Implement Primary Displays on the wayland session

Adopts the kde_outputmanagement_v2 hooks for it

src/backends/drm/drm_backend.cpp

@@ -450,12 +450,16 @@ void DrmBackend::readOutputsConfiguration()
     }
     const auto outputsInfo = KWinKScreenIntegration::outputsConfig(m_outputs);
 
+    AbstractOutput *primaryOutput = m_outputs.constFirst();
     // default position goes from left to right
     QPoint pos(0, 0);
     for (auto it = m_outputs.begin(); it != m_outputs.end(); ++it) {
         const QJsonObject outputInfo = outputsInfo[*it];
         qCDebug(KWIN_DRM) << "Reading output configuration for " << *it;
         if (!outputInfo.isEmpty()) {
+            if (outputInfo["primary"].toBool()) {
+                primaryOutput = *it;
+            }
             const QJsonObject pos = outputInfo["pos"].toObject();
             (*it)->moveTo({pos["x"].toInt(), pos["y"].toInt()});
             if (const QJsonValue scale = outputInfo["scale"]; !scale.isUndefined()) {
@@ -473,6 +477,7 @@ void DrmBackend::readOutputsConfiguration()
         }
         pos.setX(pos.x() + (*it)->geometry().width());
     }
+    setPrimaryOutput(primaryOutput);
 }
 
 void DrmBackend::enableOutput(DrmAbstractOutput *output, bool enable)

src/platform.cpp

@@ -40,6 +40,17 @@ Platform::Platform(QObject *parent)
 {
     setSoftwareCursorForced(false);
     connect(Cursors::self(), &Cursors::currentCursorRendered, this, &Platform::cursorRendered);
+
+    connect(this, &Platform::outputDisabled, this, [this] (AbstractOutput *output) {
+        if (m_primaryOutput == output) {
+            setPrimaryOutput(enabledOutputs().value(0, nullptr));
+        }
+    });
+    connect(this, &Platform::outputEnabled, this, [this] (AbstractOutput *output) {
+        if (!m_primaryOutput) {
+            setPrimaryOutput(output);
+        }
+    });
 }
 
 Platform::~Platform()
@@ -152,6 +163,10 @@ void Platform::requestOutputsChange(KWaylandServer::OutputConfigurationV2Interfa
         }
     }
 
+    if (config->primaryChanged()) {
+        setPrimaryOutput(findOutput(config->primary()->uuid()));
+    }
+
     Q_EMIT screens()->changed();
     config->setApplied();
 }
@@ -637,4 +652,14 @@ void Platform::setSceneEglGlobalShareContext(EGLContext context)
     m_globalShareContext = context;
 }
 
+void Platform::setPrimaryOutput(AbstractOutput *primary)
+{
+    if (primary == m_primaryOutput) {
+        return;
+    }
+    Q_ASSERT(kwinApp()->isTerminating() || primary->isEnabled());
+    m_primaryOutput = primary;
+    Q_EMIT primaryOutputChanged(primary);
+}
+
 }

src/platform.h

@@ -398,6 +398,18 @@ public:
     virtual AbstractOutput *createVirtualOutput(const QString &name, const QSize &size, qreal scaling);
     virtual void removeVirtualOutput(AbstractOutput *output);
 
+    /**
+     * @returns the primary output amomg the enabled outputs
+     */
+    AbstractOutput *primaryOutput() const {
+        return m_primaryOutput;
+    }
+
+    /**
+     * Assigns a the @p primary output among the enabled outputs
+     */
+    void setPrimaryOutput(AbstractOutput *primary);
+
 public Q_SLOTS:
     void pointerMotion(const QPointF &position, quint32 time);
     void pointerButtonPressed(quint32 button, quint32 time);
@@ -455,6 +467,8 @@ Q_SIGNALS:
      */
     void outputDisabled(AbstractOutput *output);
 
