412 lines
18 KiB
Python
412 lines
18 KiB
Python
"""PdfExporter：Document AST → PDF（reportlab platypus）。
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v1 为文本优先：标题/段落/行内强调与链接/列表/引用/表格/代码块/数学文本均可导出；
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function_plot 内嵌为矢量图（reportlab Drawing），mermaid 保留源码占位并记 warning。
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中文字体用 reportlab 内置 STSong-Light CID 字体，避免外部字体依赖。CID 字体无独立
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bold/italic 字重，故行内强调退化为普通文本（内容不丢、样式简化），标题靠字号区分层级。
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"""
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from __future__ import annotations
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import html as _html
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from io import BytesIO
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from reportlab.lib.enums import TA_CENTER
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from reportlab.lib.pagesizes import A4, letter
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from reportlab.lib.styles import ParagraphStyle
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from reportlab.lib.units import mm
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from reportlab.pdfbase import pdfmetrics
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from reportlab.pdfbase.cidfonts import UnicodeCIDFont
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from reportlab.platypus import (
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Paragraph,
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Indenter,
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XPreformatted,
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SimpleDocTemplate,
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Spacer,
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Table,
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TableStyle,
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)
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from reportlab.platypus.flowables import HRFlowable
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from app.contracts import ExportOptions
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from app.export.themes import CALLOUTS, pdf_palette
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from app.export.document import Document, DocumentNode, ExportResult
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from app.export.exporters._common import (
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MERMAID_WARNING,
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RAW_HTML_WARNING,
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format_meta_value,
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format_plot_diagnostic,
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safe_url,
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)
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from app.plot.render_reportlab import render_drawing
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from app.plot.renderer import FunctionPlotStaticRenderer, StaticRenderRequest
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from app.export.fonts import FONT as _FONT
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_MIME = "application/pdf"
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_PAGE_SIZES = {"a4": A4, "letter": letter}
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# 标题字号随层级递减；标题不依赖粗体（CID 无粗体字重），靠字号拉开层级
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_HEADING_SIZES = {1: 20, 2: 16, 3: 14, 4: 12, 5: 11, 6: 10.5}
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# 引用块文字颜色，与 HtmlExporter 的引用灰一致
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_QUOTE_COLOR = "#57606a"
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def _make_styles(palette) -> dict[str, ParagraphStyle]:
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body = ParagraphStyle(
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"pdf-body",
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fontName=_FONT,
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textColor=palette["text"],
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fontSize=10.5,
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leading=16,
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spaceAfter=6,
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)
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title = ParagraphStyle("pdf-title", parent=body, fontSize=22, leading=28, spaceAfter=12)
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quote = ParagraphStyle(
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"pdf-quote",
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parent=body,
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leftIndent=14,
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textColor=palette["muted"],
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spaceBefore=4,
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spaceAfter=6,
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)
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code = ParagraphStyle(
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"pdf-code",
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parent=body,
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fontSize=9,
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leading=12,
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leftIndent=6,
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rightIndent=6,
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backColor=palette["code"],
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borderColor=palette["border"],
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borderWidth=0.5,
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borderPadding=6,
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spaceBefore=4,
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spaceAfter=8,
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)
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math = ParagraphStyle("pdf-math", parent=body, alignment=TA_CENTER, spaceBefore=6)
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cell = ParagraphStyle("pdf-cell", parent=body, fontSize=10, leading=14, spaceAfter=0)
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cell_head = ParagraphStyle(
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"pdf-cell-head", parent=cell, textColor=palette["text"], fontSize=10
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)
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meta = ParagraphStyle("pdf-meta", parent=body, fontSize=8.5, leading=13, textColor=palette["muted"])
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styles: dict[str, ParagraphStyle] = {
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"body": body,
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"title": title,
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"quote": quote,
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"code": code,
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"math": math,
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"cell": cell,
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"cell_head": cell_head,
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"meta": meta,
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}
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for level, size in _HEADING_SIZES.items():
