Allow to keep running Syncthing in background when closing app

Author: Martchus

tray/android/src/io/github/martchus/syncthingtray/Activity.java

@@ -32,6 +32,15 @@ public boolean performHapticFeedback() {
         return res;
     }
 
+    public boolean minimize() {
+        runOnUiThread(new Runnable() {
+            public void run() {
+                moveTaskToBack(true);
+            }
+        });
+        return true;
+    }
+
     public boolean showToast(String message) {
         Activity activity = this;
         runOnUiThread(new Runnable() {

tray/gui/qml/Main.qml

@@ -440,19 +440,30 @@ ApplicationWindow {
         }
     }
 
-    // avoid closing app (TODO: allow to keep Syncthing running in the background)
+    // handle closing
     CustomDialog {
         id: closeDialog
         title: window.title
         contentItem: Label {
             Layout.fillWidth: true
-            text: qsTr("Do you really want to close Syncthing?")
+            text: qsTr("Do you really want to close Syncthing? You can also just quit the UI but keep running Syncthing in the backround.")
             wrapMode: Text.WordWrap
         }
         onAccepted: {
             window.forceClose = true;
             window.close();
         }
+        footer: DialogButtonBox {
+            Button {
+                text: qsTr("Run in background")
+                flat: true
+                onClicked: {
+                    closeDialog.close();
+                    App.minimize();
+                }
+                DialogButtonBox.buttonRole: DialogButtonBox.InvalidRole
+            }
+        }
     }
     onClosing: (event) => {
         if (!window.forceClose && App.launcher.running) {

tray/gui/quick/app.cpp

@@ -115,6 +115,7 @@ App::App(bool insecure, QObject *parent)
     , m_darkColorScheme(false)
     , m_darkPalette(QtUtilities::isPaletteDark())
     , m_isGuiLoaded(false)
+    , m_alwaysUnloadGuiWhenHidden(false)
     , m_unloadGuiWhenHidden(false)
 {
     m_app->installEventFilter(this);
@@ -704,7 +705,8 @@ void App::handleStateChanged(Qt::ApplicationState state)
         for (auto *const uiObject : m_uiObjects) {
             uiObject->moveToThread(nullptr);
         }
-        if (m_unloadGuiWhenHidden) {
+        if (m_unloadGuiWhenHidden || m_alwaysUnloadGuiWhenHidden) {
+            m_unloadGuiWhenHidden = false;
             unloadMain();
         }
     } else if (state & Qt::ApplicationActive) {
@@ -968,6 +970,23 @@ QVariantList App::computeDirsNeedingItems(const QModelIndex &devProxyModelIndex)
     return dirs;
 }
 
+bool App::minimize()
+{
+#ifdef Q_OS_ANDROID
+    if (!QJniObject(QNativeInterface::QAndroidApplication::context()).callMethod<jboolean>("minimize", "()Z")) {
+        emit showError(tr("Unable to minimize app."));
+        return false;
+    }
+    m_unloadGuiWhenHidden = true;
+#else
+    const auto windows = QGuiApplication::topLevelWindows();
+    for (auto *const window : windows) {
+        window->setWindowState(Qt::WindowMinimized);
+    }
+#endif
+    return true;
+}
+
 bool App::openSettings()
 {
     if (!m_settingsDir.has_value()) {
@@ -1060,7 +1079,7 @@ bool App::applySettings()
         m_connection.reconnect();
     }
     auto tweaksSettings = m_settings.value(QLatin1String("tweaks")).toObject();
-    m_unloadGuiWhenHidden = tweaksSettings.value(QLatin1String("unloadGuiWhenHidden")).toBool(false);
+    m_alwaysUnloadGuiWhenHidden = tweaksSettings.value(QLatin1String("unloadGuiWhenHidden")).toBool(false);
     applyLauncherSettings();
     invalidateStatus();
     return true;

tray/gui/quick/app.h

@@ -246,6 +246,7 @@ class App : public QObject {
     Q_INVOKABLE QString deviceDisplayName(const QString &id) const;
     Q_INVOKABLE QString dirDisplayName(const QString &id) const;
     Q_INVOKABLE QVariantList computeDirsNeedingItems(const QModelIndex &devProxyModelIndex) const;
+    Q_INVOKABLE bool minimize();
 
 Q_SIGNALS:
     void darkmodeEnabledChanged(bool darkmodeEnabled);
@@ -340,6 +341,7 @@ private Q_SLOTS:
     bool m_darkColorScheme;
     bool m_darkPalette;
     bool m_isGuiLoaded;
+    bool m_alwaysUnloadGuiWhenHidden;
     bool m_unloadGuiWhenHidden;
 };