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thumbnailing: Switch to libvips, from PIL/pillow.
This is done in as much of a drop-in fashion as possible. Note that libvips does not support animated PNGs[^1], and as such this conversion removes support for them as emoji; however, libvips includes support for webp images, which future commits will take advantage of. This removes the MAX_EMOJI_GIF_SIZE limit, since that existed to work around bugs in Pillow. MAX_EMOJI_GIF_FILE_SIZE_BYTES is fixed to actually be 128KiB (not 128MiB, as it actually was), and is counted _after_ resizing, since the point is to limit the amount of data transfer to clients. [^1]: https://github.com/libvips/libvips/discussions/2000
This commit is contained in:
Alex Vandiver
committed by
Tim Abbott
Tim Abbott
parent
9fb03cb2c7
commit
b14a33c659
@@ -1,11 +1,12 @@
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import io
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from typing import Optional, Tuple
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import logging
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import os
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from contextlib import contextmanager
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from typing import Iterator, Optional, Tuple
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from urllib.parse import urljoin
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import pyvips
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from django.utils.http import url_has_allowed_host_and_scheme
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from django.utils.translation import gettext as _
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from PIL import GifImagePlugin, Image, ImageOps, PngImagePlugin
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from PIL.Image import DecompressionBombError
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from zerver.lib.camo import get_camo_url
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from zerver.lib.exceptions import ErrorCode, JsonableError
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@@ -14,11 +15,11 @@ DEFAULT_AVATAR_SIZE = 100
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MEDIUM_AVATAR_SIZE = 500
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DEFAULT_EMOJI_SIZE = 64
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# These sizes were selected based on looking at the maximum common
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# sizes in a library of animated custom emoji, balanced against the
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# network cost of very large emoji images.
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MAX_EMOJI_GIF_SIZE = 128
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MAX_EMOJI_GIF_FILE_SIZE_BYTES = 128 * 1024 * 1024 # 128 kb
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# We refuse to deal with any image whose total pixelcount exceeds this.
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IMAGE_BOMB_TOTAL_PIXELS = 90000000
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# Reject emoji which, after resizing, have stills larger than this
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MAX_EMOJI_GIF_FILE_SIZE_BYTES = 128 * 1024 # 128 kb
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class BadImageError(JsonableError):
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@@ -39,122 +40,114 @@ def generate_thumbnail_url(path: str, size: str = "0x0") -> str:
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return get_camo_url(path)
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def resize_avatar(image_data: bytes, size: int = DEFAULT_AVATAR_SIZE) -> bytes:
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@contextmanager
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def libvips_check_image(image_data: bytes) -> Iterator[pyvips.Image]:
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# The primary goal of this is to verify that the image is valid,
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# and raise BadImageError otherwise. The yielded `source_image`
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# may be ignored, since calling `thumbnail_buffer` is faster than
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# calling `thumbnail_image` on a pyvips.Image, since the latter
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# cannot make use of shrink-on-load optimizations:
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# https://www.libvips.org/API/current/libvips-resample.html#vips-thumbnail-image
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try:
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im = Image.open(io.BytesIO(image_data))
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im = ImageOps.exif_transpose(im)
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im = ImageOps.fit(im, (size, size), Image.Resampling.LANCZOS)
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except OSError:
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source_image = pyvips.Image.new_from_buffer(image_data, "")
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except pyvips.Error:
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raise BadImageError(_("Could not decode image; did you upload an image file?"))
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except DecompressionBombError:
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if source_image.width * source_image.height > IMAGE_BOMB_TOTAL_PIXELS:
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raise BadImageError(_("Image size exceeds limit."))
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out = io.BytesIO()
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if im.mode == "CMYK":
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im = im.convert("RGB")
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im.save(out, format="png")
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return out.getvalue()
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try:
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yield source_image
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except pyvips.Error as e: # nocoverage
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logging.exception(e)
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raise BadImageError(_("Bad image!"))
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def resize_avatar(image_data: bytes, size: int = DEFAULT_AVATAR_SIZE) -> bytes:
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# This will scale up, if necessary, and will scale the smallest
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# dimension to fit. That is, a 1x1000 image will end up with the
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# one middle pixel enlarged to fill the full square.
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with libvips_check_image(image_data):
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return pyvips.Image.thumbnail_buffer(
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image_data,
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size,
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height=size,
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crop=pyvips.Interesting.CENTRE,
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).write_to_buffer(".png")
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def resize_logo(image_data: bytes) -> bytes:
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try:
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im = Image.open(io.BytesIO(image_data))
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im = ImageOps.exif_transpose(im)
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im.thumbnail((8 * DEFAULT_AVATAR_SIZE, DEFAULT_AVATAR_SIZE), Image.Resampling.LANCZOS)
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except OSError:
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raise BadImageError(_("Could not decode image; did you upload an image file?"))
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except DecompressionBombError:
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raise BadImageError(_("Image size exceeds limit."))
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out = io.BytesIO()
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if im.mode == "CMYK":
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im = im.convert("RGB")
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im.save(out, format="png")
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return out.getvalue()
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def resize_animated(im: Image.Image, size: int = DEFAULT_EMOJI_SIZE) -> bytes:
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assert im.n_frames > 1
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frames = []
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duration_info = []
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disposals = []
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# If 'loop' info is not set then loop for infinite number of times.
