Move EventFilter out of app.py

1 files changed, 111 insertions, 0 deletions

diff --git a/qutebrowser/keyinput/eventfilter.py b/qutebrowser/keyinput/eventfilter.py
new file mode 100644
index 000000000..72b82e7c1
--- /dev/null
+++ b/qutebrowser/keyinput/eventfilter.py
@@ -0,0 +1,111 @@
+# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:
+
+# Copyright 2014-2020 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
+#
+# This file is part of qutebrowser.
+#
+# qutebrowser is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# qutebrowser is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Global Qt event filter which dispatches key events."""
+
+from PyQt5.QtCore import pyqtSlot, QObject, QEvent
+from PyQt5.QtGui import QKeyEvent, QWindow
+from PyQt5.QtWidgets import QApplication
+
+from qutebrowser.keyinput import modeman
+from qutebrowser.misc import quitter
+from qutebrowser.utils import objreg
+
+
+class EventFilter(QObject):
+
+    """Global Qt event filter.
+
+    Attributes:
+        _activated: Whether the EventFilter is currently active.
+        _handlers; A {QEvent.Type: callable} dict with the handlers for an
+                   event.
+    """
+
+    def __init__(self, parent: QObject = None) -> None:
+        super().__init__(parent)
+        self._activated = True
+        self._handlers = {
+            QEvent.KeyPress: self._handle_key_event,
+            QEvent.KeyRelease: self._handle_key_event,
+            QEvent.ShortcutOverride: self._handle_key_event,
+        }
+
+    def install(self):
+        QApplication.instance().installEventFilter(self)
+
+    @pyqtSlot()
+    def shutdown(self):
+        QApplication.instance().removeEventFilter(self)
+
+    def _handle_key_event(self, event: QKeyEvent) -> bool:
+        """Handle a key press/release event.
+
+        Args:
+            event: The QEvent which is about to be delivered.
+
+        Return:
+            True if the event should be filtered, False if it's passed through.
+        """
+        active_window = QApplication.instance().activeWindow()
+        if active_window not in objreg.window_registry.values():
+            # Some other window (print dialog, etc.) is focused so we pass the
+            # event through.
+            return False
+        try:
+            man = modeman.instance('current')
+            return man.handle_event(event)
+        except objreg.RegistryUnavailableError:
+            # No window available yet, or not a MainWindow
+            return False
+
+    def eventFilter(self, obj: QObject, event: QEvent) -> bool:
+        """Handle an event.
+
+        Args:
+            obj: The object which will get the event.
+            event: The QEvent which is about to be delivered.
+
+        Return:
+            True if the event should be filtered, False if it's passed through.
+        """
+        try:
+            if not self._activated:
+                return False
+            if not isinstance(obj, QWindow):
+                # We already handled this same event at some point earlier, so
+                # we're not interested in it anymore.
+                return False
+            try:
+                handler = self._handlers[event.type()]
+            except KeyError:
+                return False
+            else:
+                return handler(event)
+        except:
+            # If there is an exception in here and we leave the eventfilter
+            # activated, we'll get an infinite loop and a stack overflow.
+            self._activated = False
+            raise
+
+
+def init():
+    event_filter = EventFilter(parent=QApplication.instance())
+    event_filter.install()
+    quitter.instance.shutting_down.connect(event_filter.shutdown)