[escher] Add methods viewWillAppear/Disappear in view controller instead

of keeping track of dataHasChanged in the selectable table view

Change-Id: Id2626f527f44714e29b9bd66e2c843193e1b57b5

apps/graph/list/list_controller.cpp

@@ -85,7 +85,6 @@ void ListController::editExpression(FunctionExpressionCell * functionCell, Ion::
     },
     [](void * context, void * sender){
     });
-  m_selectableTableView.dataHasChanged(true);
 }
 
 ListParameterController * ListController::parameterController() {
@@ -110,8 +109,6 @@ void ListController::configureFunction(Shared::Function * function) {
   StackViewController * stack = stackController();
   parameterController()->setFunction(function);
   stack->push(parameterController());
-  // Force to reload the table (deleted functions, desactivated function)
-  m_selectableTableView.dataHasChanged(true);
 }
 
 void ListController::willDisplayTitleCellAtIndex(TableViewCell * cell, int j) {

apps/graph/values/function_parameter_controller.cpp

@@ -35,7 +35,7 @@ void FunctionParameterController::setFunction(Function * function) {
 }
 
 void FunctionParameterController::didBecomeFirstResponder() {
-  m_selectableTableView.dataHasChanged(true);
+  m_selectableTableView.reloadData();
   m_selectableTableView.selectCellAtLocation(0, 0);
   app()->setFirstResponder(&m_selectableTableView);
 }

apps/graph/values/values_controller.cpp

@@ -25,7 +25,6 @@ ValuesController::ValuesController(Responder * parentResponder, FunctionStore *
   m_derivativeParameterController(DerivativeParameterController(this)),
   m_setIntervalButton(Button(this, "Regler l'intervalle",Invocation([](void * context, void * sender) {
     ValuesController * valuesController = (ValuesController *) context;
-    valuesController->hasChangedTableData();
     StackViewController * stack = ((StackViewController *)valuesController->stackController());
     stack->push(valuesController->intervalParameterController());
   }, this), KDText::FontSize::Small)),
@@ -83,20 +82,16 @@ bool ValuesController::handleEvent(Ion::Events::Event event) {
   }
   if (event == Ion::Events::OK) {
     if (activeRow() == -1) {
-      m_selectableTableView.dataHasChanged(true);
       return headerViewController()->handleEvent(event);
     }
     if (activeRow() == 0) {
       if (activeColumn() == 0) {
-        m_selectableTableView.dataHasChanged(true);
         configureAbscissa();
         return true;
       }
       if (isDerivativeColumn(activeColumn())) {
-        m_selectableTableView.dataHasChanged(true);
         configureDerivativeFunction();
       } else {
-        m_selectableTableView.dataHasChanged(true);
         configureFunction();
       }
       return true;
@@ -291,10 +286,6 @@ Responder * ValuesController::defaultController() {
   return tabController();
 }
 
-void ValuesController::hasChangedTableData() {
-  m_selectableTableView.dataHasChanged(true);
-}
-
 void ValuesController::selectCellAtLocation(int i, int j) {
   m_selectableTableView.selectCellAtLocation(i, j);
 }

apps/graph/values/values_controller.h

@@ -35,7 +35,6 @@ public:
   bool isEmpty() const override;
   const char * emptyMessage() override;
   Responder * defaultController() override;
-  void hasChangedTableData();
   void selectCellAtLocation(int i, int j);
   int activeRow();
   int activeColumn();

apps/node_list_view_controller.cpp

@@ -25,6 +25,7 @@ Node * NodeListViewController::nodeModel() {
 
 void NodeListViewController::setNodeModel(Node * nodeModel) {
   m_nodeModel = nodeModel;
+  m_selectableTableView.reloadData();
 }
 
 void NodeListViewController::setFirstSelectedRow(int firstSelectedRow) {

apps/probability/image_table_view.cpp

@@ -59,7 +59,7 @@ void ImageTableView::setCalculation(Calculation * calculation, int index) {
 }
 
 void ImageTableView::didBecomeFirstResponder() {
-  m_selectableTableView.dataHasChanged(true);
+  m_selectableTableView.reloadData();
   m_isSelected = true;
   if (m_selectableTableView.selectedRow() == -1) {
     m_selectableTableView.selectCellAtLocation(0, 0);

apps/regression/calculation_controller.cpp

@@ -220,6 +220,10 @@ int CalculationController::typeAtLocation(int i, int j) {
   return 3;
 }
 
