cocos2d-x3.2 多点缩放单点滑动

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__

#include "cocos2d.h"
USING_NS_CC;

class HelloWorld : public cocos2d::Layer
{
public:
    // there's no 'id' in cpp,so we recommend returning the class instance pointer
    static cocos2d::Scene* createScene();

    virtual bool init();
    
    // implement the "static create()" method manually
    CREATE_FUNC(HelloWorld);

    void onTouchesBegan(const std::vector<cocos2d::Touch*>& touches,cocos2d::Event* event);
    void onTouchesMoved(const std::vector<cocos2d::Touch*>& touches,cocos2d::Event* event);
    
    Sprite* bgSprite;
    Vec2 bgOrigin;
    Layer* mapLayer;
    
};

#endif // __HELLOWORLD_SCENE_H__

HelloWorld.cpp

#include "HelloWorldScene.h"

USING_NS_CC;

Scene* HelloWorld::createScene()
{
    // 'scene' is an autorelease object
    auto scene = Scene::create();
    
    // 'layer' is an autorelease object
    auto layer = HelloWorld::create();

    // add layer as a child to scene
    scene->addChild(layer);

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
    //////////////////////////////
    // 1. super init first
    if ( !Layer::init() )
    {
        return false;
    }
    
    /////////////////////////////
    mapLayer = Layer::create();
    this->addChild(mapLayer,-1);
    
    bgSprite = Sprite::create("2.jpg");
    bgSprite->setAnchorPoint(Vec2::ZERO);
    bgSprite->setPosition(Vec2::ZERO),bgOrigin = Vec2(Vec2::ZERO);
    mapLayer->addChild(bgSprite);
    
    auto treeSprite = Sprite::create("1.png");
    treeSprite->setAnchorPoint(Vec2::ZERO);
    treeSprite->setPosition(Vec2::ZERO),treeSprite->setScale(2);
    bgSprite->addChild(treeSprite,2);
    
    auto map = TMXTiledMap::create("mymap4.tmx");
    map->setAnchorPoint(Vec2::ZERO);
    map->setPosition(Vec2::ZERO),bgSprite->addChild(map,1);
    
    auto listener = EventListenerTouchAllAtOnce::create();
    listener->onTouchesBegan = CC_CALLBACK_2(HelloWorld::onTouchesBegan,this);
    listener->onTouchesMoved = CC_CALLBACK_2(HelloWorld::onTouchesMoved,this);
    _eventDispatcher->addEventListenerWithSceneGraphPriority(listener,bgSprite);
    
    return true;
}
void HelloWorld::onTouchesBegan(const std::vector<cocos2d::Touch*>& touches,cocos2d::Event* event)
{
    CCLOG("touch begin");
}


void HelloWorld::onTouchesMoved(const std::vector<cocos2d::Touch*>& touches,cocos2d::Event* event)
{
    CCLOG("touch moved");
    
    auto winSize = Director::getInstance()->getWinSize();
    if(touches.size() > 1)        // 多点进行缩放
    {
        CCLOG("多点缩放");
        // 得到当前两触摸点
        auto point1 = touches[0]->getLocation();
        auto point2 = touches[1]->getLocation();
        // 计算两点之间得距离
        auto currDistance = point1.distance(point2);
        // 计算两触摸点上一时刻之间得距离
        auto prevDistance = touches[0]->getPreviousLocation().distance(touches[1]->getPreviousLocation());
        // 两触摸点与原点的差向量，pointVec1和pointVec2是相对于bgSprite的位置
        auto pointVec1 = point1  - bgOrigin;
        auto pointVec2 = point2  - bgOrigin;
        // 两触摸点的相对中点
        auto relMidx = (pointVec1.x + pointVec2.x) / 2 ;
        auto relMidy = (pointVec1.y + pointVec2.y) / 2 ;
        // 计算bgSprite的锚点
        auto anchorX = relMidx / bgSprite->getBoundingBox().size.width;
        auto anchorY = relMidy / bgSprite->getBoundingBox().size.height;
        // 相对屏幕的中点
        auto absMidx = (point2.x + point1.x) / 2 ;
        auto absMidy = (point2.y + point1.y) / 2 ;
        
