101 lines
3.5 KiB
Python
101 lines
3.5 KiB
Python
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"""Export to PDF via a headless browser"""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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import asyncio
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from traitlets import Bool
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import concurrent.futures
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from .html import HTMLExporter
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class WebPDFExporter(HTMLExporter):
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"""Writer designed to write to PDF files.
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This inherits from :class:`HTMLExporter`. It creates the HTML using the
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template machinery, and then run pyppeteer to create a pdf.
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"""
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export_from_notebook = "PDF via pyppeteer"
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allow_chromium_download = Bool(False,
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help='Whether to allow downloading Chromium if no suitable version is found on the system.'
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).tag(config=True)
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def _check_launch_reqs(self):
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try:
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from pyppeteer import launch
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from pyppeteer.util import check_chromium
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except ModuleNotFoundError as e:
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raise RuntimeError("Pyppeteer is not installed to support Web PDF conversion. "
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"Please install `nbconvert[webpdf]` to enable.") from e
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if not self.allow_chromium_download and not check_chromium():
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raise RuntimeError("No suitable chromium executable found on the system. "
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"Please use '--allow-chromium-download' to allow downloading one.")
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return launch
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def run_pyppeteer(self, html):
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"""Run pyppeteer."""
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async def main():
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browser = await self._check_launch_reqs()(
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handleSIGINT=False,
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handleSIGTERM=False,
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handleSIGHUP=False,
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)
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page = await browser.newPage()
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await page.waitFor(100)
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await page.goto('data:text/html,'+html, waitUntil='networkidle0')
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await page.waitFor(100)
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# Floating point precision errors cause the printed
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# PDF from spilling over a new page by a pixel fraction.
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dimensions = await page.evaluate(
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"""() => {
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const rect = document.body.getBoundingClientRect();
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return {
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width: Math.ceil(rect.width) + 1,
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height: Math.ceil(rect.height) + 1,
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}
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}"""
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)
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width = dimensions['width']
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height = dimensions['height']
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# 200 inches is the maximum size for Adobe Acrobat Reader.
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pdf_data = await page.pdf(
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{
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'width': min(width, 200 * 72),
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'height': min(height, 200 * 72),
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'printBackground': True,
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}
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)
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await browser.close()
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return pdf_data
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pool = concurrent.futures.ThreadPoolExecutor()
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# TODO: when dropping Python 3.6, use
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# pdf_data = pool.submit(asyncio.run, main()).result()
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def run_coroutine(coro):
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loop = asyncio.new_event_loop()
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asyncio.set_event_loop(loop)
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return loop.run_until_complete(coro)
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pdf_data = pool.submit(run_coroutine, main()).result()
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return pdf_data
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def from_notebook_node(self, nb, resources=None, **kw):
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self._check_launch_reqs()
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html, resources = super().from_notebook_node(
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nb, resources=resources, **kw
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)
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self.log.info('Building PDF')
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pdf_data = self.run_pyppeteer(html)
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self.log.info('PDF successfully created')
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# convert output extension to pdf
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# the writer above required it to be html
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resources['output_extension'] = '.pdf'
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return pdf_data, resources
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