mobileshell: Dynamically load in heavy dependencies for singletons

components/mobileshell/qml/components/AppLaunch.qml

@@ -2,20 +2,38 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 import QtQuick
-import org.kde.plasma.private.mobileshell as MobileShell
+
-import org.kde.plasma.private.mobileshell.windowplugin as WindowPlugin
+// NOTE: This is a singleton in the mobileshell library, so we need to be careful to
+// make this load as fast as possible (since it may be loaded in other processes ex. lockscreen).
 
 pragma Singleton
 
 QtObject {
+    id: root
+
     /**
      * Activates an application by storage id if it is already running, or launch the application.
      */
     function launchOrActivateApp(storageId) {
-        const launched = WindowPlugin.WindowUtil.activateWindowByStorageId(storageId);
 
-        if (!launched) {
+        // We don't want to import WindowPlugin initially because it has side-effects and slows down initial load.
-            MobileShell.ShellUtil.launchApp(storageId);
+        // -> only import it if we actually run the function
-        }
+        const component = Qt.createQmlObject(`
+            import QtQuick
+            import org.kde.plasma.private.mobileshell as MobileShell
+            import org.kde.plasma.private.mobileshell.windowplugin as WindowPlugin
+
+            QtObject {
+                Component.onCompleted: {
+                    const launched = WindowPlugin.WindowUtil.activateWindowByStorageId("${storageId}");
+
+                    if (!launched) {
+                        MobileShell.ShellUtil.launchApp("${storageId}");
+                    }
+                }
+            }
+        `, root, "runSnippet");
+
+        component.destroy();
     }
 }

components/mobileshell/qml/components/Constants.qml

@@ -5,6 +5,9 @@ import QtQuick
 
 import org.kde.plasma.core as PlasmaCore
 
+// NOTE: This is a singleton in the mobileshell library, so we need to be careful to
+// make this load as fast as possible (since it may be loaded in other processes ex. lockscreen).
+
 pragma Singleton
 
 QtObject {

components/mobileshell/shellutil.cpp

@@ -26,16 +26,6 @@ ShellUtil::ShellUtil(QObject *parent)
     : QObject{parent}
     , m_localeConfig{KSharedConfig::openConfig(QStringLiteral("kdeglobals"), KConfig::SimpleConfig)}
 {
-    m_localeConfigWatcher = KConfigWatcher::create(m_localeConfig);
-
-    // watch for changes to locale config, to update 12/24 hour time
-    connect(m_localeConfigWatcher.data(), &KConfigWatcher::configChanged, this, [this](const KConfigGroup &group, const QByteArrayList &names) -> void {
-        if (group.name() == "Locale") {
-            // we have to reparse for new changes (from system settings)
-            m_localeConfig->reparseConfiguration();
-            Q_EMIT isSystem24HourFormatChanged();
-        }
-    });
 }
 
 ShellUtil *ShellUtil::instance()
@@ -71,6 +61,20 @@ void ShellUtil::executeCommand(const QString &command)
 
 bool ShellUtil::isSystem24HourFormat()
 {
+    // only load the config watcher if this function is actually used once
+    if (!m_localeConfigWatcher) {
+        m_localeConfigWatcher = KConfigWatcher::create(m_localeConfig);
+
+        // watch for changes to locale config, to update 12/24 hour time
+        connect(m_localeConfigWatcher.data(), &KConfigWatcher::configChanged, this, [this](const KConfigGroup &group, const QByteArrayList &names) -> void {
+            if (group.name() == "Locale") {
+                // we have to reparse for new changes (from system settings)
+                m_localeConfig->reparseConfiguration();
+                Q_EMIT isSystem24HourFormatChanged();
+            }
+        });
+    }
+
     KConfigGroup localeSettings = KConfigGroup(m_localeConfig, "Locale");
 
     QString timeFormat = localeSettings.readEntry("TimeFormat", QStringLiteral(FORMAT24H));