text: //////////////////////////////////////////////////////////////////////////
  //
  //  Copyright (c) 2017, John Haddon. 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.
  //
  //////////////////////////////////////////////////////////////////////////
  
  #ifndef GAFFERUI_ROTATEHANDLE_H
  #define GAFFERUI_ROTATEHANDLE_H
  
  #include "GafferUI/Handle.h"
  
  IECORE_PUSH_DEFAULT_VISIBILITY
  #include "OpenEXR/ImathEuler.h"
  IECORE_POP_DEFAULT_VISIBILITY
  
  namespace GafferUI
  {
  
  class GAFFERUI_API RotateHandle : public Handle
  {
  
  	public :
  
  		RotateHandle( Style::Axes axes );
  		~RotateHandle() override;
  
  		GAFFER_GRAPHCOMPONENT_DECLARE_TYPE( GafferUI::RotateHandle, RotateHandleTypeId, Handle );
  
  		void setAxes( Style::Axes axes );
  		Style::Axes getAxes() const;
  
  		// Returns a vector where each component is 0 or 1,
  		// indicating whether or not the handle will produce
  		// rotation in that axis.
  		Imath::V3i axisMask() const;
  
  		// Measured in radians
  		Imath::Eulerf rotation( const DragDropEvent &event );
  
  	protected :
  
  		void renderHandle( const Style *style, Style::State state ) const override;
  		void dragBegin( const DragDropEvent &event ) override;
  
  	private :
  
  		bool dragMove( const DragDropEvent &event );
  		bool mouseMove( const ButtonEvent &event );
  		Imath::V3f pointOnSphere( const IECore::LineSegment3f &line ) const;
  
  		void updatePreciseMotionState( const DragDropEvent &event );
  		IECore::LineSegment3f updatedLineFromEvent( const DragDropEvent &event ) const;
  
  		Style::Axes m_axes;
  		// For X, Y and Z handles.
  		AngularDrag m_drag;
  		float m_rotation;
  		// For free rotation handle.
  		Imath::M44f m_dragBeginWorldTransform;
  		Imath::V3f m_dragBeginPointOnSphere;
  		Imath::V3f m_highlightVector;
  
  		bool m_preciseMotionEnabled;
  		IECore::LineSegment3f m_preciseMotionOriginLine;
  
  };
  
  IE_CORE_DECLAREPTR( RotateHandle )
  
  } // namespace GafferUI
  
  #endif // GAFFERUI_ROTATEHANDLE_H
  