MinerU/magic_pdf/pre_proc/equations_replace.py

"""
对pymupdf返回的结构里的公式进行替换，替换为模型识别的公式结果
"""
from magic_pdf.libs.commons import fitz
import json
import os
from pathlib import Path
from loguru import logger

TYPE_INLINE_EQUATION = "inline-equation"
TYPE_INTERLINE_EQUATION = "interline-equation"


def combine_chars_to_pymudict(block_dict, char_dict):
    """
    把block级别的pymupdf 结构里加入char结构
    """
    # 因为block_dict 被裁剪过，因此先把他和char_dict文字块对齐，才能进行补充
    char_map = {tuple(item['bbox']):item for item in char_dict}
    
    for i in range(len(block_dict)): # blcok
        block = block_dict[i]
        key = block['bbox']
        char_dict_item = char_map[tuple(key)]
        char_dict_map = {tuple(item['bbox']):item for item in char_dict_item['lines']}
        for j in range(len(block['lines'])):
            lines = block['lines'][j]
            with_char_lines = char_dict_map[lines['bbox']]
            for k in range(len(lines['spans'])):
                spans = lines['spans'][k]
                try:
                    chars = with_char_lines['spans'][k]['chars']
                except Exception as e:
                    logger.error(char_dict[i]['lines'][j])
                    
                spans['chars'] = chars
                
    return block_dict


def calculate_overlap_area_2_minbox_area_ratio(bbox1, min_bbox):
    """
    计算box1和box2的重叠面积占最小面积的box的比例
    """
    # Determine the coordinates of the intersection rectangle
    x_left = max(bbox1[0], min_bbox[0])
    y_top = max(bbox1[1], min_bbox[1])
    x_right = min(bbox1[2], min_bbox[2])
    y_bottom = min(bbox1[3], min_bbox[3])

    if x_right < x_left or y_bottom < y_top:
        return 0.0

    # The area of overlap area
    intersection_area = (x_right - x_left) * (y_bottom - y_top)
    min_box_area = (min_bbox[3]-min_bbox[1])*(min_bbox[2]-min_bbox[0])
    if min_box_area==0:
        return 0
    else:
        return intersection_area / min_box_area
    

def _is_xin(bbox1, bbox2):
    area1 = abs(bbox1[2]-bbox1[0])*abs(bbox1[3]-bbox1[1])
    area2 = abs(bbox2[2]-bbox2[0])*abs(bbox2[3]-bbox2[1])
    if area1<area2:
        ratio = calculate_overlap_area_2_minbox_area_ratio(bbox2, bbox1)
    else:
        ratio = calculate_overlap_area_2_minbox_area_ratio(bbox1, bbox2)

    return ratio>0.6



def remove_text_block_in_interline_equation_bbox(interline_bboxes, text_blocks):
    """消除掉整个块都在行间公式块内部的文本块"""
    for eq_bbox in interline_bboxes:
        removed_txt_blk = []
        for text_blk in text_blocks:
            text_bbox = text_blk['bbox']
            if calculate_overlap_area_2_minbox_area_ratio(eq_bbox['bbox'], text_bbox)>=0.7:
                removed_txt_blk.append(text_blk)
        for blk in removed_txt_blk:
            text_blocks.remove(blk)

    return text_blocks



def _is_in_or_part_overlap(box1, box2) -> bool:
    """
    两个bbox是否有部分重叠或者包含
    """
    if box1 is None or box2 is None:
        return False
    
    x0_1, y0_1, x1_1, y1_1 = box1
    x0_2, y0_2, x1_2, y1_2 = box2

    return not (x1_1 < x0_2 or  # box1在box2的左边
                x0_1 > x1_2 or  # box1在box2的右边
                y1_1 < y0_2 or  # box1在box2的上边
                y0_1 > y1_2)    # box1在box2的下边


