python实现图片转PDF

为了使转换后的图片以正常比例显示在PDF中，对图片进行了缩放处理

import os

from PIL import Image
from reportlab.pdfgen import canvas


def image_resize(img, *args, multiple=None):
    """
    图片缩放
    如果按倍数缩放图片，则不用传args， 否则要传入需要缩放的width（宽）、height（高）
    :param img: 图片路径
    :param multiple: 缩放倍数, int or float default None
    :return:
    """
    image = Image.open(img)
    width, height = image.size
    try:
        if multiple:
            image.resize((int(width * multiple), int(height * multiple)), Image.ANTIALIAS).save(img, quality=95,
                                                                                                dpi=(72, 72))
        else:
            len_args = len(args)
            if len_args == 2:
                width, height = args
                image.resize((width, height), Image.ANTIALIAS).save(img, quality=95, dpi=(72, 72))
            else:
                raise ValueError('values error (expected 2, got %s)' % len_args)
    finally:
        image.close()


def image_to_pdf(img, pdf_path=None, resize=True):
    """
    图片转PDF
    :param img: 图片路径
    :param pdf_path: 生成的PDF路径
    :param resize: 是否缩放图片至A4大小
    :return: None
    """
    pix_x, pix_y = 595, 842  # 分辨率为72像素时的A4纸大小
    if not pdf_path:
        pdf_path = f'{os.path.splitext(img)[0]}.pdf'
    w, h = Image.open(img).size
    if resize:
        w, h = image_resize(img, pix_x, pix_y)
        width = (pix_x - w) // 2
        height = (pix_y - h) // 2
        user = canvas.Canvas(pdf_path)
        if width > 1 and height > 1:  # 图片size是否小于最小值
            user.drawImage(img, width, height)  # PDF中居中显示
        else:
            user.drawImage(img, 0, 0)
    else:
        user = canvas.Canvas(pdf_path, pagesize=(w, h))
        user.drawImage(img, 0, 0)
    user.showPage()
    user.save()