/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkDynamic2DLabelMapper.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
/*-------------------------------------------------------------------------
  Copyright 2008 Sandia Corporation.
  Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
  the U.S. Government retains certain rights in this software.
-------------------------------------------------------------------------*/
// .NAME vtkDynamic2DLabelMapper - draw text labels at 2D dataset points
// .SECTION Description
// vtkDynamic2DLabelMapper is a mapper that renders text at dataset
// points such that the labels do not overlap.
// Various items can be labeled including point ids, scalars,
// vectors, normals, texture coordinates, tensors, and field data components.
// This mapper assumes that the points are located on the x-y plane
// and that the camera remains perpendicular to that plane with a y-up
// axis (this can be constrained using vtkImageInteractor).
// On the first render, the mapper computes the visiblility of all labels
// at all scales, and queries this information on successive renders.
// This causes the first render to be much slower. The visibility algorithm
// is a greedy approach based on the point id, so the label for a point
// will be drawn unless the label for a point with lower id overlaps it.

// .SECTION Caveats
// Use this filter in combination with vtkSelectVisiblePoints if you want
// to label only points that are visible. If you want to label cells rather
// than points, use the filter vtkCellCenters to generate points at the
// center of the cells. Also, you can use the class vtkIdFilter to
// generate ids as scalars or field data, which can then be labeled.

// .SECTION See Also
// vtkLabeledDataMapper

// .SECTION Thanks
// This algorithm was developed in the paper
// Ken Been and Chee Yap. Dynamic Map Labeling. IEEE Transactions on 
// Visualization and Computer Graphics, Vol. 12, No. 5, 2006. pp. 773-780.

#ifndef __vtkDynamic2DLabelMapper_h
#define __vtkDynamic2DLabelMapper_h

#include "vtkLabeledDataMapper.h"

class VTK_RENDERING_EXPORT vtkDynamic2DLabelMapper : public vtkLabeledDataMapper
{
public:
  // Description:
  // Instantiate object with %%-#6.3g label format. By default, point ids
  // are labeled.
  static vtkDynamic2DLabelMapper *New();
  vtkTypeMacro(vtkDynamic2DLabelMapper, vtkLabeledDataMapper);
  void PrintSelf(ostream& os, vtkIndent indent);
  
  // Description:
  // Set the points array name to use to give priority to labels.
  // Defaults to "priority".
  void SetPriorityArrayName(const char* name);
  
  // Description:
  // Whether to reverse the priority order (i.e. low values have high priority).
  // Default is off.
  vtkSetMacro(ReversePriority, bool);
  vtkGetMacro(ReversePriority, bool);
  vtkBooleanMacro(ReversePriority, bool);
  
  // Description:
  // Set the label height padding as a percentage. The percentage 
  // is a percentage of your label height. 
  // Default is 50%.
  vtkSetMacro(LabelHeightPadding, float);
  vtkGetMacro(LabelHeightPadding, float);
  
  // Description:
  // Set the label width padding as a percentage. The percentage 
  // is a percentage of your label ^height^ (yes, not a typo). 
  // Default is 50%.
  vtkSetMacro(LabelWidthPadding, float);
  vtkGetMacro(LabelWidthPadding, float);
  
  // Description:
  // Draw non-overlapping labels to the screen.
  void RenderOpaqueGeometry(vtkViewport* viewport, vtkActor2D* actor);
  void RenderOverlay(vtkViewport *viewport, vtkActor2D *actor);

protected:
  vtkDynamic2DLabelMapper();
  ~vtkDynamic2DLabelMapper();

  // Description:
  // Calculate the current zoom scale of the viewport.
  double GetCurrentScale(vtkViewport *viewport);
  
  float* LabelWidth;
  float* LabelHeight;
  float* Cutoff;
  float ReferenceScale;
  float LabelHeightPadding;
  float LabelWidthPadding;
  
  bool ReversePriority;

private:
  vtkDynamic2DLabelMapper(const vtkDynamic2DLabelMapper&);  // Not implemented.
  void operator=(const vtkDynamic2DLabelMapper&);  // Not implemented.
};

#endif

