pdf2zh/pdf2zh/converter.py

import io
import logging
import re
from typing import (
    BinaryIO,
    Dict,
    Generic,
    List,
    Optional,
    Sequence,
    TextIO,
    Tuple,
    TypeVar,
    Union,
    cast,
)
import concurrent.futures
import mtranslate as translator
import unicodedata
import tqdm.auto
from tenacity import retry
from pdf2zh import cache
def remove_control_characters(s):
    return "".join(ch for ch in s if unicodedata.category(ch)[0]!="C")

from pdf2zh import utils
from pdf2zh.image import ImageWriter
from pdf2zh.layout import (
    LAParams,
    LTAnno,
    LTChar,
    LTComponent,
    LTContainer,
    LTCurve,
    LTFigure,
    LTImage,
    LTItem,
    LTLayoutContainer,
    LTLine,
    LTPage,
    LTRect,
    LTText,
    LTTextBox,
    LTTextBoxVertical,
    LTTextGroup,
    LTTextLine,
    TextGroupElement,
)
from pdf2zh.pdfcolor import PDFColorSpace
from pdf2zh.pdfdevice import PDFTextDevice
from pdf2zh.pdfexceptions import PDFValueError
from pdf2zh.pdffont import PDFFont, PDFUnicodeNotDefined, PDFCIDFont
from pdf2zh.pdfinterp import PDFGraphicState, PDFResourceManager
from pdf2zh.pdfpage import PDFPage
from pdf2zh.pdftypes import PDFStream
from pdf2zh.utils import (
    AnyIO,
    Matrix,
    PathSegment,
    Point,
    Rect,
    apply_matrix_pt,
    bbox2str,
    enc,
    make_compat_str,
    mult_matrix,
)

log = logging.getLogger(__name__)


class PDFLayoutAnalyzer(PDFTextDevice):
    cur_item: LTLayoutContainer
    ctm: Matrix

    def __init__(
        self,
        rsrcmgr: PDFResourceManager,
        pageno: int = 1,
        laparams: Optional[LAParams] = None,
    ) -> None:
        PDFTextDevice.__init__(self, rsrcmgr)
        self.pageno = pageno
        self.laparams = laparams
        self._stack: List[LTLayoutContainer] = []

    def begin_page(self, page: PDFPage, ctm: Matrix) -> None:
        (x0, y0, x1, y1) = page.mediabox
        (x0, y0) = apply_matrix_pt(ctm, (x0, y0))
        (x1, y1) = apply_matrix_pt(ctm, (x1, y1))
        mediabox = (0, 0, abs(x0 - x1), abs(y0 - y1))
        self.cur_item = LTPage(page.pageno, mediabox)

    def end_page(self, page: PDFPage):
        assert not self._stack, str(len(self._stack))
        assert isinstance(self.cur_item, LTPage), str(type(self.cur_item))
        # 取消默认排版分析
        # if self.laparams is not None:
        #     self.cur_item.analyze(self.laparams)
        self.pageno += 1
        return self.receive_layout(self.cur_item)

    def begin_figure(self, name: str, bbox: Rect, matrix: Matrix) -> None:
        self._stack.append(self.cur_item)
        self.cur_item = LTFigure(name, bbox, mult_matrix(matrix, self.ctm))

    def end_figure(self, _: str) -> None:
        fig = self.cur_item
        assert isinstance(self.cur_item, LTFigure), str(type(self.cur_item))
        self.cur_item = self._stack.pop()
        self.cur_item.add(fig)

    def render_image(self, name: str, stream: PDFStream) -> None:
        assert isinstance(self.cur_item, LTFigure), str(type(self.cur_item))
        item = LTImage(
            name,
            stream,
            (self.cur_item.x0, self.cur_item.y0, self.cur_item.x1, self.cur_item.y1),
        )
        self.cur_item.add(item)

    def paint_path(
        self,
        gstate: PDFGraphicState,
        stroke: bool,
        fill: bool,
        evenodd: bool,
        path: Sequence[PathSegment],
    ) -> None:
        """Paint paths described in section 4.4 of the PDF reference manual"""
        shape = "".join(x[0] for x in path)

        if shape[:1] != "m":
            # Per PDF Reference Section 4.4.1, "path construction operators may
            # be invoked in any sequence, but the first one invoked must be m
            # or re to begin a new subpath." Since pdf2zh.six already
            # converts all `re` (rectangle) operators to their equivelent
            # `mlllh` representation, paths ingested by `.paint_path(...)` that
            # do not begin with the `m` operator are invalid.
            pass

        elif shape.count("m") > 1:
            # recurse if there are multiple m's in this shape
            for m in re.finditer(r"m[^m]+", shape):
                subpath = path[m.start(0) : m.end(0)]
                self.paint_path(gstate, stroke, fill, evenodd, subpath)

        else:
            # Although the 'h' command does not not literally provide a
            # point-position, its position is (by definition) equal to the
            # subpath's starting point.
            #
            # And, per Section 4.4's Table 4.9, all other path commands place
            # their point-position in their final two arguments. (Any preceding
            # arguments represent control points on Bézier curves.)
            raw_pts = [
                cast(Point, p[-2:] if p[0] != "h" else path[0][-2:]) for p in path
            ]
            pts = [apply_matrix_pt(self.ctm, pt) for pt in raw_pts]