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loop = im.info.get("loop", 0)
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for frame_num in range(im.n_frames):
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im.seek(frame_num)
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new_frame = im.copy()
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new_frame.paste(im, (0, 0), im.convert("RGBA"))
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new_frame = ImageOps.pad(new_frame, (size, size), Image.Resampling.LANCZOS)
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frames.append(new_frame)
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if im.info.get("duration") is None: # nocoverage
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raise BadImageError(_("Corrupt animated image."))
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duration_info.append(im.info["duration"])
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if isinstance(im, GifImagePlugin.GifImageFile):
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disposals.append(
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im.disposal_method # type: ignore[attr-defined] # private member missing from stubs
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)
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elif isinstance(im, PngImagePlugin.PngImageFile):
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disposals.append(im.info.get("disposal", PngImagePlugin.Disposal.OP_NONE))
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else: # nocoverage
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raise BadImageError(_("Unknown animated image format."))
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out = io.BytesIO()
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frames[0].save(
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out,
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save_all=True,
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optimize=False,
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format=im.format,
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append_images=frames[1:],
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duration=duration_info,
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disposal=disposals,
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loop=loop,
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)
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return out.getvalue()
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# This will only scale the image down, and will resize it to
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# preserve aspect ratio and be contained within 8*AVATAR by AVATAR
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# pixels; it does not add any padding to make it exactly that
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# size. A 1000x10 pixel image will end up as 800x8; a 10x10 will
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# end up 10x10.
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with libvips_check_image(image_data):
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return pyvips.Image.thumbnail_buffer(
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image_data,
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8 * DEFAULT_AVATAR_SIZE,
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height=DEFAULT_AVATAR_SIZE,
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size=pyvips.Size.DOWN,
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).write_to_buffer(".png")
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def resize_emoji(
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image_data: bytes, size: int = DEFAULT_EMOJI_SIZE
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image_data: bytes, emoji_file_name: str, size: int = DEFAULT_EMOJI_SIZE
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) -> Tuple[bytes, bool, Optional[bytes]]:
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if len(image_data) > MAX_EMOJI_GIF_FILE_SIZE_BYTES:
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raise BadImageError(_("Image size exceeds limit."))
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# Square brackets are used for providing options to libvips' save
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# operation; these should have been filtered out earlier, so we
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# assert none are found here, for safety.
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write_file_ext = os.path.splitext(emoji_file_name)[1]
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assert "[" not in write_file_ext
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# This function returns three values:
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# 1) Emoji image data.
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# 2) If emoji is gif i.e. animated.
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# 3) If is animated then return still image data i.e. first frame of gif.
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try:
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im = Image.open(io.BytesIO(image_data))
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image_format = im.format
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if getattr(im, "n_frames", 1) > 1:
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# There are a number of bugs in Pillow which cause results
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# in resized images being broken. To work around this we
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# only resize under certain conditions to minimize the
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# chance of creating ugly images.
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should_resize = (
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im.size[0] != im.size[1] # not square
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or im.size[0] > MAX_EMOJI_GIF_SIZE # dimensions too large
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or len(image_data) > MAX_EMOJI_GIF_FILE_SIZE_BYTES # filesize too large
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# 2) If the emoji is animated.
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# 3) If it is animated, the still image data i.e. first frame of gif.
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with libvips_check_image(image_data) as source_image:
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if source_image.get_n_pages() == 1:
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return (
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pyvips.Image.thumbnail_buffer(
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image_data,
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size,
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height=size,
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crop=pyvips.Interesting.CENTRE,
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).write_to_buffer(write_file_ext),
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False,
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None,
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)
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first_still = pyvips.Image.thumbnail_buffer(
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image_data,
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size,
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height=size,
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crop=pyvips.Interesting.CENTRE,
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).write_to_buffer(".png")
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# Generate a still image from the first frame. Since
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# we're converting the format to PNG anyway, we resize unconditionally.
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still_image = im.copy()
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still_image.seek(0)
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still_image = ImageOps.exif_transpose(still_image)
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still_image = ImageOps.fit(still_image, (size, size), Image.Resampling.LANCZOS)
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out = io.BytesIO()
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still_image.save(out, format="PNG")
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still_image_data = out.getvalue()
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if should_resize:
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image_data = resize_animated(im, size)
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return image_data, True, still_image_data
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else:
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# Note that this is essentially duplicated in the
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# still_image code path, above.
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im = ImageOps.exif_transpose(im)
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im = ImageOps.fit(im, (size, size), Image.Resampling.LANCZOS)
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out = io.BytesIO()
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im.save(out, format=image_format)
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return out.getvalue(), False, None
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except OSError:
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raise BadImageError(_("Could not decode image; did you upload an image file?"))
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except DecompressionBombError:
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raise BadImageError(_("Image size exceeds limit."))
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animated = pyvips.Image.thumbnail_buffer(
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image_data,
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size,
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height=size,
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# This is passed to the loader, and means "load all
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# frames", instead of the default of just the first
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option_string="n=-1",
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)
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if animated.width != animated.get("page-height"):
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# If the image is non-square, we have to iterate the
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# frames to add padding to make it so
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if not animated.hasalpha():
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animated = animated.addalpha()
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frames = [
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frame.gravity(
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pyvips.CompassDirection.CENTRE,
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size,
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size,
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extend=pyvips.Extend.BACKGROUND,
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background=[0, 0, 0, 0],
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)
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for frame in animated.pagesplit()
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]
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animated = frames[0].pagejoin(frames[1:])
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return (animated.write_to_buffer(write_file_ext), True, first_still)
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