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styles[f"h{level}"] = ParagraphStyle(
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f"pdf-h{level}",
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parent=body,
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fontSize=size,
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leading=size * 1.4,
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spaceBefore=14 if level <= 2 else 10,
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spaceAfter=6,
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keepWithNext=True,
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)
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return styles
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class PdfExporter:
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"""实现 DocumentExporter：递归渲染 Document AST 为 PDF 字节流。"""
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def render(self, document: Document, options: ExportOptions) -> ExportResult:
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"""同步渲染；CPU 密集，调用方应放入线程执行，避免阻塞事件循环。"""
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warnings: list[str] = []
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self._palette = pdf_palette(options, warnings)
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self._styles = _make_styles(self._palette)
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if _FONT == "STSong-Light": warnings.append("PDF 使用 CID 字体，阅读器需提供中文字体；可配置 APP_EXPORT_FONT 嵌入 TrueType 字体")
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page = _PAGE_SIZES.get((options.page_size or "A4").lower(), A4)
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self._options = options
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self._plot_renderer = FunctionPlotStaticRenderer()
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# 内容区宽度（左右各 20mm 边距），供函数图像缩放适配页面
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self._plot_width = page[0] - 40 * mm - 12
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self._plot_height = page[1] - 36 * mm - 12
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buf = BytesIO()
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doc = SimpleDocTemplate(
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buf,
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pagesize=page,
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leftMargin=20 * mm,
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rightMargin=20 * mm,
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topMargin=18 * mm,
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bottomMargin=18 * mm,
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title=str(document.attributes.get("title") or "") or None,
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)
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story: list = []
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self._render_header(document, options, story)
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self._render_children(document.children, story, warnings)
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def paint_page(canvas, template):
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canvas.saveState()
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canvas.setFillColor(self._palette['page'])
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canvas.rect(0, 0, page[0], page[1], fill=1, stroke=0)
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canvas.setFillColor(self._palette['surface'])
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canvas.roundRect(12*mm, 10*mm, page[0]-24*mm, page[1]-20*mm, 5*mm, fill=1, stroke=0)
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canvas.restoreState()
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doc.build(story, onFirstPage=paint_page, onLaterPages=paint_page)
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return ExportResult(content=buf.getvalue(), mime_type=_MIME, warnings=warnings)
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async def export(self, document: Document, options: ExportOptions) -> ExportResult:
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"""契约要求的 async 接口；渲染本身同步，直接转发到 render。"""
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return self.render(document, options)
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# --- 文档头部 ---
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def _render_header(self, document: Document, options: ExportOptions, story: list) -> None:
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title = str(document.attributes.get("title") or "")
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if options.include_title and title:
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story.append(Paragraph(_html.escape(title), self._styles["title"]))
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if options.include_metadata:
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metadata = document.attributes.get("metadata")
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if metadata:
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for key, value in metadata.items():
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text = f"{_html.escape(str(key))}: {_html.escape(format_meta_value(value))}"
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story.append(Paragraph(text, self._styles["meta"]))
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# --- 块级 ---
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def _render_children(self, children: list[DocumentNode], story: list, warnings: list[str]) -> None:
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for child in children:
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self._render_block(child, story, warnings)
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def _render_block(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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if node.attributes.get('static_png'):
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from reportlab.platypus import Image
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image = Image(BytesIO(node.attributes['static_png']))
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scale = min(1, self._plot_width / image.imageWidth, self._plot_height / image.imageHeight)
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image.drawWidth = image.imageWidth * scale
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image.drawHeight = image.imageHeight * scale
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story.append(image)
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return
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handler = getattr(self, f"_block_{node.type}", None)
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if handler is not None:
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handler(node, story, warnings)
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else:
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warnings.append(f"无法表示的节点类型已跳过：{node.type}")
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def _block_heading(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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level = max(1, min(6, int(node.attributes.get("level", 1))))
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inline = self._render_inline(node.children, warnings)