            operators = [str(operation[0]) for operation in path]
            transformed_points = [
                [
                    apply_matrix_pt(self.ctm, (float(operand1), float(operand2)))
                    for operand1, operand2 in zip(operation[1::2], operation[2::2])
                ]
                for operation in path
            ]
            transformed_path = [
                cast(PathSegment, (o, *p))
                for o, p in zip(operators, transformed_points)
            ]

            if shape in {"mlh", "ml"}:
                # single line segment
                #
                # Note: 'ml', in conditional above, is a frequent anomaly
                # that we want to support.
                line = LTLine(
                    gstate.linewidth,
                    pts[0],
                    pts[1],
                    stroke,
                    fill,
                    evenodd,
                    gstate.scolor,
                    gstate.ncolor,
                    original_path=transformed_path,
                    dashing_style=gstate.dash,
                )
                self.cur_item.add(line)

            elif shape in {"mlllh", "mllll"}:
                (x0, y0), (x1, y1), (x2, y2), (x3, y3), _ = pts

                is_closed_loop = pts[0] == pts[4]
                has_square_coordinates = (
                    x0 == x1 and y1 == y2 and x2 == x3 and y3 == y0
                ) or (y0 == y1 and x1 == x2 and y2 == y3 and x3 == x0)
                if is_closed_loop and has_square_coordinates:
                    rect = LTRect(
                        gstate.linewidth,
                        (*pts[0], *pts[2]),
                        stroke,
                        fill,
                        evenodd,
                        gstate.scolor,
                        gstate.ncolor,
                        transformed_path,
                        gstate.dash,
                    )
                    self.cur_item.add(rect)
                else:
                    curve = LTCurve(
                        gstate.linewidth,
                        pts,
                        stroke,
                        fill,
                        evenodd,
                        gstate.scolor,
                        gstate.ncolor,
                        transformed_path,
                        gstate.dash,
                    )
                    self.cur_item.add(curve)
            else:
                curve = LTCurve(
                    gstate.linewidth,
                    pts,
                    stroke,
                    fill,
                    evenodd,
                    gstate.scolor,
                    gstate.ncolor,
                    transformed_path,
                    gstate.dash,
                )
                self.cur_item.add(curve)

    def render_char(
        self,
        matrix: Matrix,
        font: PDFFont,
        fontsize: float,
        scaling: float,
        rise: float,
        cid: int,
        ncs: PDFColorSpace,
        graphicstate: PDFGraphicState,
    ) -> float:
        try:
            text = font.to_unichr(cid)
            assert isinstance(text, str), str(type(text))
        except PDFUnicodeNotDefined:
            text = self.handle_undefined_char(font, cid)
        textwidth = font.char_width(cid)
        textdisp = font.char_disp(cid)
        item = LTChar(
            matrix,
            font,
            fontsize,
            scaling,
            rise,
            text,
            textwidth,
            textdisp,
            ncs,
            graphicstate,
        )
        self.cur_item.add(item)
        item.cid=cid # hack
        return item.adv

    def handle_undefined_char(self, font: PDFFont, cid: int) -> str:
        # log.debug("undefined: %r, %r", font, cid)
        return "(cid:%d)" % cid

    def receive_layout(self, ltpage: LTPage) -> None:
        pass


class PDFPageAggregator(PDFLayoutAnalyzer):
    def __init__(
        self,
        rsrcmgr: PDFResourceManager,
        pageno: int = 1,
        laparams: Optional[LAParams] = None,
    ) -> None:
        PDFLayoutAnalyzer.__init__(self, rsrcmgr, pageno=pageno, laparams=laparams)
        self.result: Optional[LTPage] = None

    def receive_layout(self, ltpage: LTPage) -> None:
        self.result = ltpage

    def get_result(self) -> LTPage:
        assert self.result is not None
        return self.result


# Some PDFConverter children support only binary I/O
IOType = TypeVar("IOType", TextIO, BinaryIO, AnyIO)


class PDFConverter(PDFLayoutAnalyzer, Generic[IOType]):
    def __init__(
        self,
        rsrcmgr: PDFResourceManager,
        outfp: IOType,
        codec: str = "utf-8",
        pageno: int = 1,
        laparams: Optional[LAParams] = None,
    ) -> None:
        PDFLayoutAnalyzer.__init__(self, rsrcmgr, pageno=pageno, laparams=laparams)
        self.outfp: IOType = outfp
        self.codec = codec
        self.outfp_binary = self._is_binary_stream(self.outfp)

    @staticmethod
    def _is_binary_stream(outfp: AnyIO) -> bool:
        """Test if an stream is binary or not"""
        if "b" in getattr(outfp, "mode", ""):
            return True
        elif hasattr(outfp, "mode"):
            # output stream has a mode, but it does not contain 'b'
            return False
        elif isinstance(outfp, io.BytesIO):
            return True
        elif isinstance(outfp, io.StringIO) or isinstance(outfp, io.TextIOBase):
            return False

        return True


class TextConverter(PDFConverter[AnyIO]):
    def __init__(
        self,
        rsrcmgr: PDFResourceManager,
        outfp: AnyIO,
        codec: str = "utf-8",
        pageno: int = 1,
        laparams: Optional[LAParams] = None,
        showpageno: bool = False,
        imagewriter: Optional[ImageWriter] = None,
        vfont: str = None,
        vchar: str = None,
        thread: int = 0,
        layout = {},
    ) -> None:
        super().__init__(rsrcmgr, outfp, codec=codec, pageno=pageno, laparams=laparams)
        self.showpageno = showpageno
        self.imagewriter = imagewriter
        self.vfont = vfont
        self.vchar = vchar
        self.thread = thread
        self.layout = layout

