Add command line option to enable libinput support

kwin_wayland gains a new command line option to enable libinput support.
This is needed as logind blanks the VT when the session controller
releases the control. So a nested compositor can seriously affect the
primary session. Thus it needs a dedicated command line switch to
enable it.

By default libinput support is disabled for kwin_x11 and can be enabled
for kwin_wayland in case KWin is compiled with libinput support.

input.cpp

@@ -172,7 +172,7 @@ InputRedirection::InputRedirection(QObject *parent)
     , m_shortcuts(new GlobalShortcutsManager(this))
 {
 #if HAVE_INPUT
-    if (kwinApp()->operationMode() != Application::OperationModeX11) {
+    if (Application::usesLibinput()) {
         LogindIntegration *logind = LogindIntegration::self();
         auto takeControl = [logind, this]() {
             if (logind->hasSessionControl()) {
@@ -199,6 +199,9 @@ InputRedirection::~InputRedirection()
 void InputRedirection::setupLibInput()
 {
 #if HAVE_INPUT
+    if (!Application::usesLibinput()) {
+        return;
+    }
     LibInput::Connection *conn = LibInput::Connection::create(this);
     if (conn) {
         // TODO: connect the motion notifiers

main.cpp

@@ -406,6 +406,18 @@ bool XcbEventFilter::nativeEventFilter(const QByteArray &eventType, void *messag
     return Workspace::self()->workspaceEvent(static_cast<xcb_generic_event_t *>(message));
 }
 
+static bool s_useLibinput = false;
+
+void Application::setUseLibinput(bool use)
+{
+    s_useLibinput = use;
+}
+
+bool Application::usesLibinput()
+{
+    return s_useLibinput;
+}
+
 } // namespace
 
 #include "main.moc"

main.h

@@ -23,6 +23,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define MAIN_H
 
 #include <kwinglobals.h>
+#include <config-kwin.h>
 
 #include <KSelectionWatcher>
 #include <KSelectionOwner>
@@ -113,6 +114,9 @@ public:
     static void setupLocalizedString();
     static void setupLoggingCategoryFilters();
 
+    static bool usesLibinput();
+    static void setUseLibinput(bool use);
+
 protected:
     Application(OperationMode mode, int &argc, char **argv);
     virtual void performStartup() = 0;

main_wayland.cpp

@@ -238,10 +238,19 @@ KWIN_EXPORT int kdemain(int argc, char * argv[])
     a.setupCommandLine(&parser);
     parser.addOption(startXServerOption);
     parser.addOption(x11DisplayOption);
+#if HAVE_INPUT
+    QCommandLineOption libinputOption(QStringLiteral("libinput"),
+                                      i18n("Enable libinput support for input events processing. Note: never use in a nested session."));
+    parser.addOption(libinputOption);
+#endif
 
     parser.process(a);
     a.processCommandLine(&parser);
 
+#if HAVE_INPUT
+    KWin::Application::setUseLibinput(parser.isSet(libinputOption));
+#endif
+
     // perform sanity checks
     // TODO: remove those two
     if (a.platformName().toLower() != QStringLiteral("xcb")) {