Widget: Display page in external browser when link in notebook is cli…

…cked

When the user clicks on a link in a notebook, the NotebookWidget calls
createWindow() in order to open a new tab to display the link. This commit
intercepts the call and creates a WebViewInBrowser object. When the URL in
that object is set, the link is opened in an external web browser.

spyder_notebook/widgets/client.py

@@ -5,9 +5,10 @@
 
 """Qt widgets for the notebook."""
 
+# Standard library imports
+import json
 import os
 import os.path as osp
-import json
 from string import Template
 import sys
 
@@ -19,10 +20,8 @@
 from qtpy.QtWidgets import (QApplication, QMenu, QVBoxLayout, QWidget,
                             QMessageBox)
 
-# Notebook imports
-from notebook.utils import url_path_join, url_escape
-
 # Third-party imports
+from notebook.utils import url_path_join, url_escape
 import requests
 
 # Spyder imports
@@ -55,6 +54,39 @@
 # -----------------------------------------------------------------------------
 # Widgets
 # -----------------------------------------------------------------------------
+class WebViewInBrowser(QWebEngineView):
+    """
+    WebView which opens document in an external browser.
+
+    This is a subclass of QWebEngineView, which as soon as the URL is set,
+    opens the web page in an external browser and closes itself. It is used
+    in NotebookWidget to open links.
+    """
+
+    def __init__(self, parent):
+        """Construct object."""
+        super().__init__(parent)
+        self.urlChanged.connect(self.open_in_browser)
+
+    def open_in_browser(self, url):
+        """
+        Open web page in external browser and close self.
+
+        Parameters
+        ----------
+        url : QUrl
+            URL of web page to open in browser
+        """
+        import webbrowser
+        try:
+            webbrowser.open(url.toString())
+        except ValueError:
+            # See: spyder-ide/spyder#9849
+            pass
+        self.stop()
+        self.close()
+
+
 class NotebookWidget(DOMWidget):
     """WebView widget for notebooks."""
 
@@ -153,6 +185,17 @@ def show_message(self, page):
         """Show a message page with the given .html file."""
         self.setHtml(page)
 
+    def createWindow(self, webWindowType):
+        """
+        Create new browser window.
+
+        This function is called by Qt if the user clicks on a link in the
+        notebook. The goal is to open the web page in an external browser.
+        To that end, we create and return an object which will open the browser
+        when Qt sets the URL.
+        """
+        return WebViewInBrowser(self.parent())
+
 
 class NotebookClient(QWidget):
     """

spyder_notebook/widgets/tests/test_client.py

@@ -7,6 +7,7 @@
 
 # Third-party imports
 import pytest
+from qtpy.QtCore import QUrl
 from qtpy.QtWidgets import QWidget
 import requests
 
@@ -47,6 +48,20 @@ def plugin(plugin_without_server):
     return plugin_without_server
 
 
+def test_notebookwidget_create_window(plugin, mocker, qtbot):
+    """Test that NotebookWidget.create_window() creates an object that calls
+    webbrowser.open() when its URL is set."""
+    widget = plugin.client.notebookwidget
+    mock_notebook_open = mocker.patch('webbrowser.open')
+    new_view = widget.createWindow(42)
+    url = 'https://www.spyder-ide.org/'
+
+    with qtbot.waitSignal(new_view.loadFinished):
+        new_view.setUrl(QUrl(url))
+
+    mock_notebook_open.assert_called_once_with(url)
+
+
 def test_notebookclient_get_kernel_id(plugin, mocker):
     """Basic unit test for NotebookClient.get_kernel_id()."""
     response = mocker.Mock()