Add qtpdf and qtpng exporters

.github/workflows/tests.yml

@@ -43,7 +43,7 @@ jobs:
         shell: bash
         run: |
           pip install codecov --user
-          pip install -e ".[execute,serve,test]" --user
+          pip install -e ".[execute,serve,qtpdf,qtpng,test]" --user
           python -m ipykernel.kernelspec --user
           # many things installed in --users need this to be in $PATH
           echo "/Users/runner/.local/bin" >> $GITHUB_PATH

nbconvert/exporters/__init__.py

@@ -7,6 +7,8 @@
 from .notebook import NotebookExporter
 from .pdf import PDFExporter
 from .python import PythonExporter
+from .qtpdf import QtPDFExporter
+from .qtpng import QtPNGExporter
 from .rst import RSTExporter
 from .script import ScriptExporter
 from .slides import SlidesExporter

nbconvert/exporters/qt_exporter.py

@@ -0,0 +1,76 @@
+import tempfile, os
+
+from jupyter_core.paths import jupyter_path
+from traitlets import default
+
+from .html import HTMLExporter
+
+
+class QtExporter(HTMLExporter):
+
+    paginate = None
+
+    def __init__(self, *args, **kwargs):
+        self.format = self.output_mimetype.split("/")[-1]
+        super().__init__(*args, **kwargs)
+
+    @default('file_extension')
+    def _file_extension_default(self):
+        return "." + self.format
+
+    @default('template_name')
+    def _template_name_default(self):
+        return "qt" + self.format
+
+    @default('template_data_paths')
+    def _template_data_paths_default(self):
+        return jupyter_path("nbconvert", "templates", "qt" + self.format)
+
+    def _check_launch_reqs(self):
+        try:
+            from PyQt5.QtWidgets import QApplication
+            from .qt_screenshot import QtScreenshot
+        except ModuleNotFoundError as e:
+            raise RuntimeError(f"PyQtWebEngine is not installed to support Qt {self.format.upper()} conversion. "
+                               f"Please install `nbconvert[qt{self.format}]` to enable.") from e
+        return QApplication, QtScreenshot
+
+    def run_pyqtwebengine(self, html):
+        """Run pyqtwebengine."""
+
+        ext = ".html"
+        temp_file = tempfile.NamedTemporaryFile(suffix=ext, delete=False)
+        filename = f"{temp_file.name[:-len(ext)]}.{self.format}"
+        with temp_file:
+            temp_file.write(html.encode('utf-8'))
+
+        try:
+            QApplication, QtScreenshot = self._check_launch_reqs()
+            app = QApplication([""])
+            s = QtScreenshot(app)
+            s.capture(f"file://{temp_file.name}", filename, self.paginate)
+        finally:
+            # Ensure the file is deleted even if pyqtwebengine raises an exception
+            os.unlink(temp_file.name)
+        data = b""
+        if os.path.exists(filename):
+            with open(filename, "rb") as f:
+                data = f.read()
+            os.unlink(filename)
+        return data
+
+    def from_notebook_node(self, nb, resources=None, **kw):
+        self._check_launch_reqs()
+        html, resources = super().from_notebook_node(
+            nb, resources=resources, **kw
+        )
+
+        self.log.info(f"Building {self.format.upper()}")
+        data = self.run_pyqtwebengine(html)
+        self.log.info(f"{self.format.upper()} successfully created")
+
+        # convert output extension
+        # the writer above required it to be html
+        resources['output_extension'] = f".{self.format}"
+
+        return data, resources

nbconvert/exporters/qt_screenshot.py

@@ -0,0 +1,51 @@
+from PyQt5.QtWidgets import QApplication
+from PyQt5 import QtCore
+from PyQt5.QtWebEngineWidgets import QWebEngineView, QWebEngineSettings
+from PyQt5.QtGui import QPageLayout, QPageSize
+
+
+class QtScreenshot(QWebEngineView):
+
+    def __init__(self, app):
+        super().__init__()
+        self.app = app
+
+    def capture(self, url, output_file, paginate):
+        self.output_file = output_file
+        self.paginate = paginate
+        self.load(QtCore.QUrl(url))
+        self.loadFinished.connect(self.on_loaded)
+        # Create hidden view without scrollbars
+        self.setAttribute(QtCore.Qt.WA_DontShowOnScreen)
+        self.page().settings().setAttribute(
+            QWebEngineSettings.ShowScrollBars, False)
+        if output_file.endswith(".pdf"):
+            self.export = self.export_pdf
+            self.page().pdfPrintingFinished.connect(lambda *args: self.app.exit())
+        elif output_file.endswith(".png"):
+            self.export = self.export_png
+        else:
+            raise RuntimeError(f"Export file extension not supported: {output_file}")
+        self.show()
+        self.app.exec()
+
+    def on_loaded(self):
+        self.size = self.page().contentsSize().toSize()
+        self.resize(self.size)
+        # Wait for resize
+        QtCore.QTimer.singleShot(1000, self.export)
+
+    def export_pdf(self):
+        if self.paginate:
+            page_size = QPageSize(QPageSize.A4)
+            page_layout = QPageLayout(page_size, QPageLayout.Portrait, QtCore.QMarginsF())
+        else:
+            factor = 0.75
+            page_size = QPageSize(QtCore.QSizeF(self.size.width() * factor, self.size.height() * factor), QPageSize.Point)
+            page_layout = QPageLayout(page_size, QPageLayout.Portrait, QtCore.QMarginsF())
+
+        self.page().printToPdf(self.output_file, pageLayout=page_layout)
+
+    def export_png(self):
+        self.grab().save(self.output_file, b"PNG")
+        self.app.quit()

