cocos2dx 2.0 CCScrollView的用法以及滑动的原理

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__

#include "cocos2d.h"

USING_NS_CC;
#include "cocos-ext.h"
USING_NS_CC_EXT;
// 校正滑动动画速度
#define ADJUST_ANIM_VELOCITY 800;

class HelloWorld : public cocos2d::CCLayer, public cocos2d::extension::CCScrollViewDelegate
{
public:
    // Here's a difference. Method 'init' in cocos2d-x returns bool, instead of returning 'id' in cocos2d-iphone
    virtual bool init();  

    // there's no 'id' in cpp, so we recommand to return the exactly class pointer
    static cocos2d::CCScene* scene();

    // a selector callback
    void menuCloseCallback(CCObject* pSender);

    // implement the "static node()" method manually
    CREATE_FUNC(HelloWorld);

public:
    void scrollViewDidScroll(cocos2d::extension::CCScrollView* view);
    void scrollViewDidZoom(CCScrollView* view);

public:
    virtual void onEnter();
    virtual void onExit();

    virtual bool ccTouchBegan(CCTouch *pTouch, CCEvent *pEvent);
    virtual void ccTouchMoved(CCTouch *pTouch, CCEvent *pEvent);
    virtual void ccTouchEnded(CCTouch *pTouch, CCEvent *pEvent);
    virtual void ccTouchCancelled(CCTouch *pTouch, CCEvent *pEvent);

private:
    // 当触摸事件结束时，校正CCScrollView的位置
    void adjustScrollView();

private:
    // 菜单回调
    void menu1Callback(CCNode *pSender);
    void menu2Callback(CCNode *pSender);

private:
    // 显示当前页
    CCLabelTTF* pLabel;

    CCScrollView *scrollView;

};

#endif // __HELLOWORLD_SCENE_H__

实现文件

 #include "HelloWorldScene.h"
 #include "SimpleAudioEngine.h"

 using namespace cocos2d;
 using namespace CocosDenshion;
 USING_NS_CC_EXT;

 CCScene* HelloWorld::scene()
 {
     // 'scene' is an autorelease object
     CCScene *scene = CCScene::create();

     // 'layer' is an autorelease object
     HelloWorld *layer = HelloWorld::create();

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

     // return the scene
     return scene;
 }
 CCLayer *layer;
 CCSprite *sprite2;
 // on "init" you need to initialize your instance
 bool HelloWorld::init()
 {
     //////////////////////////////
     // 1. super init first
     if ( !CCLayer::init() )
     {
         return false;
     }

     /////////////////////////////
     // 2. add a menu item with "X" image, which is clicked to quit the program
     //    you may modify it.

     // add a "close" icon to exit the progress. it's an autorelease object

     // ask director the window size
     CCSize size = CCDirector::sharedDirector()->getWinSize();

     layer = CCLayerColor::create(ccc4(, , ,));
     layer->setAnchorPoint(CCPointZero);
     layer->setPosition(CCPointZero);

     // CCScrollView
     scrollView = CCScrollView::create(CCSizeMake(, ), layer);

    // scrollView->setBounceable(false);

     CCSprite *sprite1 = CCSprite::create("HelloWorld.png");
     sprite2 = CCSprite::create("HelloWorld.png");
     CCSprite *sprite3 = CCSprite::create("HelloWorld.png");

     // Menu
     //CCMenuItemSprite *menuItem1 = CCMenuItemSprite::create(sprite1, sprite1, this, menu_selector(HelloWorld::menu1Callback));
 //    CCMenuItemSprite *menuItem1 = CCMenuItemSprite::create(sprite1, sprite1, this, NULL);
 //    menuItem1->setPosition(ccpAdd(CCPointZero, ccp(size.width / 2, size.height / 2)));
 //
 //    CCMenuItemSprite *menuItem2 = CCMenuItemSprite::create(sprite2, sprite2, this, NULL);
 //    menuItem2->setPosition(ccpAdd(ccp(480, 0), ccp(size.width / 2, size.height / 2)));
 //
 //    CCMenu *menu = CCMenu::create(menuItem1, menuItem2, NULL);
 //
 //    menu->setPosition(CCPointZero);
 //    layer->addChild(menu);

     sprite1->setPosition(ccpAdd(CCPointZero, ccp(size.width / , size.height / )));
     sprite2->setPosition(ccpAdd(ccp(, ), ccp(size.width / , size.height / )));
     sprite3->setPosition(ccpAdd(ccp(, ), ccp(size.width / , size.height / )));

     layer->addChild(sprite1);
     layer->addChild(sprite2);
     layer->addChild(sprite3);

     layer->setContentSize(CCSizeMake(, ));

     sprite1->setScale(0.5);
     sprite2->setScale(0.5);

     scrollView->setPosition(CCPointZero);
     scrollView->setContentOffset(CCPointZero);

     scrollView->setContentSize(CCSizeMake(*, ));
     scrollView->setContainer(layer);

     scrollView->setDirection(kCCScrollViewDirectionHorizontal);
     scrollView->setDelegate(this);

     this->addChild(scrollView);

     return true;
 }

 void HelloWorld::menuCloseCallback(CCObject* pSender)
 {
     CCDirector::sharedDirector()->end();

