refactor(pdf_parse_union): integrate LayoutLMv3 for block orderingReplace the...

refactor(pdf_parse_union): integrate LayoutLMv3 for block orderingReplace the heuristic-based block ordering algorithm with LayoutLMv3 model predictions toimprove the accuracy of block ordering on PDF pages. Additionally, refactor the span
handling during block filling to ensure spans are correctly assigned.

- Introduce LayoutLMv3ForTokenClassification from 'hantian/layoutreader' to predict block
  order.
- Implement span replacement strategy to use pymu spans for non-OCR content.
- Enhance cleanup process to free GPU memory more effectively after model use.
- Adjust block ordering logic to use median line index for text, title, and interline equation blocks.
- Refactor page parsing core logic for better maintainability.

BREAKING CHANGE: The integration of LayoutLMv3 changes the internal block handling and
ordering mechanism, which may affect downstream systems relying on the previous
implementation. Ensure to test thoroughly before deployment.

magic_pdf/pdf_parse_by_ocr.py

-from magic_pdf.pdf_parse_union_core import pdf_parse_union
+from magic_pdf.pdf_parse_union_core_v2 import pdf_parse_union
 
 
 def parse_pdf_by_ocr(pdf_bytes,

magic_pdf/pdf_parse_by_txt.py

-from magic_pdf.pdf_parse_union_core import pdf_parse_union
+from magic_pdf.pdf_parse_union_core_v2 import pdf_parse_union
 
 
 def parse_pdf_by_txt(

magic_pdf/pre_proc/ocr_detect_all_bboxes.py

@@ -60,6 +60,59 @@ def ocr_prepare_bboxes_for_layout_split(img_blocks, table_blocks, discarded_bloc
     return all_bboxes, all_discarded_blocks, drop_reasons
 
 
+def ocr_prepare_bboxes_for_layout_split_v2(img_blocks, table_blocks, discarded_blocks, text_blocks,
+                                        title_blocks, interline_equation_blocks, page_w, page_h):
+    all_bboxes = []
+    all_discarded_blocks = []
+    for image in img_blocks:
+        x0, y0, x1, y1 = image['bbox']
+        all_bboxes.append([x0, y0, x1, y1, None, None, None, BlockType.Image, None, None, None, None, image["score"]])
+
+    for table in table_blocks:
+        x0, y0, x1, y1 = table['bbox']
+        all_bboxes.append([x0, y0, x1, y1, None, None, None, BlockType.Table, None, None, None, None, table["score"]])
+
+    for text in text_blocks:
+        x0, y0, x1, y1 = text['bbox']
+        all_bboxes.append([x0, y0, x1, y1, None, None, None, BlockType.Text, None, None, None, None, text["score"]])
+
+    for title in title_blocks:
+        x0, y0, x1, y1 = title['bbox']
+        all_bboxes.append([x0, y0, x1, y1, None, None, None, BlockType.Title, None, None, None, None, title["score"]])
+
+    for interline_equation in interline_equation_blocks:
+        x0, y0, x1, y1 = interline_equation['bbox']
+        all_bboxes.append([x0, y0, x1, y1, None, None, None, BlockType.InterlineEquation, None, None, None, None, interline_equation["score"]])
+
+    '''block嵌套问题解决'''
+    '''文本框与标题框重叠，优先信任文本框'''
+    all_bboxes = fix_text_overlap_title_blocks(all_bboxes)
+    '''任何框体与舍弃框重叠，优先信任舍弃框'''
+    all_bboxes = remove_need_drop_blocks(all_bboxes, discarded_blocks)
+
+    # interline_equation 与title或text框冲突的情况，分两种情况处理
+    '''interline_equation框与文本类型框iou比较接近1的时候，信任行间公式框'''
+    all_bboxes = fix_interline_equation_overlap_text_blocks_with_hi_iou(all_bboxes)
+    '''interline_equation框被包含在文本类型框内，且interline_equation比文本区块小很多时信任文本框，这时需要舍弃公式框'''
+    # 通过后续大框套小框逻辑删除
+
+    '''discarded_blocks中只保留宽度超过1/3页面宽度的，高度超过10的，处于页面下半50%区域的（限定footnote）'''
+    for discarded in discarded_blocks:
+        x0, y0, x1, y1 = discarded['bbox']
+        all_discarded_blocks.append([x0, y0, x1, y1, None, None, None, BlockType.Discarded, None, None, None, None, discarded["score"]])
+        # 将footnote加入到all_bboxes中，用来计算layout
+        # if (x1 - x0) > (page_w / 3) and (y1 - y0) > 10 and y0 > (page_h / 2):
+        #     all_bboxes.append([x0, y0, x1, y1, None, None, None, BlockType.Footnote, None, None, None, None, discarded["score"]])
+
+    '''经过以上处理后，还存在大框套小框的情况，则删除小框'''
+    all_bboxes = remove_overlaps_min_blocks(all_bboxes)
+    all_discarded_blocks = remove_overlaps_min_blocks(all_discarded_blocks)
+    '''将剩余的bbox做分离处理，防止后面分layout时出错'''
+    all_bboxes, drop_reasons = remove_overlap_between_bbox_for_block(all_bboxes)
+
+    return all_bboxes, all_discarded_blocks, drop_reasons
+
+
 def fix_interline_equation_overlap_text_blocks_with_hi_iou(all_bboxes):
     # 先提取所有text和interline block
     text_blocks = []