AOO410/main/slideshow/source/inc/shapeattributelayerholder.hxx

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#ifndef INCLUDED_SLIDESHOW_SHAPEATTRIBUTELAYERHOLDER_HXX
#define INCLUDED_SLIDESHOW_SHAPEATTRIBUTELAYERHOLDER_HXX

#include "attributableshape.hxx"
#include "shapeattributelayer.hxx"

#include <boost/noncopyable.hpp>

namespace slideshow
{
    namespace internal
    {
        /** Holds a ShapeAttributeLayer, together with the associated
            Shape

            Use this class to hold ShapeAttributeLayer objects the
            RAII way. When this object gets deleted, it will
            automatically revoke the attribute layer for the given
            shape (this encapsulates the somewhat clumsy notification
            process that is required for shape and attribute layer
            interaction).
         */
        class ShapeAttributeLayerHolder : private boost::noncopyable
        {
        public:
            /** Create a ShapeAttributeLayerHolder instance.

            	This constructor creates an empty attribute holder, to
            	generate an attribute layer, you have to manually call
            	createAttributeLayer().
             */
            ShapeAttributeLayerHolder() :
                mpShape(),
                mpAttributeLayer()
            {
            }

            ~ShapeAttributeLayerHolder()
            {
                reset(); // ensures that the last attribute layer is
                         // correctly deregistered from the shape.
            }

            void reset()
            {
                if( mpShape && mpAttributeLayer )
                    mpShape->revokeAttributeLayer( mpAttributeLayer );
            }

            /** This constructor receives a pointer to the Shape, from
            	which attribute layers should be generated. Initially,
            	this object does not create an attribute layer, you
            	have to manually call createAttributeLayer().

                @param rShape
                Shape for which attribute layers should be generated.
            */
            bool createAttributeLayer( const AttributableShapeSharedPtr& rShape )
            {
                reset();

                mpShape = rShape;

                if( mpShape )
                    mpAttributeLayer = mpShape->createAttributeLayer();
                
                return (mpAttributeLayer.get() != NULL);
            }

            ShapeAttributeLayerSharedPtr get() const
            {
                return mpAttributeLayer;
            }

        private:
            AttributableShapeSharedPtr		mpShape;
            ShapeAttributeLayerSharedPtr	mpAttributeLayer;
        };

    }
}

#endif /* INCLUDED_SLIDESHOW_SHAPEATTRIBUTELAYERHOLDER_HXX */