Creates a 2D affine transform. An affine transform performs a linear mapping from 2D coordinates to other 2D coordinates that preserves the "straightness" and "parallelness" of lines. Such a coordinate transformation can be represented by a 3 row by 3 column matrix with an implied last row of [ 0 0 1 ]. This matrix transforms source coordinates (x,y) into destination coordinates (x',y') by considering them to be a column vector and multiplying the coordinate vector by the matrix according to the following process:

[ x']   [  m00  m01  m02  ] [ x ]   [ m00x + m01y + m02 ]
[ y'] = [  m10  m11  m12  ] [ y ] = [ m10x + m11y + m12 ]
[ 1 ]   [   0    0    1   ] [ 1 ]   [         1         ]

This class is optimized for speed and minimizes calculations based on its knowledge of the underlying matrix (as opposed to say simply performing matrix multiplication).