Sixel previews with lf

1 files changed, 85 insertions, 45 deletions

diff --git a/.config/lf/scope b/.config/lf/scope
index cc55669..139a5af 100755
--- a/.config/lf/scope
+++ b/.config/lf/scope
@@ -1,56 +1,96 @@
 #!/bin/sh
 
-# File preview handler for lf.
-
 set -C -f
-IFS="$(printf '%b_' '\n')"; IFS="${IFS%_}"
-
-image() {
-	if [ -f "$1" ] && [ -n "$DISPLAY" ] && [ -z "$WAYLAND_DISPLAY" ] && command -V ueberzug >/dev/null 2>&1; then
-		printf '{"action": "add", "identifier": "PREVIEW", "x": "%s", "y": "%s", "width": "%s", "height": "%s", "scaler": "contain", "path": "%s"}\n' "$4" "$5" "$(($2-1))" "$(($3-1))" "$1" > "$FIFO_UEBERZUG"
-	else
-		mediainfo "$6"
-	fi
+IFS="$(printf '%b_' '\n')"
+IFS="${IFS%_}"
+
+PREVIEW_DIR="${XDG_CACHE_HOME:-$HOME/.cache}/lf"
+PREVIEW_WIDTH=600 # px
+
+# TODO: Render in the original width when it's smaller than PREVIEW_WIDTH
+
+# PrefixGen: generates a hash prefix for the given file
+# This is a unique identifier for the file to preview
+PrefixGen() {
+	sha256sum "$(readlink -f "$1")" | cut -d' ' -f1
 }
 
-ifub() {
-	[ -n "$DISPLAY" ] && [ -z "$WAYLAND_DISPLAY" ] && command -V ueberzug >/dev/null 2>&1
+# SuffixGen: generates a hash suffix for the given file
+# This suffix is used to determine if the preview is outdated
+SuffixGen() {
+	stat -Lc "%Y" "$1"
 }
 
-# Note that the cache file name is a function of file information, meaning if
-# an image appears in multiple places across the machine, it will not have to
-# be regenerated once seen.
+# Prevent recursive thumbnails (if the file ends in .six)
+[ "${1##*.}" = "six" ] && cat "$1" && exit 1
 