+void CalculationController::viewWillAppear() {
+  m_selectableTableView.reloadData();
+}
+
 Responder * CalculationController::tabController() const {
   return (parentResponder()->parentResponder()->parentResponder());
 }

apps/regression/calculation_controller.h

@@ -33,6 +33,7 @@ public:
   TableViewCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
   int typeAtLocation(int i, int j) override;
+  void viewWillAppear() override;
 private:
   Responder * tabController() const;
   constexpr static int k_totalNumberOfRows = 11;

apps/sequence/list/change_type_parameter_controller.cpp

@@ -33,7 +33,7 @@ View * ChangeTypeParameterController::view() {
 }
 
 void ChangeTypeParameterController::didBecomeFirstResponder() {
-  m_selectableTableView.dataHasChanged(true);
+  m_selectableTableView.reloadData();
   m_selectableTableView.selectCellAtLocation(0, 0);
   app()->setFirstResponder(&m_selectableTableView);
 }

apps/sequence/list/list_controller.cpp

@@ -58,7 +58,7 @@ bool ListController::handleEvent(Ion::Events::Event event) {
   }
   if (event == Ion::Events::OK && m_selectableTableView.selectedColumn() == 1
       && m_selectableTableView.selectedRow() == numberOfRows() - 1) {
-    m_selectableTableView.dataHasChanged(true);
+    m_selectableTableView.reloadData();
     app()->displayModalViewController(&m_typeStackController, 0.f, 0.f, 32, 20, 20, 20);
     return true;
   }

apps/sequence/list/sequence_title_cell.cpp

@@ -105,7 +105,7 @@ bool SequenceTitleCell::handleEvent(Ion::Events::Event event) {
     m_listParameterController->setSequence(m_sequence);
     stack->push(m_listParameterController);
     SelectableTableView * table = (SelectableTableView *)parentResponder();
-    table->dataHasChanged(true);
+    table->reloadData();
     return true;
   }
   return false;

apps/sequence/list/type_parameter_controller.cpp

@@ -35,7 +35,7 @@ View * TypeParameterController::view() {
 }
 
 void TypeParameterController::didBecomeFirstResponder() {
-  m_selectableTableView.dataHasChanged(true);
+  m_selectableTableView.reloadData();
   m_selectableTableView.selectCellAtLocation(0, 0);
   app()->setFirstResponder(&m_selectableTableView);
 }

apps/settings/main_controller.cpp

@@ -35,7 +35,6 @@ View * MainController::view() {
 }
 
 void MainController::didBecomeFirstResponder() {
-  m_selectableTableView.dataHasChanged(true);
   if (m_selectableTableView.selectedRow() < 0) {
     m_selectableTableView.selectCellAtLocation(0, 0);
   }
@@ -45,7 +44,6 @@ void MainController::didBecomeFirstResponder() {
 bool MainController::handleEvent(Ion::Events::Event event) {
   if (event == Ion::Events::OK) {
     m_subController.setNodeModel(m_nodeModel->children(m_selectableTableView.selectedRow()), m_selectableTableView.selectedRow());
-    m_selectableTableView.dataHasChanged(true);
     StackViewController * stack = stackController();
     stack->push(&m_subController);
   }
@@ -92,6 +90,10 @@ void MainController::willDisplayCellForIndex(TableViewCell * cell, int index) {
   }
 }
 
+void MainController::viewWillAppear() {
+  m_selectableTableView.reloadData();
+}
+
 StackViewController * MainController::stackController() const {
   return (StackViewController *)parentResponder();
 }

apps/settings/main_controller.h

@@ -21,6 +21,7 @@ public:
   TableViewCell * reusableCell(int index) override;
   int reusableCellCount() override;
   void willDisplayCellForIndex(TableViewCell * cell, int index) override;
+  void viewWillAppear() override;
 private:
   StackViewController * stackController() const;
   constexpr static int k_totalNumberOfCell = 5;

apps/settings/sub_controller.cpp

@@ -30,7 +30,6 @@ View * SubController::view() {
 }
 
 void SubController::didBecomeFirstResponder() {
-  m_selectableTableView.dataHasChanged(true);
   m_selectableTableView.selectCellAtLocation(0, valueIndexAtPreferenceIndex(m_preferenceIndex));
   app()->setFirstResponder(&m_selectableTableView);
 }
@@ -77,6 +76,10 @@ void SubController::setNodeModel(const Node * nodeModel, int preferenceIndex) {
   m_preferenceIndex = preferenceIndex;
 }
 
