iphone - Cocos2d-x onEnter等默认方法未调用

Question

我有 2 年的 cocos2d 经验，但今天开始使用 cocos2d-x。我刚刚编写了派生菜单按钮类，它不会触发任何默认方法，如 onEnter、selected 和 all。

这是我的代码:

//MyButton.h

#include <stddef.h>
#include "cocos2d.h"

using namespace cocos2d;
class MyButton : public CCMenuItemSprite
{
    public:

    void onEnter();

    void selected();

};

//MyButton.mm

void MyButton::onEnter()
{
    CCPoint pos = this->getSelectedImage()->getPosition();
    CCSize  size = this->getSelectedImage()->getContentSize();


    this->getSelectedImage()->setPosition(ccp(pos.x+size.width*0.5f,  pos.y+size.height*0.5f));
    this->getSelectedImage()->setAnchorPoint(ccp(0.5f,0.5f));
}

void MyButton::selected()
{
    if (isEnabled())
    {
        if (this->getSelectedImage())
        {
            CCScaleTo *scale = CCScaleTo::create(0.5f, 1.3f);

            this->getSelectedImage()->runAction(scale);
        }
    }

}

MyButton * MyButton::create(CCNode* normalSprite, CCNode* selectedSprite, CCObject* target, SEL_MenuHandler selector)
{
    MyButton *btn = (MyButton*)CCMenuItemSprite::create(normalSprite, selectedSprite,target, selector);

    return btn;
}

//这是创建按钮的代码

CCSprite *start_1   = CCSprite::createWithSpriteFrameName(FRAME_MM_START);
CCSprite *start_2   = CCSprite::createWithSpriteFrameName(FRAME_MM_START);

MyButton *btnPlay =(MyButton*) MyButton::create(start_1,
                                                 start_2,
                                                 this,
                                                 menu_selector(MyMainMenu::playGame));

btnPlay->setPosition(ccp(mS.width*0.5f, mS.height*0.5f));
btnPlay->mMaxScale = 1.2f;

CCMenu* menu = CCMenu::create();
menu->setAnchorPoint( ccp(0,0) );
menu->setPosition( ccp(0,0) );
this->addChild(menu, 1);

menu->addChild(btnPlay);

Answer 1

添加一些重要的内容:

在您的 MyButton 类中，您没有 create 方法。您所做的只是创建一个 CCMenuItemSprite 实例并将其转换为按钮。这是错误的。

您应该在MyButton中添加一些内容

public static MyButton* create(CCSprite* normal_sprite, CCSprite* selected_sprite, ...);

请找到 CCMenuItemSprite 类作为示例。

第一个问题，CCMenuItemSprite::onEnter() 是虚拟的吗？

第二，我想你的 onEnter 应该如下所示

void MyButton::onEnter()
{
    CCMenuItemSprite::onEnter();
    CCPoint pos = this->getSelectedImage()->getPosition();
    CCSize  size = this->getSelectedImage()->getContentSize();


    this->getSelectedImage()->setPosition(ccp(pos.x+size.width*0.5f, pos.y+size.height*0.5f));
    this->getSelectedImage()->setAnchorPoint(ccp(0.5f,0.5f));
}

这就是 C++ 的工作原理。它与 Objective-C 不同，Objective-C 默认允许方法重载。

MyButton * MyButton::create(CCNode* normalSprite, CCNode* selectedSprite, CCObject* target, SEL_MenuHandler selector)
{    
    MyButton *pRet = new MyButton();
    pRet->initWithNormalSprite(normalSprite, selectedSprite, null, target, selector); 
    pRet->autorelease();
    return pRet;
}