From 61b1eac5b84291d0671c2458740f2126b92db9d7 Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Wed, 22 Jun 2022 12:33:32 +0200
Subject: [PATCH] platform, scenes: use std::unique_ptr for creation functions

---
 src/backends/drm/drm_backend.cpp              | 12 ++++----
 src/backends/drm/drm_backend.h                |  6 ++--
 src/backends/virtual/virtual_backend.cpp      |  8 ++---
 src/backends/virtual/virtual_backend.h        |  4 +--
 src/backends/wayland/wayland_backend.cpp      | 12 ++++----
 src/backends/wayland/wayland_backend.h        |  6 ++--
 src/backends/x11/standalone/x11_platform.cpp  |  6 ++--
 src/backends/x11/standalone/x11_platform.h    |  2 +-
 .../x11/windowed/x11windowed_backend.cpp      | 12 ++++----
 .../x11/windowed/x11windowed_backend.h        |  6 ++--
 src/composite.cpp                             | 29 +++++++++----------
 src/composite.h                               |  9 +++---
 src/input.cpp                                 | 18 +++++-------
 src/input.h                                   |  4 +--
 src/platform.cpp                              |  9 ++++--
 src/platform.h                                |  6 ++--
 src/scene.cpp                                 |  5 +---
 src/scene.h                                   |  2 +-
 src/scenes/opengl/scene_opengl.cpp            | 13 ++++-----
 src/scenes/opengl/scene_opengl.h              |  4 +--
 src/scenes/qpainter/scene_qpainter.cpp        |  9 +++---
 src/scenes/qpainter/scene_qpainter.h          |  4 +--
 22 files changed, 90 insertions(+), 96 deletions(-)

diff --git a/src/backends/drm/drm_backend.cpp b/src/backends/drm/drm_backend.cpp
index 2e475ae2db..767635fbb4 100644
--- a/src/backends/drm/drm_backend.cpp
+++ b/src/backends/drm/drm_backend.cpp
@@ -549,19 +549,19 @@ void DrmBackend::enableOutput(DrmAbstractOutput *output, bool enable)
     }
 }
 
-InputBackend *DrmBackend::createInputBackend()
+std::unique_ptr<InputBackend> DrmBackend::createInputBackend()
 {
-    return new LibinputBackend();
+    return std::make_unique<LibinputBackend>();
 }
 
-QPainterBackend *DrmBackend::createQPainterBackend()
+std::unique_ptr<QPainterBackend> DrmBackend::createQPainterBackend()
 {
-    return new DrmQPainterBackend(this);
+    return std::make_unique<DrmQPainterBackend>(this);
 }
 
-OpenGLBackend *DrmBackend::createOpenGLBackend()
+std::unique_ptr<OpenGLBackend> DrmBackend::createOpenGLBackend()
 {
-    return new EglGbmBackend(this);
+    return std::make_unique<EglGbmBackend>(this);
 }
 
 void DrmBackend::sceneInitialized()
diff --git a/src/backends/drm/drm_backend.h b/src/backends/drm/drm_backend.h
index 6db337aefa..f7c0ef7437 100644
--- a/src/backends/drm/drm_backend.h
+++ b/src/backends/drm/drm_backend.h
@@ -43,9 +43,9 @@ public:
     explicit DrmBackend(QObject *parent = nullptr);
     ~DrmBackend() override;
 
-    InputBackend *createInputBackend() override;
-    QPainterBackend *createQPainterBackend() override;
-    OpenGLBackend *createOpenGLBackend() override;
+    std::unique_ptr<InputBackend> createInputBackend() override;
+    std::unique_ptr<QPainterBackend> createQPainterBackend() override;
+    std::unique_ptr<OpenGLBackend> createOpenGLBackend() override;
 
     std::optional<DmaBufParams> testCreateDmaBuf(const QSize &size, quint32 format, const QVector<uint64_t> &modifiers) override;
     std::shared_ptr<DmaBufTexture> createDmaBufTexture(const QSize &size, quint32 format, const uint64_t modifier) override;
diff --git a/src/backends/virtual/virtual_backend.cpp b/src/backends/virtual/virtual_backend.cpp
index 3e54dd7cb5..200ed5df30 100644
--- a/src/backends/virtual/virtual_backend.cpp
+++ b/src/backends/virtual/virtual_backend.cpp
@@ -80,14 +80,14 @@ QString VirtualBackend::screenshotDirPath() const
     return m_screenshotDir->path();
 }
 