    def write_text(self, text: str) -> None:
        text = utils.compatible_encode_method(text, self.codec, "ignore")
        if self.outfp_binary:
            cast(BinaryIO, self.outfp).write(text.encode())
        else:
            cast(TextIO, self.outfp).write(text)

    def receive_layout(self, ltpage: LTPage):
        def render(item: LTItem) -> None:
            xt=None
            lt=None
            rt=None
            sstk=[]
            vstk=[]
            vlstk=[]
            pstk=[]
            lstk=[]
            var=[]
            varl=[]
            vlen=[]
            ops=""
            def vflag(font,char): # 匹配公式（和角标）字体
                if self.vfont:
                    if re.match(self.vfont,font):
                        return True
                else:
                    if re.match(r'.*\+(CM.*|MS.*|XY.*|MT.*|BL.*|.*0700|.*0500|.*Italic)',font):
                        return True
                if self.vchar and re.match(self.vchar,char):
                    return True
                return False
            ptr=0
            item=list(item)
            xt_ind=False
            while ptr<len(item): # 识别文字和公式
                child=item[ptr]
                if isinstance(child, LTChar):
                    cur_v=False
                    ind_v=False
                    if vflag(child.fontname,child.get_text()): # 识别公式和字符
                        cur_v=True
                    for box in self.layout[ltpage.pageid]: # 识别独立公式
                        b=box.block
                        if child.x1>b.x_1 and child.x0<b.x_2 and child.y1>ltpage.height-b.y_2 and child.y0<ltpage.height-b.y_1:
                            cur_v=True
                            ind_v=True
                            # lstk.append(LTLine(1,(b.x_1,ltpage.height-b.y_2),(b.x_2,ltpage.height-b.y_2)))
                            # lstk.append(LTLine(1,(b.x_1,ltpage.height-b.y_1),(b.x_2,ltpage.height-b.y_1)))
                            break
                    if ptr==len(item)-1 or not cur_v or (ind_v and not xt_ind) or (vstk and child.x0<vstk[-1].x1-ltpage.width/3): # 公式结束或公式换行截断
                        if vstk: # 公式出栈
                            sstk[-1]+=f'$v{len(var)}$'
                            var.append(vstk)
                            varl.append(vlstk)
                            vstk=[]
                            vlstk=[]
                            if ptr==len(item)-1 and cur_v: # 文档以公式结尾
                                var[-1].append(child)
                                break
                    if not vstk: # 非公式或是公式开头
                        if not ind_v and xt and child.y1 > xt.y0 - child.size*0.5 and child.y0 < xt.y1 + child.size: # 非独立公式且位于同段落
                            if child.x0 > xt.x1 + child.size*2: # 行内分离
                                lt,rt=child,child
                                sstk.append("")
                                pstk.append([child.y0,child.x0,child.x0,child.x0,child.size,child.font,False])
                            elif child.x0 > xt.x1 + 1: # 行内空格
                                sstk[-1]+=' '
                            elif child.x1 < xt.x0: # 换行，这里需要考虑一下字母修饰符的情况
                                if child.x0 < lt.x0 - child.size*2 or child.x0 > lt.x0 + child.size*1: # 基于初始位置的行间分离
                                    lt,rt=child,child
                                    sstk.append("")
                                    pstk.append([child.y0,child.x0,child.x0,child.x0,child.size,child.font,False])
                                else: # 换行空格
                                    sstk[-1]+=' '
                                    pstk[-1][6]=True # 标记原文段落存在换行
                        else: # 基于纵向距离的行间分离
                            lt,rt=child,child
                            sstk.append("")
                            pstk.append([child.y0,child.x0,child.x0,child.x0,child.size,child.font,False])
                    if not cur_v: # 文字入栈
                        sstk[-1]+=child.get_text()
                        if vflag(pstk[-1][5].fontname,''): # 公式开头，后续接文字，需要校正字体
                            pstk[-1][5]=child.font
                    else: # 公式入栈
                        vstk.append(child)
                        # if re.match(r'.*\+(CMEX.*)',child.fontname) and child.cid in [40]: # 大括号
                        #     # ops+=f"ET q 1 0 0 1 0 {child.y0} cm [] 0 d 0 J 1 w 0 0 m {ltpage.width} 0 l S Q BT "
                        #     # ops+=f"ET q 1 0 0 1 0 {child.y0-child.size*3} cm [] 0 d 0 J 1 w 0 0 m {ltpage.width} 0 l S Q BT "
                        #     while ptr+1<len(item):
                        #         child_=item[ptr+1]
                        #         if isinstance(child_, LTChar): # 公式字符
                        #             # print(child_.y0,child.y0-child.size*3,child_.y1,child.y0)
                        #             if child_.y0>child.y0-child.size*3 and child_.y1<child.y0:
                        #                 vstk.append(child_)
                        #             else:
                        #                 break
                        #         elif isinstance(child_, LTLine): # 公式线条
                        #             vlstk.append(child_)
                        #         ptr+=1
                    xt=child
                    xt_ind=ind_v
                    # 更新左右边界
                    if child.x0<lt.x0:
                        pstk[-1][2]=child.x0
                        lt=child
                    if child.x1>rt.x1:
                        pstk[-1][3]=child.x1
                        rt=child
                elif isinstance(child, LTFigure): # 图表
                    # print(f'\n\n[FIGURE] {child.name}')
                    pass
                elif isinstance(child, LTLine): # 线条
                    if vstk and child.x1-child.x0<ltpage.width/3: # 公式线条
                        vlstk.append(child)
                    else: # 全局线条
                        lstk.append(child)
