Updated the ScreenManager class and added the previousDisplay methods allong with screen refresh rate

src/app/ScreenManager.cpp

@@ -1,6 +1,8 @@
 #include "ScreenManager.h"
 
-ScreenManager::ScreenManager(Adafruit_SSD1306 &display, SDCardManager *sdCardManager) : _displayRef(display), _displayColorInverted(false), _displayDimmed(false), _enabled(true), _currentView(NO_CURRENT_VIEW), _error(OK)
+ScreenManager::ScreenManager(Adafruit_SSD1306 &display, SDCardManager *sdCardManager) : _displayRef(display), _error(OK)
+, _displayColorInverted(false), _displayDimmed(false), _enabled(true), _refreshRateHz(1), _refreshInterval(1000), _timeRef(0),_forceRefresh(false)
+, _currentView(NO_CURRENT_VIEW), _tail(NULL)
 , _viewNotFound{&(displayError), (ErrorInfo *)malloc(sizeof(ErrorInfo)), RESERVED_VIEW_UID, NULL}
 , _viewFuncUndefined{&(displayError), (ErrorInfo *)malloc(sizeof(ErrorInfo)), RESERVED_VIEW_UID, NULL}
 , _currentViewUndefined{&(displayError), (ErrorInfo *)malloc(sizeof(ErrorInfo)), RESERVED_VIEW_UID, NULL}
@@ -8,6 +10,10 @@ ScreenManager::ScreenManager(Adafruit_SSD1306 &display, SDCardManager *sdCardMan
 ,_sdCardManager(sdCardManager)
 {  
   _viewLinkedList = (ViewLinkedList) createEmptyList();
+  //We set the error messages :
+  ((ErrorInfo *)_viewNotFound.pData)->errorMessage = FPSTR("View does not exist");
+  ((ErrorInfo *)_viewFunctionFailedToExecute.pData)->errorMessage = FPSTR("View function failed\nto execute");
+  ((ErrorInfo *)_viewFuncUndefined.pData)->errorMessage = FPSTR("View function is NULL");
 }
 
 boolean ScreenManager::init()
@@ -66,8 +72,8 @@ void ScreenManager::setDefault()
 
 boolean ScreenManager::addView(boolean (*viewLogicFunction)(Adafruit_SSD1306&, void*), void *pData, const unsigned char UID)
 {
-  ViewLink viewLink ={viewLogicFunction, pData, UID, NULL};
+  ViewLink viewLink ={viewLogicFunction, pData, UID, NULL, NULL};
-  addNewLinkAtTheEnd(&_viewLinkedList, viewLink);
+  return addNewLinkAtTheEnd(&_viewLinkedList, viewLink);
 }
 
 void *ScreenManager::createEmptyList()
@@ -87,33 +93,48 @@ boolean ScreenManager::addNewLinkAtTheEnd(ViewLinkedList *viewLinkedList, ViewLi
   //Because of the const member
   memcpy(newViewLink, &viewLink, sizeof(*newViewLink));
 
-  if(isListEmpty(*viewLinkedList))*viewLinkedList = newViewLink;
+  //If this is the first link
-  else
+  if(isListEmpty(*viewLinkedList))
   {
-    if((*viewLinkedList)->UID == newViewLink->UID)
+    //The link list points to the first link (aka the head)
+    *viewLinkedList = newViewLink;
+    //The previous pointer is still NULL;
+    //The _tail pointer is the same as the head one.
+    _tail = *viewLinkedList;
+  }
+  else //If there are some links already
+  {
+    ViewLinkedList *cursor = viewLinkedList;
+    ViewLink *previousLink = NULL;
+
+    while(*cursor != NULL)
     {
-        ViewLink *link = *viewLinkedList;
+      previousLink = *cursor;
-        *viewLinkedList = newViewLink;
+      //We check if the UID already exists, if yes we replace the link
-        newViewLink->next = link->next;
+      if((*cursor)->UID == newViewLink->UID)
-        free(link);
-        return true;
-    }
-    
-    ViewLinkedList cursor = *viewLinkedList;
-    
-    while(cursor->next != NULL)
-    {
-      if(cursor->next->UID == newViewLink->UID)
       {
-        ViewLink *link = cursor->next;
+        ViewLink *toDelete = *cursor;
-        cursor->next = newViewLink;
+        *cursor = newViewLink;
-        newViewLink->next = link->next;
+        newViewLink->next = toDelete->next;
-        free(link);
+        newViewLink->previous = toDelete->previous;
+        //We check if the link as a next link registered
+        if(toDelete->next != NULL)
+        {
+          //We update it's previous link since it's going to be deleted
+          toDelete->next->previous = newViewLink;
+        }
+        //We do not forget to check if the link replaced is also the tail, in this case, we must update the tail
+        if(_tail == toDelete)_tail = newViewLink;
+        free(toDelete);
+
         return true;
-       }
+      }
-      cursor = cursor->next;
+      cursor = &(*cursor)->next;
     }
-    cursor->next = newViewLink;
+    newViewLink->previous = previousLink;
+    *cursor = newViewLink;
+    //We need to update the tail
+    _tail = newViewLink;
   }
   