        // 缩放时，为了避免出现空白的区域，需要做以下的边界处理。
        // 当bgSprite快要进入到屏幕时，修改bgSprite的位置（既absMidx和absMidy）。
        if(  bgOrigin.x > 0)
        {
            absMidx -= bgOrigin.x;
        }
        if( bgOrigin.x < -bgSprite->getBoundingBox().size.width + winSize.width )
        {
            absMidx +=  -bgSprite->getBoundingBox().size.width + winSize.width - bgOrigin.x;
        }
        if( bgOrigin.y > 0 )
        {
            absMidy -= bgOrigin.y;
        }
        if( bgOrigin.y < -bgSprite->getBoundingBox().size.height + winSize.height )
        {
            absMidy +=  -bgSprite->getBoundingBox().size.height + winSize.height - bgOrigin.y;
        }
        // 重设bgSprite锚点和位置
        bgSprite->setAnchorPoint(Vec2(anchorX,anchorY));
        bgSprite->setPosition(Vec2(absMidx,absMidy));
        // 根据两触摸点前后的距离计算缩放倍率
        auto scale = bgSprite->getScale() * ( currDistance / prevDistance);
        // 控制缩放倍率在1～4倍之间，最小倍率不能太小，不让背景将不能填充满整个屏幕。
        scale = MIN(4,MAX(1,scale));
        bgSprite->setScale(scale);
        // 更新原点位置
        bgOrigin = Vec2(absMidx,absMidy) - Vec2(bgSprite->getBoundingBox().size.width * anchorX,bgSprite->getBoundingBox().size.height * anchorY) ;
    }
    else if(touches.size() == 1)        // 单点进行移动
    {
        CCLOG("单点移动");
        // 单点时，touches中只有一个Touch对象，所以通过touches[0]就可以得到触摸对象
        auto touch = touches[0];
        // 计算滑动过程中的滑动增量
        auto diff = touch->getDelta();
        // 得到当前bgSprite的位置
        auto currentPos = bgSprite->getPosition();
        // 得到滑动后bgSprite应该所在的位置
        auto pos = currentPos + diff;
        // 得到此刻bgSprite的尺寸
        auto bgSpriteCurrSize = bgSprite->getBoundingBox().size;
        
        //边界控制，约束pos的位置
        pos.x = MIN(pos.x,bgSpriteCurrSize.width * bgSprite->getAnchorPoint().x);
        pos.x = MAX(pos.x,-bgSpriteCurrSize.width + winSize.width + bgSpriteCurrSize.width * bgSprite->getAnchorPoint().x);
        pos.y = MIN(pos.y,bgSpriteCurrSize.height * bgSprite->getAnchorPoint().y);
        pos.y = MAX(pos.y,-bgSpriteCurrSize.height + winSize.height + bgSpriteCurrSize.height * bgSprite->getAnchorPoint().y);
        // 重设bgSprite位置
        bgSprite->setPosition(pos);
        
        // 更新原点位置
        if( pos.x >= bgSpriteCurrSize.width * bgSprite->getAnchorPoint().x
           || pos.x <= -bgSpriteCurrSize.width + winSize.width + bgSpriteCurrSize.width * bgSprite->getAnchorPoint().x)
        {
            diff.x = 0;
        }
        if( pos.y >= bgSpriteCurrSize.height * bgSprite->getAnchorPoint().y
           || pos.y <= -bgSpriteCurrSize.height + winSize.height + bgSpriteCurrSize.height * bgSprite->getAnchorPoint().y)
        {
            diff.y = 0;
        }
        bgOrigin += diff;
    }
}

（编辑：李大同）

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