从excel中提取嵌入式图片的解决方法

1  发现问题

我的excel中有浮动图片和嵌入式图片，但是openpyxl的_image对象只提取到了浮动图片，通过阅读其源码发现，这是因为openpyxl只解析了drawing文件导致的，所以确定需要自己解析

2  解决思路

1、解析出media资源

2、解析出xml，这可以得到资源的rNvpr-rId-image target的关系

3、从xlrd或openpyxl中得到单元格cNvpr，定位到图片

3  解析xlsx

先把xlsx解压出来，得到的文件如下，其中xl文件夹是我们需要的

我分析了里面的所有文件，发现这两个文件存储了嵌入式图片的关键信息

• xl/cellimages.xml
• xl/_rels/cellimages.xml

打开这两个文件看看，到底存储了什么？

3.1  xl/cellimages.xml

 

有效信息在cellImage对象中

• cellImage.pic.nvPicPr.cNvPr.name：记录了函数名
• cellImage.pic.blipFill.blip.embed：记录了rId

记录这个关系，并建立映射关系 { ID_xxx: rId }

3.2  xl/_rels/cellimages.xml

 

有效信息在Relationship对象中

• Relationship.id：文件rId
• Relationship.target：图片地址

建立这个映射关系 { rId: target }

到这一步我们已经可以从函数名定位到图片资源了，剩下一步建立excel单元格和图片的关系，接下来解析excel文件

{ ID_xxx: rId } + { rId: target } = ID_xxx -> target

4  代码实现

接下来简单的代码实现，有问题可以评论区留言，看到会回复

此实现基于openpyxl

from xml.etree.ElementTree import fromstring
from io import BytesIO
from zipfile import ZipFile

from openpyxl import load_workbook
from openpyxl.packaging.relationship import get_rels_path, get_dependents
from openpyxl.xml.constants import SHEET_DRAWING_NS, REL_NS, IMAGE_NS
from openpyxl.drawing.image import Image, PILImage


def parse_element(element):
    """
    将XML解析为 {ID_XXX: rId}
    :param element:
        
            
                
                    
                
                
                    
                    
                
                
                    
                    
                    
                
                
                    
                
                
            
        
    :return:
    """
    data = {}
    xdr_namespace = "{%s}" % SHEET_DRAWING_NS
    targets = level_order_traversal(element, xdr_namespace + "nvPicPr")

    for target in targets:
        # 是一个cellimage
        cNvPr = embed = ""
        for child in target:
            if child.tag == xdr_namespace + "nvPicPr":
                cNvPr = child[0].attrib["name"]
            elif child.tag == xdr_namespace + "blipFill":
                _rel_embed = "{%s}embed" % REL_NS
                embed = child[0].attrib[_rel_embed]

        if cNvPr:
            data[cNvPr] = embed

    return data


def level_order_traversal(root, flag):
    """层次遍历，查找目标节点"""
    queue = [root]
    targets = []
    while queue:
        node = queue.pop(0)
        children = [child.tag for child in node]
        if flag in children:
            targets.append(node)
            continue

        for child in node:
            queue.append(child)

    return targets



def handle_images(deps, archive) -> []:
    """
    将图片二进制内容封装为Image对象
    """
    images = []
    if not PILImage:  # Pillow not installed, drop images
        return images

    for dep in deps:
        if dep.Type != IMAGE_NS:
            msg = "{0} image format is not supported so the image is being dropped".format(dep.Type)
            print(msg)
            continue

        try:
            image_io = archive.read(dep.target)
            image = Image(BytesIO(image_io))
        except OSError:
            msg = "The image {0} will be removed because it cannot be read".format(dep.target)
            print(msg)
            continue
        if image.format.upper() == "WMF":  # cannot save
            msg = "{0} image format is not supported so the image is being dropped".format(image.format)
            print(msg)
            continue
        image.embed = dep.id         # 文件rId
        image.target = dep.target    # 文件地址
        images.append(image)

    return images

def main():
    CELLIMAGE_PATH = "xl/cellimages.xml"
    PARSE_FILE_PATH = 'C:/Users/user/Downloads/TCI验收问题.xlsx'

    archive = ZipFile(PARSE_FILE_PATH, "r")
    wb = load_workbook(PARSE_FILE_PATH)

    src = archive.read(CELLIMAGE_PATH)                              # 打开cellImage.xml文件
    deps = get_dependents(archive, get_rels_path(CELLIMAGE_PATH))   # 解析cellImage.xml._rel文件
    image_rels = handle_images(deps=deps.Relationship, archive=archive)

    node = fromstring(src)
    cellimages_xml = parse_element(node)
    cellimages_rel = {}
    for image in image_rels:
        cellimages_rel[image.embed] = image

    for cnvpr, embed in cellimages_xml.items():
        cellimages_xml[cnvpr] = cellimages_rel.get(embed)

    # df = pd.read_excel(PARSE_FILE_PATH)
    # df["行号"] = df.index + 2
    # image_mappings = ParserXLSXEmbed(wb=wb, df=df).extract_images(start_from=max(0, 1) + 1)
    # image_mappings.update(cellimages_xml)

    archive.close()  # 关闭压缩文件对象，防止内存泄漏

    print(cellimages_xml)


if __name__ == '__main__':
    main()