-QPainterBackend *VirtualBackend::createQPainterBackend()
+std::unique_ptr<QPainterBackend> VirtualBackend::createQPainterBackend()
 {
-    return new VirtualQPainterBackend(this);
+    return std::make_unique<VirtualQPainterBackend>(this);
 }
 
-OpenGLBackend *VirtualBackend::createOpenGLBackend()
+std::unique_ptr<OpenGLBackend> VirtualBackend::createOpenGLBackend()
 {
-    return new VirtualEglBackend(this);
+    return std::make_unique<VirtualEglBackend>(this);
 }
 
 Outputs VirtualBackend::outputs() const
diff --git a/src/backends/virtual/virtual_backend.h b/src/backends/virtual/virtual_backend.h
index 51c89bb786..e3fb3d5a78 100644
--- a/src/backends/virtual/virtual_backend.h
+++ b/src/backends/virtual/virtual_backend.h
@@ -41,8 +41,8 @@ public:
     }
     QString screenshotDirPath() const;
 
-    QPainterBackend *createQPainterBackend() override;
-    OpenGLBackend *createOpenGLBackend() override;
+    std::unique_ptr<QPainterBackend> createQPainterBackend() override;
+    std::unique_ptr<OpenGLBackend> createOpenGLBackend() override;
 
     Q_INVOKABLE void setVirtualOutputs(int count, QVector<QRect> geometries = QVector<QRect>(), QVector<int> scales = QVector<int>());
 
diff --git a/src/backends/wayland/wayland_backend.cpp b/src/backends/wayland/wayland_backend.cpp
index c19c3a4e3a..04f8c44ed4 100644
--- a/src/backends/wayland/wayland_backend.cpp
+++ b/src/backends/wayland/wayland_backend.cpp
@@ -846,23 +846,23 @@ void WaylandBackend::destroyOutputs()
     }
 }
 
-InputBackend *WaylandBackend::createInputBackend()
+std::unique_ptr<InputBackend> WaylandBackend::createInputBackend()
 {
-    return new WaylandInputBackend(this);
+    return std::make_unique<WaylandInputBackend>(this);
 }
 
-OpenGLBackend *WaylandBackend::createOpenGLBackend()
+std::unique_ptr<OpenGLBackend> WaylandBackend::createOpenGLBackend()
 {
 #if HAVE_WAYLAND_EGL
-    return new WaylandEglBackend(this);
+    return std::make_unique<WaylandEglBackend>(this);
 #else
     return nullptr;
 #endif
 }
 
-QPainterBackend *WaylandBackend::createQPainterBackend()
+std::unique_ptr<QPainterBackend> WaylandBackend::createQPainterBackend()
 {
-    return new WaylandQPainterBackend(this);
+    return std::make_unique<WaylandQPainterBackend>(this);
 }
 
 void WaylandBackend::flush()
diff --git a/src/backends/wayland/wayland_backend.h b/src/backends/wayland/wayland_backend.h
index 1e8e765fc1..963d51012c 100644
--- a/src/backends/wayland/wayland_backend.h
+++ b/src/backends/wayland/wayland_backend.h
@@ -259,9 +259,9 @@ public:
     KWayland::Client::SubCompositor *subCompositor();
     KWayland::Client::ShmPool *shmPool();
 
-    InputBackend *createInputBackend() override;
-    OpenGLBackend *createOpenGLBackend() override;
-    QPainterBackend *createQPainterBackend() override;
+    std::unique_ptr<InputBackend> createInputBackend() override;
+    std::unique_ptr<OpenGLBackend> createOpenGLBackend() override;
+    std::unique_ptr<QPainterBackend> createQPainterBackend() override;
 
     void flush();
 
diff --git a/src/backends/x11/standalone/x11_platform.cpp b/src/backends/x11/standalone/x11_platform.cpp
index ecaf3b8e45..86fcd0e136 100644
--- a/src/backends/x11/standalone/x11_platform.cpp
+++ b/src/backends/x11/standalone/x11_platform.cpp
@@ -157,13 +157,13 @@ Session *X11StandalonePlatform::session() const
     return m_session.get();
 }
 