   return true;
@@ -128,25 +149,28 @@ boolean ScreenManager::removeLinkByUID(ViewLinkedList *viewLinkedList, const uns
 {
   if(isListEmpty(*viewLinkedList))return false;
 
-  if((*viewLinkedList)->UID == UID)
+  ViewLinkedList *cursor = viewLinkedList;
-  {
-    ViewLink *tmp = *viewLinkedList;
-    *viewLinkedList = (*viewLinkedList)->next;
-    free(tmp);
-    return true;
-  }
 
-  ViewLinkedList cursor = *viewLinkedList;
+  while(*cursor != NULL)
-  while(!isListEmpty(cursor->next))
   {
-    if(cursor->next->UID == UID)
+    //We check if this is the link we want to delete
+    if((*cursor)->UID == UID)
     {
-      ViewLink *tmp = cursor->next;
+      ViewLink *toDelete = *cursor;
-      cursor->next = cursor->next->next;
+      *cursor = (*cursor)->next;
-      free(tmp);
+
+      if(toDelete->next != NULL)
+      {
+        //We update the previous link of the next member since it's going to be deleted
+        toDelete->next->previous = toDelete->previous;
+      }
+      //We also update the tail if the link we delete was the tail
+      if(_tail == toDelete)_tail = toDelete->previous;
+
+      free(toDelete);
       return true;
-     }
+    }
-     cursor = cursor->next;
+    cursor = &(*cursor)->next;
   }
   return false;
 }
@@ -186,119 +210,135 @@ ViewLink* ScreenManager::getLinkByUID(ViewLinkedList viewLinkedList, const unsig
   return NULL;
 }
 
