text: //////////////////////////////////////////////////////////////////////////
  //  
  //  Copyright (c) 2013, Image Engine Design Inc. All rights reserved.
  //  
  //  Redistribution and use in source and binary forms, with or without
  //  modification, are permitted provided that the following conditions are
  //  met:
  //  
  //      * Redistributions of source code must retain the above
  //        copyright notice, this list of conditions and the following
  //        disclaimer.
  //  
  //      * Redistributions in binary form must reproduce the above
  //        copyright notice, this list of conditions and the following
  //        disclaimer in the documentation and/or other materials provided with
  //        the distribution.
  //  
  //      * Neither the name of John Haddon nor the names of
  //        any other contributors to this software may be used to endorse or
  //        promote products derived from this software without specific prior
  //        written permission.
  //  
  //  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  //  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  //  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  //  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  //  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  //  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  //  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  //  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  //  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  //  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  //  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //  
  //////////////////////////////////////////////////////////////////////////
  
  #include "IECore/CachedReader.h"
  
  #include "GafferUI/Pointer.h"
  
  using namespace GafferUI;
  
  static IECore::ConstImagePrimitivePtr g_image;
  
  void Pointer::set( IECore::ConstImagePrimitivePtr image )
  {
  	if( !image && !g_image )
  	{
  		return;
  	}
  	if( image && g_image && image->isEqualTo( g_image ) )
  	{
  		return;
  	}
  	
  	g_image = image;
  	changedSignal()();
  }
  
  const IECore::ImagePrimitive *Pointer::get()
  {
  	return g_image.get();
  }
  
  void Pointer::setFromFile( const std::string &name )
  {
  	if( !name.size() )
  	{
  		set( NULL );
  		return;
  	}
  
  	static IECore::CachedReaderPtr g_reader;
  	if( !g_reader )
  	{
  		const char *sp = getenv( "GAFFERUI_IMAGE_PATHS" );
  		sp = sp ? sp : "";
  		g_reader = new IECore::CachedReader( IECore::SearchPath( sp, ":" ) );
  	}
  
  	IECore::ConstImagePrimitivePtr image = IECore::runTimeCast<const IECore::ImagePrimitive>( g_reader->read( name ) ); 
  	if( !image )
  	{
  		throw IECore::Exception( 
  			boost::str( boost::format( "File \"%s\" does not contain an image." ) % name )
  		);
  	}
  	
  	set( image );
  }
  
  Pointer::ChangedSignal &Pointer::changedSignal()
  {
  	static ChangedSignal s;
  	return s;
  }
  