Introduced CMake option OSG_PROVIDE_READFILE option that defaults to ON, but when switched to OFF disables the building of the osgDB::read*File() methods,

forcing users to use osgDB::readRef*File() methods.  The later is preferable as it closes a potential threading bug when using paging databases in conjunction
with the osgDB::Registry Object Cache.  This threading bug occurs when one thread gets an object from the Cache via an osgDB::read*File() call where only
a pointer to the object is passed back, so taking a reference to the object is delayed till it gets reassigned to a ref_ptr<>, but at the same time another
thread calls a flush of the Object Cache deleting this object as it's referenceCount is now zero.  Using osgDB::readREf*File() makes sure the a ref_ptr<> is
passed back and the referenceCount never goes to zero.

To ensure the OSG builds when OSG_PROVIDE_READFILE is to OFF the many cases of osgDB::read*File() usage had to be replaced with a ref_ptr<> osgDB::readRef*File()
usage.  The avoid this change causing lots of other client code to be rewritten to handle the use of ref_ptr<> in place of C pointer I introduced a serious of
templte methods in various class to adapt ref_ptr<> to the underly C pointer to be passed to old OSG API's, example of this is found in include/osg/Group:

    bool addChild(Node* child); // old method which can only be used with a Node*

    tempalte<class T> bool addChild(const osg::ref_ptr<T>& child) { return addChild(child.get()); } // adapter template method

These changes together cover 149 modified files, so it's a large submission. This extent of changes are warrent to make use of the Object Cache
and multi-threaded loaded more robust.



git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/branches/OpenSceneGraph-3.4@15165 16af8721-9629-0410-8352-f15c8da7e697

include/osgVolume/Layer

@@ -71,6 +71,9 @@ class OSGVOLUME_EXPORT Layer : public osg::Object
         virtual const std::string& getFileName() const { return _filename; }
 
         void setLocator(Locator* locator) { _locator = locator; }
+
+        template<class T> void setLocator(const osg::ref_ptr<T>& locator) { setLocator(locator.get()); }
+
         Locator* getLocator() { return _locator.get(); }
         const Locator* getLocator() const { return _locator.get(); }
 
@@ -99,6 +102,8 @@ class OSGVOLUME_EXPORT Layer : public osg::Object
         /** Set the Property (or Properties via the CompositeProperty) that informs the VolumeTechnique how this layer should be rendered.*/
         void setProperty(Property* property) { _property = property; }
 
+        template<class T> void setProperty(const osg::ref_ptr<T>& p) { setProperty(p.get()); }
+
         /** Get the Property that informs the VolumeTechnique how this layer should be rendered.*/
         Property* getProperty() { return _property.get(); }
 
@@ -108,6 +113,7 @@ class OSGVOLUME_EXPORT Layer : public osg::Object
         /** Add a property, automatically creating a CompositePorperty if one isn't already assigned.*/
         void addProperty(Property* property);
 
+        template<class T> void addProperty(const osg::ref_ptr<T>& p) { addProperty(p.get()); }
 
         /** Specify whether ImageLayer requires update traversal. */
         virtual bool requiresUpdateTraversal() const { return false; }
@@ -156,6 +162,8 @@ class OSGVOLUME_EXPORT ImageLayer : public Layer
 
         void setImage(osg::Image* image);
 
+        template<class T> void setImage(const osg::ref_ptr<T>& image) { setImage(image.get()); }
+
         /** Return image associated with layer. */
         virtual osg::Image* getImage() { return _image.get(); }
 
@@ -217,11 +225,17 @@ class OSGVOLUME_EXPORT CompositeLayer : public Layer
         const std::string& getFileName(unsigned int i) const { return _layers[i].layer.valid() ? _layers[i].layer->getFileName() : _layers[i].filename; }
 
         void setLayer(unsigned int i, Layer* layer) { if (i>=_layers.size()) _layers.resize(i+1); _layers[i].layer = layer; }
+
+        template<class T> void setLayer(unsigned int i, const osg::ref_ptr<T>& layer) { setLayer(i, layer.get()); }
+
         Layer* getLayer(unsigned int i) { return i<_layers.size() ? _layers[i].layer.get() : 0; }
+
         const Layer* getLayer(unsigned int i) const { return i<_layers.size() ? _layers[i].layer.get() : 0; }
 
         void addLayer(Layer* layer) { _layers.push_back(NameLayer(layer->getFileName(),layer)); }
 
+        template<class T> void addLayer(const osg::ref_ptr<T>& layer) { addLayer(layer.get()); }
+
         void removeLayer(unsigned int i) { _layers.erase(_layers.begin()+i); }
 
         unsigned int getNumLayers() const { return _layers.size(); }

include/osgVolume/Locator

@@ -83,6 +83,9 @@ class OSGVOLUME_EXPORT Locator : public osg::Object
         };
 
         void addCallback(LocatorCallback* callback);
+        template<class T> void addCallback(const osg::ref_ptr<T>& callback) { addCallback(callback.get()); }
+
+
         void removeCallback(LocatorCallback* callback);
 
         typedef std::vector< osg::ref_ptr<LocatorCallback> > LocatorCallbacks;

include/osgVolume/Property

@@ -126,12 +126,16 @@ class OSGVOLUME_EXPORT CompositeProperty : public Property
 
         void setProperty(unsigned int i, Property* property) { if (i>=_properties.size()) _properties.resize(i+1); _properties[i] = property; }
 
+        template<class T> void setProperty(unsigned int i, const osg::ref_ptr<T>& p) { setProperty(i, p.get()); }
+
         Property* getProperty(unsigned int i) { return i<_properties.size() ? _properties[i].get() : 0; }
 
         const Property* getProperty(unsigned int i) const { return i<_properties.size() ? _properties[i].get() : 0; }
 
         void addProperty(Property* property) { _properties.push_back(property); dirty(); }
 
+        template<class T> void addProperty(const osg::ref_ptr<T>& p) { addProperty(p.get()); }
+
         void removeProperty(unsigned int i) { _properties.erase(_properties.begin()+i); }
 
         unsigned int getNumProperties() const { return _properties.size(); }