+void SubController::viewWillAppear() {
+  m_selectableTableView.reloadData();
+}
+
 StackViewController * SubController::stackController() const {
   return (StackViewController *)parentResponder();
 }

apps/settings/sub_controller.h

@@ -20,6 +20,7 @@ public:
   int reusableCellCount() override;
   void willDisplayCellForIndex(TableViewCell * cell, int index) override;
   void setNodeModel(const Node * nodeModel, int preferenceIndex);
+  void viewWillAppear() override;
 private:
   StackViewController * stackController() const;
   void setPreferenceAtIndexWithValueIndex(int preferenceIndex, int valueIndex);

apps/shared/editable_cell_table_view_controller.cpp

@@ -78,14 +78,16 @@ void EditableCellTableViewController::willDisplayCellAtLocationWithDisplayMode(T
     if (j == numberOfRows() - 1) {
       /* Display an empty line only if there is enough space for a new element in
        * data */
-      if (numberOfElements() < maxNumberOfElements()) {
+      if (numberOfElements() < maxNumberOfElements() && !myEditableValueCell->isEditing()) {
         buffer[0] = 0;
         myEditableValueCell->setText(buffer);
         return;
       }
     }
-    Complex::convertFloatToText(dataAtLocation(i, j), buffer, Complex::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits), Constant::LargeNumberOfSignificantDigits, displayMode);
-    myEditableValueCell->setText(buffer);
+    if (!myEditableValueCell->isEditing()) {
+      Complex::convertFloatToText(dataAtLocation(i, j), buffer, Complex::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits), Constant::LargeNumberOfSignificantDigits, displayMode);
+      myEditableValueCell->setText(buffer);
+    }
     return;
   }
 }
@@ -103,4 +105,9 @@ void EditableCellTableViewController::didBecomeFirstResponder() {
   app()->setFirstResponder(&m_selectableTableView);
 }
 
+
+void EditableCellTableViewController::viewWillAppear() {
+  m_selectableTableView.reloadData();
+}
+
 }

apps/shared/editable_cell_table_view_controller.h

@@ -23,6 +23,7 @@ public:
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
 
   void didBecomeFirstResponder() override;
+  void viewWillAppear() override;
 protected:
   SelectableTableView m_selectableTableView;
 private:

apps/shared/list_controller.cpp

@@ -159,6 +159,10 @@ bool ListController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
+void ListController::viewWillAppear() {
+  m_selectableTableView.reloadData();
+}
+
 StackViewController * ListController::stackController() const{
   return (StackViewController *)(parentResponder()->parentResponder());
 }

apps/shared/list_controller.h

@@ -26,6 +26,7 @@ public:
   void willDisplayCellAtLocation(TableViewCell * cell, int i, int j) override;
   void didBecomeFirstResponder() override;
   bool handleEvent(Ion::Events::Event event) override;
+  void viewWillAppear() override;
 protected:
   static constexpr KDCoordinate k_emptyRowHeight = 50;
   StackViewController * stackController() const;

apps/shared/list_parameter_controller.cpp

@@ -23,7 +23,7 @@ View * ListParameterController::view() {
 }
 
 void ListParameterController::didBecomeFirstResponder() {
-  m_selectableTableView.dataHasChanged(true);
+  m_selectableTableView.reloadData();
   if (m_selectableTableView.selectedRow() == -1) {
     m_selectableTableView.selectCellAtLocation(0, 0);
   } else {

apps/shared/store_controller.cpp

@@ -79,7 +79,6 @@ bool StoreController::handleEvent(Ion::Events::Event event) {
   }
   if (event == Ion::Events::OK && m_selectableTableView.selectedRow() == 0) {
     m_storeParameterController.selectXColumn(m_selectableTableView.selectedColumn() == 0);
-    m_selectableTableView.dataHasChanged(true);
     StackViewController * stack = ((StackViewController *)parentResponder()->parentResponder());
     stack->push(&m_storeParameterController);
     return true;

apps/statistics/calculation_controller.cpp

@@ -136,6 +136,10 @@ int CalculationController::typeAtLocation(int i, int j) {
   return i;
 }
 
