Intelligently resize an image in python

resize.py

from collections import namedtuple
from magickwand.image import Image


Size = namedtuple('Size', ['width','height'])
Point = namedtuple('Point', ['x','y'])
Rect = namedtuple('Rect', ['origin', 'size'])


class ResizeMethods:
  fit = min
  fill = max


def resize(size, filelike, method=ResizeMethods.fit):
  """
  Returns an `magickwand.image.Image` object that is resized and/or cropped
  to meet the requirements specified. available resize methods:
  
  ResizeMethods.fit  => image will fit within the bounds specified
  ResizeMethods.fill => image will fill the bounds specified, cropping if necessary
  
  `size`     `Size` tuple - how big do you want the resulting image
  `filelike` a file-like object (anything that provides a .read()) method
  `method`   function to determine in what way the scale should be determined
  
  returns    `magickwand.image.Image` object representing the image. have fun
  """
  img = Image(filelike)
  orig_size = Size(*img.size)
  width_ratio = float(size.width) / float(orig_size.width)
  height_ratio = float(size.height) / float(orig_size.height)
  scale = method(width_ratio, height_ratio)
  new_size = Size(int(float(orig_size.width) * scale), 
                  int(float(orig_size.height) * scale))
  img.size = new_size
  if method == ResizeMethods.fill:
    crop_rect = Rect(Point(0, 0), Size(int(size.width), int(size.height)))
    if new_size.width > crop_rect.size.width \
       or new_size.height > crop_rect.size.height:
      crop_rect = Rect(Point(int((new_size.width - size.width) / 2.0),
                             int((new_size.height - size.height) / 2.0)),
                       crop_rect.size) # centerfy the cropping
    img.crop(crop_rect.size, crop_rect.origin)
  return img