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| -rw-r--r-- | synapse/media/v1/thumbnailer.py | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/synapse/media/v1/thumbnailer.py b/synapse/media/v1/thumbnailer.py new file mode 100644 index 0000000000..ed09283b27 --- /dev/null +++ b/synapse/media/v1/thumbnailer.py @@ -0,0 +1,78 @@ +# -*- coding: utf-8 -*- +# Copyright 2014 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 PIL.Image + +class Thumbnailer(object): + + FORMAT_JPEG="JPEG" + FORMAT_PNG="PNG" + + def __init__(self, input_path): + self.image = PIL.Image.open(input_path) + self.width, self.height = self.image.size + + def size_preserve(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 thumbnail_scale(self, output_path, output_format, width, height): + """Rescales the image to the given dimensions""" + output = self.image.resize((width, height), PIL.Image.BILINEAR) + output.save(output_path, output_format) + + def thumbnail_crop(self, output_path, output_format, width, height): + """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. + """ + if width * self.height > height * self.width: + scaled_height = (width * self.height) // self.width + scaled_image = self.image.resize( + (width, scaled_height), PIL.Image.BILINEAR + ) + crop_top = (scaled_height - height) // 2 + crop_bottom = height + crop_top + cropped = scaled_image.crop((0, crop_top, width, crop_bottom)) + cropped.save(output_path, output_format) + else: + scaled_width = (height * self.width) // self.height + scaled_image = self.image.resize( + (scaled_width, height), PIL.Image.BILINEAR + ) + crop_left = (scaled_width - width) // 2 + crop_right = width + crop_left + cropped = scaled_image.crop((crop_left, 0, crop_right, height)) + cropped.save(output_path, output_format) |