                else:
                    # print(child)
                    pass
                ptr+=1
            log.debug('\n==========[VSTACK]==========\n')
            for id,v in enumerate(var):
                l=max([vch.x1 for vch in v])-v[0].x0
                log.debug(f'< {l:.1f} {v[0].x0:.1f} {v[0].y0:.1f} {v[0].cid} {v[0].fontname} {len(varl[id])} > $v{id}$ = {"".join([ch.get_text() for ch in v])}')
                vlen.append(l)
            log.debug('\n==========[SSTACK]==========\n')
            hash_key=cache.deterministic_hash("PDFMathTranslate")
            cache.create_cache(hash_key)
            @retry
            def worker(s): # 多线程翻译
                try:
                    if sum(map(str.islower,s))>1:
                        hash_key_paragraph = cache.deterministic_hash(s)
                        new = cache.load_paragraph(hash_key, hash_key_paragraph)
                        if new is None:
                            new=translator.translate(s,'zh-CN','en')
                            new=remove_control_characters(new)
                            cache.write_paragraph(hash_key, hash_key_paragraph, new)
                    else:
                        new=s
                    return new
                except BaseException as e:
                    log.exception(e,exc_info=False)
                    raise e
            with concurrent.futures.ThreadPoolExecutor(max_workers=self.thread) as executor:
                news = list(executor.map(worker, sstk))
            def raw_string(fcur,cstk): # 编码字符串
                if isinstance(self.fontmap[fcur],PDFCIDFont):
                    return "".join(["%04x" % ord(c) for c in cstk])
                else:
                    return "".join(["%02x" % ord(c) for c in cstk])
            for id,new in enumerate(news): # 排版文字和公式
                tx=x=pstk[id][1];y=pstk[id][0];lt=pstk[id][2];rt=pstk[id][3];ptr=0;size=pstk[id][4];font=pstk[id][5];lb=pstk[id][6];cstk='';fcur=fcur_=None
                log.debug(f"< {y} {x} {lt} {rt} {size} {font.fontname} {lb} > {sstk[id]} | {new}")
                while True:
                    if ptr==len(new): # 到达段落结尾
                        if cstk:
                            ops+=f'/{fcur} {size} Tf 1 0 0 1 {tx} {y} Tm [<{raw_string(fcur,cstk)}>] TJ '
                        break
                    vy_regex=re.match(r'\$\s*v([\d\s]*)\$',new[ptr:]) # 匹配 $vn$ 公式标记
                    if vy_regex: # 加载公式
                        vid=int(vy_regex.group(1).replace(' ',''))
                        ptr+=len(vy_regex.group(0))
                        if vid<len(vlen):
                            adv=vlen[vid]
                        else:
                            continue # 翻译器可能会自动补个越界的公式标记
                    else: # 加载文字
                        ch=new[ptr]
                        if font.char_width(ord(ch)):
                            fcur_=font.fontid
                        else:
                            if ch==' ':
                                fcur_='helv' # 半角空格
                            else:
                                fcur_='china-ss'
                        adv=self.fontmap[fcur_].char_width(ord(ch))*size
                        ptr+=1
                    if fcur_!=fcur or vy_regex or x+adv>rt: # 输出文字缓冲区：1.字体更新 2.插入公式 3.到达右边界
                        if cstk:
                            ops+=f'/{fcur} {size} Tf 1 0 0 1 {tx} {y} Tm [<{raw_string(fcur,cstk)}>] TJ '
                            cstk=''
                    if lb and x+adv>rt: # 到达右边界且原文段落存在换行
                        x=lt
                        y-=size*1.5
                    if vy_regex: # 插入公式
                        fix=0
                        if fcur!=None: # 段落内公式修正
                            if re.match(r'.*\+(CMEX.*)',var[vid][0].fontname) and var[vid][0].cid in [80,88,112,33,82]: # 根式、积分与大小求和
                                fix=var[vid][0].size*0.85
                            if re.match(r'.*\+(CMSY.*)',var[vid][0].fontname) and var[vid][0].cid in [112]: # 根式
                                fix=var[vid][0].size*0.85
                            if re.match(r'.*\+(MSAM.*)',var[vid][0].fontname) and var[vid][0].cid in [97]: # 特殊上标
                                fix=var[vid][0].size*0.85
                            if re.match(r'.*\+(CMR.*)',var[vid][0].fontname) and var[vid][0].cid in [94,126]: # 特殊上标
                                fix=var[vid][0].size*0.25
                            if re.match(r'.*\+(CM.*)7',var[vid][0].fontname): # 修正分式
                                fix=var[vid][0].size*0.55
                        for vch in var[vid]: # 排版公式字符
                            vc=chr(vch.cid)
                            ops+=f"/{vch.font.fontid} {vch.size} Tf 1 0 0 1 {x+vch.x0-var[vid][0].x0} {fix+y+vch.y0-var[vid][0].y0} Tm [<{raw_string(vch.font.fontid,vc)}>] TJ "
                        for l in varl[vid]: # 排版公式线条
                            if l.linewidth<5: # hack
                                ops+=f"ET q 1 0 0 1 {l.pts[0][0]+x-var[vid][0].x0} {l.pts[0][1]+fix+y-var[vid][0].y0} cm [] 0 d 0 J {l.linewidth} w 0 0 m {l.pts[1][0]-l.pts[0][0]} {l.pts[1][1]-l.pts[0][1]} l S Q BT "
                    else: # 插入文字缓冲区
                        if not cstk:
                            tx=x
                            if x==lt and ch==' ': # 消除段落换行空格
                                adv=0
                            else:
                                cstk+=ch
                        else:
                            cstk+=ch
                    fcur=fcur_
                    x+=adv
            for l in lstk: # 排版全局线条
                if l.linewidth<5: # hack
                    ops+=f"ET q 1 0 0 1 {l.pts[0][0]} {l.pts[0][1]} cm [] 0 d 0 J {l.linewidth} w 0 0 m {l.pts[1][0]-l.pts[0][0]} {l.pts[1][1]-l.pts[0][1]} l S Q BT "
            ops=f'BT {ops}ET '
            return ops
        ops=render(ltpage)
        return ops

