cocos2dx 3.x(点击屏幕移动精灵，拖动精灵)不需要写回调函数直接实现

//
//  MainScene.cpp
//  helloworld
//
//  Created by apple on 16/9/19.
//
//

#include "MainScene.hpp"
Scene * MainScene::createScene()
{
     auto scene = Scene::create();
    //创建层
    MainScene *layer = MainScene::create();
    scene->addChild(layer);
    return scene;
}
bool MainScene::init(){
    if (!Layer::init()) {
        return false;
    }
    
    
    sprite = Sprite::create("hu.png");
    sprite ->setPosition(50, 50);
    sprite->setAnchorPoint(Vec2(0.5, 0.5));
    this->addChild(sprite);// 添加到层
    
  
    
    //声明
    auto listener1 = EventListenerTouchOneByOne::create();
    listener1->setSwallowTouches(true);
    
    //通过 lambda 表达式 直接实现触摸事件的回掉方法
    listener1->onTouchBegan = [](Touch* touch, Event* event){
        auto target = static_cast<Sprite*>(event->getCurrentTarget());
        
        Point locationInNode = target->convertToNodeSpace(touch->getLocation());
        Size s = target->getContentSize();
        Rect rect = Rect(0, 0, s.width, s.height);
        
        if (rect.containsPoint(locationInNode))
        {
            log("sprite began... x = %f, y = %f", locationInNode.x, locationInNode.y);
            target->setOpacity(180);//点击的时候精灵颜色变暗，255为最大值，0最小
            return true;
        }
        return false;
    };
    
    
    
    listener1->onTouchMoved = [](Touch* touch, Event* event){
        auto target = static_cast<Sprite*>(event->getCurrentTarget());
        target->setPosition(target->getPosition() + touch->getDelta());
    };
    
    listener1->onTouchEnded = [=](Touch* touch, Event* event){
        auto target = static_cast<Sprite*>(event->getCurrentTarget());
        log("sprite onTouchesEnded.. ");
        target->setOpacity(255);//手势松开时使精灵恢复原来的颜色
    };
    
    
    //将触摸事件绑定到精灵身上
    _eventDispatcher->addEventListenerWithSceneGraphPriority(listener1, sprite);
    _eventDispatcher->addEventListenerWithSceneGraphPriority(listener1->clone(), sprite);
    _eventDispatcher->addEventListenerWithSceneGraphPriority(listener1->clone(), sprite);
    
    return true;
}