def remove_text_block_overlap_interline_equation_bbox(interline_eq_bboxes, pymu_block_list):
    """消除掉行行内公式有部分重叠的文本块的内容。
    同时重新计算消除重叠之后文本块的大小"""
    deleted_block = []
    for text_block in pymu_block_list:
        deleted_line = []
        for line in text_block['lines']:
            deleted_span = []
            for span in line['spans']:
                deleted_chars = []
                for char in span['chars']:
                    if any([_is_in_or_part_overlap(char['bbox'], eq_bbox['bbox']) for eq_bbox in interline_eq_bboxes]):
                        deleted_chars.append(char)
                # 检查span里没有char则删除这个span
                for char in deleted_chars:
                    span['chars'].remove(char)
                # 重新计算这个span的大小
                if len(span['chars'])==0: # 删除这个span
                    deleted_span.append(span)
                else:
                    span['bbox'] = min([b['bbox'][0] for b in span['chars']]),min([b['bbox'][1] for b in span['chars']]),max([b['bbox'][2] for b in span['chars']]), max([b['bbox'][3] for b in span['chars']])
                    
            # 检查这个span
            for span in deleted_span:
                line['spans'].remove(span)
            if len(line['spans'])==0: #删除这个line
                deleted_line.append(line)
            else:
                line['bbox'] = min([b['bbox'][0] for b in line['spans']]),min([b['bbox'][1] for b in line['spans']]),max([b['bbox'][2] for b in line['spans']]), max([b['bbox'][3] for b in line['spans']])

        # 检查这个block是否可以删除
        for line in deleted_line:
            text_block['lines'].remove(line)
        if len(text_block['lines'])==0: # 删除block
            deleted_block.append(text_block)
        else:
            text_block['bbox'] = min([b['bbox'][0] for b in text_block['lines']]),min([b['bbox'][1] for b in text_block['lines']]),max([b['bbox'][2] for b in text_block['lines']]), max([b['bbox'][3] for b in text_block['lines']])

    # 检查text block删除
    for block in deleted_block:
        pymu_block_list.remove(block)
    if len(pymu_block_list)==0:
        return []

    return pymu_block_list


def insert_interline_equations_textblock(interline_eq_bboxes, pymu_block_list):
    """在行间公式对应的地方插上一个伪造的block"""
    for eq in interline_eq_bboxes:
        bbox = eq['bbox']
        latex_content = eq['latex_text']
        text_block = {
                "number": len(pymu_block_list),
                "type": 0,
                "bbox": bbox,
                "lines": [
                    {
                        "spans": [
                            {
                                "size": 9.962599754333496,
                                "_type": TYPE_INTERLINE_EQUATION,
                                "flags": 4,
                                "font": TYPE_INTERLINE_EQUATION,
                                "color": 0,
                                "ascender": 0.9409999847412109,
                                "descender": -0.3050000071525574,
                                "text": f"\n$$\n{latex_content}\n$$\n",
                                "origin": [
                                    bbox[0],
                                    bbox[1]
                                ],
                                "bbox": bbox
                            }
                        ],
                        "wmode": 0,
                        "dir": [
                            1.0,
                            0.0
                        ],
                        "bbox": bbox
                    }
                ]
            }
        pymu_block_list.append(text_block)
        
def x_overlap_ratio(box1, box2):
    a, _, c, _ = box1
    e, _, g, _ = box2

    # 计算重叠宽度
    overlap_x = max(min(c, g) - max(a, e), 0)
    
    # 计算box1的宽度
    width1 = g - e

    # 计算重叠比例
    overlap_ratio = overlap_x / width1 if width1 != 0 else 0

    return overlap_ratio

def __is_x_dir_overlap(bbox1, bbox2):
    return not (bbox1[2]<bbox2[0] or bbox1[0]>bbox2[2])

def __y_overlap_ratio(box1, box2):
    """"""
    _, b, _, d = box1
    _, f, _, h = box2