    # Some dummy functions to save memory/CPU when all that is wanted
    # is text.  This stops all the image and drawing output from being
    # recorded and taking up RAM.
    def render_image(self, name: str, stream: PDFStream) -> None:
        if self.imagewriter is not None:
            PDFConverter.render_image(self, name, stream)

    # def paint_path(
    #     self,
    #     gstate: PDFGraphicState,
    #     stroke: bool,
    #     fill: bool,
    #     evenodd: bool,
    #     path: Sequence[PathSegment],
    # ) -> None:
    #     pass


class HTMLConverter(PDFConverter[AnyIO]):
    RECT_COLORS = {
        "figure": "yellow",
        "textline": "magenta",
        "textbox": "cyan",
        "textgroup": "red",
        "curve": "black",
        "page": "gray",
    }

    TEXT_COLORS = {
        "textbox": "blue",
        "char": "black",
    }

    def __init__(
        self,
        rsrcmgr: PDFResourceManager,
        outfp: AnyIO,
        codec: str = "utf-8",
        pageno: int = 1,
        laparams: Optional[LAParams] = None,
        scale: float = 1,
        fontscale: float = 1.0,
        layoutmode: str = "normal",
        showpageno: bool = True,
        pagemargin: int = 50,
        imagewriter: Optional[ImageWriter] = None,
        debug: int = 0,
        rect_colors: Optional[Dict[str, str]] = None,
        text_colors: Optional[Dict[str, str]] = None,
    ) -> None:
        PDFConverter.__init__(
            self,
            rsrcmgr,
            outfp,
            codec=codec,
            pageno=pageno,
            laparams=laparams,
        )

        # write() assumes a codec for binary I/O, or no codec for text I/O.
        if self.outfp_binary and not self.codec:
            raise PDFValueError("Codec is required for a binary I/O output")
        if not self.outfp_binary and self.codec:
            raise PDFValueError("Codec must not be specified for a text I/O output")

        if text_colors is None:
            text_colors = {"char": "black"}
        if rect_colors is None:
            rect_colors = {"curve": "black", "page": "gray"}

        self.scale = scale
        self.fontscale = fontscale
        self.layoutmode = layoutmode
        self.showpageno = showpageno
        self.pagemargin = pagemargin
        self.imagewriter = imagewriter
        self.rect_colors = rect_colors
        self.text_colors = text_colors
        if debug:
            self.rect_colors.update(self.RECT_COLORS)
            self.text_colors.update(self.TEXT_COLORS)
        self._yoffset: float = self.pagemargin
        self._font: Optional[Tuple[str, float]] = None
        self._fontstack: List[Optional[Tuple[str, float]]] = []
        self.write_header()

    def write(self, text: str) -> None:
        if self.codec:
            cast(BinaryIO, self.outfp).write(text.encode(self.codec))
        else:
            cast(TextIO, self.outfp).write(text)

    def write_header(self) -> None:
        self.write("<html><head>\n")
        if self.codec:
            s = (
                '<meta http-equiv="Content-Type" content="text/html; '
                'charset=%s">\n' % self.codec
            )
        else:
            s = '<meta http-equiv="Content-Type" content="text/html">\n'
        self.write(s)
        self.write("</head><body>\n")

    def write_footer(self) -> None:
        page_links = [f'<a href="#{i}">{i}</a>' for i in range(1, self.pageno)]
        s = '<div style="position:absolute; top:0px;">Page: %s</div>\n' % ", ".join(
            page_links,
        )
        self.write(s)
        self.write("</body></html>\n")

    def write_text(self, text: str) -> None:
        self.write(enc(text))

    def place_rect(
        self,
        color: str,
        borderwidth: int,
        x: float,
        y: float,
        w: float,
        h: float,
    ) -> None:
        color2 = self.rect_colors.get(color)
        if color2 is not None:
            s = (
                '<span style="position:absolute; border: %s %dpx solid; '
                'left:%dpx; top:%dpx; width:%dpx; height:%dpx;"></span>\n'
                % (
                    color2,
                    borderwidth,
                    x * self.scale,
                    (self._yoffset - y) * self.scale,
                    w * self.scale,
                    h * self.scale,
                )
            )
            self.write(s)

    def place_border(self, color: str, borderwidth: int, item: LTComponent) -> None:
        self.place_rect(color, borderwidth, item.x0, item.y1, item.width, item.height)

