chore(new_backend): add active window method

src/core/engine/windows_list.cpp

@@ -2,6 +2,9 @@
 // SPDX-License-Identifier: MIT
 
 #include "windows_list.hpp"
+
+#include <functional>
+
 #include "engine/surface.hpp"
 #include "logger.hpp"
 #include "plasma-api/workspace.hpp"
@@ -25,6 +28,19 @@ void WindowsList::remove(PlasmaApi::Client client)
     m_windowMap.erase(client);
 }
 
+std::optional<Window> WindowsList::activeWindow() const
+{
+    auto activeClient = m_workspace.activeClient();
+
+    if (activeClient.has_value()) {
+        auto it = m_windowMap.find(activeClient.value());
+        if (it != m_windowMap.end()) {
+            return it->second;
+        }
+    }
+    return {};
+}
+
 std::vector<Window> WindowsList::visibleWindowsOn(const Surface &surface) const
 {
     auto result = std::vector<Window>();

src/core/engine/windows_list.hpp

@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <optional>
+
 #include "engine/surface.hpp"
 #include "plasma-api/client.hpp"
 #include "plasma-api/workspace.hpp"
@@ -16,6 +18,8 @@ struct WindowsList {
     Window &add(PlasmaApi::Client);
     void remove(PlasmaApi::Client);
 
+    std::optional<Window> activeWindow() const;
+
     std::vector<Window> visibleWindowsOn(const Surface &surface) const;
 
 private:

src/core/plasma-api/client.hpp

@@ -13,6 +13,8 @@
 
 namespace PlasmaApi
 {
+class Workspace;
+
 class Client : public TopLevel
 {
     Q_OBJECT
@@ -134,6 +136,8 @@ public:
     //  */
     // Q_PROPERTY(bool shade READ shade WRITE set_shade)
     // BOOL_PRIMITIVE_SETGET(shade)
+
+    friend class PlasmaApi::Workspace;
 };
 
 }

src/core/plasma-api/workspace.cpp

@@ -26,6 +26,18 @@ Workspace::Workspace(const Workspace &rhs)
     wrapSignals();
 };
 
+std::optional<PlasmaApi::Client> Workspace::activeClient() const
+{
+    auto kwinClient = m_kwinImpl->property("activeClient").value<QObject *>();
+    return kwinClient ? PlasmaApi::Client(kwinClient) : std::optional<PlasmaApi::Client>();
+}
+
+void Workspace::setActiveClient(std::optional<PlasmaApi::Client> client)
+{
+    auto valueToSet = client.has_value() ? client->m_kwinImpl : nullptr;
+    m_kwinImpl->setProperty("activeClient", QVariant::fromValue(valueToSet));
+}
+
 void Workspace::wrapSignals()
 {
     auto wrapSimpleSignal = [this](const char *signalSignature) {

src/core/plasma-api/workspace.hpp

@@ -6,6 +6,8 @@
 #include <QObject>
 #include <QQmlEngine>
 
+#include <optional>
+
 #include "plasma-api/client.hpp"
 
 #include "utils.hpp"
@@ -45,6 +47,11 @@ public:
     BI_PROPERTY(QString, currentActivity, setCurrentActivity);
     BI_PROPERTY(int, desktops, setDesktops);
 
+    Q_PROPERTY(std::optional<PlasmaApi::Client> activeClient READ activeClient WRITE setActiveClient);
+
+    std::optional<PlasmaApi::Client> activeClient() const;
+    void setActiveClient(std::optional<PlasmaApi::Client> client);
+
     /**
      * Returns the geometry a Client can use with the specified option.
      * This method should be preferred over other methods providing screen sizes as the