move image utils to utils.image

cogs/emoji.py

@@ -21,6 +21,7 @@ import discord
 from discord.ext import commands
 
 import utils
+import utils.image
 from utils import errors
 
 class Emotes:
@@ -144,82 +145,12 @@ class Emotes:
 		# resize_until_small is normally blocking, because wand is.
 		# run_in_executor is magic that makes it non blocking somehow.
 		# also, None as the executor arg means "use the loop's default executor"
-		image_data = await self.bot.loop.run_in_executor(None, self.resize_until_small, image_data)
+		image_data = await self.bot.loop.run_in_executor(None, utils.image.resize_until_small, image_data)
 		return await guild.create_custom_emoji(
 			name=name,
 			image=image_data.read(),
 			reason=f'Created by {utils.format_user(self.bot, author_id)}')
 
-	@staticmethod
-	def is_animated(image_data: bytes):
-		"""Return whether the image data is animated, or raise InvalidImageError if it's not an image."""
-		type = imghdr.what(None, image_data)
-		if type == 'gif':
-			return True
-		elif type in ('png', 'jpeg'):
-			return False
-		else:
-			raise errors.InvalidImageError
-
-	@classmethod
-	def size(cls, data: io.BytesIO):
-		"""return the size, in bytes, of the data a BytesIO object represents"""
-		with cls.preserve_position(data):
-			data.seek(0, io.SEEK_END)
-			return data.tell()
-
-	class preserve_position(contextlib.AbstractContextManager):
-		def __init__(self, fp):
-			self.fp = fp
-			self.old_pos = fp.tell()
-
-		def __exit__(self, *excinfo):
-			self.fp.seek(self.old_pos)
-
-	@classmethod
-	def resize_until_small(cls, image_data: io.BytesIO):
-		"""If the image_data is bigger than 256KB, resize it until it's not"""
-		# It's important that we only attempt to resize the image when we have to,
-		# ie when it exceeds the Discord limit of 256KiB.
-		# Apparently some <256KiB images become larger when we attempt to resize them,
-		# so resizing sometimes does more harm than good.
-		max_resolution = 128  # pixels
-		size = cls.size(image_data)
-		while size > 256 * 2**10 and max_resolution >= 32:  # don't resize past 32x32 or 256KiB
-			logger.debug('image size too big (%s bytes)', size)
-			logger.debug('attempting resize to %s*%s pixels', max_resolution, max_resolution)
-			image_data = cls.thumbnail(image_data, (max_resolution, max_resolution))
-			size = cls.size(image_data)
-			max_resolution //= 2
-		return image_data
-
-	@classmethod
-	def thumbnail(cls, image_data: io.BytesIO, max_size=(128, 128)):
-		"""Resize an image in place to no more than max_size pixels, preserving aspect ratio."""
-		# Credit to @Liara#0001 (ID 136900814408122368)
-		# https://gitlab.com/Pandentia/element-zero/blob/47bc8eeeecc7d353ec66e1ef5235adab98ca9635/element_zero/cogs/emoji.py#L243-247
-		image = Image(blob=image_data)
-		image.resize(*cls.scale_resolution((image.width, image.height), max_size))
-		# we create a new buffer here because there's wand errors otherwise.
-		# specific error:
-		# MissingDelegateError: no decode delegate for this image format `' @ error/blob.c/BlobToImage/353
-		out = io.BytesIO()
-		image.save(file=out)
-		out.seek(0)
-		return out
-
-	@staticmethod
-	def scale_resolution(old_res, new_res):
-		# https://stackoverflow.com/a/6565988
-		"""Resize a resolution, preserving aspect ratio. Returned w,h will be <= new_res"""
-		old_width, old_height = old_res
-		new_width, new_height = new_res
-		old_ratio = old_width / old_height
-		new_ratio = new_width / new_height
-		if new_ratio > old_ratio:
-			return (old_width * new_height//old_height, new_height)
-		return new_width, old_height * new_width//old_width
-
 	@commands.command()
 	async def remove(self, context, name):
 		emote = await self.disambiguate(context, name)

utils/image.py

@@ -0,0 +1,67 @@
+import io
+import logging
+import contextlib
+
+logger = logging.getLogger(__name__)
+
+try:
+	from wand.image import Image
+except ImportError:
+	logger.warn('Failed to import wand.image. Image manipulation functions will be unavailable.')
+
+from utils import errors
+
+def resize_until_small(image_data: io.BytesIO):
+	"""If the image_data is bigger than 256KB, resize it until it's not"""
+	# It's important that we only attempt to resize the image when we have to,
+	# ie when it exceeds the Discord limit of 256KiB.
+	# Apparently some <256KiB images become larger when we attempt to resize them,
+	# so resizing sometimes does more harm than good.
+	max_resolution = 128  # pixels
+	image_size = size(image_data)
+	while image_size > 256 * 2**10 and max_resolution >= 32:  # don't resize past 32x32 or 256KiB
+		logger.debug('image size too big (%s bytes)', image_size)
+		logger.debug('attempting resize to %s*%s pixels', max_resolution, max_resolution)
+		image_data = thumbnail(image_data, (max_resolution, max_resolution))
+		image_size = size(image_data)
+		max_resolution //= 2
+	return image_data
+
+def size(data: io.BytesIO):
+	"""return the size, in bytes, of the data a BytesIO object represents"""
+	with preserve_position(data):
+		data.seek(0, io.SEEK_END)
+		return data.tell()
+
+def thumbnail(image_data: io.BytesIO, max_size=(128, 128)):
+	"""Resize an image in place to no more than max_size pixels, preserving aspect ratio."""
+	# Credit to @Liara#0001 (ID 136900814408122368)
+	# https://gitlab.com/Pandentia/element-zero/blob/47bc8eeeecc7d353ec66e1ef5235adab98ca9635/element_zero/cogs/emoji.py#L243-247
+	image = Image(blob=image_data)
+	image.resize(*scale_resolution((image.width, image.height), max_size))
+	# we create a new buffer here because there's wand errors otherwise.
+	# specific error:
+	# MissingDelegateError: no decode delegate for this image format `' @ error/blob.c/BlobToImage/353
+	out = io.BytesIO()
+	image.save(file=out)
+	out.seek(0)
+	return out
+
+def scale_resolution(old_res, new_res):
+	# https://stackoverflow.com/a/6565988
+	"""Resize a resolution, preserving aspect ratio. Returned w,h will be <= new_res"""
+	old_width, old_height = old_res
+	new_width, new_height = new_res
+	old_ratio = old_width / old_height
+	new_ratio = new_width / new_height
+	if new_ratio > old_ratio:
+		return (old_width * new_height//old_height, new_height)
+	return new_width, old_height * new_width//old_width
+
+class preserve_position(contextlib.AbstractContextManager):
+	def __init__(self, fp):
+		self.fp = fp
+		self.old_pos = fp.tell()
+
+	def __exit__(self, *excinfo):
+		self.fp.seek(self.old_pos)