    # 计算重叠高度
    overlap_y = max(min(d, h) - max(b, f), 0)
    
    # 计算box1的高度
    height1 = d - b

    # 计算重叠比例
    overlap_ratio = overlap_y / height1 if height1 != 0 else 0

    return overlap_ratio
    
def replace_line_v2(eqinfo, line):
    """    
    扫描这一行所有的和公式框X方向重叠的char,然后计算char的左、右x0, x1,位于这个区间内的span删除掉。
    最后与这个x0,x1有相交的span0, span1内部进行分割。
    """
    first_overlap_span = -1
    first_overlap_span_idx = -1
    last_overlap_span = -1
    delete_chars = []
    for i in range(0, len(line['spans'])):
        if line['spans'][i].get("_type", None) is not None:
            continue # 忽略，因为已经是插入的伪造span公式了
        
        for char in line['spans'][i]['chars']:
            if __is_x_dir_overlap(eqinfo['bbox'], char['bbox']):
                line_txt = ""
                for span in line['spans']:
                    span_txt = "<span>"
                    for ch in span['chars']:
                        span_txt = span_txt + ch['c']

                    span_txt = span_txt + "</span>"

                    line_txt = line_txt + span_txt
                    
                if first_overlap_span_idx == -1:
                    first_overlap_span = line['spans'][i]
                    first_overlap_span_idx = i
                last_overlap_span = line['spans'][i]
                delete_chars.append(char)

    # 第一个和最后一个char要进行检查，到底属于公式多还是属于正常span多
    if len(delete_chars)>0:
        ch0_bbox = delete_chars[0]['bbox']
        if x_overlap_ratio(eqinfo['bbox'], ch0_bbox)<0.51:
            delete_chars.remove(delete_chars[0])
    if len(delete_chars)>0:
        ch0_bbox = delete_chars[-1]['bbox']
        if x_overlap_ratio(eqinfo['bbox'], ch0_bbox)<0.51:
            delete_chars.remove(delete_chars[-1])
            
    # 计算x方向上被删除区间内的char的真实x0, x1
    if len(delete_chars):
        x0, x1 = min([b['bbox'][0] for b in delete_chars]), max([b['bbox'][2] for b in delete_chars])
    else:
        logger.debug(f"行内公式替换没有发生，尝试下一行匹配, eqinfo={eqinfo}")
        return False
        
    # 删除位于x0, x1这两个中间的span
    delete_span = []
    for span in line['spans']:
        span_box = span['bbox']
        if x0<=span_box[0] and span_box[2]<=x1:
            delete_span.append(span)
    for span in delete_span:
        line['spans'].remove(span)


    equation_span = {
                                "size": 9.962599754333496,
                                "_type": TYPE_INLINE_EQUATION,
                                "flags": 4,
                                "font": TYPE_INLINE_EQUATION,
                                "color": 0,
                                "ascender": 0.9409999847412109,
                                "descender": -0.3050000071525574,
                                "text": "",
                                "origin": [
                                    337.1410153102337,
                                    216.0205245153934
                                ],
                                "bbox": [
                                    337.1410153102337,
                                    216.0205245153934,
                                    390.4496373892022,
                                    228.50171037628277
                                ]
                            }
    #equation_span = line['spans'][0].copy()
    equation_span['text'] = f" ${eqinfo['latex_text']}$ "
    equation_span['bbox'] = [x0, equation_span['bbox'][1], x1, equation_span['bbox'][3]] 
    equation_span['origin'] = [equation_span['bbox'][0], equation_span['bbox'][1]]
    equation_span['chars'] = delete_chars
    equation_span['_type'] = TYPE_INLINE_EQUATION
    equation_span['_eq_bbox'] = eqinfo['bbox']
    line['spans'].insert(first_overlap_span_idx+1, equation_span) # 放入公式

