the region
+
+  The command line can be specified in either of the following two ways:
+
+  1) Specify a recognized command name after arguments.  The predefined
+  command-specific x11grab options are inserted into the command line,
+  either replacing the first instance of \`--' or, if no \`--' is found,
+  after the command name. For example,
+
+    ${0##*/} -s ffmpeg -r 25 -- -f alsa -i hw:0 -vcodec libx264 cast.mkv
+
+  2) Specify a single \`%' after arguments, followed by any command line.
+  The format strings %w, %h, %x, %y, %X, %Y are replaced with the width,
+  height, left-, top- right- and bottom-offset of the selected region,
+  respectively; %d is replaced with the DISPLAY environment variable.
+  A literal \`%' must be escaped as \`%%' where necessary. For example,
+
+    ${0##*/} -w % ${0##*/} -p %wx%h+%x+%y  # Yay for recursion ;)
+
+  If no command line is specified, a default ffmpeg command line is used.
 EOF
 fi
   exit $1
@@ -331,8 +383,11 @@ declare -- i=0
 declare -a corners_list
 
 while (( $# )); do
-    if [[ $1 == $cast_cmd_pattern ]]; then
-        cast_cmd=$1
+    if [[ $1 == '%' ]]; then
+        use_format_string=1
+        shift
+        break
+    elif [[ $1 == $cast_cmd_pattern ]]; then
         break
     fi
     # The rest are geometry specifications
@@ -405,57 +460,56 @@ if (( h < h_old )); then
 fi
 
 #---
-# Validate cast command, set up x11grab options
+# Inject selection geometry into cast command line and execute
 
-if shift; then
-    cast_cmdline=("$cast_cmd" "$@")
-fi
-
-# Important validation
-case $cast_cmd in
-    ffmpeg)
-        x11grab_opts=(-f x11grab -s "${w}x${h}" -i "${DISPLAY}+${_x},${_y}")
-        ;;
-    byzanz-record)
-        x11grab_opts=(--x="$_x" --y="$_y" --width="$w" --height="$h" \
-            --display="$DISPLAY")
-        ;;
-    recordmydesktop)
-        x11grab_opts=(-display "$DISPLAY" -width "$w" -height "$h")
-        # As of recordMyDesktop 0.3.8.1, x- and y-offsets default to 0, but
-        # -x and -y don't accept 0 as an argument. #FAIL
-        (( _x )) && x11grab_opts+=(-x "$_x")
-        (( _y )) && x11grab_opts+=(-y "$_y")
-        ;;
-    *)
-        error "invalid cast command: \`%s'" "$cast_cmd"
-        exit 1
-        ;;
-esac
-
-readonly cast_cmd
-
-#---
-# Insert x11grab options into cast command line.
-
-set -- "${cast_cmdline[@]}"
-
-if ! shift; then
-    error 'no cast command line specified'
-    exit 1
-fi
+declare -- cast_cmd=$1
+declare -a cast_args
 
-while (( $# )) && [[ $1 != '--' ]]; do
-    cast_args+=("$1")
-    shift
-done
-
-if shift; then  # got '--'
-    cast_args+=("${x11grab_opts[@]}" "$@")
-else  # no '--', then put x11grab options at first
-    cast_args=("${x11grab_opts[@]}" "${cast_args[@]}")
+if shift; then
+    if (( use_format_string )); then
+        while (( $# )); do
+            cast_args+=("$(format_to_string "$1")")
+            shift
+        done
+    else
+        declare -a x11grab_opts
+        case $cast_cmd in
+            byzanz-record)
+                x11grab_opts=(--x="$_x" --y="$_y" --width="$w" --height="$h" \
+                    --display="$DISPLAY")
+                ;;
+            ffmpeg)
+                x11grab_opts=(-f x11grab -s "${w}x$h" -i "$DISPLAY+$_x,$_y")
+                ;;
+            recordmydesktop)
+                x11grab_opts=(-display "$DISPLAY" -width "$w" -height "$h")
+                # As of recordMyDesktop 0.3.8.1, x- and y-offsets default to 0,
+                # but -x and -y don't accept 0 as an argument. #FAIL
+                (( _x )) && x11grab_opts+=(-x "$_x")
+                (( _y )) && x11grab_opts+=(-y "$_y")
+                ;;
+            *)
+                error "invalid cast command: \`%s'" "$cast_cmd"
+                exit 1
+                ;;
+        esac
+
+        while (( $# )) && [[ $1 != '--' ]]; do
+            cast_args+=("$1")
+            shift
+        done
+        if shift; then
+            cast_args+=("${x11grab_opts[@]}" "$@")
+        else
+            cast_args=("${x11grab_opts[@]}" "${cast_args[@]}")
+        fi
+    fi
+else
+    cast_cmd=ffmpeg
+    cast_args=(-r 25 -f x11grab -s "${w}x$h" -i "$DISPLAY+$_x,$_y" -vcodec
+        libx264 "$(printf '%s-%(%Y%m%d-%H%M%S)T.mkv' "$progname" -1)")
 fi
 
-debug_run "${cast_cmd}" "${cast_args[@]}"
+debug_run exec "$cast_cmd" "${cast_args[@]}"
 
 # vim:ts=4:sw=4:et:cc=80: