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#ifndef _SVX_ACCESSIBILITY_IACCESSIBLE_VIEW_FORWARDER_LISTENER_HXX
#define _SVX_ACCESSIBILITY_IACCESSIBLE_VIEW_FORWARDER_LISTENER_HXX

#include <sal/types.h>
#include <tools/gen.hxx>


namespace accessibility {

class IAccessibleViewForwarder;

/**	<p>The purpose of this interface is to notify a user of an
    IAccessibleViewForwarder when that view forwarder changes its
    properties.  Such a change may be one of the following:
    <ul>
    <li>Change of the coordinate transformation.</li>
    <li>Change of the visible area (which in turn results in a change of the
    coordinate transformation.</li>
    <li>Change of the validity state of the view forwarder.</li>
*/
class IAccessibleViewForwarderListener
{
public:
    /** Enumeration of the different change types.
    */
    enum ChangeType {TRANSFORMATION, VISIBLE_AREA, STATE};
    
    /** This method is called to indicate a change of the specified view
        forwarder. 
        @param aChangeType
            The type of the change.  TRANSFORMATION indicates a change of
            the coordinate transformation with a constant visible area.  If
            the visible area changes, just use VISIBLE_AREA.  This changes
            the transformation implicitly.  The value STATE indicates a
            change of the validity state.  Check the IsValid method of the
            view forwarder before doing further calls.
        @param pViewForwarder
            The modified view forwarder.  It is specified just in case that
            there is more than one view forwarder in use at the same time.
    */
    virtual void ViewForwarderChanged (ChangeType aChangeType,
        const IAccessibleViewForwarder* pViewForwarder) = 0;
};

} // end of namespace accessibility

#endif

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