+    void primaryOutputChanged(AbstractOutput *primaryOutput);
+
 protected:
     explicit Platform(QObject *parent = nullptr);
     void setSoftwareCursor(bool set);
@@ -527,6 +541,7 @@ private:
     bool m_supportsOutputChanges = false;
     bool m_isPerScreenRenderingEnabled = false;
     CompositingType m_selectedCompositor = NoCompositing;
+    AbstractOutput *m_primaryOutput = nullptr;
 };
 
 }

src/wayland_server.cpp

@@ -51,6 +51,7 @@
 #include <KWaylandServer/blur_interface.h>
 #include <KWaylandServer/outputmanagement_v2_interface.h>
 #include <KWaylandServer/outputconfiguration_v2_interface.h>
+#include <KWaylandServer/primaryoutput_v1_interface.h>
 #include <KWaylandServer/xdgactivation_v1_interface.h>
 #include <KWaylandServer/xdgdecoration_v1_interface.h>
 #include <KWaylandServer/xdgshell_interface.h>
@@ -274,6 +275,13 @@ void WaylandServer::initPlatform()
     connect(kwinApp()->platform(), &Platform::outputEnabled, this, &WaylandServer::handleOutputEnabled);
     connect(kwinApp()->platform(), &Platform::outputDisabled, this, &WaylandServer::handleOutputDisabled);
 
+    connect(kwinApp()->platform(), &Platform::primaryOutputChanged, this, [this] (AbstractOutput *primaryOutput) {
+        m_primary->setPrimaryOutput(primaryOutput->name());
+    });
+    if (auto primaryOutput = kwinApp()->platform()->primaryOutput()) {
+        m_primary->setPrimaryOutput(primaryOutput->name());
+    }
+
     const QVector<AbstractOutput *> outputs = kwinApp()->platform()->outputs();
     for (AbstractOutput *output : outputs) {
         handleOutputAdded(output);
@@ -493,6 +501,7 @@ bool WaylandServer::init(InitializationFlags flags)
             this, [](KWaylandServer::OutputConfigurationV2Interface *config) {
                 kwinApp()->platform()->requestOutputsChange(config);
     });
+    m_primary = new PrimaryOutputV1Interface(m_display, m_display);
 
     m_xdgOutputManagerV1 = new XdgOutputManagerV1Interface(m_display, m_display);
     new SubCompositorInterface(m_display, m_display);

src/wayland_server.h

@@ -38,6 +38,7 @@ class PlasmaShellInterface;
 class PlasmaWindowActivationFeedbackInterface;
 class PlasmaVirtualDesktopManagementInterface;
 class PlasmaWindowManagementInterface;
+class PrimaryOutputV1Interface;
 class OutputManagementV2Interface;
 class XdgForeignV2Interface;
 class XdgOutputManagerV1Interface;
@@ -269,6 +270,7 @@ private:
     KWaylandServer::ClientConnection *m_screenLockerClientConnection = nullptr;
     KWaylandServer::XdgForeignV2Interface *m_XdgForeign = nullptr;
     KWaylandServer::KeyStateInterface *m_keyState = nullptr;
+    KWaylandServer::PrimaryOutputV1Interface *m_primary = nullptr;
     QList<AbstractClient *> m_clients;
     InitializationFlags m_initFlags;
     QHash<AbstractWaylandOutput *, WaylandOutput *> m_waylandOutputs;

src/waylandoutputdevicev2.cpp

@@ -68,6 +68,7 @@ WaylandOutputDevice::WaylandOutputDevice(AbstractWaylandOutput *output, QObject
     m_outputDeviceV2->setCapabilities(kwinCapabilitiesToOutputDeviceCapabilities(output->capabilities()));
     m_outputDeviceV2->setVrrPolicy(kwinVrrPolicyToOutputDeviceVrrPolicy(output->vrrPolicy()));
     m_outputDeviceV2->setRgbRange(kwinRgbRangeToOutputDeviceRgbRange(output->rgbRange()));
+    m_outputDeviceV2->setName(output->name());
 
     updateModes(output);