Cocos2d—X游戏开发之 CCLabelTTF 标签详解和对齐方式设置（分数显示）（十六）

在Cocos2d—X游戏开发中，CCLabelTTF 和 CCSprite 大概是使用最多的2个类了。标签主要用于显示静态文本，可以设置字体的大小和位置等属性。

现在，我们先来看下CCLabelTTF 的基本源码。

S1，从下面的代码可以看到 CCLabelTTF 继承于 CCSprite 和 CCLabeProtocol 。

class CC_DLL CCLabelTTF : public CCSprite, public CCLabelProtocol
{
public:
    CCLabelTTF();
    virtual ~CCLabelTTF();
    const char* description();    
    
    /** creates a CCLabelTTF with a font name and font size in points
     @since v2.0.1    使用最多的创建标签的方法
     */
    static CCLabelTTF * create(const char *string, const char *fontName, float fontSize);
    
    /** creates a CCLabelTTF from a fontname, horizontal alignment, dimension in points,  and font size in points.
     @since v2.0.1
     */
    static CCLabelTTF * create(const char *string, const char *fontName, float fontSize,
                               const CCSize& dimensions, CCTextAlignment hAlignment);
  
    /** creates a CCLabel from a fontname, alignment, dimension in points and font size in points
     @since v2.0.1
     */
    static CCLabelTTF * create(const char *string, const char *fontName, float fontSize,
                               const CCSize& dimensions, CCTextAlignment hAlignment, 
                               CCVerticalTextAlignment vAlignment);
    
    
    /** Create a lable with string and a font definition*/
    static CCLabelTTF * createWithFontDefinition(const char *string, ccFontDefinition &textDefinition);
    
    /** initializes the CCLabelTTF with a font name and font size */
    bool initWithString(const char *string, const char *fontName, float fontSize);
    
    /** initializes the CCLabelTTF with a font name, alignment, dimension and font size */
    bool initWithString(const char *string, const char *fontName, float fontSize,
                        const CCSize& dimensions, CCTextAlignment hAlignment);

    /** initializes the CCLabelTTF with a font name, alignment, dimension and font size */
    bool initWithString(const char *string, const char *fontName, float fontSize,
                        const CCSize& dimensions, CCTextAlignment hAlignment, 
                        CCVerticalTextAlignment vAlignment);
    
    /** initializes the CCLabelTTF with a font name, alignment, dimension and font size */
    bool initWithStringAndTextDefinition(const char *string, ccFontDefinition &textDefinition);
    
    /** set the text definition used by this label */
    void setTextDefinition(ccFontDefinition *theDefinition);
    
    /** get the text definition used by this label */
    ccFontDefinition * getTextDefinition();
    
    
    
    /** enable or disable shadow for the label */
    void enableShadow(const CCSize &shadowOffset, float shadowOpacity, float shadowBlur, bool mustUpdateTexture = true);
    
    /** disable shadow rendering */
    void disableShadow(bool mustUpdateTexture = true);
    
    /** enable or disable stroke */
    void enableStroke(const ccColor3B &strokeColor, float strokeSize, bool mustUpdateTexture = true);
    
    /** disable stroke */
    void disableStroke(bool mustUpdateTexture = true);
    
    /** set text tinting */
    void setFontFillColor(const ccColor3B &tintColor, bool mustUpdateTexture = true);

    
    
    /** initializes the CCLabelTTF */
    bool init();

    /** Creates an label.
     */
    static CCLabelTTF * create();

    /** changes the string to render
    * @warning Changing the string is as expensive as creating a new CCLabelTTF. To obtain better performance use CCLabelAtlas
    */
    virtual void setString(const char *label);   //设置标签文字内容的一对方法，当标签内容需要时时变化时，就是它了
    virtual const char* getString(void);
    
    CCTextAlignment getHorizontalAlignment();
    void setHorizontalAlignment(CCTextAlignment alignment);   //当标签文字变化时，位置可能不如意，这时需要它设置对齐方式，横向
    
    CCVerticalTextAlignment getVerticalAlignment();
    void setVerticalAlignment(CCVerticalTextAlignment verticalAlignment);   //标签纵向对齐方式设置 
    
    CCSize getDimensions();
    void setDimensions(const CCSize &dim);
    
    float getFontSize();
    void setFontSize(float fontSize);
    
    const char* getFontName();
    void setFontName(const char *fontName);
    
private:
    bool updateTexture();
protected:
    
    /** set the text definition for this label */
    void                _updateWithTextDefinition(ccFontDefinition & textDefinition, bool mustUpdateTexture = true);
    ccFontDefinition    _prepareTextDefinition(bool adjustForResolution = false);
    
    /** Dimensions of the label in Points */
    CCSize m_tDimensions;
    /** The alignment of the label */
    CCTextAlignment         m_hAlignment;
    /** The vertical alignment of the label */
    CCVerticalTextAlignment m_vAlignment;
    /** Font name used in the label */
    std::string * m_pFontName;
    /** Font size of the label */
    float m_fFontSize;
    /** label's string */
    std::string m_string;
    
    /** font shadow */
    bool    m_shadowEnabled;
    CCSize  m_shadowOffset;
    float   m_shadowOpacity;
    float   m_shadowBlur;
    
    
    /** font stroke */
    bool        m_strokeEnabled;
    ccColor3B   m_strokeColor;
    float       m_strokeSize;
        
    /** font tint */
    ccColor3B   m_textFillColor;

    
};
           

好的，现在我们来看下CCTextAlignment的定义，是2个枚举类型。

typedef enum
{
    kCCVerticalTextAlignmentTop,
    kCCVerticalTextAlignmentCenter,
    kCCVerticalTextAlignmentBottom,
} CCVerticalTextAlignment;

typedef enum
{
    kCCTextAlignmentLeft,
    kCCTextAlignmentCenter,
    kCCTextAlignmentRight,
} CCTextAlignment;
           

S2，现在来看这个CCLabelTTF的一个小Demo。

//获取主屏幕的尺寸
	CCSize winSize = CCDirector::sharedDirector()->getWinSize();

	//创建标签
	CCLabelTTF *label = CCLabelTTF::create("Hello CCLabelTTF", "Arial", 24);
                                                                                                                                             //设置标签文字颜色
         label->setColor(ccc3(0,0,0));	
	                                                                                                                                   //设置标签位置
	label->setPosition(ccp(winSize.width/2,winSize.height/2));
	
	//设置锚点为左下角
	label->setAnchorPoint(CCPointZero);
	
	//设置标签的横向对齐方式为向左对齐，这样标签内容增加，只会向右增加
	label->setHorizontalAlignment(kCCTextAlignmentLeft);

	//添加为子节点
	this->addChild(label,1);
           

这样设置对齐方式后，标签内容在修改，始终向左对齐，贴图如下：