Save temp file next to notebook for WebPDF export

By putting the HTML file in the same location as the notebook, any
relative file paths correctly resolve. This change saves us from needing
to convert relative paths to absolute.

This slightly changes behavior by creating the temp file in the user's
working directory. We already make sure we delete this temp file, and by
adding the ".webpdf-" prefix to make it hidden, less-technical users
should never see this file at all.

Author: shreve

nbconvert/exporters/webpdf.py

@@ -78,7 +78,7 @@ def _template_name_default(self):
         """,
     ).tag(config=True)
 
-    def run_playwright(self, html):
+    def run_playwright(self, html, path=None):
         """Run playwright."""
 
         async def main(temp_file):
@@ -160,7 +160,7 @@ async def main(temp_file):
         # before calling Chromium. We also specify delete=False to ensure the
         # file is not deleted after closing (the default behavior).
         temp_file = tempfile.NamedTemporaryFile(  # noqa: SIM115
-            suffix=".html", delete=False
+            suffix=".html", prefix=".webpdf-", dir=path, delete=False
         )
         with temp_file:
             temp_file.write(html.encode("utf-8"))
@@ -174,9 +174,10 @@ async def main(temp_file):
     def from_notebook_node(self, nb, resources=None, **kw):
         """Convert from a notebook node."""
         html, resources = super().from_notebook_node(nb, resources=resources, **kw)
+        path = resources.get("metadata", {}).get("path")
 
         self.log.info("Building PDF")
-        pdf_data = self.run_playwright(html)
+        pdf_data = self.run_playwright(html, path)
         self.log.info("PDF successfully created")
 
         # convert output extension to pdf