fix: print PDF from actual editor theme CSS and shared Markdown rendering

backend/app/contracts.py

@@ -1452,6 +1452,7 @@ class ExportAsset(Contract):
 
 
 class ExportRequest(Contract):
+    print_html: str | None = None
     assets: list[ExportAsset] = Field(default_factory=list)
     title: str = Field(default="", max_length=200)
     source: ExportSource
@@ -1460,6 +1461,8 @@ class ExportRequest(Contract):
 
     @model_validator(mode="after")
     def _asset_limits(self) -> "ExportRequest":
+        if self.print_html is not None and self.format != ExportFormat.pdf:
+            raise ValueError("print_html is only supported for PDF")
         if self.format != ExportFormat.pdf:
             if len(self.assets) > 64 or any(len(asset.png_base64) > 2800000 for asset in self.assets):
                 raise ValueError("export asset count or size limit exceeded")

backend/app/export/assets.py

@@ -8,7 +8,7 @@ from app.errors import ApiError
 
 _math_lock = threading.Lock()
 
-def enrich_document(document, file_path=None, unlimited=False, options=None):
+def enrich_document(document, file_path=None, unlimited=False, options=None, preserve_alpha=False):
     """Embed Vault images and MathText, with format-specific quotas and palette."""
     from app.config import get_settings
     from urllib.parse import unquote, urlsplit
@@ -53,7 +53,7 @@ def enrich_document(document, file_path=None, unlimited=False, options=None):
                     out = BytesIO()
                     # Composite transparency over the PDF theme or the print/Word white surface.
                     rgba=image.convert('RGBA'); background=Image.new('RGBA',rgba.size,palette['surface'] if palette else 'white')
-                    background.alpha_composite(rgba); background.convert('RGB').save(out,'PNG')
+                    background.alpha_composite(rgba); (rgba if preserve_alpha else background.convert('RGB')).save(out,'PNG')
                     png=out.getvalue();total += len(png)
                     if not unlimited and total > 8_000_000: raise ValueError('resource bytes')
                     node.attributes['static_png']=png

backend/app/export/browser_pdf.py

@@ -0,0 +1,64 @@
+"""Print the app's self-contained theme snapshot with a real browser engine.
+
+A child process isolates Playwright's Windows event loop from Uvicorn and keeps
+browser lifecycle scoped to one export. Snapshot scripts/network/file loads are
+blocked; fonts and images must already be embedded by the client.
+"""
+from pathlib import Path
+import os
+import shutil
+import subprocess
+import sys
+import tempfile
+from app.export.document import ExportResult
+
+
+def browser_executable():
+    configured = os.environ.get('APP_PDF_BROWSER')
+    if configured:
+        return configured
+    for root in (os.environ.get('PROGRAMFILES(X86)', ''), os.environ.get('PROGRAMFILES', ''), os.environ.get('LOCALAPPDATA', '')):
+        if not root:
+            continue
+        for suffix in ('Microsoft/Edge/Application/msedge.exe', 'Google/Chrome/Application/chrome.exe'):
+            candidate = Path(root) / suffix
+            if candidate.is_file():
+                return str(candidate)
+    return next((p for name in ('chromium','chromium-browser','google-chrome','microsoft-edge') if (p := shutil.which(name))), None)
+
+
+def render_snapshot(snapshot: str, page_size: str) -> ExportResult:
+    with tempfile.TemporaryDirectory(prefix='notes-pdf-') as directory:
+        source = Path(directory) / 'snapshot.html'
+        output = Path(directory) / 'document.pdf'
+        source.write_text(snapshot, encoding='utf-8')
+        process = subprocess.run([sys.executable, '-m', 'app.export.browser_pdf', str(source), str(output), page_size],
+            capture_output=True, text=True, encoding='utf-8', errors='replace',
+            creationflags=getattr(subprocess, 'CREATE_NO_WINDOW', 0),
+            cwd=Path(__file__).resolve().parents[2])
+        if process.returncode:
+            raise RuntimeError('PDF browser rendering failed: ' + process.stderr[-2000:])
+        return ExportResult(content=output.read_bytes(), mime_type='application/pdf', warnings=[])
+
+
+def print_snapshot(source: Path, output: Path, page_size: str):
+    from playwright.sync_api import sync_playwright
+    with sync_playwright() as runtime:
+        browser = runtime.chromium.launch(executable_path=browser_executable(), headless=True)
+        try:
+            context = browser.new_context(java_script_enabled=False, offline=True)
+            context.route('**/*', lambda route: route.abort())
+            page = context.new_page()
+            page.set_default_timeout(0)
+            page.emulate_media(media='screen')
+            csp = "default-src 'none'; script-src 'none'; style-src 'unsafe-inline'; img-src data:; font-src data:; connect-src 'none'; frame-src 'none'; object-src 'none'; base-uri 'none'; form-action 'none'"
+            page.set_content('<meta http-equiv="Content-Security-Policy" content="'+csp+'">'+source.read_text(encoding='utf-8'), wait_until='load', timeout=0)
+            page.evaluate('async () => { await document.fonts.ready; await Promise.all([...document.images].map(image => image.decode().catch(() => {}))); }')
+            page.pdf(path=str(output), format='Letter' if page_size.lower()=='letter' else 'A4',
+                print_background=True, display_header_footer=False, prefer_css_page_size=False)
+        finally:
+            browser.close()
+
+
+if __name__ == '__main__':
+    print_snapshot(Path(sys.argv[1]), Path(sys.argv[2]), sys.argv[3])

backend/app/export/service.py

@@ -210,7 +210,7 @@ async def create_export(request: ExportRequest) -> ExportJob:
     _jobs[job_id] = job
     _cancel_flags[job_id] = asyncio.Event()
     _tasks[job_id] = asyncio.create_task(
-        _execute(job_id, request.format, markdown, title, metadata, request.options, assets)
+        _execute(job_id, request.format, markdown, title, metadata, request.options, assets, request.print_html)
     )
     return job
 
