Make QtWebEngine optional through lazy loading

spyder/api/plugins/new_api.py

@@ -159,6 +159,13 @@ class SpyderPluginV2(QObject, SpyderActionMixin, SpyderConfigurationObserver,
     # disabled. Default: True
     CAN_BE_DISABLED = True
 
+    # Qt Web Widgets may be a heavy dependency for many packagers
+    # (e.g. conda-forge)
+    # We thus ask plugins to declare whether or not they need
+    # web widgets to enhance the distribution of Spyder to users
+    # https://github.com/spyder-ide/spyder/pull/22196#issuecomment-2189377043
+    REQUIRE_WEB_WIDGETS = False
+
     # --- API: Signals -------------------------------------------------------
     # ------------------------------------------------------------------------
     # Signals here are automatically connected by the Spyder main window and

spyder/app/mainwindow.py

@@ -54,7 +54,10 @@
 from qtpy import QtSvg  # analysis:ignore
 
 # Avoid a bug in Qt: https://bugreports.qt.io/browse/QTBUG-46720
-from qtpy import QtWebEngineWidgets  # analysis:ignore
+try:
+    from qtpy.QtWebEngineWidgets import WEBENGINE
+except ImportError:
+    WEBENGINE = False
 
 from qtawesome.iconic_font import FontError
 
@@ -759,12 +762,6 @@ def setup(self):
         registry_external_plugins = {}
         for plugin in all_plugins.values():
             plugin_name = plugin.NAME
-            # Disable panes that use web widgets (currently Help and Online
-            # Help) if the user asks for it.
-            # See spyder-ide/spyder#16518
-            if self._cli_options.no_web_widgets:
-                if "help" in plugin_name:
-                    continue
             plugin_main_attribute_name = (
                 self._INTERNAL_PLUGINS_MAPPING[plugin_name]
                 if plugin_name in self._INTERNAL_PLUGINS_MAPPING
@@ -791,6 +788,18 @@ def setup(self):
             if plugin_name in enabled_plugins:
                 PluginClass = internal_plugins[plugin_name]
                 if issubclass(PluginClass, SpyderPluginV2):
+                    # Disable plugins that use web widgets (currently Help and
+                    # Online Help) if the user asks for it.
+                    # See spyder-ide/spyder#16518
+                    # The plugins that require QtWebengine must declare
+                    # themselves as needing that dependency
+                    # https://github.com/spyder-ide/spyder/pull/22196#issuecomment-2189377043
+                    if PluginClass.REQUIRE_WEB_WIDGETS and (
+                        not WEBENGINE or
+                        self._cli_options.no_web_widgets
+                    ):
+                        continue
+
                     PLUGIN_REGISTRY.register_plugin(self, PluginClass,
                                                     external=False)
 

spyder/plugins/help/plugin.py

@@ -46,6 +46,7 @@ class Help(SpyderDockablePlugin):
     LOG_PATH = get_conf_path(CONF_SECTION)
     FONT_SIZE_DELTA = DEFAULT_SMALL_DELTA
     DISABLE_ACTIONS_WHEN_HIDDEN = False
+    REQUIRE_WEB_WIDGETS = True
 
     # Signals
     sig_focus_changed = Signal()  # TODO: What triggers this?

spyder/plugins/help/widgets.py

@@ -17,9 +17,8 @@
 from qtpy import PYQT5
 from qtpy.QtCore import Qt, QUrl, Signal, Slot, QPoint
 from qtpy.QtGui import QColor
-from qtpy.QtWebEngineWidgets import WEBENGINE, QWebEnginePage
 from qtpy.QtWidgets import (QActionGroup, QComboBox, QLabel, QLineEdit,
-                            QMessageBox, QSizePolicy, QStackedLayout,
+                            QMessageBox, QSizePolicy, QStackedWidget,
                             QVBoxLayout, QWidget)
 
 # Local imports
@@ -36,11 +35,16 @@
 from spyder.utils.image_path_manager import get_image_path
 from spyder.utils.palette import QStylePalette
 from spyder.utils.qthelpers import start_file
-from spyder.widgets.browser import FrameWebView
 from spyder.widgets.comboboxes import EditableComboBox
 from spyder.widgets.findreplace import FindReplace
 from spyder.widgets.simplecodeeditor import SimpleCodeEditor
 
+# In case WebEngine is not available (e.g. in Conda-forge)
+try:
+    from qtpy.QtWebEngineWidgets import WEBENGINE
+except ImportError:
+    WEBENGINE = False
+
 
 # --- Constants
 # ----------------------------------------------------------------------------
@@ -157,6 +161,9 @@ def __init__(self, parent):
             QWidget.__init__(self, parent)
             SpyderWidgetMixin.__init__(self, class_parent=parent)
 
