174 lines
6.9 KiB
Python
174 lines
6.9 KiB
Python
# Copyright 2014-2016 OpenMarket Ltd
|
|
# Copyright 2020-2021 The Matrix.org Foundation C.I.C.
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
|
# you may not use this file except in compliance with the License.
|
|
# You may obtain a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
|
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
# See the License for the specific language governing permissions and
|
|
# limitations under the License.
|
|
import logging
|
|
from io import BytesIO
|
|
from typing import Tuple
|
|
|
|
from PIL import Image
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
EXIF_ORIENTATION_TAG = 0x0112
|
|
EXIF_TRANSPOSE_MAPPINGS = {
|
|
2: Image.FLIP_LEFT_RIGHT,
|
|
3: Image.ROTATE_180,
|
|
4: Image.FLIP_TOP_BOTTOM,
|
|
5: Image.TRANSPOSE,
|
|
6: Image.ROTATE_270,
|
|
7: Image.TRANSVERSE,
|
|
8: Image.ROTATE_90,
|
|
}
|
|
|
|
|
|
class ThumbnailError(Exception):
|
|
"""An error occurred generating a thumbnail."""
|
|
|
|
|
|
class Thumbnailer:
|
|
|
|
FORMATS = {"image/jpeg": "JPEG", "image/png": "PNG"}
|
|
|
|
@staticmethod
|
|
def set_limits(max_image_pixels: int) -> None:
|
|
Image.MAX_IMAGE_PIXELS = max_image_pixels
|
|
|
|
def __init__(self, input_path: str):
|
|
try:
|
|
self.image = Image.open(input_path)
|
|
except OSError as e:
|
|
# If an error occurs opening the image, a thumbnail won't be able to
|
|
# be generated.
|
|
raise ThumbnailError from e
|
|
except Image.DecompressionBombError as e:
|
|
# If an image decompression bomb error occurs opening the image,
|
|
# then the image exceeds the pixel limit and a thumbnail won't
|
|
# be able to be generated.
|
|
raise ThumbnailError from e
|
|
|
|
self.width, self.height = self.image.size
|
|
self.transpose_method = None
|
|
try:
|
|
# We don't use ImageOps.exif_transpose since it crashes with big EXIF
|
|
#
|
|
# Ignore safety: Pillow seems to acknowledge that this method is
|
|
# "private, experimental, but generally widely used". Pillow 6
|
|
# includes a public getexif() method (no underscore) that we might
|
|
# consider using instead when we can bump that dependency.
|
|
#
|
|
# At the time of writing, Debian buster (currently oldstable)
|
|
# provides version 5.4.1. It's expected to EOL in mid-2022, see
|
|
# https://wiki.debian.org/DebianReleases#Production_Releases
|
|
image_exif = self.image._getexif() # type: ignore
|
|
if image_exif is not None:
|
|
image_orientation = image_exif.get(EXIF_ORIENTATION_TAG)
|
|
assert isinstance(image_orientation, int)
|
|
self.transpose_method = EXIF_TRANSPOSE_MAPPINGS.get(image_orientation)
|
|
except Exception as e:
|
|
# A lot of parsing errors can happen when parsing EXIF
|
|
logger.info("Error parsing image EXIF information: %s", e)
|
|
|
|
def transpose(self) -> Tuple[int, int]:
|
|
"""Transpose the image using its EXIF Orientation tag
|
|
|
|
Returns:
|
|
A tuple containing the new image size in pixels as (width, height).
|
|
"""
|
|
if self.transpose_method is not None:
|
|
# Safety: `transpose` takes an int rather than e.g. an IntEnum.
|
|
# self.transpose_method is set above to be a value in
|
|
# EXIF_TRANSPOSE_MAPPINGS, and that only contains correct values.
|
|
self.image = self.image.transpose(self.transpose_method) # type: ignore[arg-type]
|
|
self.width, self.height = self.image.size
|
|
self.transpose_method = None
|
|
# We don't need EXIF any more
|
|
self.image.info["exif"] = None
|
|
return self.image.size
|
|
|
|
def aspect(self, max_width: int, max_height: int) -> Tuple[int, int]:
|
|
"""Calculate the largest size that preserves aspect ratio which
|
|
fits within the given rectangle::
|
|
|
|
(w_in / h_in) = (w_out / h_out)
|
|
w_out = min(w_max, h_max * (w_in / h_in))
|
|
h_out = min(h_max, w_max * (h_in / w_in))
|
|
|
|
Args:
|
|
max_width: The largest possible width.
|
|
max_height: The largest possible height.
|
|
"""
|
|
|
|
if max_width * self.height < max_height * self.width:
|
|
return max_width, (max_width * self.height) // self.width
|
|
else:
|
|
return (max_height * self.width) // self.height, max_height
|
|
|
|
def _resize(self, width: int, height: int) -> Image.Image:
|
|
# 1-bit or 8-bit color palette images need converting to RGB
|
|
# otherwise they will be scaled using nearest neighbour which
|
|
# looks awful.
|
|
#
|
|
# If the image has transparency, use RGBA instead.
|
|
if self.image.mode in ["1", "L", "P"]:
|
|
mode = "RGB"
|
|
if self.image.info.get("transparency", None) is not None:
|
|
mode = "RGBA"
|
|
self.image = self.image.convert(mode)
|
|
return self.image.resize((width, height), Image.ANTIALIAS)
|
|
|
|
def scale(self, width: int, height: int, output_type: str) -> BytesIO:
|
|
"""Rescales the image to the given dimensions.
|
|
|
|
Returns:
|
|
BytesIO: the bytes of the encoded image ready to be written to disk
|
|
"""
|
|
scaled = self._resize(width, height)
|
|
return self._encode_image(scaled, output_type)
|
|
|
|
def crop(self, width: int, height: int, output_type: str) -> BytesIO:
|
|
"""Rescales and crops the image to the given dimensions preserving
|
|
aspect::
|
|
(w_in / h_in) = (w_scaled / h_scaled)
|
|
w_scaled = max(w_out, h_out * (w_in / h_in))
|
|
h_scaled = max(h_out, w_out * (h_in / w_in))
|
|
|
|
Args:
|
|
max_width: The largest possible width.
|
|
max_height: The largest possible height.
|
|
|
|
Returns:
|
|
BytesIO: the bytes of the encoded image ready to be written to disk
|
|
"""
|
|
if width * self.height > height * self.width:
|
|
scaled_height = (width * self.height) // self.width
|
|
scaled_image = self._resize(width, scaled_height)
|
|
crop_top = (scaled_height - height) // 2
|
|
crop_bottom = height + crop_top
|
|
cropped = scaled_image.crop((0, crop_top, width, crop_bottom))
|
|
else:
|
|
scaled_width = (height * self.width) // self.height
|
|
scaled_image = self._resize(scaled_width, height)
|
|
crop_left = (scaled_width - width) // 2
|
|
crop_right = width + crop_left
|
|
cropped = scaled_image.crop((crop_left, 0, crop_right, height))
|
|
return self._encode_image(cropped, output_type)
|
|
|
|
def _encode_image(self, output_image: Image.Image, output_type: str) -> BytesIO:
|
|
output_bytes_io = BytesIO()
|
|
fmt = self.FORMATS[output_type]
|
|
if fmt == "JPEG":
|
|
output_image = output_image.convert("RGB")
|
|
output_image.save(output_bytes_io, fmt, quality=80)
|
|
return output_bytes_io
|