Cocos2d-2.x_跑马灯效果

#ifndef __HELLO_WORLD_H__
#define __HELLO_WORLD_H__

#include "cocos2d.h"
#include "cocos-ext.h"

USING_NS_CC;
USING_NS_CC_EXT;

class HelloWorld : public cocos2d::CCLayer 
{
public:
	HelloWorld();
    virtual ~HelloWorld();
    
    static cocos2d::CCScene* scene();

	virtual bool init();

	void scroll(float tm);

	CREATE_FUNC(HelloWorld);

};

#endif

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


HelloWorld::HelloWorld()
{
}

HelloWorld::~HelloWorld()
{

}

CCScene* HelloWorld::scene()
{
	CCScene *scene = CCScene::create();
	HelloWorld *layer = HelloWorld::create();
	scene->addChild(layer);

	return scene;
}

bool HelloWorld::init()
{
	if (!CCLayer::init())
	{
		return false;
	}

	CCSize visibleSize = CCDirector::sharedDirector()->getVisibleSize();
	
	//添加背景图片
	CCSprite * background = CCSprite::create("HelloWorld.png");
	background->setPosition(ccp(visibleSize.width / 2, visibleSize.height / 2));
	this->addChild(background, 1);

	//设置文本信息
	CCLabelTTF * text = CCLabelTTF::create("跑马灯，跑马灯，跑马灯，跑马灯，跑马灯!", "Arial", 22);
	text->setColor(ccc3(0, 255, 255));
	text->setPosition(ccp(visibleSize.width / 2, visibleSize.height * 4 / 5));
	this->addChild(text, 1, 0);

	//使用定时器，每0.005秒回调一次，产生移动的效果
	this->schedule(schedule_selector(HelloWorld::scroll), 0.005f);
	return true;
}

void HelloWorld::scroll(float tm)
{
	CCSize visibleSize = CCDirector::sharedDirector()->getVisibleSize();

	CCLabelTTF * text = (CCLabelTTF *)this->getChildByTag(0);
	CCPoint point = text->getPosition();
	text->setPosition(ccp(point.x - 1, point.y));

	//当text完全出去的时候重新设置它的坐标
	float width = text->getContentSize().width;
	if (point.x < -width / 2)
	{
		text->setPosition(ccp(visibleSize.width + width / 2, visibleSize.height * 4 / 5));
	}
}