add lockDenied event to the backend

Lock screens need to know when to exit without an unlock.

Author: PaideiaDilemma

include/hyprtoolkit/core/Backend.hpp

@@ -87,6 +87,11 @@ namespace Hyprtoolkit {
                 Get notified when a new output was added.
             */
             Hyprutils::Signal::CSignalT<Hyprutils::Memory::CSharedPointer<IOutput>> outputAdded;
+
+            /*
+                Sent when the compositor denies us as the exclusive lock screen client.
+            */
+            Hyprutils::Signal::CSignalT<> lockDenied;
         } m_events;
 
         HT_HIDDEN : CBackend();

src/core/platforms/WaylandPlatform.cpp

@@ -655,6 +655,8 @@ SP<CCExtSessionLockV1> CWaylandPlatform::aquireSessionLock() {
 
         m_waylandState.sessionLockState.lock->setFinished([this](CCExtSessionLockV1* r) {
             g_logger->log(HT_LOG_ERROR, "We got denied by the compositor to be the exclusive lock screen client. Is there another lock screen active?");
+            g_backend->m_events.lockDenied.emit();
+
             for (const auto& w : m_lockSurfaces) {
                 if (w.expired())
                     continue;

tests/SimpleSessionLock.cpp

@@ -121,6 +121,9 @@ int main(int argc, char** argv, char** envp) {
     }
 
     backend->m_events.outputAdded.listenStatic(createLockSurface);
+    backend->m_events.lockDenied.listenStatic([]{
+        std::println("Lock denied!");
+    });
 
     for (const auto& o: backend->getOutputs()) {
         createLockSurface(o);