Show notification when modifier keys are used

If the relevant accessibility setting is enabled

BUG: 395559

src/plugins/CMakeLists.txt

@@ -113,6 +113,10 @@ add_subdirectory(windowview)
 add_subdirectory(wobblywindows)
 add_subdirectory(zoom)
 
+if (KWIN_BUILD_NOTIFICATIONS)
+    add_subdirectory(keynotification)
+endif()
+
 if (KWIN_BUILD_DECORATIONS)
     add_subdirectory(kdecorations)
 endif()

src/plugins/keynotification/CMakeLists.txt

@@ -0,0 +1,15 @@
+# SPDX-FileCopyrightText: 2024 Nicolas Fella <nicolas.fella@kdab.com>
+# SPDX-License-Identifier: BSD-3-Clause
+
+kcoreaddons_add_plugin(KeyNotificationPlugin INSTALL_NAMESPACE "kwin/plugins")
+
+target_compile_definitions(KeyNotificationPlugin PRIVATE
+    -DTRANSLATION_DOMAIN=\"kwin\"
+)
+
+target_sources(KeyNotificationPlugin PRIVATE
+    main.cpp
+    keynotification.cpp
+)
+target_link_libraries(KeyNotificationPlugin PRIVATE kwin KF6::Notifications KF6::I18n XKB::XKB)
+

src/plugins/keynotification/keynotification.cpp

@@ -0,0 +1,119 @@
+/*
+    SPDX-FileCopyrightText: 2024 Nicolas Fella <nicolas.fella@kdab.com>
+
+    SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+*/
+
+#include "keynotification.h"
+#include "keyboard_input.h"
+#include "xkb.h"
+
+#include <KLocalizedString>
+#include <KNotification>
+
+namespace KWin
+{
+KeyNotificationPlugin::KeyNotificationPlugin()
+    : m_configWatcher(KConfigWatcher::create(KSharedConfig::openConfig("kaccessrc")))
+{
+    const QLatin1String groupName("Keyboard");
+    connect(m_configWatcher.get(), &KConfigWatcher::configChanged, this, [this, groupName](const KConfigGroup &group) {
+        if (group.name() == groupName) {
+            loadConfig(group);
+        }
+    });
+    loadConfig(m_configWatcher->config()->group(groupName));
+
+    connect(input()->keyboard(), &KeyboardInputRedirection::ledsChanged, this,
+            &KeyNotificationPlugin::ledsChanged);
+
+    connect(input()->keyboard()->xkb(), &Xkb::modifierStateChanged, this, &KeyNotificationPlugin::modifiersChanged);
+}
+
+void KeyNotificationPlugin::ledsChanged(LEDs leds)
+{
+    if (m_enabled) {
+        if (!m_currentLEDs.testFlag(LED::CapsLock) && leds.testFlag(LED::CapsLock)) {
+            sendNotification("lockkey-locked", i18n("The Caps Lock key has been activated"));
+        }
+
+        if (m_currentLEDs.testFlag(LED::CapsLock) && !leds.testFlag(LED::CapsLock)) {
+            sendNotification("lockkey-unlocked", i18n("The Caps Lock key is now inactive"));
+        }
+
+        if (!m_currentLEDs.testFlag(LED::NumLock) && leds.testFlag(LED::NumLock)) {
+            sendNotification("lockkey-locked", i18n("The Num Lock key has been activated"));
+        }
+
+        if (m_currentLEDs.testFlag(LED::NumLock) && !leds.testFlag(LED::NumLock)) {
+            sendNotification("lockkey-unlocked", i18n("The Num Lock key is now inactive"));
+        }
+
+        if (!m_currentLEDs.testFlag(LED::ScrollLock) && leds.testFlag(LED::ScrollLock)) {
+            sendNotification("lockkey-locked", i18n("The Scroll Lock key has been activated"));
+        }
+
+        if (m_currentLEDs.testFlag(LED::ScrollLock) && !leds.testFlag(LED::ScrollLock)) {
+            sendNotification("lockkey-unlocked", i18n("The Scroll Lock key is now inactive"));
+        }
+    }
+
+    m_currentLEDs = leds;
+}
+
+void KeyNotificationPlugin::modifiersChanged()
+{
+    Qt::KeyboardModifiers mods = input()->keyboard()->xkb()->modifiers();
+
+    if (m_enabled) {
+        if (!m_currentModifiers.testFlag(Qt::ShiftModifier) && mods.testFlag(Qt::ShiftModifier)) {
+            sendNotification("modifierkey-latched", i18n("The Shift key is now active."));
+        }
+
+        if (m_currentModifiers.testFlag(Qt::ShiftModifier) && !mods.testFlag(Qt::ShiftModifier)) {
+            sendNotification("modifierkey-unlatched", i18n("The Shift key is now inactive."));
+        }
+
+        if (!m_currentModifiers.testFlag(Qt::ControlModifier) && mods.testFlag(Qt::ControlModifier)) {
+            sendNotification("modifierkey-latched", i18n("The Control key is now active."));
+        }
+
+        if (m_currentModifiers.testFlag(Qt::ControlModifier) && !mods.testFlag(Qt::ControlModifier)) {
+            sendNotification("modifierkey-unlatched", i18n("The Control key is now inactive."));
+        }
+
+        if (!m_currentModifiers.testFlag(Qt::AltModifier) && mods.testFlag(Qt::AltModifier)) {
+            sendNotification("modifierkey-latched", i18n("The Alt key is now active."));
+        }
+
+        if (m_currentModifiers.testFlag(Qt::AltModifier) && !mods.testFlag(Qt::AltModifier)) {
+            sendNotification("modifierkey-unlatched", i18n("The Alt key is now inactive."));
+        }
+
+        if (!m_currentModifiers.testFlag(Qt::MetaModifier) && mods.testFlag(Qt::MetaModifier)) {
+            sendNotification("modifierkey-latched", i18n("The Meta key is now active."));
+        }
+
+        if (m_currentModifiers.testFlag(Qt::MetaModifier) && !mods.testFlag(Qt::AltModifier)) {
+            sendNotification("modifierkey-unlatched", i18n("The Meta key is now inactive."));
+        }
+    }
+
+    m_currentModifiers = input()->keyboard()->xkb()->modifiers();
+}
+
+void KeyNotificationPlugin::sendNotification(const QString &eventId, const QString &text)
+{
+    KNotification *notification = new KNotification(QStringLiteral("modifierkey-locked"));
+    notification->setComponentName(QStringLiteral("kaccess"));
+    notification->setText(text);
+    notification->sendEvent();
+}
+
+void KeyNotificationPlugin::loadConfig(const KConfigGroup &group)
+{
+    m_enabled = group.readEntry("kNotifyModifiers", false);
+}
+}
+
+#include "moc_keynotification.cpp"

