More robust object parenting.

src/Object.cpp

@@ -22,15 +22,23 @@ namespace Magnum {
 void Object::setParent(Object* parent) {
     if(_parent == parent) return;
 
-    /* Remove the object from old parent children list */
-    if(_parent != 0)
-        _parent->_children.erase(this);
-
     /* Set new parent and add the object to new parent children list */
     if(parent != 0) {
+
+        /* Only Fry can be his own grandfather */
+        Object* p = parent;
+        while(p != 0 && p->parent() != p) {
+            if(p == this) return;
+            p = p->parent();
+        }
+
         parent->_children.insert(this);
     }
 
+    /* Remove the object from old parent children list */
+    if(_parent != 0)
+        _parent->_children.erase(this);
+
     _parent = parent;
 }
 

src/Object.h

@@ -25,6 +25,8 @@
 
 namespace Magnum {
 
+class Scene;
+
 /**
  * @brief Base for all positioned objects
  *
@@ -34,6 +36,8 @@ namespace Magnum {
 class Object {
     DISABLE_COPY(Object)
 
+    friend class Scene;
+
     public:
         /**
          * @brief Constructor
@@ -60,7 +64,7 @@ class Object {
         inline const std::set<Object*>& children() const { return _children; }
 
         /** @brief Set parent object */
-        void setParent(Object* parent);
+        virtual void setParent(Object* parent);
 
         /** @brief Transformation matrix */
         inline Matrix4 transformation() const { return _transformation; }

src/Scene.h

@@ -26,7 +26,7 @@ namespace Magnum {
 /** @brief Scene */
 class Scene: public Object {
     private:
-        Object::setParent;
+        virtual void setParent(Object* parent) {}
         Object::setTransformation;
 
     public:
@@ -39,6 +39,7 @@ class Scene: public Object {
 
         /** @brief Constructor */
         inline Scene(): Object(0), _features(0), _camera(0) {
+            _parent = this;
             setClearColor(0.1f, 0.1f, 0.1f, 1.0f);
         }
 

src/Test/CMakeLists.txt

@@ -1,2 +1,3 @@
 magnum_add_test(ObjectTest ObjectTest.h ObjectTest.cpp Magnum)
 magnum_add_test(CameraTest CameraTest.h CameraTest.cpp Magnum)
+magnum_add_test(SceneTest SceneTest.h SceneTest.cpp Magnum)

src/Test/ObjectTest.cpp

@@ -30,6 +30,14 @@ void ObjectTest::parenting() {
     QVERIFY(childOne->parent() == &root);
     QVERIFY(root.children().size() == 2);
 
+    /* A object cannot be parent of itself */
+    childOne->setParent(childOne);
+    QVERIFY(childOne->parent() == &root);
+
+    /* In fact, cyclic dependencies are not allowed at all */
+    root.setParent(childTwo);
+    QVERIFY(root.parent() == 0);
+
     /* Reparent to another */
     childTwo->setParent(childOne);
     QVERIFY(root.children().size() == 1 && *root.children().begin() == childOne);

src/Test/SceneTest.cpp

@@ -0,0 +1,38 @@
+/*
+    Copyright © 2010 Vladimír Vondruš <mosra@centrum.cz>
+
+    This file is part of Magnum.
+
+    Magnum is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License version 3
+    only, as published by the Free Software Foundation.
+
+    Magnum is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU Lesser General Public License version 3 for more details.
+*/
+
+#include "SceneTest.h"
+
+#include <QtTest/QTest>
+
+#include "Scene.h"
+
+QTEST_APPLESS_MAIN(Magnum::Test::SceneTest)
+
+namespace Magnum { namespace Test {
+
+void SceneTest::parent() {
+    Scene scene;
+
+    QVERIFY(scene.parent() == &scene);
+
+    /* Scene parent cannot be changed */
+    Object* scenePointer = &scene;
+    Object* object = new Object;
+    scenePointer->setParent(object);
+    QVERIFY(scene.parent() == &scene);
+}
+
+}}

src/Test/SceneTest.h

@@ -0,0 +1,33 @@
+#ifndef Magnum_Test_SceneTest_h
+#define Magnum_Test_SceneTest_h
+/*
+    Copyright © 2010 Vladimír Vondruš <mosra@centrum.cz>
+
+    This file is part of Magnum.
+
+    Magnum is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License version 3
+    only, as published by the Free Software Foundation.
+
+    Magnum is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU Lesser General Public License version 3 for more details.
+*/
+
+#include <QtCore/QObject>
+
+#include "Object.h"
+
+namespace Magnum { namespace Test {
+
+class SceneTest: public QObject {
+    Q_OBJECT
+
+    private slots:
+        void parent();
+};
+
+}}
+
+#endif