DSArrow.h

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//# DSArrow.h: Arrow implementation for "DisplayShapes"
//# Copyright (C) 1998,1999,2000,2001,2002
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//#        Internet email: aips2-request@nrao.edu.
//#        Postal address: AIPS++ Project Office
//#                        National Radio Astronomy Observatory
//#                        520 Edgemont Road
//#                        Charlottesville, VA 22903-2475 USA
//#
//# $Id: 

#ifndef TRIALDISPLAY_DSARROW_H
#define TRIALDISPLAY_DSARROW_H

#include <casa/aips.h>

#include <display/DisplayShapes/DSLine.h> 
#include <display/DisplayShapes/DSPoly.h>

#include <casa/Arrays/Matrix.h>
#include <casa/Arrays/Vector.h>

namespace casa { //# NAMESPACE CASA - BEGIN

class PixelCanvas;
template <class T> class DParameterRange;

// <summary>
// Arrow implementation;adds a polygon to a DSLine to represent the arrow head
// </summary>
//
// <prerequisite>
// <li> <linkto class="DSLine">DSLine</linkto>
// <li> <linkto class="DSPoly">DSPoly</linkto>
// <li> <linkto class="DisplayShape">DisplayShape</linkto>
// </prerequisite>
//
// <etymology>
// DSArrow is a method of managing the drawing of a line and polygon onto a 
// PixelCanvas.
// </etymology>
//
// <synopsis>
// DSArrow simply extends from DSLine, and adds the management of a polygon
// to it. The polygon is used to represent the arrow head, and various options
// regarding its apppearance can be changed.
//
// There are generally two ways to make DisplayShape(s); To create them in 
// "one hit" by providing arguments to the constructor, or by using the 
// default constructor and then the "setOptions" method. A simple interface 
// for all classes inheriting from the 
// <linkto class="DisplayShape">DisplayShape</linkto> class is provided by 
// <linkto class="DisplayShapeInterface">DisplayShapeInterface</linkto>.
// </synopsis>
//
// <motivation>
// It was thought, especially in an annotations context, that an Arrow would be
// a usefull drawing tool.
// </motivation>
//
// <example>
// <srcblock>
// Vector<Float> startPoint(2); startPoint[0] = 100; startPoint[1] = 100;
// Vector<Float> endPoint(2);   endPoint[0] = 200;   endPoint[1] = 200;
//
// DSArrow* myArrow = 
// new DSArrow(startPoint, endPoint, DSArrow::Filled_Triangle, 10);
//
// myArrow->move(10,10);
//
// Vector<Float> newStart(2); newStart[0] = 50; newStart[1] = 50;
// myArrow->setStartPoint(newStart);
//
// Record newArrow;
// newArrow.define("arrowheadsize", 6);
//
// myArrow->setOptions(newArrow);
// myArrow->draw(myPixelCanvas);
// etc..
// </srcblock>
// </example>

class DSArrow : public DSLine {

public: 

  // Supported arrow head types
  enum ArrowHead { Open_Triangle, Filled_Triangle , Cool_Triangle};

  // For checking setoptions(arrowheadstyle = ?) 
  static const int numArrowHeads = 3; 


  // Default constructor. In order to make the arrow "valid", it must 
  // be supplied with a valid start and end point.
  DSArrow();

  // The start and end point are in pixel co-ordinates.
  DSArrow(const Vector<Float> &startPoint, const Vector<Float> &endPoint, 
          DSArrow::ArrowHead style = DSArrow::Cool_Triangle, 
          const Int arrowHeadSize = 8);

  // Copy constructor
  DSArrow(const DSArrow& other);

  // Destructor
  virtual ~DSArrow();
  
  // Standard Display Shape functions
  // <group>
  virtual void draw(PixelCanvas *pc);
  virtual void move(const Float& dX, const Float& dY);
  virtual void rotate(const Float& angle);
  virtual void scale(const Float& scaleFactor);
  virtual void setCenter(const Float& xPos, const Float& yPos);
  // </group>

  // Does nothing currently
  virtual void rotateAbout(const Float& angle, const Float& aboutX, 
                             const Float& aboutY);

  // Standard (changePoint) and specific funtions for altering the arrow. the 
  // changePoint method with only one argument will move the closest point to 
  // the specified new point. When speciffyin 'n', in this case only 0 or
  // 1 are valid. The 'startpoint' is the one with the arrow head on it.
  // <group>
  virtual void setStartPoint(const Vector<Float>& startPoint);
  virtual void setEndPoint(const Vector<Float>& endPoint);
  virtual void changePoint(const Vector<Float>&pos, const Int n);
  virtual void changePoint(const Vector<Float>& pos);
  // </group>

  // These are to enable the use of arrows more easily in vector plots
  // <group>
  virtual void setLength(const Float& pixelLength);
  virtual void setAngle(const Float& angle);
  // </group>

  // Return an option record describing the shape
  virtual Record getOptions();
  
  // Set options. 
  virtual Bool setOptions(const Record& newSettings);

protected:

private: 
  // If someone calls "setLength" before "setCenter", we can store our
  // length until they DO call setLength;
  Float itsLength;
  
  // Make a new arrow head (which is simply a DSPoly)
  virtual void buildArrowHead();
  
  // Caluclate angle etc.
  virtual void updateArrowHead();

  // Set default options
  virtual void setDefaultOptions();

  // Construct the line segment of the arrow when we have 
  // valid start / end points
  virtual void make();

  DParameterRange<Int>* itsHeadSize;

  DSPoly* itsArrowHead;

  // Temp storage while I am being set up
  // <group>
  Vector<Float> itsStartPoint;
  Vector<Float> itsEndPoint;
  // </group>

  // A Matrix of the unRotated arrow head 
  Matrix<Float> itsUnrotatedHead;

  // Offset needed to make sure the tip of the arrow is at the end of
  // the line.
  Float itsOffset;

  // Style of arrow head
  DSArrow::ArrowHead itsArrowHeadStyle;

  // Have I been supplied with valid points yet
  Bool itsValidStart,itsValidEnd;
};


} //# NAMESPACE CASA - END

#endif