/// <summary>
/// Change the current state of UI, if allowed by timeouts
/// </summary>
/// <param name="newState">the state to change to</param>
/// <param name="choice">customer informatiom</param>
/// <param name="force">always change the state and update timer</param>
/// <returns>true iff the change was "officially" made (timeouts are reset)</returns>
/// Note: we want to prevent too frequent updates here so the customer can react to the prompts
public bool Update(ShoppingScreenState newState, ShoppingChoice choice = ShoppingChoice.TopLeft, bool force = false)
{
if (!force)
{
// Take care of the cases when there is no real change of state
if (newState == CurrentScreenState)
{
return(false); // keep waiting for change of state
}
TimeSpan sinceLastUpdate = DateTime.Now - lastStateChangeTime;
switch (CurrentScreenState)
{
// Delay state change to prevent flickering
case ShoppingScreenState.Selected:
if (sinceLastUpdate.TotalMilliseconds < 5000)
{
return(false); // let user to absorb the info
}
break;
case ShoppingScreenState.Choice:
if (sinceLastUpdate.TotalMilliseconds < 1000)
{
return(false); // wait for gaze stabilization
}
break;
}
}
// Now do change the state
switch (newState)
{
case ShoppingScreenState.Choice:
break;
case ShoppingScreenState.Selected:
SetSelectedSubstate(choice);
break;
}
lastStateChangeTime = DateTime.Now;
CurrentScreenState = newState;
return(true);
}
public Visibility IsSelected(ShoppingScreenState sss)
{
return(sss == ShoppingScreenState.Selected ? Visibility.Visible : Visibility.Collapsed);
}
// Helpers for function bindings
public Visibility IsChoice(ShoppingScreenState sss)
{
return(sss == ShoppingScreenState.Choice ? Visibility.Visible : Visibility.Collapsed);
}