libkwineffects: Drop QtQuick dummy window hack

The dummy window hack was needed to ensure hidpi rendering on Wayland.
We introduced QQuickRenderTarget::setDevicePixelRatio() in Qt 6.3, so
the hack can be removed now.

src/effects/outputlocator/outputlocator.cpp

@@ -74,13 +74,9 @@ void OutputLocatorEffect::show()
         return;
     }
 
-    // Needed until Qt6 https://codereview.qt-project.org/c/qt/qtdeclarative/+/361506
-    m_dummyWindow = std::make_unique<QWindow>();
-    m_dummyWindow->create();
-
     const auto screens = effects->screens();
     for (const auto screen : screens) {
-        auto scene = new OffscreenQuickScene(this, m_dummyWindow.get());
+        auto scene = new OffscreenQuickScene(this);
         scene->setSource(m_qmlUrl, {{QStringLiteral("outputName"), outputName(screen)}, {QStringLiteral("resolution"), screen->geometry().size()}, {QStringLiteral("scale"), screen->devicePixelRatio()}});
         QRectF geometry(0, 0, scene->rootItem()->implicitWidth(), scene->rootItem()->implicitHeight());
         geometry.moveCenter(screen->geometry().center());

src/effects/outputlocator/outputlocator.h

@@ -9,7 +9,6 @@
 #include <kwineffects.h>
 
 #include <QTimer>
-#include <QWindow>
 
 namespace KWin
 {
@@ -31,7 +30,6 @@ public Q_SLOTS:
 private:
     QUrl m_qmlUrl;
     QTimer m_showTimer;
-    std::unique_ptr<QWindow> m_dummyWindow;
     QMap<EffectScreen *, OffscreenQuickScene *> m_scenesByScreens;
 };
 }

src/effects/showfps/showfpseffect.cpp

@@ -9,7 +9,6 @@
 #include "showfpseffect.h"
 
 #include <QQmlContext>
-#include <QWindow>
 
 namespace KWin
 {
@@ -69,9 +68,7 @@ void ShowFpsEffect::prePaintScreen(ScreenPrePaintData &data, std::chrono::millis
     }
 
     if (!m_scene) {
-        m_window = std::make_unique<QWindow>();
-        m_window->create();
-        m_scene = std::make_unique<OffscreenQuickScene>(nullptr, m_window.get());
+        m_scene = std::make_unique<OffscreenQuickScene>(nullptr);
         const auto url = QUrl::fromLocalFile(QStandardPaths::locate(QStandardPaths::GenericDataLocation, QStringLiteral("kwin/effects/showfps/qml/main.qml")));
         m_scene->setSource(url, {{QStringLiteral("effect"), QVariant::fromValue(this)}});
     }

src/effects/showfps/showfpseffect.h

@@ -48,7 +48,6 @@ Q_SIGNALS:
     void paintChanged();
 
 private:
-    std::unique_ptr<QWindow> m_window;
     std::unique_ptr<OffscreenQuickScene> m_scene;
 
     int m_maximumFps = 0;

src/libkwineffects/kwinoffscreenquickview.cpp

@@ -34,35 +34,6 @@
 namespace KWin
 {
 
-class EffectQuickRenderControl : public QQuickRenderControl
-{
-    Q_OBJECT
-
-public:
-    explicit EffectQuickRenderControl(OffscreenQuickView *view, QWindow *renderWindow)
-        : QQuickRenderControl(view)
-        , m_view(view)
-        , m_renderWindow(renderWindow)
-    {
-    }
-
-    QWindow *renderWindow(QPoint *offset) override
-    {
-        if (offset) {
-            if (m_renderWindow) {
-                *offset = m_renderWindow->mapFromGlobal(m_view->geometry().topLeft());
-            } else {
-                *offset = QPoint(0, 0);
-            }
-        }
-        return m_renderWindow;
-    }
-
-private:
-    OffscreenQuickView *m_view;
-    QPointer<QWindow> m_renderWindow;
-};
-
 class Q_DECL_HIDDEN OffscreenQuickView::Private
 {
 public:
@@ -111,20 +82,10 @@ OffscreenQuickView::OffscreenQuickView(QObject *parent)
 }
 
