[apps/graph/values] Change interval model

Change-Id: Iae085abd6bc975559b3204ef19bc25fe4eb4aba0

apps/graph/app.cpp

@@ -11,7 +11,7 @@ App::App(::Context * context) :
   m_listController(ListController(nullptr, &m_functionStore)),
   m_listStackViewController(StackViewController(&m_tabViewController, &m_listController)),
   m_graphController(GraphController(nullptr, &m_functionStore, &m_evaluateContext)),
-  m_valuesController(ValuesController(nullptr, &m_functionStore, &m_evaluateContext)),
+  m_valuesController(nullptr, &m_functionStore, &m_evaluateContext),
   m_valuesStackViewController(StackViewController(&m_tabViewController, &m_valuesController)),
   m_tabViewController(&m_inputViewController, &m_listStackViewController, &m_graphController, &m_valuesStackViewController),
   m_inputViewController(this, &m_tabViewController)

apps/graph/values/interval.cpp

@@ -3,24 +3,23 @@
 
 namespace Graph {
 
-Interval::Interval(float start, float end, float step) :
-  m_start(start),
-  m_end(end),
-  m_step(step)
+Interval::Interval() :
+  m_start(0),
+  m_end(0),
+  m_step(0),
+  m_needCompute(false)
 {
 }
 
 int Interval::numberOfElements() {
-  if (m_start > m_end) {
-    return 0;
-  } else {
-    return 1 + (m_end - m_start)/m_step;
-  }
+  computeElements();
+  return m_numberOfElements;
 }
 
 float Interval::element(int i) {
   assert(i >= 0 && i < numberOfElements());
-  return m_start + i*m_step;
+  computeElements();
+  return m_intervalBuffer[i];
 }
 
 float Interval::start() {
@@ -37,14 +36,39 @@ float Interval::step() {
 
 void Interval::setStart(float f) {
   m_start = f;
+  m_needCompute = true;
 }
 
 void Interval::setEnd(float f) {
   m_end = f;
+  m_needCompute = true;
 }
 
 void Interval::setStep(float f) {
   m_step = f;
+  m_needCompute = true;
+}
+
+void Interval::setElement(int i, float f) {
+  assert(i < numberOfElements());
+  computeElements();
+  m_intervalBuffer[i] = f;
+}
+
+void Interval::computeElements() {
+  if (!m_needCompute) {
+    return;
+  }
+  if ( m_start > m_end) {
+    m_numberOfElements = 0;
+  } else {
+    m_numberOfElements = m_step > 0 ? 1 + (m_end - m_start)/m_step : k_maxNumberOfElements;
+    m_numberOfElements = m_numberOfElements > k_maxNumberOfElements ? k_maxNumberOfElements : m_numberOfElements;
+  }
+  for (int i = 0; i < m_numberOfElements; i += 1) {
+    m_intervalBuffer[i] = m_start + i * m_step;
+  }
+  m_needCompute = false;
 }
 
 }

apps/graph/values/interval.h

@@ -5,8 +5,9 @@ namespace Graph {
 
 class Interval {
 public:
-  Interval(float start, float end, float step);
-
+  Interval();
+  // Delete the implicit copy constructor: the object is heavy
+  Interval(const Interval&) = delete;
   int numberOfElements();
   float element(int i);
   float start();
@@ -15,11 +16,17 @@ public:
   void setStart(float f);
   void setEnd(float f);
   void setStep(float f);
-
+  void setElement(int i, float f);
 private:
+  // TODO: decide the max number of elements after optimization
+  constexpr static int k_maxNumberOfElements = 500;
+  void computeElements();
+  int m_numberOfElements;
+  float m_intervalBuffer[k_maxNumberOfElements];
   float m_start;
   float m_end;
   float m_step;
+  bool m_needCompute;
 };
 
 }

apps/graph/values/values_controller.cpp

@@ -10,7 +10,6 @@ ValuesController::ValuesController(Responder * parentResponder, FunctionStore *
   m_activeCellY(-1),
   m_functionStore(functionStore),
   m_evaluateContext(evaluateContext),
-  m_interval(Interval(-1.0f, 1.0f, 0.25f)),
   m_parameterController(ValuesParameterController(this, &m_interval)),
   m_setIntervalButton(Button(this, "Regler l'intervalle",Invocation([](void * context, void * sender) {
     ValuesController * valuesController = (ValuesController *) context;
@@ -18,6 +17,9 @@ ValuesController::ValuesController(Responder * parentResponder, FunctionStore *
     stack->push(valuesController->parameterController());
   }, this)))
 {
+  m_interval.setStart(0);
+  m_interval.setEnd(10);
+  m_interval.setStep(1);
 }
 
 const char * ValuesController::title() const {