-OpenGLBackend *X11StandalonePlatform::createOpenGLBackend()
+std::unique_ptr<OpenGLBackend> X11StandalonePlatform::createOpenGLBackend()
 {
     switch (options->glPlatformInterface()) {
 #if HAVE_EPOXY_GLX
     case GlxPlatformInterface:
         if (hasGlx()) {
-            return new GlxBackend(m_x11Display, this);
+            return std::make_unique<GlxBackend>(m_x11Display, this);
         } else {
             qCWarning(KWIN_X11STANDALONE) << "Glx not available, trying EGL instead.";
             // no break, needs fall-through
@@ -171,7 +171,7 @@ OpenGLBackend *X11StandalonePlatform::createOpenGLBackend()
         }
 #endif
     case EglPlatformInterface:
-        return new EglBackend(m_x11Display, this);
+        return std::make_unique<EglBackend>(m_x11Display, this);
     default:
         // no backend available
         return nullptr;
diff --git a/src/backends/x11/standalone/x11_platform.h b/src/backends/x11/standalone/x11_platform.h
index dbd85b5dee..3b230cad23 100644
--- a/src/backends/x11/standalone/x11_platform.h
+++ b/src/backends/x11/standalone/x11_platform.h
@@ -38,7 +38,7 @@ public:
     bool initialize() override;
     Session *session() const override;
 
-    OpenGLBackend *createOpenGLBackend() override;
+    std::unique_ptr<OpenGLBackend> createOpenGLBackend() override;
     Edge *createScreenEdge(ScreenEdges *parent) override;
     void createPlatformCursor(QObject *parent = nullptr) override;
     bool requiresCompositing() const override;
diff --git a/src/backends/x11/windowed/x11windowed_backend.cpp b/src/backends/x11/windowed/x11windowed_backend.cpp
index cb13f20d83..dfcff56519 100644
--- a/src/backends/x11/windowed/x11windowed_backend.cpp
+++ b/src/backends/x11/windowed/x11windowed_backend.cpp
@@ -662,19 +662,19 @@ X11WindowedInputDevice *X11WindowedBackend::touchDevice() const
     return m_touchDevice;
 }
 
-OpenGLBackend *X11WindowedBackend::createOpenGLBackend()
+std::unique_ptr<OpenGLBackend> X11WindowedBackend::createOpenGLBackend()
 {
-    return new X11WindowedEglBackend(this);
+    return std::make_unique<X11WindowedEglBackend>(this);
 }
 
-QPainterBackend *X11WindowedBackend::createQPainterBackend()
+std::unique_ptr<QPainterBackend> X11WindowedBackend::createQPainterBackend()
 {
-    return new X11WindowedQPainterBackend(this);
+    return std::make_unique<X11WindowedQPainterBackend>(this);
 }
 
-InputBackend *X11WindowedBackend::createInputBackend()
+std::unique_ptr<InputBackend> X11WindowedBackend::createInputBackend()
 {
-    return new X11WindowedInputBackend(this);
+    return std::make_unique<X11WindowedInputBackend>(this);
 }
 
 void X11WindowedBackend::warpPointer(const QPointF &globalPos)
diff --git a/src/backends/x11/windowed/x11windowed_backend.h b/src/backends/x11/windowed/x11windowed_backend.h
index d0beb1bb4e..906666017a 100644
--- a/src/backends/x11/windowed/x11windowed_backend.h
+++ b/src/backends/x11/windowed/x11windowed_backend.h
@@ -115,9 +115,9 @@ public:
         return m_hasXInput;
     }
 
-    OpenGLBackend *createOpenGLBackend() override;
-    QPainterBackend *createQPainterBackend() override;
-    InputBackend *createInputBackend() override;
+    std::unique_ptr<OpenGLBackend> createOpenGLBackend() override;
+    std::unique_ptr<QPainterBackend> createQPainterBackend() override;
+    std::unique_ptr<InputBackend> createInputBackend() override;
     void warpPointer(const QPointF &globalPos) override;
 
