contentdb/app/blueprints/thumbnails/__init__.py

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# ContentDB
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# Copyright (C) 2018-21 rubenwardy
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#
# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
from flask import abort, send_file, Blueprint, current_app
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import os
from PIL import Image
bp = Blueprint("thumbnails", __name__)
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ALLOWED_RESOLUTIONS = [(100, 67), (270, 180), (350, 233), (1100, 520)]
ALLOWED_EXTENSIONS = {"png", "webp", "jpg"}
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def mkdir(path):
assert path != "" and path is not None
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try:
if not os.path.isdir(path):
os.mkdir(path)
except FileExistsError:
pass
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def resize_and_crop(img_path, modified_path, size):
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with Image.open(img_path) as img:
# Get current and desired ratio for the images
img_ratio = img.size[0] / float(img.size[1])
desired_ratio = size[0] / float(size[1])
# Is more portrait than target, scale and crop
if desired_ratio > img_ratio:
img = img.resize((int(size[0]), int(size[0] * img.size[1] / img.size[0])),
Image.BICUBIC)
box = (0, (img.size[1] - size[1]) / 2, img.size[0], (img.size[1] + size[1]) / 2)
img = img.crop(box)
# Is more landscape than target, scale and crop
elif desired_ratio < img_ratio:
img = img.resize((int(size[1] * img.size[0] / img.size[1]), int(size[1])),
Image.BICUBIC)
box = ((img.size[0] - size[0]) / 2, 0, (img.size[0] + size[0]) / 2, img.size[1])
img = img.crop(box)
# Is exactly the same ratio as target
else:
img = img.resize(size, Image.BICUBIC)
if modified_path.endswith(".jpg") and img.mode != "RGB":
img = img.convert("RGB")
img.save(modified_path, lossless=True)
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def find_source_file(img):
upload_dir = current_app.config["UPLOAD_DIR"]
source_filepath = os.path.join(upload_dir, img)
if os.path.isfile(source_filepath):
return source_filepath
period = source_filepath.rfind(".")
start = source_filepath[:period]
ext = source_filepath[period + 1:]
if ext not in ALLOWED_EXTENSIONS:
abort(404)
for other_ext in ALLOWED_EXTENSIONS:
other_path = f"{start}.{other_ext}"
if ext != other_ext and os.path.isfile(other_path):
return other_path
abort(404)
@bp.route("/thumbnails/<int:level>/<img>")
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def make_thumbnail(img, level):
if level > len(ALLOWED_RESOLUTIONS) or level <= 0:
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abort(403)
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w, h = ALLOWED_RESOLUTIONS[level - 1]
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thumbnail_dir = current_app.config["THUMBNAIL_DIR"]
mkdir(thumbnail_dir)
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output_dir = os.path.join(thumbnail_dir, str(level))
mkdir(output_dir)
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cache_filepath = os.path.join(output_dir, img)
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if not os.path.isfile(cache_filepath):
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source_filepath = find_source_file(img)
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resize_and_crop(source_filepath, cache_filepath, (w, h))
res = send_file(cache_filepath)
res.headers["Cache-Control"] = "max-age=604800" # 1 week
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return res