转载：http://blog.csdn.net/zy19940906/article/details/43967747
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);