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story.append(Paragraph(inline, self._styles[f"h{level}"]))
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def _block_paragraph(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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story.append(Paragraph(self._render_inline(node.children, warnings), self._styles["body"]))
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def _block_callout(self, node, story, warnings):
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kind = node.attributes['kind']
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icon, color = CALLOUTS[kind]
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from reportlab.lib.colors import HexColor
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background = HexColor(self._palette['code'])
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if .2126*background.red + .7152*background.green + .0722*background.blue < .5:
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color = {'#0969da':'#a5d6ff','#7041a0':'#d2a8ff','#176f41':'#7ee787','#805400':'#f2cc60','#b42318':'#ffa198','#57606a':self._palette['muted']}[color]
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title = self._render_inline(node.children[0].children,warnings)
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style = ParagraphStyle('callout-'+kind,parent=self._styles['body'],textColor=color,
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backColor=self._palette['code'],borderColor=color,borderWidth=1,borderPadding=6,spaceBefore=8,spaceAfter=8)
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story.append(Paragraph(_html.escape(icon)+' '+title,style))
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self._render_children(node.children[1:],story,warnings)
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def _block_blockquote(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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# 引用块的直接子节点是块级节点（paragraph/list 等），不能交给行内渲染器，
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# 否则正文会被当作「无法表示的行内节点」丢弃；逐个渲染并继承引用缩进/颜色。
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for child in node.children:
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if child.type == "paragraph":
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story.append(
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Paragraph(self._render_inline(child.children, warnings), self._styles["quote"])
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)
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elif child.type == "list":
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self._block_list(child, story, warnings, indent=14, color=self._palette['muted'])
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else:
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self._render_block(child, story, warnings)
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def _block_list(
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self,
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node: DocumentNode,
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story: list,
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warnings: list[str],
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indent: int = 14,
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color: str | None = None,
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) -> None:
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ordered = bool(node.attributes.get("ordered"))
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for index, item in enumerate(node.children, start=1):
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self._block_list_item(item, story, warnings, ordered, index, indent, color)
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def _block_list_item(
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self,
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item: DocumentNode,
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story: list,
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warnings: list[str],
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ordered: bool,
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index: int,
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indent: int,
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color: str | None = None,
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) -> None:
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if item.attributes.get("task"):
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marker = "☑ " if item.attributes.get("checked") else "☐ "
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else:
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marker = f"{index}. " if ordered else "• "
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style_kwargs: dict = dict(
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parent=self._styles["body"],
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leftIndent=indent,
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firstLineIndent=-7,
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spaceAfter=2,
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)
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if color:
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style_kwargs["textColor"] = color
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style = ParagraphStyle(f"pdf-li-{indent}-{color or 'normal'}", **style_kwargs)
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# 按 AST 顺序逐段输出：正文暂存为行内标记文本，遇到嵌套列表先 flush 再递归、
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# 之后继续后续正文，保持「父段—子列表—后续段」的原始顺序（而不是把所有正文
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# 都挤到子列表之前）。直接行内节点（text/strong/link 等）走 _render_inline_node，
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# 保留加粗/链接等语义，不能只渲染其 children 而丢掉格式。
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parts: list[str] = []
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first = True
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def flush() -> None:
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nonlocal first
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text = "<br/>".join(parts)
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if first:
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text = marker + text
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first = False
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if text:
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story.append(Paragraph(text, style))
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parts.clear()
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for child in item.children:
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if child.type == "list":
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flush()
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self._block_list(child, story, warnings, indent + 14, color)
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elif child.type == "paragraph":
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parts.append(self._render_inline(child.children, warnings))
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elif hasattr(self, f"_block_{child.type}"):
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flush()
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# Keep block content inside the list frame, including tables and callouts.
