Make EffectWindowVisibleRef mandatory when refrencing window visibility in effects

This should prevent a stray visiblity unrefrence in an effect from crashing kwin.

src/effects.cpp

@@ -1931,14 +1931,14 @@ EffectWindowImpl::~EffectWindowImpl()
 {
 }
 
-void EffectWindowImpl::refVisible(int reason)
+void EffectWindowImpl::refVisible(const EffectWindowVisibleRef *holder)
 {
-    m_windowItem->refVisible(reason);
+    m_windowItem->refVisible(holder->reason());
 }
 
-void EffectWindowImpl::unrefVisible(int reason)
+void EffectWindowImpl::unrefVisible(const EffectWindowVisibleRef *holder)
 {
-    m_windowItem->unrefVisible(reason);
+    m_windowItem->unrefVisible(holder->reason());
 }
 
 void EffectWindowImpl::addRepaint(const QRect &r)

src/effects.h

@@ -380,9 +380,6 @@ public:
     explicit EffectWindowImpl(Window *window);
     ~EffectWindowImpl() override;
 
-    void refVisible(int reason) override;
-    void unrefVisible(int reason) override;
-
     void addRepaint(const QRect &r) override;
     void addRepaintFull() override;
     void addLayerRepaint(const QRect &r) override;
@@ -505,6 +502,9 @@ public:
     QVariant data(int role) const override;
 
 private:
+    void refVisible(const EffectWindowVisibleRef *holder) override;
+    void unrefVisible(const EffectWindowVisibleRef *holder) override;
+
     Window *m_window;
     WindowItem *m_windowItem; // This one is used only during paint pass.
     QHash<int, QVariant> dataMap;

src/libkwineffects/kwineffects.h

@@ -2019,6 +2019,7 @@ Q_SIGNALS:
     void changed();
 };
 
+class EffectWindowVisibleRef;
 /**
  * @short Representation of a window used by/for Effect classes.
  *
@@ -2342,9 +2343,6 @@ public:
     virtual void refWindow() = 0;
     virtual void unrefWindow() = 0;
 
-    virtual void refVisible(int reason) = 0;
-    virtual void unrefVisible(int reason) = 0;
-
     virtual bool isDeleted() const = 0;
 
     virtual bool isMinimized() const = 0;
@@ -2698,6 +2696,11 @@ public:
      */
     virtual void unreferencePreviousWindowPixmap() = 0;
 
+protected:
+    friend EffectWindowVisibleRef;
+    virtual void refVisible(const EffectWindowVisibleRef *holder) = 0;
+    virtual void unrefVisible(const EffectWindowVisibleRef *holder) = 0;
+
 private:
     class Private;
     QScopedPointer<Private> d;
@@ -2773,7 +2776,7 @@ public:
         : m_window(window)
         , m_reason(reason)
     {
-        m_window->refVisible(reason);
+        m_window->refVisible(this);
     }
 
     EffectWindowVisibleRef(const EffectWindowVisibleRef &other)
@@ -2781,24 +2784,29 @@ public:
         , m_reason(other.m_reason)
     {
         if (m_window) {
-            m_window->refVisible(m_reason);
+            m_window->refVisible(this);
         }
     }
 
     ~EffectWindowVisibleRef()
     {
         if (m_window) {
-            m_window->unrefVisible(m_reason);
+            m_window->unrefVisible(this);
         }
     }
 
+    int reason() const
+    {
+        return m_reason;
+    }
+
     EffectWindowVisibleRef &operator=(const EffectWindowVisibleRef &other)
     {
         if (other.m_window) {
-            other.m_window->refVisible(other.m_reason);
+            other.m_window->refVisible(&other);
         }
         if (m_window) {
-            m_window->unrefVisible(m_reason);
+            m_window->unrefVisible(this);
         }
         m_window = other.m_window;
         m_reason = other.m_reason;