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   1  <?php
   2  /**
   3   * File containing the ezcGraphTransformation class
   4   *
   5   * @package Graph
   6   * @version 1.5
   7   * @copyright Copyright (C) 2005-2009 eZ Systems AS. All rights reserved.
   8   * @license http://ez.no/licenses/new_bsd New BSD License
   9   * @access private
  10   */
  11  /**
  12   * Class defining transformations
  13   *
  14   * Three dimensional matrices (3x3) may be used to specify transformation of
  15   * points, vectors and complexer structures in a two dimensional cartesian
  16   * coordinate system. For more details have a look here:
  17   * http://en.wikipedia.org/wiki/Transformation_matrix
  18   *
  19   * There are some classes extending this basic tranformation class, to
  20   * give you more convinient access to the creation of such transformation
  21   * matrices, which are:
  22   * 
  23   * - ezcGraphRotation (rotations of objects)
  24   * - ezcGraphTranslation (moving of objects)
  25   *
  26   * @version 1.5
  27   * @package Graph
  28   * @access private
  29   */
  30  class ezcGraphTransformation extends ezcGraphMatrix
  31  {
  32      /**
  33       * Constructor
  34       *
  35       * Creates a matrix with 3x3 dimensions. Optionally accepts an array to 
  36       * define the initial matrix values. If no array is given an identity 
  37       * matrix is created.
  38       * 
  39       * @param array $values
  40       * @return void
  41       */
  42      public function __construct( array $values = null )
  43      {
  44          parent::__construct( 3, 3, $values );
  45      }
  46  
  47      /**
  48       * Multiplies two matrices
  49       *
  50       * Multiply current matrix with another matrix and returns the result 
  51       * matrix.
  52       *
  53       * @param ezcGraphMatrix $matrix Second factor
  54       * @return ezcGraphMatrix Result matrix
  55       */
  56      public function multiply( ezcGraphMatrix $matrix ) 
  57      {
  58          $mColumns = $matrix->columns();
  59  
  60          // We want to ensure, that the matrix stays 3x3
  61          if ( ( $this->columns !== $matrix->rows() ) &&
  62               ( $this->rows !== $mColumns ) )
  63          {
  64              throw new ezcGraphMatrixInvalidDimensionsException( $this->columns, $this->rows, $mColumns, $matrix->rows() );
  65          }
  66  
  67          $result = parent::multiply( $matrix );
  68  
  69          // The matrix dimensions stay the same, so that we can modify $this.
  70          for ( $i = 0; $i < $this->rows; ++$i ) 
  71          {
  72              for ( $j = 0; $j < $mColumns; ++$j ) 
  73              {
  74                  $this->set( $i, $j, $result->get( $i, $j ) );
  75              }
  76          }
  77  
  78          return $this;
  79      }
  80  
  81      /**
  82       * Transform a coordinate with the current transformation matrix.
  83       * 
  84       * @param ezcGraphCoordinate $coordinate 
  85       * @return ezcGraphCoordinate
  86       */
  87      public function transformCoordinate( ezcGraphCoordinate $coordinate )
  88      {
  89          $vector = new ezcGraphMatrix( 3, 1, array( array( $coordinate->x ), array( $coordinate->y ), array( 1 ) ) );
  90          $vector = parent::multiply( $vector );
  91  
  92          return new ezcGraphCoordinate( $vector->get( 0, 0 ), $vector->get( 1, 0 ) );
  93      }
  94  }
  95  
  96  ?>