+void CalculationController::viewWillAppear() {
+  m_selectableTableView.reloadData();
+}
+
 Responder * CalculationController::tabController() const {
   return (parentResponder()->parentResponder()->parentResponder());
 }

apps/statistics/calculation_controller.h

@@ -31,6 +31,7 @@ public:
   TableViewCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
   int typeAtLocation(int i, int j) override;
+  void viewWillAppear() override;
 private:
   Responder * tabController() const;
   constexpr static int k_totalNumberOfRows = 13;

escher/include/escher/alternate_empty_view_controller.h

@@ -12,6 +12,8 @@ public:
   const char * title() const override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
+  void viewWillAppear() override;
+  void viewWillDisappear() override;
 private:
   class ContentView : public View {
   public:

escher/include/escher/app.h

@@ -22,7 +22,6 @@ class App : public Responder {
 public:
   constexpr static uint8_t Magic = 0xA8;
   App(Container * container, ViewController * rootViewController, const char * name = nullptr, const char * upperName = nullptr, const Image * icon = nullptr);
-  void setWindow(Window * window);
   void setFirstResponder(Responder * responder);
   Responder * firstResponder();
   void processEvent(Ion::Events::Event event);
@@ -35,6 +34,11 @@ public:
   const char * upperName();
   const Image * icon();
   uint8_t m_magic; // Poor man's RTTI
+
+
+  virtual void didBecomeActive(Window * window);
+  virtual void willBecomeInactive();
+
 protected:
   ModalViewController m_modalViewController;
 private:

escher/include/escher/editable_text_cell.h

@@ -18,6 +18,7 @@ public:
   View * subviewAtIndex(int index) override;
   void layoutSubviews() override;
   void didBecomeFirstResponder() override;
+  bool isEditing();
   void setEditing(bool isEditing);
   constexpr static int k_bufferLength = 255;
 private:

escher/include/escher/even_odd_editable_text_cell.h

@@ -17,6 +17,7 @@ public:
   View * subviewAtIndex(int index) override;
   void layoutSubviews() override;
   void didBecomeFirstResponder() override;
+  bool isEditing();
   void setEditing(bool isEditing);
 private:
   EditableTextCell m_editableCell;

escher/include/escher/header_view_controller.h

@@ -16,6 +16,8 @@ public:
   void didBecomeFirstResponder() override;
   bool handleEvent(Ion::Events::Event event) override;
   bool setSelectedButton(int selectedButton);
+  void viewWillAppear() override;
+  void viewWillDisappear() override;
 private:
   class ContentView : public View {
   public:

escher/include/escher/modal_view_controller.h

@@ -16,6 +16,8 @@ public:
     KDCoordinate topMargin = 0, KDCoordinate leftMargin = 0,  KDCoordinate bottomMargin = 0, KDCoordinate rightMargin = 0);
   void dismissModalViewController();
   bool isDisplayingModal();
+  void viewWillAppear() override;
+  void viewWillDisappear() override;
 private:
   class ContentView : public View {
   public:

escher/include/escher/selectable_table_view.h

@@ -30,13 +30,11 @@ public:
   void deselectTable();
   bool selectCellAtLocation(int i, int j);
   TableViewCell * selectedCell();
-  void dataHasChanged(bool dataHasChanged);
 protected:
   SelectableTableViewDelegate * m_delegate;
 private:
   int m_selectedCellX;
   int m_selectedCellY;
-  bool m_dataHasChanged;
 };
 
 #endif

escher/include/escher/stack_view_controller.h

@@ -21,6 +21,8 @@ public:
   const char * title() const override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
+  void viewWillAppear() override;
+  void viewWillDisappear() override;
 private:
   class ControllerView : public View {
   public:

escher/include/escher/tab_view_controller.h

@@ -17,6 +17,8 @@ public:
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
   void didResignFirstResponder() override;
+  void viewWillAppear() override;
+  void viewWillDisappear() override;
 private:
   class ContentView : public View {
   public:

escher/include/escher/view_controller.h

@@ -19,6 +19,8 @@ public:
   ViewController(Responder * parentResponder);
   virtual const char * title() const;
   virtual View * view() = 0;
+  virtual void viewWillAppear();
+  virtual void viewWillDisappear();
 };
 
 #endif

escher/src/alternate_empty_view_controller.cpp

@@ -74,3 +74,15 @@ void AlternateEmptyViewController::didBecomeFirstResponder() {
     app()->setFirstResponder(m_contentView.mainViewController());
   }
 }
+
+void AlternateEmptyViewController::viewWillAppear() {
+  if (!m_contentView.alternateEmptyViewDelegate()->isEmpty()) {
+    m_contentView.mainViewController()->viewWillAppear();
+  }
+}
+
+void AlternateEmptyViewController::viewWillDisappear() {
+  if (!m_contentView.alternateEmptyViewDelegate()->isEmpty()) {
+    m_contentView.mainViewController()->viewWillDisappear();
+  }
+}

escher/src/app.cpp

@@ -17,16 +17,6 @@ App::App(Container * container, ViewController * rootViewController, const char
 {
 }
 
