Python Pillow 等比缩放

import base64
import re
from io import BytesIO

from PIL import Image
class ImageScaleTool(object):
    @classmethod
    def base64_to_image(cls, base64_str) -> Image:
        base64_data = re.sub('^data:image/.+;base64,', '', base64_str)
        byte_data = base64.b64decode(base64_data)
        image_data = BytesIO(byte_data)
        img = Image.open(image_data)
        return img

    @classmethod
    def image_to_base64(cls, image: Image, img_format='png'):
        container = BytesIO()
        image.save(container, format(img_format))
        data = base64.b64encode(container.getvalue()).decode()
        return f'data:image/{img_format};base64,' + data

    @classmethod
    def scale_image(cls, image: Image, min_width, min_height) -> Image:
        w, h = image.size
        if w <= min_width and h <= min_height:
            return image
        if (1.0 * w / min_width) > (1.0 * h / min_height):
            scale = 1.0 * w / min_width
            new_im = image.resize((int(w / scale), int(h / scale)))

        else:
            scale = 1.0 * h / min_height
            new_im = image.resize((int(w / scale), int(h / scale)))
        return new_im

    @classmethod
    def scale_base64_img(cls, base64_str: str, width: int, height: int) -> str:
        """将base64图片缩放"""
        if width <= 0 or height <= 0:
            return ''
        try:
            image = cls.scale_image(cls.base64_to_image(base64_str), width, height)
            res_str = cls.image_to_base64(image)
        except Exception as e:
            print('scale_base64_img error:', e)
            return ''
        return res_str