    # logger.info(f"==>text is 【{line_txt}】, equation is 【{eqinfo['latex_text']}】")
    
    # 第一个、和最后一个有overlap的span进行分割,然后插入对应的位置
    first_span_chars = [char for char in first_overlap_span['chars'] if (char['bbox'][2]+char['bbox'][0])/2<x0]
    tail_span_chars  = [char for char in last_overlap_span['chars'] if (char['bbox'][0]+char['bbox'][2])/2>x1]
    
    if len(first_span_chars)>0:
        first_overlap_span['chars'] = first_span_chars
        first_overlap_span['text'] = ''.join([char['c'] for char in first_span_chars])
        first_overlap_span['bbox'] = (first_overlap_span['bbox'][0], first_overlap_span['bbox'][1], max([chr['bbox'][2] for chr in first_span_chars]), first_overlap_span['bbox'][3])
        # first_overlap_span['_type'] = "first"
    else:
        # 删掉
        if first_overlap_span not in delete_span:
            line['spans'].remove(first_overlap_span)
        

    if len(tail_span_chars)>0:
        if last_overlap_span==first_overlap_span: # 这个时候应该插入一个新的
            tail_span_txt = ''.join([char['c'] for char in tail_span_chars])
            last_span_to_insert =  last_overlap_span.copy()
            last_span_to_insert['chars'] = tail_span_chars
            last_span_to_insert['text'] = ''.join([char['c'] for char in tail_span_chars])
            last_span_to_insert['bbox'] = (min([chr['bbox'][0] for chr in tail_span_chars]), last_overlap_span['bbox'][1], last_overlap_span['bbox'][2], last_overlap_span['bbox'][3])
            # 插入到公式对象之后
            equation_idx = line['spans'].index(equation_span)
            line['spans'].insert(equation_idx+1, last_span_to_insert) # 放入公式
        else: # 直接修改原来的span
            last_overlap_span['chars'] = tail_span_chars
            last_overlap_span['text'] = ''.join([char['c'] for char in tail_span_chars])
            last_overlap_span['bbox'] = (min([chr['bbox'][0] for chr in tail_span_chars]), last_overlap_span['bbox'][1], last_overlap_span['bbox'][2], last_overlap_span['bbox'][3])
    else:
        # 删掉
        if last_overlap_span not in delete_span and last_overlap_span!=first_overlap_span:
            line['spans'].remove(last_overlap_span)
            
    remain_txt = ""
    for span in line['spans']:
        span_txt = "<span>"
        for char in span['chars']:
            span_txt = span_txt + char['c']

        span_txt = span_txt + "</span>"

        remain_txt = remain_txt + span_txt
    
    # logger.info(f"<== succ replace, text is 【{remain_txt}】, equation is 【{eqinfo['latex_text']}】")
    
    return True


def replace_eq_blk(eqinfo, text_block):
    """替换行内公式"""
    for line in text_block['lines']:
        line_bbox = line['bbox']
        if _is_xin(eqinfo['bbox'], line_bbox) or __y_overlap_ratio(eqinfo['bbox'], line_bbox)>0.6: # 定位到行, 使用y方向重合率是因为有的时候，一个行的宽度会小于公式位置宽度：行很高，公式很窄，
            replace_succ =  replace_line_v2(eqinfo, line)
            if not replace_succ: # 有的时候，一个pdf的line高度从API里会计算的有问题，因此在行内span级别会替换不成功，这就需要继续重试下一行
                continue
            else:
                break
    else:
        return False
    return True


def replace_inline_equations(inline_equation_bboxes, raw_text_blocks):
    """替换行内公式"""
    for eqinfo in inline_equation_bboxes:
        eqbox = eqinfo['bbox']
        for blk in raw_text_blocks:
            if _is_xin(eqbox, blk['bbox']):
                if not replace_eq_blk(eqinfo, blk):
                    logger.error(f"行内公式没有替换成功：{eqinfo} ")
                else:
                    break

