pptx_encode_images.py

#!/usr/bin/env python

import os
import glob
import sys
import json
import subprocess
import zipfile
import io
import shutil

import lxml.etree
import wand
import wand.image

def wand_convert(img_bytes:bytes, input_format=None, output_format:str="jpeg", quality:int=80):
    f_output = io.BytesIO()
    with wand.image.Image(blob=img_bytes, format=input_format) as img_input:
        with img_input.clone() as img_output:
            # img_size = img_output.size
            # img_output.resize(img_size[0]//2, img_size[1]//2)
            img_output.format = output_format
            img_output.compression_quality = quality
            img_output.save(file=f_output)
    return f_output.getvalue()

pptx_path_src = "src.pptx"
pptx_path_dst = "dst.pptx"

image_path_xml_rels_set = set()
with zipfile.ZipFile(pptx_path_dst, "w", compression=zipfile.ZIP_DEFLATED) as zip_pptx_dst:
    with zipfile.ZipFile(pptx_path_src, "r") as zip_pptx_src:

        filepath_inzip_list = zip_pptx_src.namelist()
        # print(filepath_inzip_list)

        xml_rels_list = []
        otherfile_inzip_set = set()
        for filepath_inzip in filepath_inzip_list:

            if os.path.dirname(filepath_inzip)=="ppt/slides/_rels" and filepath_inzip.endswith(".xml.rels"):
                xml_rels_list.append(filepath_inzip)
            elif filepath_inzip=="[Content_Types].xml":
                continue
            else:
                otherfile_inzip_set.add(filepath_inzip)

        content_types_xml_path = "[Content_Types].xml"
        sys.stderr.write(f"info: {content_types_xml_path}\n")
        with zip_pptx_src.open(content_types_xml_path, "r") as f_xml:
            xml_bytes = f_xml.read()

        doc = lxml.etree.fromstring(xml_bytes)
        has_jpg = False
        for relationship in doc.iterfind("./Default", doc.nsmap):
            if relationship.attrib["Extension"] == 'jpg':
                has_jpg = True
        if not has_jpg:
            default_jpg = lxml.etree.Element("Default", nsmap=doc.nsmap)
            default_jpg.attrib["Extension"] = "jpg"
            default_jpg.attrib["ContentType"] = "image/jpeg"
            doc.append(default_jpg)

        with zip_pptx_dst.open(content_types_xml_path, "w") as f_xml:
            f_xml.write(lxml.etree.tostring(doc, xml_declaration=True, encoding='UTF-8', standalone=True))

        for xml_rels_path_inzip in xml_rels_list:

            sys.stderr.write(f"info: {xml_rels_path_inzip}\n")
            with zip_pptx_src.open(xml_rels_path_inzip, "r") as f_xml:
                xml_bytes = f_xml.read()

            doc = lxml.etree.fromstring(xml_bytes)

            for relationship in doc.iterfind("./Relationship", doc.nsmap):
                if relationship.attrib["Type"] != 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/image':
                    continue

                image_path_xml_rels = relationship.attrib["Target"]

                # sys.stderr.write(f"info: {image_path_xml_rels}\n")
                image_path_inzip = os.path.normpath(os.path.join("ppt/slides", image_path_xml_rels)).replace(os.sep, "/")
                sys.stderr.write(f"info: {image_path_inzip}\n")
                if image_path_inzip in otherfile_inzip_set:
                    otherfile_inzip_set.remove(image_path_inzip)

                image_name, image_ext = os.path.splitext(image_path_inzip)
                image_enc_path_inzip = image_name + ".jpg"
                
                image_enc_path_xml_rels = os.path.relpath(image_enc_path_inzip, "ppt/slides").replace(os.sep, "/")
                relationship.attrib["Target"] = image_enc_path_xml_rels

                if image_path_xml_rels in image_path_xml_rels_set:
                    continue
                else:
                    image_path_xml_rels_set.add(image_path_xml_rels)

                sys.stderr.write(f"info: {image_enc_path_inzip}\n")

                with zip_pptx_src.open(image_path_inzip, "r") as f_img:
                    img_bytes = f_img.read()

                img_enc_bytes = wand_convert(img_bytes)

                with zip_pptx_dst.open(image_enc_path_inzip, "w") as f_img:
                    f_img.write(img_enc_bytes)

            sys.stderr.write(f"info: {xml_rels_path_inzip}\n")
            with zip_pptx_dst.open(xml_rels_path_inzip, "w") as f_xml:
                # f_xml.write(b'<?xml version="1.0" encoding="UTF-8" standalone="yes"?>\n'+lxml.etree.tostring(doc))
                f_xml.write(lxml.etree.tostring(doc, xml_declaration=True, encoding='UTF-8', standalone=True))

        for filepath_inzip in otherfile_inzip_set:
            sys.stderr.write(f"info: {filepath_inzip}\n")
            with zip_pptx_src.open(filepath_inzip, "r") as f_src:
                with zip_pptx_dst.open(filepath_inzip, "w") as f_dst:
                    shutil.copyfileobj(f_src, f_dst)