Callback Feature

The section is an introduction to callback functions in C++ and Lua.

C++

1 Click the root node as illustrated.

2 In the Properties panel, choose Advanced -> CallBack Feature -> Custom Class, name the Custom class, for example, MyClass.

3 Select the widget that needs to add callback feature, then select Properties -> Advanced -> Callback method, and name the method. For example: select Touch, and name it as onTouch.

4 Create a customized class in C++. The class must conform the following requirements.

• Inherit WidgetCallBackHandlerProtocol & Node (or other classes inherited from node ).

• Overwrite the following interfaces:

  onLocateTouchCallback 
  
  onLocateClickCallback 
  
  onLocateEventCallback 
  

  Go back to the handlers of Touch, Click and Event (You can choose to edit the callback property that has been used). For example,

  //.h file 
  

  #ifndef TestCppMyClass
  #define TestCppMyClass
  #include “cocos2d.h”
  #include “cocostudio/CocoStudio.h”
  #include “cocostudio/WidgetCallBackHandlerProtocol.h”
  class MyClass : public cocos2d::Node, public cocostudio::WidgetCallBackHandlerProtocol
  {
  public:

  CREATE_FUNC(MyClass) 
  MyClass(); 
  virtual cocos2d::ui::Widget::ccWidgetTouchCallback 
  onLocateTouchCallback(const std::string &callBackName); 
  virtual cocos2d::ui::Widget::ccWidgetClickCallback 
  onLocateClickCallback(const std::string &callBackName); 
  virtual cocos2d::ui::Widget::ccWidgetEventCallback 
  onLocateEventCallback(const std::string &callBackName); 
  void onTouch(cocos2d::Ref* sender, cocos2d::ui::Widget::TouchEventType type); 
  void onClick(cocos2d::Ref* sender); 
  void onEvent(cocos2d::Ref* sender, int eventType); 
  

  private:

  std::vector<std::string> _touchTypes; 
  std::string _click; 
  std::vector<std::string> _eventTypes; 
  

  };
  //.cpp file
  #include “MyClass.h”
  #include “ui/UIText.h”

  USING_NS_CC;
  using namespace std;
  using namespace cocos2d::ui;

  MyClass::MyClass()
  {}

  Widget::ccWidgetTouchCallback MyClass::onLocateTouchCallback(const string &callBackName)
  {

  if (callBackName == "onTouch")
  { 
      return CC_CALLBACK_2(MyClass::onTouch, this); 
  } 
  return nullptr; 
  

  }

  Widget::ccWidgetClickCallback MyClass::onLocateClickCallback(const string &callBackName)
  {

  if (callBackName == "onClick") 
  { 
      return CC_CALLBACK_1(MyClass::onClick, this); 
  } 
  return nullptr; 
  

  }

  Widget::ccWidgetEventCallback MyClass::onLocateEventCallback(const string &callBackName)
  {

  if (callBackName == "onEvent") 
  { 
      return CC_CALLBACK_2(MyClass::onEvent, this); 
  } 
  return nullptr; 
  

  }

  void MyClass::onTouch(cocos2d::Ref* object, cocos2d::ui::Widget::TouchEventType type)
  {

  CCLOG("onTouch"); 
  

  }

  void MyClass::onClick(cocos2d::Ref* sender)
  {

  CCLOG("onClick"); 
  

  }

  void MyClass::onEvent(cocos2d::Ref* sender, int eventType)
  {

  CCLOG("onEvent"); 
  

  }

• Create a factory class for the class created in step 3.

This class mush inherit cocostudio::NodeReader, and then overwrite the following three interfaces.

Getlnstance— return to factory class example

Purge—delete factory class

createNodeWithFlatBuffers—create the class edited in step 4, and invoke setPropsWithFlatBuffers, as following,

purge
createNodeWithFlatBuffers

For example,

//.h file

#ifndef __cocos2d_libs__MyClassReader__
#define __cocos2d_libs__MyClassReader__

#include "cocos2d.h"
#include "cocostudio/CocosStudioExport.h"
#include "cocostudio/WidgetReader/NodeReader/NodeReader.h"

class MyClassReader : public cocostudio::NodeReader
{       
public:
    MyClassReader() {};
    ~MyClassReader() {};   
    static MyClassReader* getInstance();
    static void purge();
    cocos2d::Node* createNodeWithFlatBuffers(const flatbuffers::Table* nodeOptions);
};

#endif /*defined(__cocos2d_libs__MyClassReader__) */ 

//.cpp file
#include "MyClassReader.h"
#include "MyClass.h"

USING_NS_CC;

static MyClassReader* _instanceMyClassReader = nullptr;
MyClassReader* MyClassReader::getInstance()
{
    if (!_instanceMyClassReader)
    {
        _instanceMyClassReader = new MyClassReader();
    }
    return _instanceMyClassReader;
}

void MyClassReader::purge()
{
    CC_SAFE_DELETE(_instanceMyClassReader);
}

Node* MyClassReader::createNodeWithFlatBuffers(const flatbuffers::Table *nodeOptions)
{
    MyClass* node = MyClass::create();
    setPropsWithFlatBuffers(node, nodeOptions);
    return node;
} 

5 Register this interface to CSLoader before using createNode.

CSLoader* instance = CSLoader::getInstance();
instance->registReaderObject("MyClassReader",(ObjectFactory::Instance)MyClassReader::getInstance);

6 Load your node.

Load your node with CreateNode. Because your custom class has been entrusted to the factory class, which will create your custom class in CreateNode and call onLocateTouchCallback，onLocateClickCallback and onLocateEventCallback to implement code correction and editor binding.

Lua

For Lua, see the tutorial Binding Custom Class to Lua Runtime in cocos.

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