 OffscreenQuickView::OffscreenQuickView(QObject *parent, ExportMode exportMode)
-    : OffscreenQuickView(parent, nullptr, exportMode)
-{
-}
-
-OffscreenQuickView::OffscreenQuickView(QObject *parent, QWindow *renderWindow)
-    : OffscreenQuickView(parent, renderWindow, effects ? ExportMode::Texture : ExportMode::Image)
-{
-}
-
-OffscreenQuickView::OffscreenQuickView(QObject *parent, QWindow *renderWindow, ExportMode exportMode)
     : QObject(parent)
     , d(new OffscreenQuickView::Private)
 {
-    d->m_renderControl = std::make_unique<EffectQuickRenderControl>(this, renderWindow);
+    d->m_renderControl = std::make_unique<QQuickRenderControl>();
 
     d->m_view = std::make_unique<QQuickWindow>(d->m_renderControl.get());
     d->m_view->setFlags(Qt::FramelessWindowHint);
@@ -263,7 +224,11 @@ void OffscreenQuickView::update()
                 return;
             }
         }
-        d->m_view->setRenderTarget(QQuickRenderTarget::fromOpenGLTexture(d->m_fbo->texture(), d->m_fbo->size()));
+
+        QQuickRenderTarget renderTarget = QQuickRenderTarget::fromOpenGLTexture(d->m_fbo->texture(), d->m_fbo->size());
+        renderTarget.setDevicePixelRatio(d->m_view->devicePixelRatio());
+
+        d->m_view->setRenderTarget(renderTarget);
     }
 
     d->m_renderControl->polishItems();
@@ -559,18 +524,6 @@ OffscreenQuickScene::OffscreenQuickScene(QObject *parent)
 {
 }
 
-OffscreenQuickScene::OffscreenQuickScene(QObject *parent, QWindow *renderWindow)
-    : OffscreenQuickView(parent, renderWindow)
-    , d(new OffscreenQuickScene::Private)
-{
-}
-
-OffscreenQuickScene::OffscreenQuickScene(QObject *parent, QWindow *renderWindow, ExportMode exportMode)
-    : OffscreenQuickView(parent, renderWindow, exportMode)
-    , d(new OffscreenQuickScene::Private)
-{
-}
-
 OffscreenQuickScene::OffscreenQuickScene(QObject *parent, OffscreenQuickView::ExportMode exportMode)
     : OffscreenQuickView(parent, exportMode)
     , d(new OffscreenQuickScene::Private)

src/libkwineffects/kwinoffscreenquickview.h

@@ -62,20 +62,6 @@ public:
      */
     OffscreenQuickView(QObject *parent);
 
-    /**
-     * Construct a new OffscreenQuickView with the specified @a parent and the
-     * render window @a renderWindow. The render window can be used by QtQuick
-     * to compute the scale factor.
-     */
-    OffscreenQuickView(QObject *parent, QWindow *renderWindow);
-
-    /**
-     * Construct a new OffscreenQuickView with the specified @a parent and the
-     * render window @a renderWindow. The render window can be used by QtQuick
-     * to compute the scale factor.
-     */
-    OffscreenQuickView(QObject *parent, QWindow *renderWindow, ExportMode exportMode);
-
     /**
      * Construct a new KWinQuickView explicitly stating an export mode
      */
@@ -180,8 +166,6 @@ class KWINEFFECTS_EXPORT OffscreenQuickScene : public OffscreenQuickView
 public:
     OffscreenQuickScene(QObject *parent);
     OffscreenQuickScene(QObject *parent, ExportMode exportMode);
-    OffscreenQuickScene(QObject *parent, QWindow *renderWindow);
-    OffscreenQuickScene(QObject *parent, QWindow *renderWindow, ExportMode exportMode);
     ~OffscreenQuickScene();
 