@@ -249,6 +249,7 @@ async def _execute(
     metadata: dict | None,
     options: ExportOptions,
     assets: dict | None = None,
+    print_html: str | None = None,
 ) -> None:
     """后台渲染：排队 → 解析 → 导出 → 写文件 → 挂载产物元信息。"""
     cancel_event = _cancel_flags[job_id]
@@ -275,17 +276,21 @@ async def _execute(
 
         # 解析与渲染都是 CPU 密集的同步工作，放入线程执行避免阻塞事件循环，
         # 使运行中的取消能在渲染边界生效；写文件前再次检查取消。
-        document = await asyncio.to_thread(parse_document, markdown)
-        document.attributes["title"] = title
-        from app.export.assets import attach_assets
-        attach_assets(document, assets or {})
-        if metadata:
-            document.attributes["metadata"] = metadata
+        if format == ExportFormat.pdf and print_html is not None:
+            from app.export.browser_pdf import render_snapshot
+            result = await asyncio.to_thread(render_snapshot, print_html, options.page_size)
+        else:
+            document = await asyncio.to_thread(parse_document, markdown)
+            document.attributes["title"] = title
+            from app.export.assets import attach_assets
+            attach_assets(document, assets or {})
+            if metadata:
+                document.attributes["metadata"] = metadata
 
-        from app.export.assets import enrich_document
-        resource_warnings = await asyncio.to_thread(enrich_document, document, (metadata or {}).get('file_path'), format == ExportFormat.pdf, options)
-        result = await asyncio.to_thread(_render_document, document, options, format)
-        result.warnings[:0] = resource_warnings
+            from app.export.assets import enrich_document
+            resource_warnings = await asyncio.to_thread(enrich_document, document, (metadata or {}).get('file_path'), format == ExportFormat.pdf, options)
+            result = await asyncio.to_thread(_render_document, document, options, format)
+            result.warnings[:0] = resource_warnings
         if cancel_event.is_set():
             raise ExportCancelled()
         if format != ExportFormat.pdf and len(result.content) > MAX_EXPORT_BYTES:
@@ -398,3 +403,29 @@ async def wait_for_export(job_id: str) -> ExportJob | None:
     if task is not None:
         await task
     return _jobs.get(job_id)
+
+
+async def preview_resources(request: ExportRequest):
+    """Prepare Vault images and vector plots for the shared browser renderer."""
+    import base64
+    from app.export.assets import enrich_document
+    from app.plot.parser import parse_source
+    from app.plot.render import render_svg
+    from app.export.document import Document
+    markdown, _, metadata = await _resolve_source(request.source, True)
+    def prepare():
+        document = parse_document(markdown)
+        images, plots = [], []
+        def visit(node):
+            if node.type == 'image':
+                warnings = enrich_document(Document(node_id='pdf-resources', children=[node]), (metadata or {}).get('file_path'), True, request.options, preserve_alpha=True)
+                raw = node.attributes.get('static_png')
+                images.append({'source': node.attributes.get('src',''), 'data': 'data:image/png;base64,'+base64.b64encode(raw).decode() if raw else None, 'warnings': warnings})
+            if node.type == 'function_plot':
+                parsed = parse_source(node.text, unlimited=True)
+                result = render_svg(parsed.plot, request.options.theme_id, unlimited=True) if parsed.plot else None
+                plots.append({'source':node.text, 'svg':result.content if result else '', 'warnings':[d.message for d in parsed.diagnostics]+(result.warnings if result else [])})
+            for child in node.children: visit(child)
+        for child in document.children: visit(child)
+        return {'images':images,'plots':plots}
+    return await asyncio.to_thread(prepare)

backend/app/plot/render.py

@@ -476,9 +476,9 @@ def _labels_svg(geo: PlotGeometry) -> str:
     return "".join(parts)
 
 
-def render_svg(plot: FunctionPlot, theme_id: str = 'light') -> StaticRenderResult:
+def render_svg(plot: FunctionPlot, theme_id: str = 'light', unlimited: bool = False) -> StaticRenderResult:
     """把已解析的 FunctionPlot 渲染为内嵌 SVG。"""
-    geo = compute_geometry(plot)
+    geo = compute_geometry(plot, unlimited=unlimited)
     legend_height = ((len(plot.expressions) + 1) // 2) * 24
     height = geo.height + legend_height
     parts: list[str] = [

backend/app/routes.py

@@ -1547,6 +1547,11 @@ async def create_export(request: ExportRequest) -> ExportJob:
     return await export_service.create_export(request)
 
 
+@router.post("/exports/preview-resources", tags=["Export"])
+async def export_preview_resources(request: ExportRequest):
+    return await export_service.preview_resources(request)
+
+
 @router.get(
     "/exports",
     response_model=ExportJobListResponse,