     QVector<CompositingType> supportedCompositors() const override
diff --git a/src/composite.cpp b/src/composite.cpp
index 3f7eadb4b3..451cb4575e 100644
--- a/src/composite.cpp
+++ b/src/composite.cpp
@@ -186,7 +186,7 @@ bool Compositor::attemptOpenGLCompositing()
         kwinApp()->platform()->createOpenGLSafePoint(Platform::OpenGLSafePoint::PostInit);
     });
 
-    QScopedPointer<OpenGLBackend> backend(kwinApp()->platform()->createOpenGLBackend());
+    std::unique_ptr<OpenGLBackend> backend = kwinApp()->platform()->createOpenGLBackend();
     if (!backend) {
         return false;
     }
@@ -197,13 +197,13 @@ bool Compositor::attemptOpenGLCompositing()
         return false;
     }
 
-    QScopedPointer<Scene> scene(SceneOpenGL::createScene(backend.data(), this));
+    std::unique_ptr<Scene> scene = SceneOpenGL::createScene(backend.get());
     if (!scene || scene->initFailed()) {
         return false;
     }
 
-    m_backend = backend.take();
-    m_scene = scene.take();
+    m_backend = std::move(backend);
+    m_scene = std::move(scene);
 
     // set strict binding
     if (options->isGlStrictBindingFollowsDriver()) {
@@ -216,18 +216,18 @@ bool Compositor::attemptOpenGLCompositing()
 
 bool Compositor::attemptQPainterCompositing()
 {
-    QScopedPointer<QPainterBackend> backend(kwinApp()->platform()->createQPainterBackend());
+    std::unique_ptr<QPainterBackend> backend(kwinApp()->platform()->createQPainterBackend());
     if (!backend || backend->isFailed()) {
         return false;
     }
 
-    QScopedPointer<Scene> scene(SceneQPainter::createScene(backend.data(), this));
+    std::unique_ptr<Scene> scene = SceneQPainter::createScene(backend.get());
     if (!scene || scene->initFailed()) {
         return false;
     }
 
-    m_backend = backend.take();
-    m_scene = scene.take();
+    m_backend = std::move(backend);
+    m_scene = std::move(scene);
 
     qCDebug(KWIN_CORE) << "QPainter compositing has been successfully initialized";
     return true;
@@ -366,7 +366,7 @@ void Compositor::startupWithWorkspace()
     const QVector<Output *> outputs = kwinApp()->platform()->enabledOutputs();
     if (kwinApp()->operationMode() == Application::OperationModeX11) {
         auto workspaceLayer = new RenderLayer(outputs.constFirst()->renderLoop());
-        workspaceLayer->setDelegate(new SceneDelegate(m_scene));
+        workspaceLayer->setDelegate(new SceneDelegate(m_scene.get()));
         workspaceLayer->setGeometry(workspace()->geometry());
         connect(workspace(), &Workspace::geometryChanged, workspaceLayer, [workspaceLayer]() {
             workspaceLayer->setGeometry(workspace()->geometry());
@@ -400,7 +400,7 @@ void Compositor::startupWithWorkspace()
     }
 
     // Sets also the 'effects' pointer.
-    kwinApp()->platform()->createEffectsHandler(this, m_scene);
+    kwinApp()->platform()->createEffectsHandler(this, m_scene.get());
 
     Q_EMIT compositingToggled(true);
 
@@ -425,7 +425,7 @@ void Compositor::addOutput(Output *output)
     Q_ASSERT(kwinApp()->operationMode() != Application::OperationModeX11);
 
     auto workspaceLayer = new RenderLayer(output->renderLoop());
-    workspaceLayer->setDelegate(new SceneDelegate(m_scene, output));
+    workspaceLayer->setDelegate(new SceneDelegate(m_scene.get(), output));
     workspaceLayer->setGeometry(output->rect());
     connect(output, &Output::geometryChanged, workspaceLayer, [output, workspaceLayer]() {
         workspaceLayer->setGeometry(output->rect());
@@ -531,11 +531,8 @@ void Compositor::stop()
     disconnect(kwinApp()->platform(), &Platform::outputEnabled, this, &Compositor::addOutput);
     disconnect(kwinApp()->platform(), &Platform::outputDisabled, this, &Compositor::removeOutput);
 
