UIButton 的实现原理

.cpp文件：

#include "HelloWorldScene.h"
#include "ui/CocosGUI.h"
#include "cocostudio/CocoStudio.h"
#include "an01.h"

using namespace cocos2d::ui;
const char* font_UIListViewTest = "fonts/Marker Felt.ttf";
USING_NS_CC;
Scene* HelloWorld::createScene()
{
    // 'scene' is an autorelease object
    auto scene = Scene::create();
    
    // 'layer' is an autorelease object
    auto layer = HelloWorld::create();

    // add layer as a child to scene
    scene->addChild(layer);

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
    //////////////////////////////
    // 1. super init first
    if ( !Layer::init() )
    {
        return false;
    }
    
    Size visibleSize = Director::getInstance()->getVisibleSize();
    Vec2 origin = Director::getInstance()->getVisibleOrigin();

    /////////////////////////////
    // 2. add a menu item with "X" image, which is clicked to quit the program
    //    you may modify it.

    // add a "close" icon to exit the progress. it's an autorelease object
    auto closeItem = MenuItemImage::create(
                                           "CloseNormal.png",
                                           "CloseSelected.png",
                                           CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));
    
	closeItem->setPosition(Vec2(origin.x + visibleSize.width - closeItem->getContentSize().width/2 ,
                                origin.y + closeItem->getContentSize().height/2));

    // create menu, it's an autorelease object
    auto menu = Menu::create(closeItem, NULL);
    menu->setPosition(Vec2::ZERO);
    this->addChild(menu, 1);

    /////////////////////////////
    // 3. add your codes below...

    // add a label shows "Hello World"
    // create and initialize a label
    
    auto label = Label::createWithTTF("Hello World", "fonts/Marker Felt.ttf", 24);
    
    // position the label on the center of the screen
    label->setPosition(Vec2(origin.x + visibleSize.width/2,
                            origin.y + visibleSize.height - label->getContentSize().height));

    // add the label as a child to this layer
    this->addChild(label, 1);
	////
	//Size widgetSize = _widget->getContentSize();

	// Add a label in which the button events will be displayed
	_displayValueLabel = Text::create("No Event", "fonts/Marker Felt.ttf", 32);
	_displayValueLabel->setAnchorPoint(Vec2(0.5f, -1.0f));
	_displayValueLabel->setPosition(Vec2(visibleSize.width / 2.0f, visibleSize.height / 2.0f));
	addChild(_displayValueLabel);

	// Add the alert
	Text* alert = Text::create("Button", "fonts/Marker Felt.ttf", 30);
	alert->setColor(Color3B(159, 168, 176));

	alert->setPosition(Vec2(visibleSize.width / 2.0f,
		visibleSize.height / 2.0f - alert->getContentSize().height * 1.75f));

	addChild(alert);

	// Create the button
	Button* button = Button::create("cocosui/animationbuttonnormal.png",
		"cocosui/animationbuttonpressed.png");
	CCLOG("content size should be greater than 0:  width = %f, height = %f", button->getContentSize().width,
		button->getContentSize().height);
	button->setPosition(Vec2(visibleSize.width / 2.0f, visibleSize.height / 2.0f));
	button->addTouchEventListener(CC_CALLBACK_2(HelloWorld::touchEvent, this));
	button->setZoomScale(0.4f);
	button->setPressedActionEnabled(true);
	addChild(button);
	button->setOpacity(100);
	// Create the imageview
	ImageView* imageView = ImageView::create();

	imageView->setPosition(Vec2(visibleSize.width / 2.0f + 50 + button->getContentSize().width / 2,
		visibleSize.height / 2.0f));
	imageView->setTag(12);

	addChild(imageView);



	return true;
}

void HelloWorld::touchEvent(Ref *pSender, Widget::TouchEventType type)
{
	switch (type)
	{
	case Widget::TouchEventType::BEGAN:
		_displayValueLabel->setString(StringUtils::format("Touch Down"));
		break;

	case Widget::TouchEventType::MOVED:
		_displayValueLabel->setString(StringUtils::format("Touch Move"));
		break;

	case Widget::TouchEventType::ENDED:
	{
		_displayValueLabel->setString(StringUtils::format("Touch Up"));
		ImageView* imageView = (ImageView*)getChildByTag(12);
		imageView->setVisible(false);
		imageView->loadTexture("cocosui/ccicon.png");
		imageView->setOpacity(0);
		imageView->setVisible(true);
		imageView->runAction(Sequence::create(FadeIn::create(0.5), DelayTime::create(1.0), FadeOut::create(0.5), nullptr));
		Button *btn = (Button*)pSender;
		auto sc = an01::createScene();
		auto reScene = TransitionSplitCols::create(5.0f, sc);
	//	gridNodeTarget->runAction(PageTurn3D::create(2.0f, Size(15, 10)));
		Director::getInstance()->pushScene(reScene);
		btn->loadTextureNormal("cocosui/animationbuttonnormal.png");
	}
	break;

	case Widget::TouchEventType::CANCELED:
		_displayValueLabel->setString(StringUtils::format("Touch Cancelled"));
		break;

	default:
		break;
	}
}


void HelloWorld::menuCloseCallback(Ref* pSender)
{
    Director::getInstance()->end();

#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
    exit(0);
#endif
}

.h文件：

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__
#include "cocos2d.h"
#include "cocos-ext.h"
#include "ui/CocosGUI.h"
using namespace cocos2d::ui;

class HelloWorld : public cocos2d::Layer
{
public:
    static cocos2d::Scene* createScene();
	
    virtual bool init();
	void touchEvent(cocos2d::Ref* sender, cocos2d::ui::Widget::TouchEventType type);
    // a selector callback
    void menuCloseCallback(cocos2d::Ref* pSender);
protected:
	//cocos2d::ui::Text* _displayValueLabel;
	//cocos2d::ui::Text* _displayValueLabel;
	cocos2d::ui::Text* _displayValueLabel;
	cocos2d::Layer* _uiLayer;
	cocos2d::ui::Layout* _widget;
	CREATE_FUNC(HelloWorld);
};

#endif // __HELLOWORLD_SCENE_H__

效果：