    return raw_text_blocks

def remove_chars_in_text_blocks(text_blocks):
    """删除text_blocks里的char"""
    for blk in text_blocks:
        for line in blk['lines']:
            for span in line['spans']:
                _ = span.pop("chars", "no such key")
    return text_blocks


def replace_equations_in_textblock(raw_text_blocks, inline_equation_bboxes, interline_equation_bboxes):
    """
    替换行间和和行内公式为latex
    """
    
    raw_text_blocks = remove_text_block_in_interline_equation_bbox(interline_equation_bboxes, raw_text_blocks) # 消除重叠：第一步，在公式内部的
    raw_text_blocks = remove_text_block_overlap_interline_equation_bbox(interline_equation_bboxes, raw_text_blocks) # 消重，第二步，和公式覆盖的
    insert_interline_equations_textblock(interline_equation_bboxes, raw_text_blocks)
    
    raw_text_blocks = replace_inline_equations(inline_equation_bboxes, raw_text_blocks)
    
    return raw_text_blocks
    

def draw_block_on_pdf_with_txt_replace_eq_bbox(json_path, pdf_path):
    """
    """
    new_pdf = f"{Path(pdf_path).parent}/{Path(pdf_path).stem}.step3-消除行内公式text_block.pdf"
    with open(json_path, "r", encoding='utf-8') as f:
        obj = json.loads(f.read())

    if os.path.exists(new_pdf):
        os.remove(new_pdf)
    new_doc = fitz.open('')
    
    doc = fitz.open(pdf_path)
    new_doc = fitz.open(pdf_path)
    for i in range(len(new_doc)):
        page = new_doc[i]
        inline_equation_bboxes = obj[f"page_{i}"]['inline_equations']
        interline_equation_bboxes = obj[f"page_{i}"]['interline_equations']
        raw_text_blocks = obj[f'page_{i}']['preproc_blocks']
        raw_text_blocks = remove_text_block_in_interline_equation_bbox(interline_equation_bboxes, raw_text_blocks) # 消除重叠：第一步，在公式内部的
        raw_text_blocks = remove_text_block_overlap_interline_equation_bbox(interline_equation_bboxes, raw_text_blocks) # 消重，第二步，和公式覆盖的
        insert_interline_equations_textblock(interline_equation_bboxes, raw_text_blocks)
        raw_text_blocks = replace_inline_equations(inline_equation_bboxes, raw_text_blocks)
        
        
        # 为了检验公式是否重复，把每一行里，含有公式的span背景改成黄色的
        color_map = [fitz.pdfcolor['blue'],fitz.pdfcolor['green']]
        j = 0
        for blk in raw_text_blocks:
            for i,line in enumerate(blk['lines']):
                
                # line_box = line['bbox']
                # shape = page.new_shape()
                # shape.draw_rect(line_box)
                # shape.finish(color=fitz.pdfcolor['red'], fill=color_map[j%2], fill_opacity=0.3)
                # shape.commit()
                # j = j+1
                
                for i, span in enumerate(line['spans']):
                    shape_page = page.new_shape()
                    span_type = span.get('_type')
                    color = fitz.pdfcolor['blue']
                    if span_type=='first':
                        color = fitz.pdfcolor['blue']
                    elif span_type=='tail':
                        color = fitz.pdfcolor['green']
                    elif span_type==TYPE_INLINE_EQUATION:
                        color = fitz.pdfcolor['black']
                    else:
                        color = None
                        
                    b = span['bbox']
                    shape_page.draw_rect(b)
                    
                    shape_page.finish(color=None, fill=color, fill_opacity=0.3)
                    shape_page.commit()

    new_doc.save(new_pdf)
    logger.info(f"save ok {new_pdf}")
    final_json = json.dumps(obj, ensure_ascii=False,indent=2)
    with open("equations_test/final_json.json", "w") as f:
        f.write(final_json)
    
    return new_pdf


if __name__=="__main__":
    # draw_block_on_pdf_with_txt_replace_eq_bbox(new_json_path, equation_color_pdf)
    pass