 #if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
     exit();
 #endif
 }

 void HelloWorld::scrollViewDidScroll(cocos2d::extension::CCScrollView *view)
 {
 }

 void HelloWorld::scrollViewDidZoom(cocos2d::extension::CCScrollView *view)
 {
 }

 void HelloWorld::onEnter()
 {
     CCLayer::onEnter();
     // 这里的第三个参数一定要设置成false，
     // true 即HelloWorld层吞噬掉触摸事件
     // false 即HelloWorld层与CCScrollView对象先后处理触摸事件
   //  CCDirector::sharedDirector()->getTouchDispatcher()->addTargetedDelegate(this, 1, false);
 }

 void HelloWorld::onExit()
 {
     CCDirector::sharedDirector()->getTouchDispatcher()->removeDelegate(this);
     CCLayer::onExit();
 }

 bool HelloWorld::ccTouchBegan(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)
 {
       auto postion=   pTouch->getLocation();
       auto p2= layer->convertToNodeSpace(postion);
 //    printf("p1.x=%f,p1.y=%f\n",postion.x,postion.y);
 //    printf("p2.x=%f,p2.y=%f\n",p2.x,p2.y);

     auto rect =sprite2->boundingBox();
     if(rect.containsPoint(p2)){
         int ffff=;
         ffff++;
       //  printf("摸到了\n");
     }

     int ffffr=;
     ffffr++;

     return true;
 }

 void HelloWorld::ccTouchMoved(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)
 {
    // CCLOG("move");
 }

 void HelloWorld::ccTouchEnded(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)
 {
     adjustScrollView();
 }

 void HelloWorld::ccTouchCancelled(cocos2d::CCTouch *pTouch, cocos2d::CCEvent *pEvent)
 {
     adjustScrollView();
 }

 void HelloWorld::adjustScrollView()
 {
      // 关闭CCScrollView中的自调整
     scrollView->unscheduleAllSelectors();

     int x = scrollView->getContentOffset().x;
     int offset = (int) x % ;

     printf("x=%d,offset=%d\n",x,offset);
     // 调整位置
     CCPoint adjustPos;
     // 调整动画时间
     float adjustAnimDelay;

     if (offset < -) {
         // 计算下一页位置，时间
         adjustPos = ccpSub(scrollView->getContentOffset(), ccp( + offset, ));
         adjustAnimDelay = (float) ( + offset) / ADJUST_ANIM_VELOCITY;
         printf("-240调整后的坐标=%f\n",adjustPos.x);
     }
     else {
         // 计算当前页位置，时间
         adjustPos = ccpSub(scrollView->getContentOffset(), ccp(offset, ));

         // 这里要取绝对值，否则在第一页往左翻动的时，保证adjustAnimDelay为正数
         adjustAnimDelay = (float) abs(offset) / ADJUST_ANIM_VELOCITY;

         printf("现在的位移=%f\n",scrollView->getContentOffset().x);

         printf(">240调整后的坐标=%f\n",adjustPos.x);
     }

     // 调整位置
     scrollView->setContentOffsetInDuration(adjustPos, adjustAnimDelay);
 }

 void HelloWorld::menu1Callback(cocos2d::CCNode *pSender)
 {
     CCLOG("menu1Callback");
 }

 void HelloWorld::menu2Callback(cocos2d::CCNode *pSender)
 {
     CCLOG("menu2Callback");
 }

这里主要研究的是他的显示，以及当滑动停止的时候，有个加速度还要滑动一段，具体如何实现，是研究的CCScrollView源码，如下

 void CCScrollView::deaccelerateScrolling(float dt)
 {
     if (m_bDragging)
     {
         this->unschedule(schedule_selector(CCScrollView::deaccelerateScrolling));
         return;
     }

     float newX, newY;
     CCPoint maxInset, minInset;

     m_pContainer->setPosition(ccpAdd(m_pContainer->getPosition(), m_tScrollDistance));

     if (m_bBounceable)
     {
         maxInset = m_fMaxInset;
         minInset = m_fMinInset;
     }
     else
     {
         maxInset = this->maxContainerOffset();
         minInset = this->minContainerOffset();
     }
     printf("maxinset.x=%f,mininset.x=%f\n",maxInset.x,minInset.x);
     //96,-1056

     //check to see if offset lies within the inset bounds
     newX     = MIN(m_pContainer->getPosition().x, maxInset.x);
     newX     = MAX(newX, minInset.x);
     newY     = MIN(m_pContainer->getPosition().y, maxInset.y);
     newY     = MAX(newY, minInset.y);

     newX = m_pContainer->getPosition().x;
     newY = m_pContainer->getPosition().y;

     m_tScrollDistance     = ccpSub(m_tScrollDistance, ccp(newX - m_pContainer->getPosition().x, newY - m_pContainer->getPosition().y));
     m_tScrollDistance     = ccpMult(m_tScrollDistance, SCROLL_DEACCEL_RATE);
     this->setContentOffset(ccp(newX,newY));

     if ((fabsf(m_tScrollDistance.x) <= SCROLL_DEACCEL_DIST &&
          fabsf(m_tScrollDistance.y) <= SCROLL_DEACCEL_DIST) ||
         newY > maxInset.y || newY < minInset.y ||
         newX > maxInset.x || newX < minInset.x ||
         newX == maxInset.x || newX == minInset.x ||
         newY == maxInset.y || newY == minInset.y)
     {
         this->unschedule(schedule_selector(CCScrollView::deaccelerateScrolling));
         this->relocateContainer(true);
     }
 }

每次坐标增加

m_tScrollDistance，但是

m_tScrollDistance会每次变为0.95*m_tScrollDistance，达到减速的效果