    def place_image(
        self,
        item: LTImage,
        borderwidth: int,
        x: float,
        y: float,
        w: float,
        h: float,
    ) -> None:
        if self.imagewriter is not None:
            name = self.imagewriter.export_image(item)
            s = (
                '<img src="%s" border="%d" style="position:absolute; '
                'left:%dpx; top:%dpx;" width="%d" height="%d" />\n'
                % (
                    enc(name),
                    borderwidth,
                    x * self.scale,
                    (self._yoffset - y) * self.scale,
                    w * self.scale,
                    h * self.scale,
                )
            )
            self.write(s)

    def place_text(
        self,
        color: str,
        text: str,
        x: float,
        y: float,
        size: float,
    ) -> None:
        color2 = self.text_colors.get(color)
        if color2 is not None:
            s = (
                '<span style="position:absolute; color:%s; left:%dpx; '
                'top:%dpx; font-size:%dpx;">'
                % (
                    color2,
                    x * self.scale,
                    (self._yoffset - y) * self.scale,
                    size * self.scale * self.fontscale,
                )
            )
            self.write(s)
            self.write_text(text)
            self.write("</span>\n")

    def begin_div(
        self,
        color: str,
        borderwidth: int,
        x: float,
        y: float,
        w: float,
        h: float,
        writing_mode: str = "False",
    ) -> None:
        self._fontstack.append(self._font)
        self._font = None
        s = (
            '<div style="position:absolute; border: %s %dpx solid; '
            "writing-mode:%s; left:%dpx; top:%dpx; width:%dpx; "
            'height:%dpx;">'
            % (
                color,
                borderwidth,
                writing_mode,
                x * self.scale,
                (self._yoffset - y) * self.scale,
                w * self.scale,
                h * self.scale,
            )
        )
        self.write(s)

    def end_div(self, color: str) -> None:
        if self._font is not None:
            self.write("</span>")
        self._font = self._fontstack.pop()
        self.write("</div>")

    def put_text(self, text: str, fontname: str, fontsize: float) -> None:
        font = (fontname, fontsize)
        if font != self._font:
            if self._font is not None:
                self.write("</span>")
            # Remove subset tag from fontname, see PDF Reference 5.5.3
            fontname_without_subset_tag = fontname.split("+")[-1]
            self.write(
                '<span style="font-family: %s; font-size:%dpx">'
                % (fontname_without_subset_tag, fontsize * self.scale * self.fontscale),
            )
            self._font = font
        self.write_text(text)

    def put_newline(self) -> None:
        self.write("<br>")

    def receive_layout(self, ltpage: LTPage) -> None:
        def show_group(item: Union[LTTextGroup, TextGroupElement]) -> None:
            if isinstance(item, LTTextGroup):
                self.place_border("textgroup", 1, item)
                for child in item:
                    show_group(child)

        def render(item: LTItem) -> None:
            child: LTItem
            if isinstance(item, LTPage):
                self._yoffset += item.y1
                self.place_border("page", 1, item)
                if self.showpageno:
                    self.write(
                        '<div style="position:absolute; top:%dpx;">'
                        % ((self._yoffset - item.y1) * self.scale),
                    )
                    self.write(
                        f'<a name="{item.pageid}">Page {item.pageid}</a></div>\n',
                    )
                for child in item:
                    render(child)
                if item.groups is not None:
                    for group in item.groups:
                        show_group(group)
            elif isinstance(item, LTCurve):
                self.place_border("curve", 1, item)
            elif isinstance(item, LTFigure):
                self.begin_div("figure", 1, item.x0, item.y1, item.width, item.height)
                for child in item:
                    render(child)
                self.end_div("figure")
            elif isinstance(item, LTImage):
                self.place_image(item, 1, item.x0, item.y1, item.width, item.height)
            elif self.layoutmode == "exact":
                if isinstance(item, LTTextLine):
                    self.place_border("textline", 1, item)
                    for child in item:
                        render(child)
                elif isinstance(item, LTTextBox):
                    self.place_border("textbox", 1, item)
                    self.place_text(
                        "textbox",
                        str(item.index + 1),
                        item.x0,
                        item.y1,
                        20,
                    )
                    for child in item:
                        render(child)
                elif isinstance(item, LTChar):
                    self.place_border("char", 1, item)
                    self.place_text(
                        "char",
                        item.get_text(),
                        item.x0,
                        item.y1,
                        item.size,
                    )
            elif isinstance(item, LTTextLine):
                for child in item:
                    render(child)
                if self.layoutmode != "loose":
                    self.put_newline()
            elif isinstance(item, LTTextBox):
                self.begin_div(
                    "textbox",
                    1,
                    item.x0,
                    item.y1,
                    item.width,
                    item.height,
                    item.get_writing_mode(),
                )
                for child in item:
                    render(child)
                self.end_div("textbox")
            elif isinstance(item, LTChar):
                fontname = make_compat_str(item.fontname)
                self.put_text(item.get_text(), fontname, item.size)
            elif isinstance(item, LTText):
                self.write_text(item.get_text())

        render(ltpage)
        self._yoffset += self.pagemargin

    def close(self) -> None:
        self.write_footer()


class XMLConverter(PDFConverter[AnyIO]):
    CONTROL = re.compile("[\x00-\x08\x0b-\x0c\x0e-\x1f]")

    def __init__(
        self,
        rsrcmgr: PDFResourceManager,
        outfp: AnyIO,
        codec: str = "utf-8",
        pageno: int = 1,
        laparams: Optional[LAParams] = None,
        imagewriter: Optional[ImageWriter] = None,
        stripcontrol: bool = False,
    ) -> None:
        PDFConverter.__init__(
            self,
            rsrcmgr,
            outfp,
            codec=codec,
            pageno=pageno,
            laparams=laparams,
        )