 case "$(file --dereference --brief --mime-type -- "$1")" in
-	image/avif) CACHE="${XDG_CACHE_HOME:-$HOME/.cache}/lf/thumb.$(stat --printf '%n\0%i\0%F\0%s\0%W\0%Y' -- "$(readlink -f "$1")" | sha256sum | cut -d' ' -f1)"
-		[ ! -f "$CACHE" ] && convert "$1" "$CACHE.jpg"
-		image "$CACHE.jpg" "$2" "$3" "$4" "$5" "$1" ;;
-	image/vnd.djvu)
-		CACHE="${XDG_CACHE_HOME:-$HOME/.cache}/lf/thumb.$(stat --printf '%n\0%i\0%F\0%s\0%W\0%Y' -- "$(readlink -f "$1")" | sha256sum | cut -d' ' -f1)"
-		[ ! -f "$CACHE" ] && djvused "$1" -e 'select 1; save-page-with /dev/stdout' | convert -density 200 - "$CACHE.jpg" > /dev/null 2>&1
-		image "$CACHE.jpg" "$2" "$3" "$4" "$5" "$1" ;;
-	image/*) image "$1" "$2" "$3" "$4" "$5" "$1" ;;
-	text/html) lynx -width="$4" -display_charset=utf-8 -dump "$1" ;;
-	text/troff) man ./ "$1" | col -b ;;
-	text/* | */xml | application/json | application/x-ndjson) bat --terminal-width "$(($4-2))" -f "$1" ;;
-	audio/* | application/octet-stream) mediainfo "$1" || exit 1 ;;
-	video/* )
-		CACHE="${XDG_CACHE_HOME:-$HOME/.cache}/lf/thumb.$(stat --printf '%n\0%i\0%F\0%s\0%W\0%Y' -- "$(readlink -f "$1")" | sha256sum | cut -d' ' -f1)"
-		[ ! -f "$CACHE" ] && ffmpegthumbnailer -i "$1" -o "$CACHE" -s 0
-		image "$CACHE" "$2" "$3" "$4" "$5" "$1"
-		;;
-	*/pdf)
-		CACHE="${XDG_CACHE_HOME:-$HOME/.cache}/lf/thumb.$(stat --printf '%n\0%i\0%F\0%s\0%W\0%Y' -- "$(readlink -f "$1")" | sha256sum | cut -d' ' -f1)"
-		[ ! -f "$CACHE.jpg" ] && pdftoppm -jpeg -f 1 -singlefile "$1" "$CACHE"
-		image "$CACHE.jpg" "$2" "$3" "$4" "$5" "$1"
-		;;
-	*/epub+zip|*/mobi*)
-		CACHE="${XDG_CACHE_HOME:-$HOME/.cache}/lf/thumb.$(stat --printf '%n\0%i\0%F\0%s\0%W\0%Y' -- "$(readlink -f "$1")" | sha256sum | cut -d' ' -f1)"
-		[ ! -f "$CACHE.jpg" ] && gnome-epub-thumbnailer "$1" "$CACHE.jpg"
-		image "$CACHE.jpg" "$2" "$3" "$4" "$5" "$1"
-		;;
-	application/*zip) atool --list -- "$1" ;;
-	*opendocument*) odt2txt "$1" ;;
-	application/pgp-encrypted) gpg -d -- "$1" ;;
+text/html)
+	lynx -width="$4" -display_charset=utf-8 -dump "$1"
+	;;
+text/troff)
+	man ./ "$1" | col -b
+	;;
+text/* | */xml | application/json | application/x-ndjson)
+	bat --terminal-width "$(($4 - 2))" -f "$1"
+	;;
+audio/* | application/octet-stream)
+	mediainfo "$1" || exit 1
+	;;
+image/vnd.djvu)
+	prefix="$(PrefixGen "$1")"
+	suffix="$(SuffixGen "$1")"
+	filename="$prefix-$suffix"
+	[ ! -f "$PREVIEW_DIR/$filename.six" ] && {
+		rm -f "$PREVIEW_DIR/$prefix-*"
+		djvused "$1" -e 'select 1; save-page-with /dev/stdout' |
+			convert djvu:- png:- |
+			img2sixel -S -E size -q high -w $PREVIEW_WIDTH -o "$PREVIEW_DIR/$filename.six"
+	}
+	cat "$PREVIEW_DIR/$filename.six"
+	;;
+image/*)
+	prefix="$(PrefixGen "$1")"
+	suffix="$(SuffixGen "$1")"
+	filename="$prefix-$suffix"
+	[ ! -f "$PREVIEW_DIR/$filename.six" ] && {
+		rm -f "$PREVIEW_DIR/$prefix-*"
+		img2sixel -S -E size -q high -w $PREVIEW_WIDTH "$1" -o "$PREVIEW_DIR/$filename.six"
+	}
+	cat "$PREVIEW_DIR/$filename.six"
+	;;
+*/pdf)
+	prefix="$(PrefixGen "$1")"
+	suffix="$(SuffixGen "$1")"
+	filename="$prefix-$suffix"
+	[ ! -f "$PREVIEW_DIR/$filename.six" ] && {
+		rm -f "$PREVIEW_DIR/$prefix-*"
+		pdftocairo -singlefile -scale-to-x $PREVIEW_WIDTH -scale-to-y -1 -png "$1" - |
+			img2sixel -S -E size -q high -o "$PREVIEW_DIR/$filename.six"
+	}
+	cat "$PREVIEW_DIR/$filename.six"
+	;;
+video/*)
+	prefix="$(PrefixGen "$1")"
+	suffix="$(SuffixGen "$1")"
+	filename="$prefix-$suffix"
+	# XXX: thumbnail seems to get re-generated every time the file is selected
+	[ ! -f "$PREVIEW_DIR/$filename.six" ] && {
+		rm -f "$PREVIEW_DIR/$prefix-*"
+		ffmpegthumbnailer -i "$1" -s 0 -c png -f -o - |
+			img2sixel -S -E size -q high -w $PREVIEW_WIDTH -o "$PREVIEW_DIR/$filename.six"
+	}
+	cat "$PREVIEW_DIR/$filename.six"
+	;;
+application/*zip)
+	atool --list -- "$1"
+	;;
+*opendocument*)
+	odt2txt "$1"
+	;;
+application/pgp-encrypted)
+	gpg -d -- "$1"
+	;;
 esac
+
 exit 1