-boolean ScreenManager::displayView(const int UID)
+void ScreenManager::run()
+{
+  if((millis() - _timeRef < _refreshInterval && !_forceRefresh) || !_enabled) return;
+
+  _timeRef = millis();
+  
+  if(((_error == OK || _error == VIEW_FAILED_TO_EXECUTE) || _forceRefresh) && _currentView != NO_CURRENT_VIEW)
+  {
+    _displayRef.clearDisplay();
+    _displayRef.setCursor(0,0);
+    _displayRef.setTextSize(1);
+
+    switch(_error)
+    {
+      case OK:
+      case VIEW_FAILED_TO_EXECUTE:
+        if(!(*_currentView->viewLogicFunction)(_displayRef, _currentView->pData))
+        {
+          _displayRef.clearDisplay();
+          //Error while executing the view function
+          ((ErrorInfo *)_viewFunctionFailedToExecute.pData)->viewUID = _currentView->UID;
+          (*_viewFunctionFailedToExecute.viewLogicFunction)(_displayRef, _viewFunctionFailedToExecute.pData);
+        
+          _error = VIEW_FAILED_TO_EXECUTE;
+        }
+        else
+          _error = OK;
+       break;
+       case VIEW_NOT_FOUND:
+          (*_viewNotFound.viewLogicFunction)(_displayRef, _viewNotFound.pData);
+        break;
+       case VIEW_FUNC_UNDEFINED:
+          (*_viewFuncUndefined.viewLogicFunction)(_displayRef, _viewFuncUndefined.pData);
+        break;
+    }
+    
+    _displayRef.display();
+    _forceRefresh = false;
+  }
+}
+
+boolean ScreenManager::displayView(const uint8_t UID)
 {
   if(!_enabled) return true;
-  //Reset draw settings:
+  _forceRefresh = true;
-  _displayRef.clearDisplay();
-  _displayRef.setCursor(0,0);
-  _displayRef.setTextSize(1);
-  
-  
-  if(UID == -1 && _currentView == NO_CURRENT_VIEW)
-  {
-    //We display an error message on the screen
-    ((ErrorInfo *)_currentViewUndefined.pData)->errorMessage = FPSTR("Could not display current view");
-    ((ErrorInfo *)_currentViewUndefined.pData)->viewUID = UID;
-    (*_currentViewUndefined.viewLogicFunction)(_displayRef, _currentViewUndefined.pData);
-    _displayRef.display();
-
-    _error = CURRENT_VIEW_UNDEFINED;
-    return false;
-  }
-  else if(UID == -1)
-  {
-    if(_currentView->viewLogicFunction == NULL)
-    {
-      //We display an error message on the screen
-      ((ErrorInfo *)_viewFuncUndefined.pData)->errorMessage = FPSTR("View function is NULL");
-      ((ErrorInfo *)_viewFuncUndefined.pData)->viewUID = _currentView->UID;
-      (*_viewFuncUndefined.viewLogicFunction)(_displayRef, _viewFuncUndefined.pData);
-      _displayRef.display();
-
-      _error = VIEW_FUNC_UNDEFINED;
-      return false;
-    }
-    else if(!(*_currentView->viewLogicFunction)(_displayRef, _currentView->pData))
-    {
-      //We display an error message on the screen
-      _displayRef.clearDisplay();
-      ((ErrorInfo *)_viewFunctionFailedToExecute.pData)->errorMessage = FPSTR("View function failed\nto execute");
-      ((ErrorInfo *)_viewFunctionFailedToExecute.pData)->viewUID = _currentView->UID;
-      (*_viewFunctionFailedToExecute.viewLogicFunction)(_displayRef, _viewFunctionFailedToExecute.pData);
-      _displayRef.display();
-
-      _error = VIEW_FAILED_TO_EXECUTE;
-      return false;
-    }
-
-    _error = OK;
-    _displayRef.display();
-    return true;
-  }
-    
   ViewLink *viewLink = getLinkByUID(_viewLinkedList, UID);
+  
   if(viewLink == NULL)
   {
     //We display an error message on the screen
-    ((ErrorInfo *)_viewNotFound.pData)->errorMessage = FPSTR("View does not exist");
     ((ErrorInfo *)_viewNotFound.pData)->viewUID = UID;
-    (*_viewNotFound.viewLogicFunction)(_displayRef, _viewNotFound.pData);
-    _displayRef.display();
-
     _error = VIEW_NOT_FOUND;
-    _currentView = &_viewNotFound;
     return false;
-  }else if(viewLink->viewLogicFunction == NULL)
+  }
+  else if(viewLink->viewLogicFunction == NULL)
   {
     //We display an error message on the screen
-    ((ErrorInfo *)_viewFuncUndefined.pData)->errorMessage = FPSTR("View function is NULL");
     ((ErrorInfo *)_viewFuncUndefined.pData)->viewUID = UID;
-    (*_viewFuncUndefined.viewLogicFunction)(_displayRef, _viewFuncUndefined.pData);
-    _displayRef.display();
-
     _error = VIEW_FUNC_UNDEFINED;
     _currentView = viewLink;
     return false;
   }
-  
-  
-  if(!(*viewLink->viewLogicFunction)(_displayRef, viewLink->pData))
-  {
-    //We display an error message on the screen
-      _displayRef.clearDisplay();
-      ((ErrorInfo *)_viewFunctionFailedToExecute.pData)->errorMessage = FPSTR("View function failed\nto execute");
-      ((ErrorInfo *)_viewFunctionFailedToExecute.pData)->viewUID = UID;
-      (*_viewFunctionFailedToExecute.viewLogicFunction)(_displayRef, _viewFunctionFailedToExecute.pData);
-      _displayRef.display();
 
-      _error = VIEW_FAILED_TO_EXECUTE;
-      _currentView = viewLink;
-      return false;
-  }
-  
-  _displayRef.display();
   _currentView = viewLink;
   _error = OK;
-  return true;
+  run();
+  return _error == OK;
 }
 
