private void LoadSurvey()
{
QuestionView v = vg.InitialQuestion();
InitializePropertyCallback(v);
surveyContent.Children.Insert(0, v);
}
public void OnNextClicked(object sender, EventArgs args)
{
QuestionView v = vg.NextQuestion();
if (v == null)
{
DisplayAlert("Done!", "Thank you for filling the survey", "Submit", "Change").ContinueWith(t =>
{
if (t.Result == true)
{
IOController.WriteSurveyResult(vg.SurveyScheme, vg.CurrentViews);
_tflp.Reschedule();
this.navigationContent.Navigation.PopAsync();
this.navigationContent.Navigation.PopAsync();
}
}, TaskScheduler.FromCurrentSynchronizationContext());
}
else
{
InitializePropertyCallback(v);
surveyContent.Children.RemoveAt(0);
surveyContent.Children.Insert(0, v);
this.goToNextButton.IsEnabled = v.IsAnswered;
this.goToPreviousButton.IsEnabled = true;
}
}
// when reading from a saved survey TODO
// public ViewGenerator (List<QuestionView> aq, Survey s) : this(s)
// {
// generatedViews = aq;
// }
/// <summary>
/// Moves to the next question
/// </summary>
/// <returns>The next question.</returns>
public QuestionView NextQuestion()
{
QuestionView oldView = generatedViews [currentQuestion.Value];
// loop as long as we have a next question in the survey definition
while (ProgressQuestion())
{
QuestionView newView = null;
if (generatedViews.ContainsKey(currentQuestion.Value))
{
newView = generatedViews [currentQuestion.Value];
}
else
{
newView = GetQuestionView(currentQuestion.Value);
generatedViews.Add(currentQuestion.Value, newView);
}
LinkedList <QuestionView> preqViewList = new LinkedList <QuestionView> ();
foreach (Prerequisite p in currentQuestion.Value.Prerequisites)
{
QuestionView q;
if (generatedViews.TryGetValue(p.Question, out q))
{
if (CurrentViews.Find(generatedViews [q.question]) != null)
{
preqViewList.AddLast(generatedViews [p.Question]);
}
}
}
if (PrerequisiteController.calculatePrerequisite(currentQuestion.Value, preqViewList))
{
if (CurrentViews.Find(newView) == null)
{
CurrentViews.AddAfter(CurrentViews.Find(oldView), newView);
}
return(newView);
}
else
{
if (CurrentViews.Find(newView) != null)
{
CurrentViews.Remove(CurrentViews.Find(generatedViews [currentQuestion.Value]));
}
}
}
return(null);
}
/// <summary>
/// Gets initial question
/// </summary>
/// <returns>The initial question.</returns>
public QuestionView InitialQuestion()
{
// empty initialization
CurrentViews = new LinkedList <QuestionView> ();
generatedViews = new Dictionary <QuestionReference, QuestionView> ();
currentSurveyPart = SurveyScheme.SurveyParts.First;
currentQuestion = currentSurveyPart.Value.Questions.First;
QuestionView currentQuestionView = GetQuestionView(currentQuestion.Value);
generatedViews.Add(currentQuestion.Value, currentQuestionView);
CurrentViews.AddLast(currentQuestionView);
return(currentQuestionView);
}
private void InitializePropertyCallback(QuestionView v)
{
v.PropertyChanged += (object sender, PropertyChangedEventArgs e) => {
switch (e.PropertyName)
{
case "IsAnswered":
if (((QuestionView)sender).IsAnswered == true)
{
this.goToNextButton.IsEnabled = true;
}
else
{
this.goToNextButton.IsEnabled = false;
}
break;
}
};
}
public void OnPreviousClicked(object sender, EventArgs args)
{
QuestionView v = vg.PreviousQuestion();
if (v != null)
{
InitializePropertyCallback(v);
this.goToNextButton.IsEnabled = v.IsAnswered;
this.goToPreviousButton.IsEnabled = true;
surveyContent.Children.RemoveAt(0);
surveyContent.Children.Insert(0, v);
}
else
{
this.goToPreviousButton.IsEnabled = false;
// TODO go to the main menu? But HW button available
}
}
/// <summary>
/// Moves to the previous question.
/// </summary>
/// <returns>The previous question.</returns>
public QuestionView PreviousQuestion()
{
QuestionView currentView = generatedViews [currentQuestion.Value];
LinkedListNode <QuestionView> currentViewNode = CurrentViews.Find(currentView);
if (currentViewNode.Previous == null)
{
return(null);
}
QuestionView previousView = currentViewNode.Previous.Value;
QuestionReference previousReference = previousView.question;
while (currentQuestion.Value != previousReference)
{
if (!RegressQuestion())
{
throw new ArgumentOutOfRangeException("Could not find the predecessor for the question");
}
}
return(previousView);
}
