backends/libinput: update screens on Workspace::outputsChanged

Using OutputBackend::outputsQueried can cause problems because it's emitted
before output settings like enablement get adjusted to the new output configuration.
It also doesn't react to output changes initiated by KScreen and is in the
way of plans to use multiple output backends at the same time.

BUG: 461901

src/backends/libinput/connection.cpp

@@ -136,7 +136,6 @@ void Connection::doSetup()
             deactivate();
         }
     });
-    connect(kwinApp()->outputBackend(), &OutputBackend::outputsQueried, this, &Connection::updateScreens);
     handleEvent();
 }
 

src/backends/libinput/libinputbackend.cpp

@@ -46,4 +46,9 @@ void LibinputBackend::initialize()
     m_connection->setup();
 }
 
+void LibinputBackend::updateScreens()
+{
+    m_connection->updateScreens();
+}
+
 } // namespace KWin

src/backends/libinput/libinputbackend.h

@@ -29,6 +29,7 @@ public:
     ~LibinputBackend() override;
 
     void initialize() override;
+    void updateScreens() override;
 
 private:
     QThread m_thread;

src/core/inputbackend.h

@@ -31,6 +31,10 @@ public:
     {
     }
 
+    virtual void updateScreens()
+    {
+    }
+
 Q_SIGNALS:
     void deviceAdded(InputDevice *device);
     void deviceRemoved(InputDevice *device);

src/input.cpp

@@ -2588,6 +2588,7 @@ void InputRedirection::init()
 
 void InputRedirection::setupWorkspace()
 {
+    connect(workspace(), &Workspace::outputsChanged, this, &InputRedirection::updateScreens);
     if (waylandServer()) {
         m_keyboard->init();
         m_pointer->init();
@@ -2602,6 +2603,13 @@ void InputRedirection::setupWorkspace()
     }
 }
 
+void InputRedirection::updateScreens()
+{
+    for (const auto &backend : m_inputBackends) {
+        backend->updateScreens();
+    }
+}
+
 QObject *InputRedirection::lastInputHandler() const
 {
     return m_lastInputDevice;

src/input.h

@@ -302,6 +302,7 @@ public Q_SLOTS:
 
 private Q_SLOTS:
     void handleInputConfigChanged(const KConfigGroup &group);
+    void updateScreens();
 
 private:
     void setupInputBackends();