method invert

Source

void invert() {

  num a =   this.a;
  num b =   this.b;
  num c =   this.c;
  num d =   this.d;
  num tx =  this.tx;
  num ty =  this.ty;
  num det = this.det;

  _data[0] =   d / det;
  _data[1] = - b / det;
  _data[2] = - c / det;
  _data[3] =   a / det;
  _data[4] = - tx * _data[0] - ty * _data[2];
  _data[5] = - tx * _data[1] - ty * _data[3];
}