Set gtk-modules to auto-load appmenu-gtk-module

Summary:
Makes it work out of the box for both GTK 2 and GTK 3 applications.
Since both krdb and kde-gt-config overwrite their respective `gtkrc-2.0` we use a watcher to re-add our config key afterwards.

Test Plan:
Tested Pluma (Gtk3), now has global menu
Tested Gimp and Inkscape, now have global menu
When module isn't installed, prints a warning on console, shouldn't be too bad

Reviewers: #plasma, davidedmundson, fvogt, hein

Reviewed By: #plasma, hein

Subscribers: cgiboudeaux, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D15315

gmenu-dbusmenu-proxy/CMakeLists.txt

@@ -38,6 +38,7 @@ target_link_libraries(gmenudbusmenuproxy
     Qt5::Core
     Qt5::X11Extras
     Qt5::DBus
+    KF5::CoreAddons
     KF5::ConfigCore
     KF5::WindowSystem
     XCB::XCB

gmenu-dbusmenu-proxy/menuproxy.cpp

@@ -32,8 +32,10 @@
 #include <QFileInfo>
 #include <QHash>
 #include <QStandardPaths>
+#include <QTimer>
 
 #include <KConfigGroup>
+#include <KDirWatch>
 #include <KSharedConfig>
 #include <KWindowSystem>
 
@@ -59,10 +61,15 @@ static const QByteArray s_gtkAppMenuObjectPath = QByteArrayLiteral("_GTK_APP_MEN
 static const QByteArray s_kdeNetWmAppMenuServiceName = QByteArrayLiteral("_KDE_NET_WM_APPMENU_SERVICE_NAME");
 static const QByteArray s_kdeNetWmAppMenuObjectPath = QByteArrayLiteral("_KDE_NET_WM_APPMENU_OBJECT_PATH");
 
+static const QString s_gtkModules = QStringLiteral("gtk-modules");
+static const QString s_appMenuGtkModule = QStringLiteral("appmenu-gtk-module");
+
 MenuProxy::MenuProxy()
     : QObject()
     , m_xConnection(QX11Info::connection())
     , m_serviceWatcher(new QDBusServiceWatcher(this))
+    , m_gtk2RcWatch(new KDirWatch(this))
+    , m_writeGtk2SettingsTimer(new QTimer(this))
 {
     m_serviceWatcher->setConnection(QDBusConnection::sessionBus());
     m_serviceWatcher->setWatchMode(QDBusServiceWatcher::WatchForUnregistration |
@@ -88,8 +95,23 @@ MenuProxy::MenuProxy()
         qCDebug(DBUSMENUPROXY) << "No global menu service available, waiting for it to start before doing anything";
 
         // be sure when started to restore gtk menus when there's no dbus menu around in case we crashed
-        setGtkShellShowsMenuBar(false);
+        enableGtkSettings(false);
+    }
+
+    // kde-gtk-config just deletes and re-creates the gtkrc-2.0, watch this and add out config to it again
+    m_writeGtk2SettingsTimer->setSingleShot(true);
+    m_writeGtk2SettingsTimer->setInterval(1000);
+    connect(m_writeGtk2SettingsTimer, &QTimer::timeout, this, &MenuProxy::writeGtk2Settings);
+
+    auto startGtk2SettingsTimer = [this] {
+        if (!m_writeGtk2SettingsTimer->isActive()) {
+            m_writeGtk2SettingsTimer->start();
         }
+    };
+
+    connect(m_gtk2RcWatch, &KDirWatch::created, this, startGtk2SettingsTimer);
+    connect(m_gtk2RcWatch, &KDirWatch::dirty, this, startGtk2SettingsTimer);
+    m_gtk2RcWatch->addFile(gtkRc2Path());
 }
 
 MenuProxy::~MenuProxy()
@@ -104,7 +126,7 @@ bool MenuProxy::init()
         return false;
     }
 
-    setGtkShellShowsMenuBar(true);
+    enableGtkSettings(true);
 
     connect(KWindowSystem::self(), &KWindowSystem::windowAdded, this, &MenuProxy::onWindowAdded);
     connect(KWindowSystem::self(), &KWindowSystem::windowRemoved, this, &MenuProxy::onWindowRemoved);
@@ -123,7 +145,7 @@ bool MenuProxy::init()
 
 void MenuProxy::teardown()
 {
-    setGtkShellShowsMenuBar(false);
+    enableGtkSettings(false);
 
     QDBusConnection::sessionBus().unregisterService(s_ourServiceName);
 
@@ -134,30 +156,115 @@ void MenuProxy::teardown()
     m_windows.clear();
 }
 
-void MenuProxy::setGtkShellShowsMenuBar(bool show)
+void MenuProxy::enableGtkSettings(bool enable)
 {
-    qCDebug(DBUSMENUPROXY) << "Setting gtk-shell-shows-menu-bar to" << show << "which will" << (show ? "hide" : "show") << "menu bars in applications";
+    m_enabled = enable;
 
