public static ConstraintSolver Instance()
{
if (_constraintSolver == null)
{
_constraintSolver = new ConstraintSolver();
}
return(_constraintSolver);
}
/// <summary>
/// This is just to try passing back an invalid memento.
/// </summary>
public void BadUnexecute()
{
Console.WriteLine("\nBad Undo!\n");
ConstraintSolver solver = ConstraintSolver.Instance();
// Restore bad state
solver.SetMemento(_state);
// Adjust constraints for reversed movement
solver.Solve();
}
/// <summary>
/// This is just to try passing back in an invalid memento.
/// </summary>
public void BadExecute()
{
Console.WriteLine("\nBad Execute!\n");
ConstraintSolver solver = ConstraintSolver.Instance();
solver.ChangeState();
// Creating an object that is NOT a memento and storing it in the memento slot!
object graphic = new Graphic();
_state = graphic;
}
public void Unexecute()
{
Console.WriteLine("\nUndo!\n");
ConstraintSolver solver = ConstraintSolver.Instance();
// Reverse graphic movement
_delta.X = -_delta.X;
_delta.Y = -_delta.Y;
_target.Move(_delta);
// Restore state
solver.SetMemento(_state);
// Adjust constraints for reversed movement
solver.Solve();
}
public override void Execute()
{
Console.WriteLine("\nExecute!\n");
ConstraintSolver solver = ConstraintSolver.Instance();
// This is done just to show the current state.
solver.Solve();
// Create a memento
// Acting as caretaker by storing it here
_state = solver.CreateMemento();
// Move graphic
_target.Move(_delta);
// Adjust constraints for movement
solver.ChangeState();
solver.Solve();
}
