Cocos2d-x 3.0標(biāo)簽類Label

Cocos2d-x 3.0后推出了新的標(biāo)簽類Label，這種標(biāo)簽通過使用FreeType[1]來使它在不同的平臺(tái)上有相同的視覺效果。由于使用更快的緩存代理，它的渲染也將更加快速。Label提供了描邊和陰影等特性。

Label類的類圖如下圖所示：

創(chuàng)建Label類靜態(tài)create函數(shù)常用的有如下幾個(gè)：

static Label* createWithSystemFont(conststd::string &text,             //是要顯示的文字                             
                  const std::string& font,                                                       //系統(tǒng)字體名  
                  float fontSize,                                                            //字體的大小  
                  const Size& dimensions = Size::ZERO,                            //在屏幕上占用的區(qū)域大小,可省略  
                  TextHAlignment  hAlignment = TextHAlignment::LEFT,          //文字橫向?qū)R方式,可省略  
                  TextVAlignment  vAlignment = TextVAlignment::TOP)   //文字縱向?qū)R方式,可省略  
   
static Label* createWithTTF(conststd::string & text,  
         const std::string &  fontFile,                                                              //字體文件  
         float fontSize,  
         const Size &  dimensions = Size::ZERO,                                           //可省略  
         TextHAlignment          hAlignment= TextHAlignment::LEFT,          //可省略  
         TextVAlignment           vAlignment= TextVAlignment::TOP              //可省略  
    )       
   
static Label* createWithTTF(constTTFConfig& ttfConfig,  
         const std::string& text,  
         TextHAlignment alignment =TextHAlignment::LEFT,  
         int maxLineWidth = 0  
    )  
   
static Label* createWithBMFont(conststd::string& bmfontFilePath,          //位圖字體文件  
         const std::string&  text,                                                              
         const TextHAlignment& alignment =TextHAlignment::LEFT, //可省略  
         int maxLineWidth = 0,                                                                       //可省略  
         const Point&  p_w_picpathOffset = Point::ZERO                                //可省略  
    )

其中createWithSystemFont是創(chuàng)建系統(tǒng)字體標(biāo)簽對(duì)象，createWithTTF是創(chuàng)建TTF字體標(biāo)簽對(duì)象，createWithBMFont是創(chuàng)建位圖字體標(biāo)簽對(duì)象。

下面我們通過一個(gè)實(shí)例介紹一下，它們的使用。這個(gè)實(shí)例如圖下圖所示。

下面我們看看HelloWorldScene.cpp中init函數(shù)如下：

bool HelloWorld::init()  
{  
   if ( !Layer::init() )  
   {  
       return false;  
   }  
     
   Size visibleSize = Director::getInstance()->getVisibleSize();  
   Point origin = Director::getInstance()->getVisibleOrigin();  
   auto closeItem = MenuItemImage::create(  
                                          "CloseNormal.png",  
                                          "CloseSelected.png",  
                                 CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));  
     
    closeItem->setPosition(Point(origin.x+ visibleSize.width - closeItem->getContentSize().width/2 ,  
                                origin.y + closeItem->getContentSize().height/2));  
   
    
   auto menu = Menu::create(closeItem, NULL);  
   menu->setPosition(Point::ZERO);  
   this->addChild(menu, 1);  
     
    autolabel1 = Label::createWithSystemFont("Hello World1","Arial", 36);                                   ①  
    label1->setPosition(Point(origin.x+ visibleSize.width/2,  
         origin.y + visibleSize.height - 100));  
    this->addChild(label1,1);  
   
    autolabel2 = Label::createWithTTF("Hello World2", "fonts/MarkerFelt.ttf", 36);                       ②  
    label2->setPosition(Point(origin.x+ visibleSize.width/2,  
         origin.y + visibleSize.height - 200));  
    this->addChild(label2,1);  
   
    autolabel3 = Label::createWithBMFont("fonts/BMFont.fnt", "HelloWorld3");                            ③  
    label3->setPosition(Point(origin.x+ visibleSize.width/2,  
         origin.y + visibleSize.height - 300));  
    this->addChild(label3,1);  
   
    TTFConfigttfConfig("fonts/Marker Felt.ttf",  
         36,  
         GlyphCollection::DYNAMIC);                                                                                                  ④  
    autolabel4 = Label::createWithTTF(ttfConfig, "Hello World4");                                                  ⑤  
    label4->setPosition(Point(origin.x+ visibleSize.width/2,  
         origin.y + visibleSize.height - 400));  
    this->addChild(label4, 1);  
   
    ttfConfig.outlineSize= 4;                                                                                                     ⑥  
    autolabel5 = Label::createWithTTF(ttfConfig, "Hello World5");                                                  ⑦  
    label5->setPosition(Point(origin.x+ visibleSize.width/2,  
         origin.y + visibleSize.height - 500));  
    label5->enableShadow(Color4B(255,255,255,128),Size(4, -4));                                        ⑧  
    label5->setColor(Color3B::RED);                                                                                                 ⑨  
    this->addChild(label5,1);  
   
 return true;  
              }

在上面的代碼中第①是通過createWithSystemFont函數(shù)創(chuàng)建Label對(duì)象，第②行代碼是通過createWithTTF是創(chuàng)建TTF字體標(biāo)簽對(duì)象，第③行代碼是createWithBMFont是創(chuàng)建位圖字體標(biāo)簽對(duì)象。

第④行代碼TTFConfig ttfConfig("fonts/Marker Felt.ttf", 36, GlyphCollection::DYNAMIC)是創(chuàng)建一個(gè)TTFConfig結(jié)構(gòu)體變量，TTFConfig結(jié)構(gòu)體的定義如下：

_ttfConfig(constchar* filePath = "",                                                                         //字體文件路徑  
    int  size = 12,                                                                                            //字體大小  
    constGlyphCollection& glyphCollection = GlyphCollection::DYNAMIC,     //字體庫類型  
    constchar * customGlyphCollection = nullptr,                                     //自定義字體庫  
    booluseDistanceField = false,                                                                         //用戶是否可縮放字體  
    intoutline = 0                                                                                                      //字體描邊  
               )

第⑤行代碼Label::createWithTTF(ttfConfig,"Hello World4")是通過指定TTFConfig創(chuàng)建TTF字體標(biāo)簽。第⑥行代碼ttfConfig.outlineSize = 4設(shè)置TTFConfig的描邊字段。第⑦行代碼Label::createWithTTF(ttfConfig,"Hello World5")是重新創(chuàng)建TTF字體標(biāo)簽。

第⑧行代碼label5->enableShadow(Color4B(255,255,255,128),Size(4, -4))是設(shè)置標(biāo)簽的陰影效果。第⑨行代碼label5->setColor(Color3B::RED)是設(shè)置標(biāo)簽的顏色。

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