     QQmlContext *rootContext() const;

src/libkwineffects/kwinquickeffect.cpp

@@ -13,7 +13,6 @@
 #include <QQmlIncubator>
 #include <QQuickItem>
 #include <QQuickWindow>
-#include <QWindow>
 
 namespace KWin
 {
@@ -71,7 +70,6 @@ public:
     std::map<EffectScreen *, std::unique_ptr<QuickSceneView>> views;
     QPointer<QuickSceneView> mouseImplicitGrab;
     bool running = false;
-    std::unique_ptr<QWindow> dummyWindow;
 };
 
 bool QuickSceneEffectPrivate::isItemOnScreen(QQuickItem *item, EffectScreen *screen) const
@@ -85,7 +83,7 @@ bool QuickSceneEffectPrivate::isItemOnScreen(QQuickItem *item, EffectScreen *scr
 }
 
 QuickSceneView::QuickSceneView(QuickSceneEffect *effect, EffectScreen *screen)
-    : OffscreenQuickView(effect, QuickSceneEffectPrivate::get(effect)->dummyWindow.get())
+    : OffscreenQuickView(effect)
     , m_effect(effect)
     , m_screen(screen)
 {
@@ -460,17 +458,6 @@ void QuickSceneEffect::startInternal()
     // Install an event filter to monitor cursor shape changes.
     qApp->installEventFilter(this);
 
-    // This is an ugly hack to make hidpi rendering work as expected on wayland until we switch
-    // to Qt 6.3 or newer. See https://codereview.qt-project.org/c/qt/qtdeclarative/+/361506
-    if (effects->waylandDisplay()) {
-        d->dummyWindow.reset(new QWindow());
-        d->dummyWindow->setOpacity(0);
-        d->dummyWindow->resize(1, 1);
-        d->dummyWindow->setFlag(Qt::FramelessWindowHint);
-        d->dummyWindow->setVisible(true);
-        d->dummyWindow->requestActivate();
-    }
-
     const QList<EffectScreen *> screens = effects->screens();
     for (EffectScreen *screen : screens) {
         addScreen(screen);
@@ -493,7 +480,6 @@ void QuickSceneEffect::stopInternal()
 
     d->incubators.clear();
     d->views.clear();
-    d->dummyWindow.reset();
     d->running = false;
     qApp->removeEventFilter(this);
     effects->ungrabKeyboard();

src/plugins/kdecorations/aurorae/src/aurorae.cpp

@@ -313,18 +313,7 @@ void Decoration::init()
         m_item->setParentItem(visualParent.value<QQuickItem *>());
         visualParent.value<QQuickItem *>()->setProperty("drawBackground", false);
     } else {
-
-        // This is an ugly hack to make hidpi rendering work as expected on wayland until we switch
-        // to Qt 6.3 or newer. See https://codereview.qt-project.org/c/qt/qtdeclarative/+/361506
-        if (KWin::effects && KWin::effects->waylandDisplay()) {
-            m_dummyWindow.reset(new QWindow());
-            m_dummyWindow->setOpacity(0);
-            m_dummyWindow->resize(1, 1);
-            m_dummyWindow->setFlag(Qt::FramelessWindowHint);
-            m_dummyWindow->setVisible(true);
-        }
-
-        m_view = std::make_unique<KWin::OffscreenQuickView>(this, m_dummyWindow.get(), KWin::OffscreenQuickView::ExportMode::Image);
+        m_view = std::make_unique<KWin::OffscreenQuickView>(this, KWin::OffscreenQuickView::ExportMode::Image);
         m_item->setParentItem(m_view->contentItem());
         auto updateSize = [this]() {
             m_item->setSize(m_view->contentItem()->size());

src/plugins/kdecorations/aurorae/src/aurorae.h

@@ -80,7 +80,6 @@ private:
     KWin::Borders *m_padding;
     QString m_themeName;
 
-    std::unique_ptr<QWindow> m_dummyWindow;
     std::unique_ptr<KWin::OffscreenQuickView> m_view;
 };