实话说这个玩意也不是我原创的，网上只能找到C++版本的，我改写成了Lua版。

初学cocos-lua各种记不住API也是醉了……总之写的很苦逼但是最后结果是好的，我在有一些地方做了少许微调使操作杆更符合现实逻辑。

下面上代码：

local HRocker = class("HRocker",function()
    return cc.Layer:create();
end)

function HRocker.create(cpoint,radius,control,background)
    local rocker = HRocker.new(cpoint,background);
    local eventDispatcher = rocker:getEventDispatcher();
    eventDispatcher:addEventListenerWithSceneGraPHPriority(rocker:bindListener(),rocker);
    return rocker;
end

function HRocker:ctor(cpoint,background)
    self.isActive = false;
    self.radius = radius;
    self.max_radius = radius - control:getContentSize().width;
    self.currentPoint = cpoint;
    self.centerPoint = cpoint;
    self.controlSprite = control;
    self.controlSprite:setPosition(cpoint);
    background:setPosition(cpoint);
    
    background:setTag(88);
    self:addChild(background);
    self:addChild(self.controlSprite);
    
    self.schedulerID = nil;
    
    self:setCascadeOpacityEnabled(true);
    cclog("%s",type(cpoint));
    self.bindListener();
    self:active();
end

function HRocker:active()
    if( not self.isActive ) then
        self.isActive = true;
        local updatePos = function()
            local now_point = cc.p(self.controlSprite:getPosition()) ;
            local point = cc.pAdd( 
                now_point,cc.pMul(
                    cc.pSub(self.currentPoint,now_point),0.5
                ) 
            );
            self.controlSprite:setPosition(point);
        end
        self.schedulerID = cc.Director:getInstance():getScheduler():scheduleScriptFunc(updatePos,1.0 / 60,false);
    end
end

function HRocker:inactive()
	if( self.isActive ) then
        self.isActive = false;
        cc.Director:getInstance():getScheduler():unscheduleScriptEntry(self.schedulerID);
	end
end

function HRocker:bindListener()
    local ccTouchBegan = function(pTouch,pEvent)
        if( not self.isActive ) then
            return false;
        end

        local touchPoint = pTouch.getLocation(pTouch);
        if ( cc.pGetDistance(touchPoint,self.centerPoint)  > self.radius) then
            return false;
        end
        
        self:setOpacity(255);
        self.currentPoint = touchPoint;
        return true;
    end
    
    local ccTouchMoved = function(pTouch,pEvent)
        local touchPoint = pTouch.getLocation(pTouch);
        if (cc.pGetDistance(touchPoint,self.centerPoint) > self.radius) then
            self.currentPoint =cc.pAdd( self.centerPoint,cc.pMul(cc.pNormalize(cc.pSub(touchPoint,self.centerPoint)),( self.radius - self.max_radius )));
        else
            self.currentPoint = touchPoint;
        end
    end
    

    local ccTouchEnded = function(pTouch,pEvent)
        cclog("touch end");
        self.currentPoint = self.centerPoint;
        self:setOpacity(255 * 0.4);
    end
    
    local listener = cc.EventListenerTouchOneByOne:create();
    listener:registerScriptHandler(ccTouchBegan,cc.Handler.EVENT_TOUCH_BEGAN );
    listener:registerScriptHandler(ccTouchMoved,cc.Handler.EVENT_TOUCH_MOVED );
    listener:registerScriptHandler(ccTouchEnded,cc.Handler.EVENT_TOUCH_ENDED );
    
    return listener;
end

function HRocker:getDirection()
    return cc.pNormalize(cc.pSub(self.centerPoint,self.currentPoint));
end

function HRocker:getVelocity()
    return cc.pDistanceSQ(self.centerPoint,self.currentPoint);
end


return HRocker;