nbconvert/exporters/qtpdf.py

@@ -0,0 +1,30 @@
+"""Export to PDF via a headless browser"""
+
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+from traitlets import Bool
+
+from .qt_exporter import QtExporter
+
+
+class QtPDFExporter(QtExporter):
+    """Writer designed to write to PDF files.
+
+    This inherits from :class:`HTMLExporter`. It creates the HTML using the
+    template machinery, and then uses pyqtwebengine to create a pdf.
+    """
+    export_from_notebook = "PDF via HTML"
+
+    paginate = Bool(
+        True,
+        help="""
+        Split generated notebook into multiple pages.
+
+        If False, a PDF with one long page will be generated.
+
+        Set to True to match behavior of LaTeX based PDF generator
+        """
+    ).tag(config=True)
+
+    output_mimetype = "application/pdf"

nbconvert/exporters/qtpng.py

@@ -0,0 +1,17 @@
+"""Export to PNG via a headless browser"""
+
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+from .qt_exporter import QtExporter
+
+
+class QtPNGExporter(QtExporter):
+    """Writer designed to write to PNG files.
+
+    This inherits from :class:`HTMLExporter`. It creates the HTML using the
+    template machinery, and then uses pyqtwebengine to create a png.
+    """
+    export_from_notebook = "PNG via HTML"
+
+    output_mimetype = "image/png"

nbconvert/exporters/tests/test_qtpdf.py

@@ -0,0 +1,19 @@
+"""Tests for the qtpdf preprocessor"""
+
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+from .base import ExportersTestsBase
+from ..qtpdf import QtPDFExporter
+
+class TestQtPDFExporter(ExportersTestsBase):
+    """Contains test functions for qtpdf.py"""
+
+    exporter_class = QtPDFExporter
+
+    def test_export(self):
+        """
+        Can a TemplateExporter export something?
+        """
+        (output, resources) = QtPDFExporter().from_filename(self._get_notebook())
+        assert len(output) > 0

nbconvert/exporters/tests/test_qtpng.py

@@ -0,0 +1,19 @@
+"""Tests for the qtpng preprocessor"""
+
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+from .base import ExportersTestsBase
+from ..qtpng import QtPNGExporter
+
+class TestQtPNGExporter(ExportersTestsBase):
+    """Contains test functions for qtpng.py"""
+
+    exporter_class = QtPNGExporter
+
+    def test_export(self):
+        """
+        Can a TemplateExporter export something?
+        """
+        (output, resources) = QtPNGExporter().from_filename(self._get_notebook())
+        assert len(output) > 0

nbconvert/nbconvertapp.py

@@ -650,6 +650,7 @@ def initialize(self, argv=None):
         self.config.TemplateExporter.exclude_input_prompt = True
         self.config.ExecutePreprocessor.enabled = True
         self.config.WebPDFExporter.paginate = False
+        self.config.QtPDFExporter.paginate = False
 
         super().initialize(argv)
 

pyproject.toml

@@ -45,6 +45,8 @@ html = "nbconvert.exporters:HTMLExporter"
 slides = "nbconvert.exporters:SlidesExporter"
 latex = "nbconvert.exporters:LatexExporter"
 pdf = "nbconvert.exporters:PDFExporter"
+qtpdf = "nbconvert.exporters:QtPDFExporter"
+qtpng = "nbconvert.exporters:QtPNGExporter"
 webpdf = "nbconvert.exporters:WebPDFExporter"
 markdown = "nbconvert.exporters:MarkdownExporter"
 python = "nbconvert.exporters:PythonExporter"
@@ -64,6 +66,8 @@ test = [
     "pyppeteer>=1,<1.1",
 ]
 serve = ["tornado>=6.1"]
+qtpdf = ["pyqtwebengine>=5.15"]
+qtpng = ["pyqtwebengine>=5.15"]
 webpdf = ["pyppeteer>=1,<1.1"]
 docs = [
     "sphinx>=1.5.1",

share/jupyter/nbconvert/templates/qtpdf/conf.json

@@ -0,0 +1,6 @@
+{
+    "base_template": "lab",
+    "mimetypes": {
+        "application/pdf": true
+    }
+}

share/jupyter/nbconvert/templates/qtpdf/index.pdf.j2

@@ -0,0 +1 @@
+{%- extends 'lab/index.html.j2' -%}

share/jupyter/nbconvert/templates/qtpng/conf.json

@@ -0,0 +1,6 @@
+{
+    "base_template": "lab",
+    "mimetypes": {
+        "image/png": true
+    }
+}

share/jupyter/nbconvert/templates/qtpng/index.png.j2

@@ -0,0 +1 @@
+{%- extends 'lab/index.html.j2' -%}