From 0c0fb99919bc00578ef80aafa39526b072a04505 Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Sat, 11 Feb 2023 14:05:54 +0200
Subject: [PATCH] kwineffects: Add SceneView attached property

SceneView attached property is a more script friendly way to pass the
information about a screen view from C++ to QML code.
---
 src/libkwineffects/kwinquickeffect.cpp | 57 +++++++++++++++++++++-----
 src/libkwineffects/kwinquickeffect.h   | 11 ++++-
 2 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/src/libkwineffects/kwinquickeffect.cpp b/src/libkwineffects/kwinquickeffect.cpp
index df7d1c8369..2902e26049 100644
--- a/src/libkwineffects/kwinquickeffect.cpp
+++ b/src/libkwineffects/kwinquickeffect.cpp
@@ -18,22 +18,41 @@
 namespace KWin
 {
 
+static QHash<QQuickWindow *, QuickSceneView *> s_views;
+
 class QuickSceneViewIncubator : public QQmlIncubator
 {
 public:
-    QuickSceneViewIncubator(const std::function<void(QuickSceneViewIncubator *)> &statusChangedCallback)
+    QuickSceneViewIncubator(QuickSceneEffect *effect, EffectScreen *screen, const std::function<void(QuickSceneViewIncubator *)> &statusChangedCallback)
         : QQmlIncubator(QQmlIncubator::Asynchronous)
+        , m_effect(effect)
+        , m_screen(screen)
         , m_statusChangedCallback(statusChangedCallback)
     {
     }
 
+    std::unique_ptr<QuickSceneView> result()
+    {
+        return std::move(m_view);
+    }
+
+    void setInitialState(QObject *object) override
+    {
+        m_view = std::make_unique<QuickSceneView>(m_effect, m_screen);
+        m_view->setAutomaticRepaint(false);
+        m_view->setRootItem(qobject_cast<QQuickItem *>(object));
+    }
+
     void statusChanged(QQmlIncubator::Status status) override
     {
         m_statusChangedCallback(this);
     }
 
 private:
+    QuickSceneEffect *m_effect;
+    EffectScreen *m_screen;
     std::function<void(QuickSceneViewIncubator *)> m_statusChangedCallback;
+    std::unique_ptr<QuickSceneView> m_view;
 };
 
 class QuickSceneEffectPrivate
@@ -74,10 +93,13 @@ QuickSceneView::QuickSceneView(QuickSceneEffect *effect, EffectScreen *screen)
     connect(screen, &EffectScreen::geometryChanged, this, [this, screen]() {
         setGeometry(screen->geometry());
     });
+
+    s_views.insert(window(), this);
 }
 
 QuickSceneView::~QuickSceneView()
 {
+    s_views.remove(window());
 }
 
 QQuickItem *QuickSceneView::rootItem() const
@@ -130,6 +152,23 @@ void QuickSceneView::scheduleRepaint()
     effects->addRepaint(geometry());
 }
 
+QuickSceneView *QuickSceneView::findView(QQuickItem *item)
+{
+    return s_views.value(item->window());
+}
+
+QuickSceneView *QuickSceneView::qmlAttachedProperties(QObject *object)
+{
+    QQuickItem *item = qobject_cast<QQuickItem *>(object);
+    if (item) {
+        if (QuickSceneView *view = findView(item)) {
+            return view;
+        }
+    }
+    qCWarning(LIBKWINEFFECTS) << "Could not find SceneView for" << object;
+    return nullptr;
+}
+
 QuickSceneEffect::QuickSceneEffect(QObject *parent)
     : Effect(parent)
     , d(new QuickSceneEffectPrivate)
@@ -366,21 +405,19 @@ void QuickSceneEffect::addScreen(EffectScreen *screen)
     properties["width"] = screen->geometry().width();
     properties["height"] = screen->geometry().height();
 
-    auto incubator = new QuickSceneViewIncubator([this, screen](QuickSceneViewIncubator *incubator) {
+    auto incubator = new QuickSceneViewIncubator(this, screen, [this, screen](QuickSceneViewIncubator *incubator) {
         if (incubator->isReady()) {
-            auto view = new QuickSceneView(this, screen);
-            view->setRootItem(qobject_cast<QQuickItem *>(incubator->object()));
+            auto view = incubator->result();
             if (view->contentItem()) {
                 view->contentItem()->setFocus(false);
             }
-            view->setAutomaticRepaint(false);
-            connect(view, &QuickSceneView::repaintNeeded, this, [view]() {
-                effects->addRepaint(view->geometry());
+            connect(view.get(), &QuickSceneView::repaintNeeded, this, [screen]() {
+                effects->addRepaint(screen->geometry());
             });
-            connect(view, &QuickSceneView::renderRequested, view, &QuickSceneView::scheduleRepaint);
-            connect(view, &QuickSceneView::sceneChanged, view, &QuickSceneView::scheduleRepaint);
+            connect(view.get(), &QuickSceneView::renderRequested, view.get(), &QuickSceneView::scheduleRepaint);
+            connect(view.get(), &QuickSceneView::sceneChanged, view.get(), &QuickSceneView::scheduleRepaint);
             view->scheduleRepaint();
-            d->views[screen].reset(view);
+            d->views[screen] = std::move(view);
         } else if (incubator->isError()) {
             qCWarning(LIBKWINEFFECTS) << "Could not create a view for QML file" << d->qmlComponent->url();
             qCWarning(LIBKWINEFFECTS) << incubator->errors();
diff --git a/src/libkwineffects/kwinquickeffect.h b/src/libkwineffects/kwinquickeffect.h
index 008a07bb22..61f092a8e3 100644
--- a/src/libkwineffects/kwinquickeffect.h
+++ b/src/libkwineffects/kwinquickeffect.h
@@ -9,6 +9,8 @@
 #include "kwineffects.h"
 #include "kwinoffscreenquickview.h"
 
+#include <QQmlEngine>
+
 namespace KWin
 {
 
@@ -26,6 +28,8 @@ class QuickSceneEffectPrivate;
 class KWINEFFECTS_EXPORT QuickSceneView : public OffscreenQuickView
 {
     Q_OBJECT
+    Q_PROPERTY(QuickSceneEffect *effect READ effect CONSTANT)
+    Q_PROPERTY(EffectScreen *screen READ screen CONSTANT)
 
 public:
     explicit QuickSceneView(QuickSceneEffect *effect, EffectScreen *screen);
@@ -41,6 +45,9 @@ public:
     void markDirty();
     void resetDirty();
 
+    static QuickSceneView *findView(QQuickItem *item);
+    static QuickSceneView *qmlAttachedProperties(QObject *object);
+
 public Q_SLOTS:
     void scheduleRepaint();
 
@@ -96,7 +103,7 @@ public:
 
     /**
      * Get a view at the given direction from the active view
-     * Returns null if no other views exist in the given direction 
+     * Returns null if no other views exist in the given direction
      */
     Q_INVOKABLE KWin::QuickSceneView *getView(Qt::Edge edge);
 
@@ -166,3 +173,5 @@ private:
 };
 
 } // namespace KWin
+
+QML_DECLARE_TYPEINFO(KWin::QuickSceneView, QML_HAS_ATTACHED_PROPERTIES)