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);};

大致的参数也已经写完，然后分别来两种情况的例子：

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);

顺时针radial类型：

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);