-void App::setWindow(Window * window) {
-  View * view = m_modalViewController.view();
-  assert(m_modalViewController.app() == this);
-  window->setContentView(view);
-  if (m_firstResponder == nullptr) {
-    setFirstResponder(&m_modalViewController);
-  }
-  window->redraw();
-}
-
 void App::processEvent(Ion::Events::Event event) {
   Responder * responder = m_firstResponder;
   bool didHandleEvent = false;
@@ -81,4 +71,19 @@ void App::displayWarning(const char * warningMessage) {
 
 const Container * App::container() const {
   return m_container;
-}
+}
+
+void App::didBecomeActive(Window * window) {
+  View * view = m_modalViewController.view();
+  assert(m_modalViewController.app() == this);
+  window->setContentView(view);
+  if (m_firstResponder == nullptr) {
+    setFirstResponder(&m_modalViewController);
+  }
+  window->redraw();
+  m_modalViewController.viewWillAppear();
+}
+
+void App::willBecomeInactive() {
+  m_modalViewController.viewWillDisappear();
+}

escher/src/container.cpp

@@ -10,8 +10,13 @@ Container::Container() :
 }
 
 void Container::switchTo(App * app) {
+  if (m_activeApp) {
+    m_activeApp->willBecomeInactive();
+  }
   m_activeApp = app;
-  m_activeApp->setWindow(window());
+  if (m_activeApp) {
+    m_activeApp->didBecomeActive(window());
+  }
 }
 
 App * Container::activeApp() {

escher/src/editable_text_cell.cpp

@@ -48,6 +48,10 @@ void EditableTextCell::didBecomeFirstResponder() {
   app()->setFirstResponder(&m_textField);
 }
 
+bool EditableTextCell::isEditing() {
+  return m_textField.isEditing();
+}
+
 void EditableTextCell::setEditing(bool isEditing) {
   m_textField.setEditing(isEditing);
 }

escher/src/even_odd_editable_text_cell.cpp

@@ -48,6 +48,10 @@ void EvenOddEditableTextCell::didBecomeFirstResponder() {
   app()->setFirstResponder(&m_editableCell);
 }
 
+bool EvenOddEditableTextCell::isEditing() {
+  return m_editableCell.isEditing();
+}
+
 void EvenOddEditableTextCell::setEditing(bool isEditing) {
   m_editableCell.setEditing(isEditing);
 }

escher/src/header_view_controller.cpp

@@ -131,3 +131,11 @@ bool HeaderViewController::handleEvent(Ion::Events::Event event) {
   }
   return false;
 }
+
+void HeaderViewController::viewWillAppear() {
+  m_contentView.mainViewController()->viewWillAppear();
+}
+
+void HeaderViewController::viewWillDisappear() {
+  m_contentView.mainViewController()->viewWillDisappear();
+}

escher/src/modal_view_controller.cpp

@@ -115,14 +115,18 @@ void ModalViewController::displayModalViewController(ViewController * vc, float
   m_currentModalViewController = vc;
   vc->setParentResponder(this);
   m_previousResponder = app()->firstResponder();
+  m_regularViewController->viewWillDisappear();
   m_contentView.presentModalView(vc->view(), verticalAlignment, horizontalAlignment, topMargin, leftMargin, bottomMargin, rightMargin);
   app()->setFirstResponder(vc);
+  m_currentModalViewController->viewWillAppear();
 }
 
 void ModalViewController::dismissModalViewController() {
+  m_currentModalViewController->viewWillDisappear();
   m_currentModalViewController = nullptr;
   app()->setFirstResponder(m_previousResponder);
   m_contentView.dismissModalView();
+  m_regularViewController->viewWillAppear();
 }
 
 void ModalViewController::didBecomeFirstResponder() {
@@ -142,3 +146,17 @@ bool ModalViewController::handleEvent(Ion::Events::Event event) {
   }
   return false;
 }
+
+void ModalViewController::viewWillAppear() {
+  if (m_contentView.isDisplayingModal()) {
+    m_currentModalViewController->viewWillAppear();
+  }
+  m_regularViewController->viewWillAppear();
+}
+
+void ModalViewController::viewWillDisappear() {
+  if (m_contentView.isDisplayingModal()) {
+    m_currentModalViewController->viewWillDisappear();
+  }
+  m_regularViewController->viewWillDisappear();
+}

escher/src/selectable_table_view.cpp

@@ -9,8 +9,7 @@ SelectableTableView::SelectableTableView(Responder * parentResponder, TableViewD
   Responder(parentResponder),
   m_delegate(delegate),
   m_selectedCellX(0),
-  m_selectedCellY(-1),
-  m_dataHasChanged(true)
+  m_selectedCellY(-1)
 {
 }
 