-    // mostly taken from kde-gtk-config
-    QString root = QStandardPaths::writableLocation(QStandardPaths::GenericConfigLocation);
-    if (root.isEmpty()) {
-        root = QFileInfo(QDir::home(), QStringLiteral(".config")).absoluteFilePath();
+    writeGtk2Settings();
+    writeGtk3Settings();
+
+    // TODO use gconf/dconf directly or at least signal a change somehow?
+}
+
+QString MenuProxy::gtkRc2Path()
+{
+    return QDir::homePath() + QLatin1String("/.gtkrc-2.0");
+}
+
+QString MenuProxy::gtk3SettingsIniPath()
+{
+    return QStandardPaths::writableLocation(QStandardPaths::GenericConfigLocation) + QLatin1String("/gtk-3.0/settings.ini");
+}
+
+void MenuProxy::writeGtk2Settings()
+{
+    qCDebug(DBUSMENUPROXY) << "Writing gtkrc-2.0 to" << (m_enabled ? "enable" : "disable") << "global menu support";
+
+    QFile rcFile(gtkRc2Path());
+    if (!rcFile.open(QIODevice::ReadWrite | QIODevice::Text)) {
+        return;
+    }
+
+    QByteArray content;
+
+    QStringList gtkModules;
+
+    while (!rcFile.atEnd()) {
+        const QByteArray rawLine = rcFile.readLine();
+
+        const QString line = QString::fromUtf8(rawLine.trimmed());
+
+        if (!line.startsWith(s_gtkModules)) {
+            // keep line as-is
+            content += rawLine;
+            continue;
         }
 
-    const QString settingsFilePath = root + QStringLiteral("/gtk-3.0/settings.ini");
+        const int equalSignIdx = line.indexOf(QLatin1Char('='));
+        if (equalSignIdx < 1) {
+            continue;
+        }
+
+        gtkModules = line.mid(equalSignIdx + 1).split(QLatin1Char(':'), QString::SkipEmptyParts);
+
+        break;
+    }
+
+    addOrRemoveAppMenuGtkModule(gtkModules);
+
+    if (!gtkModules.isEmpty()) {
+        content += QStringLiteral("%1=%2").arg(s_gtkModules, gtkModules.join(QLatin1Char(':'))).toUtf8();
+    }
 
-    auto cfg = KSharedConfig::openConfig(settingsFilePath, KConfig::NoGlobals);
+    qCDebug(DBUSMENUPROXY) << "  gtk-modules:" << gtkModules;
+
+    m_gtk2RcWatch->stopScan();
+
+    // now write the new contents of the file
+    rcFile.resize(0);
+    rcFile.write(content);
+    rcFile.close();
+
+    m_gtk2RcWatch->startScan();
+}
+
+void MenuProxy::writeGtk3Settings()
+{
+    qCDebug(DBUSMENUPROXY) << "Writing gtk-3.0/settings.ini" << (m_enabled ? "enable" : "disable") << "global menu support";
+
+    // mostly taken from kde-gtk-config
+    auto cfg = KSharedConfig::openConfig(gtk3SettingsIniPath(), KConfig::NoGlobals);
     KConfigGroup group(cfg, "Settings");
 
-    if (show) {
+    QStringList gtkModules = group.readEntry("gtk-modules", QString()).split(QLatin1Char(':'), QString::SkipEmptyParts);
+    addOrRemoveAppMenuGtkModule(gtkModules);
+
+    if (!gtkModules.isEmpty()) {
+        group.writeEntry("gtk-modules", gtkModules.join(QLatin1Char(':')));
+    } else {
+        group.deleteEntry("gtk-modules");
+    }
+
+    qCDebug(DBUSMENUPROXY) << "  gtk-modules:" << gtkModules;
+
+    if (m_enabled) {
         group.writeEntry("gtk-shell-shows-menubar", 1);
     } else {
         group.deleteEntry("gtk-shell-shows-menubar");
     }
 
+    qCDebug(DBUSMENUPROXY) << "  gtk-shell-shows-menubar:" << (m_enabled ? 1 : 0);
+
     group.sync();
+}
 
-    // TODO use gconf/dconf directly or at least signal a change somehow?
+void MenuProxy::addOrRemoveAppMenuGtkModule(QStringList &list)
+{
+    if (m_enabled && !list.contains(s_appMenuGtkModule)) {
+        list.append(s_appMenuGtkModule);
+    } else if (!m_enabled) {
+        list.removeAll(s_appMenuGtkModule);
+    }
 }
 
 void MenuProxy::onWindowAdded(WId id)

gmenu-dbusmenu-proxy/menuproxy.h

@@ -27,6 +27,9 @@
 #include <xcb/xcb_atom.h>
 
 class QDBusServiceWatcher;
+class QTimer;
+
+class KDirWatch;
 
 class Window;
 
@@ -46,7 +49,15 @@ private:
     bool init();
     void teardown();
 
-    void setGtkShellShowsMenuBar(bool show);
+    static QString gtkRc2Path();
+    static QString gtk3SettingsIniPath();
+
+    void enableGtkSettings(bool enabled);
+
+    void writeGtk2Settings();
+    void writeGtk3Settings();
+
+    void addOrRemoveAppMenuGtkModule(QStringList &list);
 
     xcb_connection_t *m_xConnection;
 
@@ -58,4 +69,9 @@ private:
 
     QDBusServiceWatcher *m_serviceWatcher;
 
+    KDirWatch *m_gtk2RcWatch;
+    QTimer *m_writeGtk2SettingsTimer;
+
+    bool m_enabled = false;
+
 };