Use PlasmaWindowManagement wayland interface to trigger showing desktop mode

Introduces new dependency on KWayland and uses it to try to resolve the
PlasmaWindowManagement interface. If available that's used to trigger
showing desktop state.

CMakeLists.txt

@@ -27,6 +27,10 @@ find_package(Qt5 ${QT_MIN_VERSION} CONFIG REQUIRED Core Gui Widgets Qml Quick Te
 
 find_package(KF5 ${KF5_MIN_VERSION} REQUIRED COMPONENTS Plasma Service Declarative I18n)
 find_package(KF5 REQUIRED COMPONENTS PlasmaQuick DBusAddons Notifications)
+find_package(KF5Wayland CONFIG)
+set_package_properties(KF5Wayland PROPERTIES
+                       TYPE REQUIRED
+                       PURPOSE "Required for interacting with the compositor")
 
 
 feature_summary(WHAT ALL INCLUDE_QUIET_PACKAGES FATAL_ON_MISSING_REQUIRED_PACKAGES)

containments/taskpanel/CMakeLists.txt

@@ -13,6 +13,7 @@ target_link_libraries(plasma_containment_phone_taskpanel
                       Qt5::Qml
                       KF5::I18n
                       KF5::Service
+                      KF5::WaylandClient
                      )
 
 

containments/taskpanel/package/contents/code/showdesktop.js

@@ -1,2 +0,0 @@
-
-workspace.slotToggleShowDesktop();

containments/taskpanel/package/contents/ui/main.qml

@@ -35,11 +35,21 @@ Rectangle {
     property Item toolBox
     
     PlasmaComponents.ToolButton {
+        id: showDesktopButton
         height: parent.height
         width: height
         anchors.horizontalCenter: parent.horizontalCenter
         iconSource: "go-home"
-        onClicked: plasmoid.nativeInterface.executeScript("showdesktop");
+        checkable: true
+        onCheckedChanged: {
+            plasmoid.nativeInterface.showDesktop = checked;
+        }
+        Connections {
+            target: plasmoid.nativeInterface
+            onShowingDesktopChanged: {
+                showDesktopButton.checked = plasmoid.nativeInterface.showDesktop;
+            }
+        }
     }
 
     PlasmaComponents.ToolButton {
@@ -49,4 +59,4 @@ Rectangle {
         iconSource: "window-close"
         onClicked: plasmoid.nativeInterface.executeScript("close");
     }
-}
+}

containments/taskpanel/taskpanel.cpp

@@ -26,12 +26,19 @@
 
 #include <Plasma/Package>
 
+#include <KWayland/Client/connection_thread.h>
+#include <KWayland/Client/plasmawindowmanagement.h>
+#include <KWayland/Client/registry.h>
+
 static const QString s_kwinService = QStringLiteral("org.kde.KWin");
 
 TaskPanel::TaskPanel(QObject *parent, const QVariantList &args)
     : Plasma::Containment(parent, args)
+    , m_showingDesktop(false)
+    , m_windowManagement(nullptr)
 {
     setHasConfigurationInterface(true);
+    initWayland();
 }
 
 TaskPanel::~TaskPanel()
@@ -61,6 +68,43 @@ void TaskPanel::executeScript(const QString &script)
     }
 }
 
+void TaskPanel::requestShowingDesktop(bool showingDesktop)
+{
+    if (!m_windowManagement) {
+        return;
+    }
+    m_windowManagement->setShowingDesktop(showingDesktop);
+}
+
+void TaskPanel::initWayland()
+{
+    if (!QGuiApplication::platformName().startsWith(QLatin1String("wayland"), Qt::CaseInsensitive)) {
+        return;
+    }
+    using namespace KWayland::Client;
+    ConnectionThread *connection = ConnectionThread::fromApplication(this);
+    if (!connection) {
+        return;
+    }
+    Registry *registry = new Registry(this);
+    registry->create(connection);
+    connect(registry, &Registry::plasmaWindowManagementAnnounced, this,
+        [this, registry] (quint32 name, quint32 version) {
+            m_windowManagement = registry->createPlasmaWindowManagement(name, version, this);
+            connect(m_windowManagement, &PlasmaWindowManagement::showingDesktopChanged, this,
+                [this] (bool showing) {
+                    if (showing == m_showingDesktop) {
+                        return;
+                    }
+                    m_showingDesktop = showing;
+                    emit showingDesktopChanged(m_showingDesktop);
+                }
+            );
+        }
+    );
+    registry->setup();
+}
+
 K_EXPORT_PLASMA_APPLET_WITH_JSON(taskpanel, TaskPanel, "metadata.json")
 
 #include "taskpanel.moc"

containments/taskpanel/taskpanel.h

@@ -24,9 +24,18 @@
 
 #include <Plasma/Containment>
 
+namespace KWayland
+{
+namespace Client
+{
+class PlasmaWindowManagement;
+}
+}
+
 class TaskPanel : public Plasma::Containment
 {
     Q_OBJECT
+    Q_PROPERTY(bool showDesktop READ isShowingDesktop WRITE requestShowingDesktop NOTIFY showingDesktopChanged)
 
 public:
     TaskPanel( QObject *parent, const QVariantList &args );
@@ -34,7 +43,18 @@ public:
 
     Q_INVOKABLE void executeScript(const QString &script);
 
+    bool isShowingDesktop() const {
+        return m_showingDesktop;
+    }
+    void requestShowingDesktop(bool showingDesktop);
+
+Q_SIGNALS:
+    void showingDesktopChanged(bool);
+
 private:
+    void initWayland();
+    bool m_showingDesktop;
+    KWayland::Client::PlasmaWindowManagement *m_windowManagement;
 
 };