        # write() assumes a codec for binary I/O, or no codec for text I/O.
        if self.outfp_binary == (not self.codec):
            raise PDFValueError("Codec is required for a binary I/O output")

        self.imagewriter = imagewriter
        self.stripcontrol = stripcontrol
        self.write_header()

    def write(self, text: str) -> None:
        if self.codec:
            cast(BinaryIO, self.outfp).write(text.encode(self.codec))
        else:
            cast(TextIO, self.outfp).write(text)

    def write_header(self) -> None:
        if self.codec:
            self.write('<?xml version="1.0" encoding="%s" ?>\n' % self.codec)
        else:
            self.write('<?xml version="1.0" ?>\n')
        self.write("<pages>\n")

    def write_footer(self) -> None:
        self.write("</pages>\n")

    def write_text(self, text: str) -> None:
        if self.stripcontrol:
            text = self.CONTROL.sub("", text)
        self.write(enc(text))

    def receive_layout(self, ltpage: LTPage) -> None:
        def show_group(item: LTItem) -> None:
            if isinstance(item, LTTextBox):
                self.write(
                    '<textbox id="%d" bbox="%s" />\n'
                    % (item.index, bbox2str(item.bbox)),
                )
            elif isinstance(item, LTTextGroup):
                self.write('<textgroup bbox="%s">\n' % bbox2str(item.bbox))
                for child in item:
                    show_group(child)
                self.write("</textgroup>\n")

        def render(item: LTItem) -> None:
            child: LTItem
            if isinstance(item, LTPage):
                s = '<page id="%s" bbox="%s" rotate="%d">\n' % (
                    item.pageid,
                    bbox2str(item.bbox),
                    item.rotate,
                )
                self.write(s)
                for child in item:
                    render(child)
                if item.groups is not None:
                    self.write("<layout>\n")
                    for group in item.groups:
                        show_group(group)
                    self.write("</layout>\n")
                self.write("</page>\n")
            elif isinstance(item, LTLine):
                s = '<line linewidth="%d" bbox="%s" />\n' % (
                    item.linewidth,
                    bbox2str(item.bbox),
                )
                self.write(s)
            elif isinstance(item, LTRect):
                s = '<rect linewidth="%d" bbox="%s" />\n' % (
                    item.linewidth,
                    bbox2str(item.bbox),
                )
                self.write(s)
            elif isinstance(item, LTCurve):
                s = '<curve linewidth="%d" bbox="%s" pts="%s"/>\n' % (
                    item.linewidth,
                    bbox2str(item.bbox),
                    item.get_pts(),
                )
                self.write(s)
            elif isinstance(item, LTFigure):
                s = f'<figure name="{item.name}" bbox="{bbox2str(item.bbox)}">\n'
                self.write(s)
                for child in item:
                    render(child)
                self.write("</figure>\n")
            elif isinstance(item, LTTextLine):
                self.write('<textline bbox="%s">\n' % bbox2str(item.bbox))
                for child in item:
                    render(child)
                self.write("</textline>\n")
            elif isinstance(item, LTTextBox):
                wmode = ""
                if isinstance(item, LTTextBoxVertical):
                    wmode = ' wmode="vertical"'
                s = '<textbox id="%d" bbox="%s"%s>\n' % (
                    item.index,
                    bbox2str(item.bbox),
                    wmode,
                )
                self.write(s)
                for child in item:
                    render(child)
                self.write("</textbox>\n")
            elif isinstance(item, LTChar):
                s = (
                    '<text font="%s" bbox="%s" colourspace="%s" '
                    'ncolour="%s" size="%.3f">'
                    % (
                        enc(item.fontname),
                        bbox2str(item.bbox),
                        item.ncs.name,
                        item.graphicstate.ncolor,
                        item.size,
                    )
                )
                self.write(s)
                self.write_text(item.get_text())
                self.write("</text>\n")
            elif isinstance(item, LTText):
                self.write("<text>%s</text>\n" % item.get_text())
            elif isinstance(item, LTImage):
                if self.imagewriter is not None:
                    name = self.imagewriter.export_image(item)
                    self.write(
                        '<image src="%s" width="%d" height="%d" />\n'
                        % (enc(name), item.width, item.height),
                    )
                else:
                    self.write(
                        '<image width="%d" height="%d" />\n'
                        % (item.width, item.height),
                    )
            else:
                assert False, str(("Unhandled", item))

        render(ltpage)

    def close(self) -> None:
        self.write_footer()


class HOCRConverter(PDFConverter[AnyIO]):
    """Extract an hOCR representation from explicit text information within a PDF."""

    #   Where text is being extracted from a variety of types of PDF within a
    #   business process, those PDFs where the text is only present in image
    #   form will need to be analysed using an OCR tool which will typically
    #   output hOCR. This converter extracts the explicit text information from
    #   those PDFs that do have it and uses it to genxerate a basic hOCR
    #   representation that is designed to be used in conjunction with the image
    #   of the PDF in the same way as genuine OCR output would be, but without the
    #   inevitable OCR errors.