-    delete m_scene;
-    m_scene = nullptr;
-
-    delete m_backend;
-    m_backend = nullptr;
+    m_scene.reset();
+    m_backend.reset();
 
     m_state = State::Off;
     Q_EMIT compositingToggled(false);
diff --git a/src/composite.h b/src/composite.h
index 34304f2247..badff5523a 100644
--- a/src/composite.h
+++ b/src/composite.h
@@ -14,6 +14,7 @@
 #include <QObject>
 #include <QRegion>
 #include <QTimer>
+#include <memory>
 
 namespace KWin
 {
@@ -70,11 +71,11 @@ public:
 
     Scene *scene() const
     {
-        return m_scene;
+        return m_scene.get();
     }
     RenderBackend *backend() const
     {
-        return m_backend;
+        return m_backend.get();
     }
 
     /**
@@ -152,8 +153,8 @@ private:
     QTimer m_releaseSelectionTimer;
     QList<xcb_atom_t> m_unusedSupportProperties;
     QTimer m_unusedSupportPropertyTimer;
-    Scene *m_scene = nullptr;
-    RenderBackend *m_backend = nullptr;
+    std::unique_ptr<Scene> m_scene;
+    std::unique_ptr<RenderBackend> m_backend;
     QHash<RenderLoop *, RenderLayer *> m_superlayers;
 };
 
diff --git a/src/input.cpp b/src/input.cpp
index 668ce248b2..6d25c9f4b9 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -2573,7 +2573,6 @@ InputRedirection::InputRedirection(QObject *parent)
 
 InputRedirection::~InputRedirection()
 {
-    qDeleteAll(m_inputBackends);
     m_inputBackends.clear();
     m_inputDevices.clear();
 
@@ -3066,26 +3065,25 @@ void InputRedirection::disableTouchpads()
     }
 }
 
-void InputRedirection::addInputBackend(InputBackend *inputBackend)
+void InputRedirection::addInputBackend(std::unique_ptr<InputBackend> &&inputBackend)
 {
-    Q_ASSERT(!m_inputBackends.contains(inputBackend));
-    m_inputBackends.append(inputBackend);
-
-    connect(inputBackend, &InputBackend::deviceAdded, this, &InputRedirection::addInputDevice);
-    connect(inputBackend, &InputBackend::deviceRemoved, this, &InputRedirection::removeInputDevice);
+    connect(inputBackend.get(), &InputBackend::deviceAdded, this, &InputRedirection::addInputDevice);
+    connect(inputBackend.get(), &InputBackend::deviceRemoved, this, &InputRedirection::removeInputDevice);
 
     inputBackend->setConfig(InputConfig::self()->inputConfig());
     inputBackend->initialize();
+
+    m_inputBackends.push_back(std::move(inputBackend));
 }
 
 void InputRedirection::setupInputBackends()
 {
-    InputBackend *inputBackend = kwinApp()->platform()->createInputBackend();
+    std::unique_ptr<InputBackend> inputBackend = kwinApp()->platform()->createInputBackend();
     if (inputBackend) {
-        addInputBackend(inputBackend);
+        addInputBackend(std::move(inputBackend));
     }
     if (waylandServer()) {
-        addInputBackend(new FakeInputBackend());
+        addInputBackend(std::make_unique<FakeInputBackend>());
     }
 }
 
diff --git a/src/input.h b/src/input.h
index a922399212..64aff0268e 100644
--- a/src/input.h
+++ b/src/input.h
@@ -322,7 +322,7 @@ private:
     void installInputEventFilter(InputEventFilter *filter);
     void updateLeds(LEDs leds);
     void updateAvailableInputDevices();
-    void addInputBackend(InputBackend *inputBackend);
+    void addInputBackend(std::unique_ptr<InputBackend> &&inputBackend);
     KeyboardInputRedirection *m_keyboard;
     PointerInputRedirection *m_pointer;
     TabletInputRedirection *m_tablet;
@@ -331,7 +331,7 @@ private:
 
