Create retina @2x and non-retina resized images from @3x sized images

build_ios_resizes.py

#!/usr/bin/env python
import os

import sys
print(sys.executable)


def resize_images_in_path(path, out_dir, imagemagic=False):
    """Build 2x and 1x downsized images by 3x images in directory."""
    dirs = os.listdir(path)

    assert (out_dir and os.path.realpath(path) != os.path.realpath(out_dir)), (
        "Error, output dir and input dir must be different!")

    if out_dir:
        try:
            os.makedirs(out_dir)
        except OSError:
            pass

    for item in dirs:
        full_path = os.path.join(path, item)
        file_name, ext = os.path.splitext(item)

        if not os.path.isfile(full_path):
            continue

        if not ext in ('.png', '.jpg'):
            continue

        # if not file_name.endswith('@3x'):
        #     continue

        if imagemagic:
            make_resizes_from_3x_wand(full_path, out_dir=out_dir)
        else:
            make_resizes_from_3x_pillow(full_path, out_dir=out_dir)


def make_resizes_from_3x_wand(path, out_dir=None):
    """Make images resizes with Wand + ImageMagic."""
    from wand.image import Image

    file_name, ext = os.path.splitext(path)

    with Image(filename=path) as im:
        # 3x
        file_3x = get_out_filepath(path, suffix='@3x', out_dir=out_dir)
        im.save(filename=file_3x)

        # 2x
        size_2x = (int(im.size[0] * 2/3), int(im.size[1] * 2/3))
        file_2x = get_out_filepath(path, suffix='@2x', out_dir=out_dir)
        im.resize(*size_2x)
        im.save(filename=file_2x)

        # 1x
        size_1x = (im.size[0] * 1/2, im.size[1] * 1/2)
        file_1x = get_out_filepath(path, suffix='', out_dir=out_dir)
        im.resize(*size_1x)
        im.save(filename=file_1x)


def get_out_filepath(path, suffix='', out_dir=None):
    """Get output file path with scheme [output dir]/[base name][suffix].[ext]"""
    if not out_dir:
        out_dir = os.path.dirname(path)
    file_name = os.path.basename(path)
    base, ext = os.path.splitext(file_name)
    return os.path.join(out_dir, base + suffix + ext)


def make_resizes_from_3x_pillow(path, out_dir=None):
    """Make images resizes with Pillow."""
    from PIL import Image

    file_name, ext = os.path.splitext(path)

    im = Image.open(path)

    # 3x
    file_3x = get_out_filepath(path, suffix='@3x', out_dir=out_dir)
    im.save(file_3x, optimize=True)

    # 2x
    size_2x = (im.size[0] * 2/3, im.size[1] * 2/3)
    file_2x = get_out_filepath(path, suffix='@2x', out_dir=out_dir)
    im_2x = im.resize(size_2x, Image.ANTIALIAS)
    im_2x.save(file_2x, optimize=True)

    # 1x
    size_1x = (im.size[0] * 1/3, im.size[1] * 1/3)
    file_1x = get_out_filepath(path, suffix='', out_dir=out_dir)
    im_1x = im.resize(size_1x, Image.ANTIALIAS)
    im_1x.save(file_1x, optimize=True)


if __name__ == '__main__':
    out_dir = os.path.join(os.getcwd(), 'Build')
    resize_images_in_path(os.getcwd(), out_dir=out_dir, imagemagic=True)