Add qtpdf and qtpng exporters

.github/workflows/tests.yml

@@ -22,55 +22,84 @@ jobs:
           - os: "macos-latest"
             python-version: "3.9"
           - os: "ubuntu-latest"
-            python-version: "pypy-3.8"
+            python-version: "3.10"
       fail-fast: false
     steps:
       - name: Check out repository code
         uses: actions/checkout@v2
       - name: Run base setup actions
         uses: jupyterlab/maintainer-tools/.github/actions/base-setup@v1
-
+      - uses: conda-incubator/setup-miniconda@v2
+        with:
+          mamba-version: "*"
+          channels: conda-forge
+      - name: Install conda-forge python
+        shell: bash -l {0}
+        run: |
+          mamba create -n nbconvert
+          conda activate nbconvert
+          mamba install python=${{ matrix.python-version }}
+      - name: Install conda-forge dependencies
+        shell: bash -l {0}
+        run: |
+          mamba create -n nbconvert
+          conda activate nbconvert
+          mamba install pip pyqtwebengine pandoc pyxdg
       - name: Install Linux dependencies
         if: startsWith(runner.os, 'Linux')
         run: |
           sudo apt-get update
           sudo apt-get install texlive-plain-generic inkscape texlive-xetex
-
-          # pandoc is not up to date in the ubuntu repos, so we install directly
-          wget https://github.com/jgm/pandoc/releases/download/2.17.1.1/pandoc-2.17.1.1-1-amd64.deb && sudo dpkg -i pandoc-2.17.1.1-1-amd64.deb
-
+          sudo apt-get install xvfb x11-utils libxkbcommon-x11-0
       - name: Install package dependencies
-        shell: bash
+        shell: bash -l {0}
         run: |
-          pip install codecov --user
-          pip install -e ".[execute,serve,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
+          conda activate nbconvert
+          pip install codecov
+          pip install -e ".[execute,serve,test]"
+          which python
+          python -m ipykernel.kernelspec --sys-prefix
 
       - name: List installed packages
+        shell: bash -l {0}
         run: |
+          conda activate nbconvert
           pip freeze
           pip check
 
       - name: Run tests with coverage
-        if: ${{ !startsWith(matrix.python-version, 'pypy') && !startsWith(runner.os, 'Windows')  }}
-        shell: bash
+        if: ${{ startsWith(runner.os, 'macos')  }}
+        shell: bash -l {0}
         run: |
+          conda activate nbconvert
           # See https://github.com/pyppeteer/pyppeteer/pull/321
-          pip install -U websockets --user
+          pip install -U websockets
           python -m pytest --cov nbconvert -vv
 
       - name: Run tests on pypy and Windows
-        if: ${{ startsWith(matrix.python-version, 'pypy') || startsWith(runner.os, 'Windows')  }}
-        shell: bash
+        if: ${{ startsWith(runner.os, 'linux') }}
+        shell: bash -l {0}
         run: |
+          conda activate nbconvert
           # See https://github.com/pyppeteer/pyppeteer/pull/321
-          pip install -U websockets --user
+          pip install -U websockets
+          #python -m pytest -vv
+          xvfb-run --auto-servernum `which coverage` run -m pytest -vv
+
+      - name: Run tests on pypy and Windows
+        if: ${{ startsWith(runner.os, 'Windows') }}
+        shell: bash -l {0}
+        run: |
+          conda activate nbconvert
+          # See https://github.com/pyppeteer/pyppeteer/pull/321
+          pip install -U websockets
           python -m pytest -vv
 
       - name: Code coverage
-        run: codecov
+        shell: bash -l {0}
+        run: |
+          conda activate nbconvert
+          codecov
 
   # Run "pre-commit run --all-files --hook-stage=manual"
   pre-commit:

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 +1,59 @@
+import os
+import sys
+import tempfile
+
+from traitlets import default
+
+from .html import HTMLExporter
+
+
+class QtExporter(HTMLExporter):
+
+    paginate = None
+
+    @default("file_extension")
+    def _file_extension_default(self):
+        return ".html"
+
+    def _check_launch_reqs(self):
+        if sys.platform.startswith("win") and self.format == "png":
+            raise RuntimeError("Exporting to PNG using Qt is currently not supported on Windows.")
+        from .qt_screenshot import QT_INSTALLED
+
+        if not QT_INSTALLED:
+            raise RuntimeError(
+                f"PyQtWebEngine is not installed to support Qt {self.format.upper()} conversion. "
+                f"Please install `nbconvert[qt{self.format}]` to enable."
+            )
+        from .qt_screenshot import QtScreenshot
+
+        return QtScreenshot
+
+    def _run_pyqtwebengine(self, html):
+        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:
+            QtScreenshot = self._check_launch_reqs()
+            s = QtScreenshot()
+            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)
+        return s.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 +1,77 @@
+import os
+
+try:
+    from PyQt5 import QtCore
+    from PyQt5.QtGui import QPageLayout, QPageSize
+    from PyQt5.QtWebEngineWidgets import QWebEngineSettings, QWebEngineView
+    from PyQt5.QtWidgets import QApplication
+
+    QT_INSTALLED = True
+except ModuleNotFoundError:
+    QT_INSTALLED = False
+
+
+if QT_INSTALLED:
+    APP = None
+    if not QApplication.instance():
+        APP = QApplication([])
+
+    class QtScreenshot(QWebEngineView):
+        def __init__(self):
+            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)
+            self.data = b""
+            if output_file.endswith(".pdf"):
+                self.export = self.export_pdf
+
+                def cleanup(*args):
+                    self.app.quit()
+                    self.get_data()
+
+                self.page().pdfPrintingFinished.connect(cleanup)
+            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, "PNG")
+            self.app.quit()
+            self.get_data()
+
+        def get_data(self):
+            if os.path.exists(self.output_file):
+                with open(self.output_file, "rb") as f:
+                    self.data = f.read()
+                os.unlink(self.output_file)

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"
+    format = "pdf"
+
+    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)

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"
+    format = "png"

nbconvert/exporters/tests/test_qtpdf.py

@@ -0,0 +1,24 @@
+"""Tests for the qtpdf preprocessor"""
+
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+import pytest
+
+from ..qt_screenshot import QT_INSTALLED
+from ..qtpdf import QtPDFExporter
+from .base import ExportersTestsBase
+
+
+@pytest.mark.skipif(not QT_INSTALLED, reason="PyQtWebEngine not installed")
+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 +1,31 @@
+"""Tests for the qtpng preprocessor"""
+
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+import os
+
+import pytest
+
+from ..qt_screenshot import QT_INSTALLED
+from ..qtpng import QtPNGExporter
+from .base import ExportersTestsBase
+
+
+@pytest.mark.skipif(not QT_INSTALLED, reason="PyQtWebEngine not installed")
+class TestQtPNGExporter(ExportersTestsBase):
+    """Contains test functions for qtpng.py"""
+
+    exporter_class = QtPNGExporter
+
+    def test_export(self):
+        """
+        Can a TemplateExporter export something?
+        """
+        if os.name == "nt":
+            # currently not supported
+            with pytest.raises(RuntimeError) as exc_info:
+                (output, resources) = QtPNGExporter().from_filename(self._get_notebook())
+        else:
+            (output, resources) = QtPNGExporter().from_filename(self._get_notebook())
+            assert len(output) > 0

nbconvert/exporters/webpdf.py

@@ -38,8 +38,6 @@ class WebPDFExporter(HTMLExporter):
         """,
     ).tag(config=True)
 
-    output_mimetype = "text/html"
-
     @default("file_extension")
     def _file_extension_default(self):
         return ".html"

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)