     GlobalShortcutsManager *m_shortcuts;
 
-    QList<InputBackend *> m_inputBackends;
+    std::vector<std::unique_ptr<InputBackend>> m_inputBackends;
     QList<InputDevice *> m_inputDevices;
 
     QList<IdleDetector *> m_idleDetectors;
diff --git a/src/platform.cpp b/src/platform.cpp
index ca5ebeb88f..8198e1c380 100644
--- a/src/platform.cpp
+++ b/src/platform.cpp
@@ -15,11 +15,14 @@
 #include "cursor.h"
 #include "dmabuftexture.h"
 #include "effects.h"
+#include "inputbackend.h"
+#include "openglbackend.h"
 #include "outline.h"
 #include "output.h"
 #include "outputconfiguration.h"
 #include "overlaywindow.h"
 #include "pointer_input.h"
+#include "qpainterbackend.h"
 #include "scene.h"
 #include "screenedge.h"
 #include "screens.h"
@@ -66,17 +69,17 @@ PlatformCursorImage Platform::cursorImage() const
     return PlatformCursorImage(cursor->image(), cursor->hotspot());
 }
 
-InputBackend *Platform::createInputBackend()
+std::unique_ptr<InputBackend> Platform::createInputBackend()
 {
     return nullptr;
 }
 
-OpenGLBackend *Platform::createOpenGLBackend()
+std::unique_ptr<OpenGLBackend> Platform::createOpenGLBackend()
 {
     return nullptr;
 }
 
-QPainterBackend *Platform::createQPainterBackend()
+std::unique_ptr<QPainterBackend> Platform::createQPainterBackend()
 {
     return nullptr;
 }
diff --git a/src/platform.h b/src/platform.h
index a7517e52f9..ac47080ac8 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -66,9 +66,9 @@ public:
 
     virtual Session *session() const = 0;
     virtual bool initialize() = 0;
-    virtual InputBackend *createInputBackend();
-    virtual OpenGLBackend *createOpenGLBackend();
-    virtual QPainterBackend *createQPainterBackend();
+    virtual std::unique_ptr<InputBackend> createInputBackend();
+    virtual std::unique_ptr<OpenGLBackend> createOpenGLBackend();
+    virtual std::unique_ptr<QPainterBackend> createQPainterBackend();
     virtual std::optional<DmaBufParams> testCreateDmaBuf(const QSize &size, quint32 format, const QVector<uint64_t> &modifiers);
     virtual std::shared_ptr<DmaBufTexture> createDmaBufTexture(const QSize &size, quint32 format, const uint64_t modifier);
     std::shared_ptr<DmaBufTexture> createDmaBufTexture(const DmaBufParams &attributes);
diff --git a/src/scene.cpp b/src/scene.cpp
index 36bed2eae3..f55cef585e 100644
--- a/src/scene.cpp
+++ b/src/scene.cpp
@@ -131,10 +131,7 @@ QRect SceneDelegate::viewport() const
 // Scene
 //****************************************
 
-Scene::Scene(QObject *parent)
-    : QObject(parent)
-{
-}
+Scene::Scene() = default;
 
 Scene::~Scene()
 {
diff --git a/src/scene.h b/src/scene.h
index 7812d80140..687ce1f3cf 100644
--- a/src/scene.h
+++ b/src/scene.h
@@ -72,7 +72,7 @@ class KWIN_EXPORT Scene : public QObject
     Q_OBJECT
 
 public:
-    explicit Scene(QObject *parent = nullptr);
+    explicit Scene();
     ~Scene() override;
 
     void initialize();
diff --git a/src/scenes/opengl/scene_opengl.cpp b/src/scenes/opengl/scene_opengl.cpp
index 890d33ca43..560096a4ab 100644
--- a/src/scenes/opengl/scene_opengl.cpp
+++ b/src/scenes/opengl/scene_opengl.cpp
@@ -45,9 +45,8 @@ namespace KWin
  * SceneOpenGL
  ***********************************************/
 