@@ -27,11 +26,6 @@ int SelectableTableView::selectedColumn() {
 }
 
 void SelectableTableView::didBecomeFirstResponder() {
-  if (m_dataHasChanged) {
-    reloadData();
-    scrollToCell(m_selectedCellX, m_selectedCellY);
-    m_dataHasChanged = false;
-  }
   if (m_delegate) {
     m_delegate->tableViewDidChangeSelection(this, 0, -1);
   }
@@ -98,7 +92,3 @@ bool SelectableTableView::handleEvent(Ion::Events::Event event) {
   }
   return false;
 }
-
-void SelectableTableView::dataHasChanged(bool dataHasChanged) {
-  m_dataHasChanged = dataHasChanged;
-}

escher/src/stack_view_controller.cpp

@@ -91,6 +91,10 @@ void StackViewController::push(ViewController * vc, KDColor textColor, KDColor b
   m_view.pushStack(vc->title(), textColor, backgroundColor, separatorColor);
   m_children[m_numberOfChildren++] = vc;
   setupActiveViewController();
+  if (m_numberOfChildren > 1) {
+    m_children[m_numberOfChildren-2]->viewWillDisappear();
+  }
+  vc->viewWillAppear();
 }
 
 void StackViewController::pop() {
@@ -100,6 +104,8 @@ void StackViewController::pop() {
   vc->setParentResponder(nullptr);
   m_numberOfChildren--;
   setupActiveViewController();
+  vc->viewWillDisappear();
+  m_children[m_numberOfChildren-1]->viewWillAppear();
 }
 
 void StackViewController::setupActiveViewController() {
@@ -129,3 +135,17 @@ bool StackViewController::handleEvent(Ion::Events::Event event) {
 View * StackViewController::view() {
   return &m_view;
 }
+
+void StackViewController::viewWillAppear() {
+  ViewController * vc = m_children[m_numberOfChildren-1];
+  if (m_numberOfChildren > 0 && vc) {
+    vc->viewWillAppear();
+  }
+}
+
+void StackViewController::viewWillDisappear() {
+  ViewController * vc = m_children[m_numberOfChildren-1];
+  if (m_numberOfChildren > 0 && vc) {
+    vc->viewWillDisappear();
+  }
+}

escher/src/tab_view_controller.cpp

@@ -94,12 +94,17 @@ bool TabViewController::handleEvent(Ion::Events::Event event) {
 void TabViewController::setActiveTab(int8_t i) {
   ViewController * activeVC = m_children[i];
   if (i  != m_activeChildIndex) {
-    //TODO assert(i <= m_numberOfchildren);
+    assert(i <= m_numberOfChildren);
     m_view.setActiveView(activeVC->view());
     m_view.m_tabView.setActiveIndex(i);
+    if (m_activeChildIndex >= 0) {
+      m_children[m_activeChildIndex]->viewWillDisappear();
+    }
     m_activeChildIndex = i;
-  }
-
+    if (i >= 0) {
+      m_children[i]->viewWillAppear();
+    }
+  } else {}
   app()->setFirstResponder(activeVC);
 }
 
@@ -141,3 +146,13 @@ uint8_t TabViewController::numberOfTabs() {
 const char * TabViewController::tabName(uint8_t index) {
   return m_children[index]->title();
 }
+
+void TabViewController::viewWillAppear() {
+  ViewController * activeVC = m_children[m_activeChildIndex];
+  activeVC->viewWillAppear();
+}
+
+void TabViewController::viewWillDisappear() {
+  ViewController * activeVC = m_children[m_activeChildIndex];
+  activeVC->viewWillDisappear();
+}

escher/src/view_controller.cpp

@@ -8,3 +8,9 @@ ViewController::ViewController(Responder * parentResponder) :
 const char * ViewController::title() const {
   return nullptr;
 }
+
+void ViewController::viewWillAppear() {
+}
+
+void ViewController::viewWillDisappear() {
+}