aws lambda 图片裁剪服务开发记录

作者: 许一沐 | 来源:发表于2021-03-23 23:42 被阅读0次

在控制url参数时总想找个轻松省事的方式来按某种规则解析字符串,偏偏正则又是个坑爹东西,又不想每次去查手册,总想一劳永逸的解决问题,没办法只能吃一次苦,记录下来便于以后使用吧

def extract_values(
    string, pattern, lowercase=False, whitespace=None,
    strip_values=False,delimiters=['{', '}']
):
    # Checking for lowercase convertion
    if lowercase:
        string = string.lower()

    # Checking for a sequence in delimiters
    try:
        delimiters = tuple(delimiters)
    except TypeError:
        return {}

    # Checking for just two delimiters
    if len(delimiters) != 2:
        return {}

    # Check if whitespace should be removed
    if whitespace is not None:
        # Make sure it's an integer
        try:
            whitespace = int(whitespace)
        except TypeError:
            return {}

        # Make sure it's a non-negative integer
        if whitespace < 0:
            return {}

        # Now remove whitespace
        if whitespace == 0:
            # Removing all whitespace from each value
            string = re.sub('\s',  '', string)
        else:
            # Removing only extra whitespace from each value
            string = re.sub(
                '(\s)\s{%d,}' % (whitespace - 1), '\\1', string
            )

    # Helper regular expressions
    splitter = re.compile('(%s\w+%s)' % (delimiters[0], delimiters[1]))
    extracter = re.compile('%s(\w+)%s' % (delimiters[0], delimiters[1]))

    # Split pattern into parts including named groups
    parts = splitter.split(pattern)

    # Expand group or escape non-group
    for idx, p in enumerate(parts):
        # Part is a named group
        if splitter.match(p):
            name = extracter.search(p).groups()[0]
            parts[idx] = '(?P<%s>.+)' % name
        # Part is something else
        else:
            # Escape values with special semantics in regular expressions
            parts[idx] = re.escape(p)

    # Build expanded pattern
    expanded_pattern = '^%s$' % ''.join(parts)

    try:
        # Attempt to extract values
        value_dict = re.match(expanded_pattern, string).groupdict()

        # Check if values must be stripped
        if strip_values:
            for name in value_dict:
                value_dict[name] = value_dict[name].strip()

        # Finally, return values
        return value_dict

    except re.error:
        return {}

    except AttributeError:
        # No regexp match, just return an empty dictionary
        return {}

print(extract_values('380-250-80-j', '{width}-{height}-{quality}-{format}'))

print(extract_values('/2012/08/12/test.html', '/{year}/{month}/{day}/{title}.html'))
print(extract_values('John Doe <john@example.com> (http://example.com)', '{name} <{email}> ({url})'))
print(extract_values('from 4th October  to 10th  October', 'from `from` to `to`', strip_values=True, whitespace=1, delimiters=['`', '`']))
print(extract_values('Convert 1500 Grams to Kilograms', 'convert {quantity} {from_unit} to {to_unit}', lowercase=True))
print(extract_values('The time is 4:35pm here at Lima, Peru', 'The time is :time here at :city', delimiters=[':', '']))

结果还是很香的啊

{'width': '380', 'height': '250', 'quality': '80', 'format': 'j'}
{'year': '2012', 'month': '08', 'day': '12', 'title': 'test'}
{'name': 'John Doe', 'email': 'john@example.com', 'url': 'http://example.com'}
{'from': '4th October', 'to': '10th October'}
{'quantity': '1500', 'from_unit': 'grams', 'to_unit': 'kilograms'}
{'time': '4:35pm', 'city': 'Lima, Peru'}

又重温了 python的语法, 凑合着用吧

# coding=utf-8
# author=toohamster
import os
from PIL import Image
from resizeimage import resizeimage
import re
import mimetypes

# https://stackoverflow.com/questions/10607468/how-to-reduce-the-image-file-size-using-pil

def extract_values(string, pattern, lowercase=False, whitespace=None,strip_values=False,delimiters=['{', '}']):
    # Checking for lowercase convertion
    if lowercase:
        string = string.lower()

    # Checking for a sequence in delimiters
    try:
        delimiters = tuple(delimiters)
    except TypeError:
        return {}

    # Checking for just two delimiters
    if len(delimiters) != 2:
        return {}

    # Check if whitespace should be removed
    if whitespace is not None:
        # Make sure it's an integer
        try:
            whitespace = int(whitespace)
        except TypeError:
            return {}

        # Make sure it's a non-negative integer
        if whitespace < 0:
            return {}

        # Now remove whitespace
        if whitespace == 0:
            # Removing all whitespace from each value
            string = re.sub('\s',  '', string)
        else:
            # Removing only extra whitespace from each value
            string = re.sub(
                '(\s)\s{%d,}' % (whitespace - 1), '\\1', string
            )

    # Helper regular expressions
    splitter = re.compile('(%s\w+%s)' % (delimiters[0], delimiters[1]))
    extracter = re.compile('%s(\w+)%s' % (delimiters[0], delimiters[1]))

