Cocos2d-x 3.0標簽類Label

Cocos2d-x 3.0後推出了新的標簽類Label這種標簽通過使用FreeType[1]來使它在不同的平台上有相同的視覺效果。由於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

創建Label類靜態create函數常用的有如下幾個

static Label* createWithSystemFont(conststd::string &text,             //是要顯示的文字                           
                  const std::string& font,                                                       //係統字體名
                  float fontSize,                                                            //字體的大小
                  const Size& dimensions = Size::ZERO,                            //在屏幕上占用的區域大小,可省略
                  TextHAlignment  hAlignment = TextHAlignment::LEFT,          //文字橫向對齊方式,可省略
                  TextVAlignment  vAlignment = TextVAlignment::TOP)   //文字縱向對齊方式,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&  imageOffset = Point::ZERO                                //可省略
    )

其中createWithSystemFont是創建係統字體標簽對象createWithTTF是創建TTF字體標簽對象createWithBMFont是創建位圖字體標簽對象。

下麵我們通過一個實例介紹一下它們的使用。這個實例如圖下圖所示。

下麵我們看看HelloWorldScene.cpp中init函數如下

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;
              }

在上麵的代碼中第①是通過createWithSystemFont函數創建Label對象第②行代碼是通過createWithTTF是創建TTF字體標簽對象第③行代碼是createWithBMFont是創建位圖字體標簽對象。

第④行代碼TTFConfig ttfConfig("fonts/Marker Felt.ttf", 36, GlyphCollection::DYNAMIC)是創建一個TTFConfig結構體變量TTFConfig結構體的定義如下

_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創建TTF字體標簽。第⑥行代碼ttfConfig.outlineSize = 4設置TTFConfig的描邊字段。第⑦行代碼Label::createWithTTF(ttfConfig,"Hello World5")是重新創建TTF字體標簽。