Avoiding 'convert' calls in scope.sh

[zaeph]

Runtime Environment

• Operating system and version: Arch
• Terminal emulator and version: Terminator 1.91, Terminology 1.3.2
• Python version: 3.7.2
• Ranger version/commit: 1.9.2
• Locale: en_GB

Context

We're making a handful of convert calls in scope.sh, some of which could be easily avoided if we reworked the code for previewing images.
Notably, working on #1443 which implements font previews, I couldn't get our previews to open a .png preview despite using the proper hash. It wasn't coming form w3m either because it can handle .png just fine. Reviewing the code, I've stumbled upon this:

ranger/ranger/core/actions.py

Lines 1019 to 1023 in b4cb267

	def sha1_encode(path):
	if version_info[0] < 3:
	return os.path.join(ranger.args.cachedir, sha1(path).hexdigest()) + '.jpg'
	return os.path.join(ranger.args.cachedir,
	sha1(path.encode('utf-8', 'backslashreplace')).hexdigest()) + '.jpg'

So, .jpg are hard-coded, and since the program I use to generate font previews only outputs .png or .bmp, I have to resort to a convert call which is not an elegant solution.

ranger/ranger/data/scope.sh

Lines 132 to 151 in f9de84d

	# Font
	application/font*|application/*opentype)
	preview_png="/tmp/$(basename "${IMAGE_CACHE_PATH%.*}").png"
	if fontimage -o "${preview_png}" \
	--pixelsize "120" \
	--fontname \
	--pixelsize "80" \
	--text " ABCDEFGHIJKLMNOPQRSTUVWXYZ " \
	--text " abcdefghijklmnopqrstuvwxyz " \
	--text " 0123456789.:,;(*!?') ff fl fi ffi ffl " \
	--text " The quick brown fox jumps over the lazy dog. " \
	"${FILE_PATH}";
	then
	convert -- "${preview_png}" "${IMAGE_CACHE_PATH}" \
	&& rm "${preview_png}" \
	&& exit 6
	else
	exit 1
	fi
	;;

Whilst the aforementioned is clearly something that we could avoid by modifying actions.py, there are other calls to convert inside scope.sh which we could also reconsider for the sake of efficiency.

ranger/ranger/data/scope.sh

Lines 97 to 100 in b4cb267

	# SVG
	# image/svg+xml)
	# convert "${FILE_PATH}" "${IMAGE_CACHE_PATH}" && exit 6
	# exit 1;;

ranger/ranger/data/scope.sh

Lines 102 to 111 in b4cb267

	# Image
	image/*)
	local orientation
	orientation="$( identify -format '%[EXIF:Orientation]\n' -- "${FILE_PATH}" )"
	# If orientation data is present and the image actually
	# needs rotating ("1" means no rotation)...
	if [[ -n "$orientation" && "$orientation" != 1 ]]; then
	# ...auto-rotate the image according to the EXIF data.
	convert -- "${FILE_PATH}" -auto-orient "${IMAGE_CACHE_PATH}" && exit 6
	fi

HTH

[toonn]

We should still allow the cached format to be different from the actual format though, since they might render faster. I'm thinking TIF or SVG.