    # Split pattern into parts including named groups
    parts = splitter.split(pattern)

    # Expand group or escape non-group
    for idx, p in enumerate(parts):
        # Part is a named group
        if splitter.match(p):
            name = extracter.search(p).groups()[0]
            parts[idx] = '(?P<%s>.+)' % name
        # Part is something else
        else:
            # Escape values with special semantics in regular expressions
            parts[idx] = re.escape(p)

    # Build expanded pattern
    expanded_pattern = '^%s$' % ''.join(parts)

    try:
        # Attempt to extract values
        value_dict = re.match(expanded_pattern, string).groupdict()

        # Check if values must be stripped
        if strip_values:
            for name in value_dict:
                value_dict[name] = value_dict[name].strip()

        # Finally, return values
        return value_dict

    except re.error:
        return {}

    except AttributeError:
        # No regexp match, just return an empty dictionary
        return {}


def parseImageMetas(meta_str, extension):

    o = extract_values(meta_str, 's-{width}x{height}x{quality}x{format}')

    if 'width' not in o or o['width'].isdigit() != True or int(o['width']) < 1:
        return None

    o['width'] = int(o['width'])

    if 'height' not in o or o['height'].isdigit() != True or int(o['height']) < 1:
        return None

    o['height'] = int(o['height'])

    if 'quality' not in o or o['quality'].isdigit() != True or int(o['quality']) < 1:
        return None

    o['quality'] = int(o['quality'])

    if (o['quality'] > 90):
        o['quality'] = 90

    formats = {
        'j': "JPEG",
        'p': "PNG",
        'w': "WEBP",
        'o': extension
    }

    o['format'] = formats.get(o['format'], extension)
    o['mime'] = mimetypes.guess_type("example." + o['format'])[0]
    
    return o

def parseImageUrl(url, real_img_format=False):

    new_file = url[0:].split('?')[0]
    spath = new_file.split("/")
    new_filename = spath[-1]

    tmp = new_filename.split('_', 1)
    if len(tmp) != 2:
        return None

    meta_str = tmp[0]

    if real_img_format == False:
        extension = os.path.splitext(new_file)[1][1:].strip().upper()
        extension = 'JPEG' if extension == 'JPG' else extension
    else:
        extension = real_img_format

    return parseImageMetas(meta_str, extension)

def resizeImage(new_file):
    img_path = new_file

    new_file = new_file.split('?')[0]
    spath = new_file.split("/")
    new_filename = spath[-1]
    tmp = new_filename.split('_', 1)

    if len(tmp) != 2:
        print("path error")
        return None

    origin_file = '/'.join(spath[:-1]) + '/' + tmp[1]

    resize_type = 'others'
    if tmp[0].startswith('s-'):
        resize_type = 's'
        size_tmp = tmp[0].split('-', 1)
        size = size_tmp[1]
    else:
        size = tmp[0]

    if resize_type != 's':
        print("不支持此指令!")
        return None
    
    im = Image.open(origin_file)

    print("原图: " + origin_file + " sizeof " + str(os.path.getsize(origin_file)))
    print(im.format, im.mode, im.size)

    img_metas = parseImageUrl(img_path, im.format)
    if img_metas == None:
        print("param format error!")
        return None

    img = resizeimage.resize_cover(im, [img_metas['width'], img_metas['height']], False)

    if img_metas['format'] == 'JPEG':
        img.convert("RGB")

    # JPEG 时 quality 能控制图片生成的大小, optimize 不起作用; PNG 的时候 optimize 能控制图片大小, quality 不起作用
    # subsampling=0, quality=95,optimize=True

    img.save(img_path, img_metas['format'], subsampling=0, quality=img_metas['quality'], optimize=True)

    print(img_path + " sizeof " + str(os.path.getsize(img_path)))


# // image/png | image/jpeg | image/gif | image/webp

resizeImage("/Users/toohamster/test/s-725x360x80xj_dcdf_55537.jpg")
resizeImage("/Users/toohamster/test/s-725x360x75xj_dcdf_55537.jpg")
resizeImage("/Users/toohamster/test/s-725x360x70xj_dcdf_55537.jpg")

安装依赖库:

pip3.7 install Pillow==8.0.1
pip3.7 install python-resize-image==1.1.19
pip3.7 install piexif==1.1.3

打印结果:

/usr/local/bin/python3 /Users/toohamster/workspace/test/demo.py
原图: /Users/toohamster/test/dcdf_55537.jpg sizeof 133921
JPEG RGB (700, 350)
/Users/toohamster/test/s-725x360x80xj_dcdf_55537.jpg sizeof 75246
原图: /Users/toohamster/test/dcdf_55537.jpg sizeof 133921
JPEG RGB (700, 350)
/Users/toohamster/test/s-725x360x75xj_dcdf_55537.jpg sizeof 65268
原图: /Users/toohamster/test/dcdf_55537.jpg sizeof 133921
JPEG RGB (700, 350)
/Users/toohamster/test/s-725x360x70xj_dcdf_55537.jpg sizeof 59009

Process finished with exit code 0

aws lambda 图片裁剪服务开发记录

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