src/plugins/keynotification/keynotification.h

@@ -0,0 +1,34 @@
+/*
+    SPDX-FileCopyrightText: 2024 Nicolas Fella <nicolas.fella@kdab.com>
+
+    SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+*/
+
+#pragma once
+
+#include "effect/globals.h"
+#include "plugin.h"
+
+#include <KConfigGroup>
+#include <KConfigWatcher>
+
+namespace KWin
+{
+class KeyNotificationPlugin : public KWin::Plugin
+{
+    Q_OBJECT
+public:
+    explicit KeyNotificationPlugin();
+
+private:
+    void loadConfig(const KConfigGroup &group);
+    void ledsChanged(KWin::LEDs leds);
+    void modifiersChanged();
+    void sendNotification(const QString &eventId, const QString &text);
+
+    KConfigWatcher::Ptr m_configWatcher;
+    bool m_enabled = false;
+    KWin::LEDs m_currentLEDs;
+    Qt::KeyboardModifiers m_currentModifiers;
+};
+}

src/plugins/keynotification/main.cpp

@@ -0,0 +1,32 @@
+/*
+    SPDX-FileCopyrightText: 2024 Nicolas Fella <nicolas.fella@kdab.com>
+
+    SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+*/
+
+#include "main.h"
+#include "plugin.h"
+
+#include "keynotification.h"
+
+class KWIN_EXPORT KeyNotificationFactory : public KWin::PluginFactory
+{
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID PluginFactory_iid FILE "metadata.json")
+    Q_INTERFACES(KWin::PluginFactory)
+
+public:
+    std::unique_ptr<KWin::Plugin> create() const override
+    {
+        switch (KWin::kwinApp()->operationMode()) {
+        case KWin::Application::OperationModeXwayland:
+        case KWin::Application::OperationModeWaylandOnly:
+            return std::make_unique<KWin::KeyNotificationPlugin>();
+        case KWin::Application::OperationModeX11:
+        default:
+            return nullptr;
+        }
+    }
+};
+
+#include "main.moc"

src/plugins/keynotification/metadata.json

@@ -0,0 +1,5 @@
+{
+    "KPlugin": {
+        "EnabledByDefault": true
+    }
+}