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story.append(Indenter(left=indent))
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self._render_block(child, story, warnings)
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story.append(Indenter(left=-indent))
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else:
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parts.append(self._render_inline_node(child, warnings))
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flush()
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def _block_table(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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rows = node.children
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if not rows:
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return
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data: list[list[Paragraph]] = []
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head_row_count = 0
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for row in rows:
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head = bool(row.attributes.get("head"))
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if head:
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head_row_count += 1
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cells = [
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Paragraph(
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self._render_inline(cell.children, warnings),
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self._styles["cell_head" if cell.attributes.get("head") else "cell"],
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)
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for cell in row.children
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]
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data.append(cells)
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table = Table(data, repeatRows=head_row_count)
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commands = [
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("GRID", (0, 0), (-1, -1), 0.5, self._palette["border"]),
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("VALIGN", (0, 0), (-1, -1), "TOP"),
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("LEFTPADDING", (0, 0), (-1, -1), 6),
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("RIGHTPADDING", (0, 0), (-1, -1), 6),
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("TOPPADDING", (0, 0), (-1, -1), 4),
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("BOTTOMPADDING", (0, 0), (-1, -1), 4),
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]
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if head_row_count:
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commands.append(("BACKGROUND", (0, 0), (-1, head_row_count - 1), self._palette["code"]))
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table.setStyle(TableStyle(commands))
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story.append(table)
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def _block_code_block(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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story.append(XPreformatted(_html.escape(node.text), self._styles["code"]))
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def _block_thematic_break(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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story.append(Spacer(1, 4))
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story.append(HRFlowable(width="100%", color=self._palette["border"], thickness=0.5))
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story.append(Spacer(1, 6))
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def _block_mermaid(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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warnings.append(MERMAID_WARNING)
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story.append(XPreformatted(_html.escape(node.text), self._styles["code"]))
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def _block_function_plot(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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# 解析与渲染共同纳入局部异常回退：单个图像失败只回退占位 + warning，
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# 绝不阻断整篇导出（含复杂表达式触发的 RecursionError 等异常）。
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try:
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request = StaticRenderRequest(
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kind="function_plot", source=node.text, theme=self._options.theme_id
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)
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from app.plot.parser import parse_source
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parsed = parse_source(request.source, unlimited=True)
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for diag in parsed.diagnostics:
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warnings.append(format_plot_diagnostic(diag))
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if parsed.plot is None:
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story.append(XPreformatted(_html.escape(node.text), self._styles["code"]))
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return
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# Drawing 本身即 Flowable，缩放后追加到 story，与 HTML 视觉一致
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drawing = render_drawing(parsed.plot, width=self._plot_width, palette=self._palette, unlimited=True, max_height=self._plot_height)
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story.append(drawing)
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except Exception as exc:
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warnings.append(f"函数图像：解析或渲染失败，已回退占位（{exc}）")
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story.append(XPreformatted(_html.escape(node.text), self._styles["code"]))
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def _block_math_block(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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story.append(Paragraph(f"$${_html.escape(node.text)}$$", self._styles["math"]))
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def _block_html_block(self, node: DocumentNode, story: list, warnings: list[str]) -> None:
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# 原始 HTML 不可信，按纯文本保留正文
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warnings.append(RAW_HTML_WARNING)
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story.append(Paragraph(_html.escape(node.text), self._styles["body"]))
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# --- 行内（产出 reportlab Paragraph 标记文本） ---
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def _render_inline(self, children: list[DocumentNode], warnings: list[str]) -> str:
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return "".join(self._render_inline_node(child, warnings) for child in children)
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def _render_inline_node(self, node: DocumentNode, warnings: list[str]) -> str:
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if node.attributes.get('static_png'):
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import base64
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from PIL import Image as PILImage
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raw = node.attributes['static_png']
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with PILImage.open(BytesIO(raw)) as image:
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scale = min(.4 if node.type.startswith('math') else 1, 350/image.width, 160/image.height)
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width, height = image.width*scale, image.height*scale
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data = base64.b64encode(raw).decode()
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return f'<img src="data:image/png;base64,{data}" width="{width}" height="{height}" valign="middle"/>'
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t = node.type
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if t == "text":
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return _html.escape(node.text)
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if t in ("strong", "emphasis"):
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return self._render_inline(node.children, warnings)
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if t == "codespan":
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return f'<font size="9">{_html.escape(node.text)}</font>'
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if t == "link":
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inner = self._render_inline(node.children, warnings)
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href = str(node.attributes.get("href") or "")
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safe_href = safe_url(href)
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if safe_href is None:
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warnings.append(f"链接协议不安全，已降级为纯文本：{href!r}")
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return inner
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return f'<a href="{_html.escape(safe_href)}" color="{self._palette["accent"]}">{inner}</a>'
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if t == "image":
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src = str(node.attributes.get("src") or "")
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alt = str(node.attributes.get("alt") or "")
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if safe_url(src) is None:
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warnings.append(f"图片地址不安全，已跳过：{src!r}")
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else:
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warnings.append("图片未内嵌到 PDF，已用替代文本表示")
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return _html.escape(alt) if alt else ""
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if t == "math_inline":
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return f"\\({_html.escape(node.text)}\\)"
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if t == "linebreak":
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return "<br/>"
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warnings.append(f"无法表示的行内节点已跳过：{t}")
|
||
return ""
|