    #   The converter does not handle images, diagrams or text colors.

    #   In the examples processed by the contributor it was necessary to set
    #   LAParams.all_texts to True.

    CONTROL = re.compile(r"[\x00-\x08\x0b-\x0c\x0e-\x1f]")

    def __init__(
        self,
        rsrcmgr: PDFResourceManager,
        outfp: AnyIO,
        codec: str = "utf8",
        pageno: int = 1,
        laparams: Optional[LAParams] = None,
        stripcontrol: bool = False,
    ):
        PDFConverter.__init__(
            self,
            rsrcmgr,
            outfp,
            codec=codec,
            pageno=pageno,
            laparams=laparams,
        )
        self.stripcontrol = stripcontrol
        self.within_chars = False
        self.write_header()

    def bbox_repr(self, bbox: Rect) -> str:
        (in_x0, in_y0, in_x1, in_y1) = bbox
        # PDF y-coordinates are the other way round from hOCR coordinates
        out_x0 = int(in_x0)
        out_y0 = int(self.page_bbox[3] - in_y1)
        out_x1 = int(in_x1)
        out_y1 = int(self.page_bbox[3] - in_y0)
        return f"bbox {out_x0} {out_y0} {out_x1} {out_y1}"

    def write(self, text: str) -> None:
        if self.codec:
            encoded_text = text.encode(self.codec)
            cast(BinaryIO, self.outfp).write(encoded_text)
        else:
            cast(TextIO, self.outfp).write(text)

    def write_header(self) -> None:
        if self.codec:
            self.write(
                "<html xmlns='http://www.w3.org/1999/xhtml' "
                "xml:lang='en' lang='en' charset='%s'>\n" % self.codec,
            )
        else:
            self.write(
                "<html xmlns='http://www.w3.org/1999/xhtml' "
                "xml:lang='en' lang='en'>\n",
            )
        self.write("<head>\n")
        self.write("<title></title>\n")
        self.write(
            "<meta http-equiv='Content-Type' content='text/html;charset=utf-8' />\n",
        )
        self.write(
            "<meta name='ocr-system' content='pdf2zh.six HOCR Converter' />\n",
        )
        self.write(
            "  <meta name='ocr-capabilities'"
            " content='ocr_page ocr_block ocr_line ocrx_word'/>\n",
        )
        self.write("</head>\n")
        self.write("<body>\n")

    def write_footer(self) -> None:
        self.write("<!-- comment in the following line to debug -->\n")
        self.write(
            "<!--script src='https://unpkg.com/hocrjs'></script--></body></html>\n",
        )

    def write_text(self, text: str) -> None:
        if self.stripcontrol:
            text = self.CONTROL.sub("", text)
        self.write(text)

    def write_word(self) -> None:
        if len(self.working_text) > 0:
            bold_and_italic_styles = ""
            if "Italic" in self.working_font:
                bold_and_italic_styles = "font-style: italic; "
            if "Bold" in self.working_font:
                bold_and_italic_styles += "font-weight: bold; "
            self.write(
                "<span style='font:\"%s\"; font-size:%d; %s' "
                "class='ocrx_word' title='%s; x_font %s; "
                "x_fsize %d'>%s</span>"
                % (
                    (
                        self.working_font,
                        self.working_size,
                        bold_and_italic_styles,
                        self.bbox_repr(self.working_bbox),
                        self.working_font,
                        self.working_size,
                        self.working_text.strip(),
                    )
                ),
            )
        self.within_chars = False

    def receive_layout(self, ltpage: LTPage) -> None:
        def render(item: LTItem) -> None:
            if self.within_chars and isinstance(item, LTAnno):
                self.write_word()
            if isinstance(item, LTPage):
                self.page_bbox = item.bbox
                self.write(
                    "<div class='ocr_page' id='%s' title='%s'>\n"
                    % (item.pageid, self.bbox_repr(item.bbox)),
                )
                for child in item:
                    render(child)
                self.write("</div>\n")
            elif isinstance(item, LTTextLine):
                self.write(
                    "<span class='ocr_line' title='%s'>" % (self.bbox_repr(item.bbox)),
                )
                for child_line in item:
                    render(child_line)
                self.write("</span>\n")
            elif isinstance(item, LTTextBox):
                self.write(
                    "<div class='ocr_block' id='%d' title='%s'>\n"
                    % (item.index, self.bbox_repr(item.bbox)),
                )
                for child in item:
                    render(child)
                self.write("</div>\n")
            elif isinstance(item, LTChar):
                if not self.within_chars:
                    self.within_chars = True
                    self.working_text = item.get_text()
                    self.working_bbox = item.bbox
                    self.working_font = item.fontname
                    self.working_size = item.size
                elif len(item.get_text().strip()) == 0:
                    self.write_word()
                    self.write(item.get_text())
                else:
                    if (
                        self.working_bbox[1] != item.bbox[1]
                        or self.working_font != item.fontname
                        or self.working_size != item.size
                    ):
                        self.write_word()
                        self.working_bbox = item.bbox
                        self.working_font = item.fontname
                        self.working_size = item.size
                    self.working_text += item.get_text()
                    self.working_bbox = (
                        self.working_bbox[0],
                        self.working_bbox[1],
                        item.bbox[2],
                        self.working_bbox[3],
                    )

        render(ltpage)

    def close(self) -> None:
        self.write_footer()