+        from qtpy.QtWebEngineWidgets import QWebEnginePage
+        from spyder.widgets.browser import FrameWebView
+
         self.webview = FrameWebView(self)
         self.webview.setup()
 

spyder/plugins/ipythonconsole/widgets/main_widget.py

@@ -22,8 +22,8 @@
 import qstylizer.style
 from qtconsole.client import QtKernelClient
 from qtpy.QtCore import Signal, Slot
-from qtpy.QtGui import QColor
-from qtpy.QtWebEngineWidgets import WEBENGINE
+from qtpy.QtGui import QColor, QKeySequence
+from qtpy.QtPrintSupport import QPrintDialog, QPrinter
 from qtpy.QtWidgets import (
     QApplication, QHBoxLayout, QLabel, QMessageBox, QVBoxLayout, QWidget)
 from traitlets.config.loader import Config, load_pyconfig_files
@@ -46,11 +46,16 @@
 from spyder.utils import encoding, programs, sourcecode
 from spyder.utils.misc import get_error_match, remove_backslashes
 from spyder.utils.palette import QStylePalette
-from spyder.widgets.browser import FrameWebView
 from spyder.widgets.findreplace import FindReplace
 from spyder.widgets.tabs import Tabs
 from spyder.plugins.ipythonconsole.utils.stdfile import StdFile
 
+# In case WebEngine is not available (e.g. in Conda-forge)
+try:
+    from qtpy.QtWebEngineWidgets import WEBENGINE
+except ImportError:
+    WEBENGINE = False
+
 
 # Logging
 logger = logging.getLogger(__name__)
@@ -308,7 +313,7 @@ def __init__(self, name=None, plugin=None, parent=None):
         self.enable_infowidget = True
         if plugin:
             cli_options = plugin.get_command_line_options()
-            if cli_options.no_web_widgets:
+            if cli_options.no_web_widgets or not WEBENGINE:
                 self.enable_infowidget = False
 
         # Attrs for testing
@@ -351,6 +356,8 @@ def __init__(self, name=None, plugin=None, parent=None):
 
         # Info widget
         if self.enable_infowidget:
+            from spyder.widgets.browser import FrameWebView
+
             self.infowidget = FrameWebView(self)
             if WEBENGINE:
                 self.infowidget.page().setBackgroundColor(

spyder/plugins/onlinehelp/plugin.py

@@ -32,6 +32,7 @@ class OnlineHelp(SpyderDockablePlugin):
     CONF_FILE = False
     WIDGET_CLASS = PydocBrowser
     LOG_PATH = get_conf_path(NAME)
+    REQUIRE_WEB_WIDGETS = True
 
     # --- Signals
     # ------------------------------------------------------------------------

spyder/plugins/onlinehelp/widgets.py

@@ -17,17 +17,21 @@
 # Third party imports
 from qtpy.QtCore import Qt, QThread, QUrl, Signal, Slot
 from qtpy.QtGui import QCursor
-from qtpy.QtWebEngineWidgets import WEBENGINE
 from qtpy.QtWidgets import QApplication, QLabel, QVBoxLayout
 
 # Local imports
 from spyder.api.translations import _
 from spyder.api.widgets.main_widget import PluginMainWidget
 from spyder.plugins.onlinehelp.pydoc_patch import _start_server, _url_handler
-from spyder.widgets.browser import FrameWebView, WebViewActions
 from spyder.widgets.comboboxes import UrlComboBox
 from spyder.widgets.findreplace import FindReplace
 
+# In case WebEngine is not available (e.g. in Conda-forge)
+try:
+    from qtpy.QtWebEngineWidgets import WEBENGINE
+except ImportError:
+    WEBENGINE = False
+
 
 # --- Constants
 # ----------------------------------------------------------------------------
@@ -139,6 +143,8 @@ class PydocBrowser(PluginMainWidget):
     """
 
     def __init__(self, name=None, plugin=None, parent=None):
+        from spyder.widgets.browser import FrameWebView
+
         super().__init__(name, plugin, parent=parent)
 
         self._is_running = False
@@ -194,6 +200,8 @@ def get_focus_widget(self):
         return self.url_combo
 
     def setup(self):
+        from spyder.widgets.browser import WebViewActions
+
         # Actions
         home_action = self.create_action(
             PydocBrowserActions.Home,
@@ -244,6 +252,8 @@ def setup(self):
         self.sig_toggle_view_changed.connect(self.initialize)
 
     def update_actions(self):
+        from spyder.widgets.browser import WebViewActions
+
         stop_action = self.get_action(WebViewActions.Stop)
         refresh_action = self.get_action(WebViewActions.Refresh)
 
@@ -272,6 +282,8 @@ def _continue_initialization(self):
 
     def _handle_url_combo_activation(self):
         """Load URL from combo box first item."""
+        from spyder.widgets.browser import WebViewActions
+
         if not self._is_running:
             text = str(self.url_combo.currentText())
             self.go_to(self.text_to_url(text))