-boolean ScreenManager::displayNextView()
+void ScreenManager::displayNextView()
 {
+  _forceRefresh = true;
+  _error = OK;
   if(_currentView == NO_CURRENT_VIEW && !isListEmpty(_viewLinkedList))
   {
     _currentView = _viewLinkedList;
-    return displayView();
   }
-    
+  else if(!isListEmpty(_currentView->next))
-  if(!isListEmpty(_currentView->next))
   {
     _currentView = _currentView->next;
-    return displayView();
+  }
+  //End of the views, we cycle again :)
+  else if(isListEmpty(_currentView->next) && !isListEmpty(_viewLinkedList))
+  {
+    _currentView = _viewLinkedList;
   }
 
-  _currentView = _viewLinkedList;
+  //We check if the view function is defined :
-  return displayView();
+  if(_currentView != NO_CURRENT_VIEW)
+  {
+    if(_currentView->viewLogicFunction == NULL)
+    {
+      ((ErrorInfo *)_viewFuncUndefined.pData)->viewUID = _currentView->UID;
+      _error = VIEW_FUNC_UNDEFINED;
+    }
+  }
+
+  run();
+}
+
+void ScreenManager::displayPreviousView()
+{
+  _forceRefresh = true;
+  _error = OK;
+  if(_currentView == NO_CURRENT_VIEW && !isListEmpty(_tail))
+  {
+    _currentView = _tail;
+  }
+  else if(!isListEmpty(_currentView->previous))
+  {
+    _currentView = _currentView->previous;
+  }
+  //End of the views, we cycle again :)
+  else if(isListEmpty(_currentView->previous) && !isListEmpty(_tail))
+  {
+    _currentView = _tail;
+  }
+
+  //We check if the view function is defined :
+  if(_currentView != NO_CURRENT_VIEW)
+  {
+    if(_currentView->viewLogicFunction == NULL)
+    {
+      ((ErrorInfo *)_viewFuncUndefined.pData)->viewUID = _currentView->UID;
+      _error = VIEW_FUNC_UNDEFINED;
+    }
+  }
+
+  run();
 }
 
 void ScreenManager::invertDisplayColor(const boolean inverted)
@@ -354,6 +394,20 @@ void ScreenManager::clearDisplay(const boolean bufferOnly)
   }
 }
 
+void ScreenManager::clearViews()
+{
+  ViewLinkedList cursor = _viewLinkedList;
+  while(!isListEmpty(cursor))
+  {
+    ViewLink *toDelete = cursor;
+    cursor = cursor->next;
+    free(cursor);
+  }
+  //Do not forget to mark the list as empty
+  _viewLinkedList = NULL;
+  _tail = NULL;
+}
+
 void ScreenManager::setEnabled(boolean value)
 {
   _enabled = value;

src/app/ScreenManager.h

@@ -16,18 +16,21 @@ class ScreenManager
   
     boolean addView(boolean (*viewLogicFunction)(Adafruit_SSD1306&, void*), void *pData, const unsigned char UID);
     boolean removeView(const unsigned char UID);
-    boolean displayView(const int UID = -1);
+    boolean displayView(const uint8_t UID);
-    boolean displayNextView();
+    void displayNextView();
+    void displayPreviousView();
     boolean applyCfgFromSD();
     void invertDisplayColor(const boolean inverted);
     void orientDisplay(const Orientation orientation);
     void dimDisplay(const boolean dimmed);
     void clearDisplay(const boolean bufferOnly = false);
+    void clearViews();
     void sleep();
     void wakeUp();
     void setEnabled(boolean value);
     boolean getEnabled();
     boolean init();
+    void run();
     
     Error getError() const;
     const char* getErrorMessage() const;
@@ -58,7 +61,11 @@ class ScreenManager
     boolean _displayColorInverted;
     boolean _displayDimmed;
     boolean _enabled;
-    ViewLink* _currentView;
+    uint8_t _refreshRateHz;
+    uint16_t _refreshInterval;
+    uint64_t _timeRef;
+    boolean _forceRefresh;
+    ViewLink *_currentView, *_tail;
     ViewLink _viewNotFound, _viewFuncUndefined, _currentViewUndefined, _viewFunctionFailedToExecute;
     SDCardManager *_sdCardManager;