cocos2dx3.0进度条的简析

可以说，进度条是游戏中特别常用的一个控件，大部分游戏都会需要用到资源加载条，技能道具的cd，或者是时间条。最近特别喜欢看底层，自我感觉底层是一个让人熟悉整个框架的特别好的方式，这次就来看下进度条的底层，感受一下。

class CC_DLL ProgressTimer : public Node
#ifdef EMSCRIPTEN,public GLBufferedNode
#endif // EMSCRIPTEN
{
public:
    /** Types of progress
     @since v0.99.1
     */
    enum class Type//进度条类型枚举，顾名思义，radial是圆形增减的进度条，bar是单方向增减的进度条
    {
        /// Radial Counter-Clockwise
        RADIAL,/// Bar
        BAR,};
    
    /** Creates a progress timer with the sprite as the shape the timer goes through */
    static ProgressTimer* create(Sprite* sp);//通过精灵去创建该对象

    /** Change the percentage to change progress. */
    inline Type getType() const { return _type; }//返回进度条类型

    /** Percentages are from 0 to 100 */
    inline float getPercentage() const {return _percentage; }//返回当前显示部分的百分值

    /** The image to show the progress percentage,retain */
    inline Sprite* getSprite() const { return _sprite; }
   //设置当前显示部分的百分值，精灵，类型
   void setPercentage(float percentage); 
   void setSprite(Sprite *sprite); 
   void setType(Type type); 
/** * @js setReverseDirection * @lua setReverseDirection */
    void setReverseProgress(bool reverse);//设置进度条的方向，圆形增减类型有效，设置顺时针和逆时针
   inline bool isReverseDirection() { return _reverseDirection; };
   inline void setReverseDirection(bool value) { _reverseDirection = value; };
/** * Midpoint is used to modify the progress start position.
* If you're using radials type then the midpoint changes the center point
 * If you're using bar type the the midpoint changes the bar growth
* it expands from the center but clamps to the sprites edge so: 
* you want a left to right then set the midpoint all the way to Point(0,y)
* you want a right to left then set the midpoint all the way to Point(1,y) 
* you want a bottom to top then set the midpoint all the way to Point(x,0)
* you want a top to bottom then set the midpoint all the way to Point(x,1) */
    /**
     根据注释可知，setmidPoint是设置进度条的圆心点，即开始位置，默认都是图片的中心位置，如果是圆形的，那么改变中心点，如果是bar型的，那么改变的是它的增长点
    */
        void setMidpoint(const Point& point);
 /** Returns the Midpoint */ Point getMidpoint() const; /** * This allows the bar type to move the component at a specific rate * Set the component to 0 to make sure it stays at 100%. * For example you want a left to right bar but not have the height stay 100% * Set the rate to be Point(0,1); and set the midpoint to = Point(0,.5f); */
      /**根据注释可知，BarChangeRate是设置进度条方向，如果是圆形的，好像不用设置，如果是bar型的，那么改变的是它的增减方向，例如Point(0,1)表示从下到上，Point（1,0）表示的是从左到右，（1，1）表示四周往中间，这些都是默认的midpoint，此时都是中心点，如果要从上到下，那么设置barchangerate为（0，1），设置midpoint为（0，0），从右到左亦然。
    */
    inline void setBarChangeRate(const Point& barChangeRate ) { _barChangeRate = barChangeRate; }
 /** Returns the BarChangeRate */ 
      inline Point getBarChangeRate() const { return _barChangeRate; } 
      virtual void draw(Renderer *renderer,const kmMat4 &transform,bool transformUpdated) override;
      virtual void setAnchorPoint(const Point& anchorPoint) override; 
      virtual void setColor(const Color3B &color) override;
      virtual const Color3B& getColor() const override;
      virtual void setOpacity(GLubyte opacity) override;
      virtual GLubyte getOpacity() const override;
 CC_CONSTRUCTOR_ACCESS: /** * @js ctor */ ProgressTimer(); /** * @js NA * @lua NA */
      virtual ~ProgressTimer();
 /** Initializes a progress timer with the sprite as the shape the timer goes through */
       bool initWithSprite(Sprite* sp);
 protected: 
      void onDraw(const kmMat4 &transform,bool transformUpdated); 
      Tex2F textureCoordFromAlphaPoint(Point alpha);
      Vertex2F vertexFromAlphaPoint(Point alpha); 
void updateProgress(void);
 void updateBar(void);
 void updateRadial(void);
 virtual void updateColor(void) override; 
Point boundaryTexCoord(char index);
 Type _type;
 Point _midpoint;
 Point _barChangeRate; 
float _percentage;
 Sprite *_sprite;
 int _vertexDataCount;
 V2F_C4B_T2F *_vertexData;
 CustomCommand _customCommand;
 bool _reverseDirection;
private:
 CC_DISALLOW_COPY_AND_ASSIGN(ProgressTimer);};

从上到下bar类型

 //time's background
    spritetime1=Sprite::create("biao1.png");
    spritetime1->setAnchorPoint(Point(0,1));
    spritetime1->setPosition(Point(WinRect::LeftBottom().x+5+10,WinRect::Top().y-3-10-3));
    this->addChild(spritetime1,6);
    //time's value
    auto spritetime2=Sprite::create("biao2.png");
    progress=ProgressTimer::create(spritetime2);
    progress->setAnchorPoint(Point(0,1));
    progress->setType(cocos2d::ProgressTimer::Type::BAR);
    progress->setPosition(Point(WinRect::LeftBottom().x+6+10,WinRect::Top().y-3-13-3));
    //set began Point
    progress->setMidpoint(Point(0,0));
    progress->setBarChangeRate(Point(0,1));
    progress->setPercentage(100);//value
    this->addChild(progress,7);
//显示当前时间的label，可忽略
    Myinterface::getInstance()->setTime(m_itime);
    auto str = __String::createWithFormat("%f",m_itime);
    numsTTF=Label::createWithSystemFont("0","Thonburi",24);
    numsTTF->setString(str->getCString());
    numsTTF->setAnchorPoint(Point(0,1));
    numsTTF->setPosition(Point(WinRect::LeftBottom().x+150,WinRect::Top().y-15-10));
    numsTTF->setColor(Color3B::BLACK);
    this->addChild(numsTTF,8);
    numsTTF->setVisible(true);

Sprite*sprite;
    sprite=Sprite::createWithSpriteFrameName("black.png");
    auto boomprogress=ProgressTimer::create(sprite);
    boomprogress->setTag(type);
    boomprogress->setType(cocos2d::ProgressTimer::Type::RADIAL);
    boomprogress->setAnchorPoint(Point(0.5,0.5));
    boomprogress->setPosition(p);
    this->addChild(boomprogress,7);
    boomprogress->setReverseProgress(true);
    //action
    auto to = ProgressFromTo::create(10,100,0);//十秒内从100走到0
    auto pCall_N = CallFuncN::create(CC_CALLBACK_1(gameScene::maskcallback,this));//走完之后来个回调函数，这里我是用来当做技能cd
    auto pSequeue = Sequence::create(to,pCall_N,NULL);
    boomprogress->runAction(pSequeue);

（编辑：李大同）

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