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/trunk@15164 16af8721-9629-0410-8352-f15c8da7e697

src/osgWidget/Browser.cpp

@@ -105,7 +105,7 @@ bool Browser::assign(BrowserImage* browserImage, const GeometryHints& hints)
 
 bool Browser::open(const std::string& hostname, const GeometryHints& hints)
 {
-    osg::ref_ptr<osg::Image> image = osgDB::readImageFile(hostname+".gecko");
+    osg::ref_ptr<osg::Image> image = osgDB::readRefImageFile(hostname+".gecko");
     return assign(dynamic_cast<BrowserImage*>(image.get()), hints);
 }
 

src/osgWidget/Frame.cpp

@@ -273,7 +273,7 @@ Frame* Frame::createSimpleFrameWithSingleTexture(
 // Inspired by: http://www.wowwiki.com/EdgeFiles
 Frame* Frame::createSimpleFrameWithSingleTexture(
     const std::string& name,
-    osg::Image*        image,
+    osg::ref_ptr<osg::Image> image,
     point_type         width,
     point_type         height,
     unsigned int       flags,
@@ -347,14 +347,14 @@ osg::Image* createNatifEdgeImageFromTheme(osg::Image* theme);
 
 Frame* Frame::createSimpleFrameFromTheme(
     const std::string& name,
-    osg::Image*        image,
+    osg::ref_ptr<osg::Image> image,
     point_type         width,
     point_type         height,
     unsigned int       flags,
     Frame*             exFrame
 ) {
 
-    osg::ref_ptr<osg::Image> natifImage = createNatifEdgeImageFromTheme(image);
+    osg::ref_ptr<osg::Image> natifImage = createNatifEdgeImageFromTheme(image.get());
     Frame* frame;
 
     frame = createSimpleFrameWithSingleTexture(name, natifImage.get(), width, height, flags, exFrame);

src/osgWidget/PdfReader.cpp

@@ -67,7 +67,7 @@ bool PdfReader::assign(PdfImage* pdfImage, const GeometryHints& hints)
                 osg::StateAttribute::ON);
 
     osg::ref_ptr<osgViewer::InteractiveImageHandler> iih = new osgViewer::InteractiveImageHandler(_pdfImage.get());
-    
+
     pictureQuad->setEventCallback(iih.get());
     pictureQuad->setCullCallback(iih.get());
 
@@ -78,7 +78,7 @@ bool PdfReader::assign(PdfImage* pdfImage, const GeometryHints& hints)
 
 bool PdfReader::open(const std::string& filename, const GeometryHints& hints)
 {
-    osg::ref_ptr<osg::Image> image = osgDB::readImageFile(filename);
+    osg::ref_ptr<osg::Image> image = osgDB::readRefImageFile(filename);
     return assign(dynamic_cast<PdfImage*>(image.get()), hints);
 }
 

src/osgWidget/VncClient.cpp

@@ -62,7 +62,7 @@ bool VncClient::assign(VncImage* vncImage, const GeometryHints& hints)
                 osg::StateAttribute::ON);
 
     osg::ref_ptr<osgViewer::InteractiveImageHandler> iih = new osgViewer::InteractiveImageHandler(_vncImage.get());
-    
+
     pictureQuad->setEventCallback(iih.get());
     pictureQuad->setCullCallback(iih.get());
 
@@ -73,7 +73,7 @@ bool VncClient::assign(VncImage* vncImage, const GeometryHints& hints)
 
 bool VncClient::connect(const std::string& hostname, const GeometryHints& hints)
 {
-    osg::ref_ptr<osg::Image> image = osgDB::readImageFile(hostname+".vnc");
+    osg::ref_ptr<osg::Image> image = osgDB::readRefImageFile(hostname+".vnc");
     return assign(dynamic_cast<VncImage*>(image.get()), hints);
 }
 

src/osgWidget/Widget.cpp

@@ -339,7 +339,8 @@ bool Widget::setImage(const std::string& filePath, bool setTexCoords, bool useTe
         return false;
     }
 
-    return setImage(osgDB::readImageFile(filePath), setTexCoords, useTextRect);
+    osg::ref_ptr<osg::Image> image = osgDB::readRefImageFile(filePath);
+    return setImage(image.get(), setTexCoords, useTextRect);
 }
 
 bool Widget::setTexture(osg::Texture* texture, bool setTexCoords, bool useTextRect) {