renders svg or other images to mobile device sizes

prepare-images.py

#!/usr/bin/env python

import os
import sys


SCALES = {
  1: ['mdpi/', ''],
  1.5: ['hdpi/'],
  2: ['xxdpi/', '@2x'],
  3: ['xxhdpi/', '@3x'],
}


def main():
  import argparse
  parser = argparse.ArgumentParser()

  parser.add_argument('--size', '-s', type=int, required=True,
                      help='base 1x size to generate')
  parser.add_argument('--out', '-o', type=str, default='.',
                      help='path to output to')
  parser.add_argument('--crush', '-p', action='store_true',
                      help='whether to pngcrush')
  parser.add_argument('files', type=str, nargs='+',
                      help='image files to render')
  args = parser.parse_args()

  if args.size <= 16:
    sys.stderr.write('warning: Quick Look seems to ignore sizes <= 16px\n')
    sys.stderr.write('\n')

  # Move to output folder, create Android output paths.
  cwd = os.getcwd()
  try:
    os.mkdir(args.out)
  except:
    pass  # ignore
  os.chdir(args.out)
  for _, outs in SCALES.items():
    for approach in outs:
      if approach.endswith('/') and not os.path.isdir(approach):
        os.mkdir(approach)

  # Enumerate and render files on Mac OS X.
  for path in args.files:
    name, ext = os.path.splitext(path)
    in_path = os.path.join(cwd, path)
    out_path = '{}{}.png'.format(os.path.basename(name), ext)
    print(name)
    sys.stderr.write('using out_path={}\n'.format(out_path))

    # Render each file at the right scale.
    for scale, outs in SCALES.items():
      size = int(args.size * scale)
      os.system('qlmanage -t -s {} -o . {} >/dev/null 2>&1'.format(size, in_path))
      print('>> {}'.format(size))

      # pngcrush if requested
      if args.crush:
        os.system('pngcrush -ow {} >/dev/null'.format(out_path))

      # Link into multiple approaches.
      for approach in outs:
        if approach.endswith('/'):
          cname = approach + name + '.png'
        else:
          cname = name + approach + '.png'
        os.link(out_path, cname)

      os.unlink(out_path)


if __name__ == '__main__':
  main()