98 lines
3.4 KiB
Python
98 lines
3.4 KiB
Python
# -*- coding: utf-8 -*-
|
|
# Copyright 2014-2016 OpenMarket Ltd
|
|
#
|
|
# 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
|
|
|
|
import PIL.Image as Image
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
|
|
class Thumbnailer(object):
|
|
|
|
FORMATS = {
|
|
"image/jpeg": "JPEG",
|
|
"image/png": "PNG",
|
|
}
|
|
|
|
def __init__(self, input_path):
|
|
self.image = Image.open(input_path)
|
|
self.width, self.height = self.image.size
|
|
|
|
def aspect(self, max_width, max_height):
|
|
"""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 larget 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 scale(self, width, height, output_type):
|
|
"""Rescales the image to the given dimensions.
|
|
|
|
Returns:
|
|
BytesIO: the bytes of the encoded image ready to be written to disk
|
|
"""
|
|
scaled = self.image.resize((width, height), Image.ANTIALIAS)
|
|
return self._encode_image(scaled, output_type)
|
|
|
|
def crop(self, width, height, output_type):
|
|
"""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 larget 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.image.resize(
|
|
(width, scaled_height), Image.ANTIALIAS
|
|
)
|
|
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.image.resize(
|
|
(scaled_width, height), Image.ANTIALIAS
|
|
)
|
|
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, output_type):
|
|
output_bytes_io = BytesIO()
|
|
output_image.save(output_bytes_io, self.FORMATS[output_type], quality=80)
|
|
return output_bytes_io
|