-SceneOpenGL::SceneOpenGL(OpenGLBackend *backend, QObject *parent)
-    : Scene(parent)
-    , m_backend(backend)
+SceneOpenGL::SceneOpenGL(OpenGLBackend *backend)
+    : m_backend(backend)
 {
     // We only support the OpenGL 2+ shader API, not GL_ARB_shader_objects
     if (!hasGLVersion(2, 0)) {
@@ -70,13 +69,13 @@ SceneOpenGL::~SceneOpenGL()
     }
 }
 
-SceneOpenGL *SceneOpenGL::createScene(OpenGLBackend *backend, QObject *parent)
+std::unique_ptr<SceneOpenGL> SceneOpenGL::createScene(OpenGLBackend *backend)
 {
     if (SceneOpenGL::supported(backend)) {
-        return new SceneOpenGL(backend, parent);
+        return std::make_unique<SceneOpenGL>(backend);
+    } else {
+        return nullptr;
     }
-
-    return nullptr;
 }
 
 bool SceneOpenGL::initFailed() const
diff --git a/src/scenes/opengl/scene_opengl.h b/src/scenes/opengl/scene_opengl.h
index 31842258e6..ecd146ce6a 100644
--- a/src/scenes/opengl/scene_opengl.h
+++ b/src/scenes/opengl/scene_opengl.h
@@ -49,7 +49,7 @@ public:
         const bool hardwareClipping;
     };
 
-    explicit SceneOpenGL(OpenGLBackend *backend, QObject *parent = nullptr);
+    explicit SceneOpenGL(OpenGLBackend *backend);
     ~SceneOpenGL() override;
     bool initFailed() const override;
     void paint(RenderTarget *renderTarget, const QRegion &region) override;
@@ -72,7 +72,7 @@ public:
     QVector<QByteArray> openGLPlatformInterfaceExtensions() const override;
     std::shared_ptr<GLTexture> textureForOutput(Output *output) const override;
 
-    static SceneOpenGL *createScene(OpenGLBackend *backend, QObject *parent);
+    static std::unique_ptr<SceneOpenGL> createScene(OpenGLBackend *backend);
     static bool supported(OpenGLBackend *backend);
 
 protected:
diff --git a/src/scenes/qpainter/scene_qpainter.cpp b/src/scenes/qpainter/scene_qpainter.cpp
index 1c521b3414..502dca6191 100644
--- a/src/scenes/qpainter/scene_qpainter.cpp
+++ b/src/scenes/qpainter/scene_qpainter.cpp
@@ -30,14 +30,13 @@ namespace KWin
 //****************************************
 // SceneQPainter
 //****************************************
-SceneQPainter *SceneQPainter::createScene(QPainterBackend *backend, QObject *parent)
+std::unique_ptr<SceneQPainter> SceneQPainter::createScene(QPainterBackend *backend)
 {
-    return new SceneQPainter(backend, parent);
+    return std::unique_ptr<SceneQPainter>(new SceneQPainter(backend));
 }
 
-SceneQPainter::SceneQPainter(QPainterBackend *backend, QObject *parent)
-    : Scene(parent)
-    , m_backend(backend)
+SceneQPainter::SceneQPainter(QPainterBackend *backend)
+    : m_backend(backend)
     , m_painter(new QPainter())
 {
 }
diff --git a/src/scenes/qpainter/scene_qpainter.h b/src/scenes/qpainter/scene_qpainter.h
index 692ca5e170..f688b5f8e6 100644
--- a/src/scenes/qpainter/scene_qpainter.h
+++ b/src/scenes/qpainter/scene_qpainter.h
@@ -44,14 +44,14 @@ public:
         return m_backend;
     }
 
-    static SceneQPainter *createScene(QPainterBackend *backend, QObject *parent);
+    static std::unique_ptr<SceneQPainter> createScene(QPainterBackend *backend);
 
 protected:
     void paintBackground(const QRegion &region) override;
     void paintOffscreenQuickView(OffscreenQuickView *w) override;
 
 private:
-    explicit SceneQPainter(QPainterBackend *backend, QObject *parent = nullptr);
+    explicit SceneQPainter(QPainterBackend *backend);
 
     void renderSurfaceItem(QPainter *painter, SurfaceItem *surfaceItem) const;
     void renderDecorationItem(QPainter *painter, DecorationItem *decorationItem) const;