(原创)cocos2d-x 3.0 示例代码分析4：VisibleRect

在上一篇中（链接：http://www.cnblogs.com/wodehao0808/p/4087607.html），有这样一段代码：

#include "VisibleRect.h"   // 辅助类VisibleRect类得到获取视口

我们看看这个做了什么，有什么用处~~~

// VisibleRect.h
// 星月倾心贡献~~~~

// 可视窗口区域
// 将窗口分为9部分，类似与一个“米”字。

#ifndef __VISIBLERECT_H__
#define __VISIBLERECT_H__

#include "cocos2d.h"

class VisibleRect
{
public:
    // 以下全是静态方法，调用方式：例如：VisibleRect::center()

    static cocos2d::Rect getVisibleRect();  // 获得可视窗口大小

    static cocos2d::Point left();         // 窗口：左中
    static cocos2d::Point right();        // 窗口：右中
    static cocos2d::Point top();          // 窗口：上中
    static cocos2d::Point bottom();       // 窗口：下中
    static cocos2d::Point center();       // 窗口：中中
    static cocos2d::Point leftTop();      // 窗口：左上
    static cocos2d::Point rightTop();     // 窗口：右上
    static cocos2d::Point leftBottom();   // 窗口：左下
    static cocos2d::Point rightBottom();  // 窗口：右下

private:  // 私有静态
    static void lazyInit();  // 偷懒的初始化（获取代码比较长，所以偷懒写在一个函数里）（星月：我喜欢。。。^_^）（小白:我也喜欢..^_^）
    static cocos2d::Rect s_visibleRect;  //  可视区域
};

#endif /* __VISIBLERECT_H__ */

// VisibleRect.cpp
// 星月倾心贡献~~~~

/****************************************************************************
 Copyright (c) 2013-2014 Chukong Technologies Inc.

 http://www.cocos2d-x.org

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 ****************************************************************************/

#include "VisibleRect.h"

USING_NS_CC;

Rect VisibleRect::s_visibleRect;  // 初始化静态变量：可视区域

// 初始化
void VisibleRect::lazyInit()
{
    // no lazy init
    // Useful if we change the resolution in runtime
    // 获得：可视区域
    s_visibleRect = Director::getInstance()->getOpenGLView()->getVisibleRect();
}

// 获得可视区域
Rect VisibleRect::getVisibleRect()
{
    lazyInit();
    return s_visibleRect;
}

// 窗口：左中
Point VisibleRect::left()
{
    lazyInit();
    return Point(s_visibleRect.origin.x, s_visibleRect.origin.y+s_visibleRect.size.height/2);
}

// 窗口：右中
Point VisibleRect::right()
{
    lazyInit();
    return Point(s_visibleRect.origin.x+s_visibleRect.size.width, s_visibleRect.origin.y+s_visibleRect.size.height/2);
}

// 窗口：上中
Point VisibleRect::top()
{
    lazyInit();
    return Point(s_visibleRect.origin.x+s_visibleRect.size.width/2, s_visibleRect.origin.y+s_visibleRect.size.height);
}

// 窗口：下中
Point VisibleRect::bottom()
{
    lazyInit();
    return Point(s_visibleRect.origin.x+s_visibleRect.size.width/2, s_visibleRect.origin.y);
}

// 窗口：中中
Point VisibleRect::center()
{
    lazyInit();
    return Point(s_visibleRect.origin.x+s_visibleRect.size.width/2, s_visibleRect.origin.y+s_visibleRect.size.height/2);
}

// 窗口：左上
Point VisibleRect::leftTop()
{
    lazyInit();
    return Point(s_visibleRect.origin.x, s_visibleRect.origin.y+s_visibleRect.size.height);
}

// 窗口：右上
Point VisibleRect::rightTop()
{
    lazyInit();
    return Point(s_visibleRect.origin.x+s_visibleRect.size.width, s_visibleRect.origin.y+s_visibleRect.size.height);
}

// 窗口：左下
Point VisibleRect::leftBottom()
{
    lazyInit();
    return s_visibleRect.origin;
}

// 窗口：右下
Point VisibleRect::rightBottom()
{
    lazyInit();
    return Point(s_visibleRect.origin.x+s_visibleRect.size.width, s_visibleRect.origin.y);
}

这个实现还是比较容易理解的，现在说下他的用法。

比如：你有一个sprite，要让它：在可视区域的左边界，同时在可视区域上边界。

两个需求：左边界，顶点。

有了上面这个就很容易实现了。

如下：

// 创建一个sprite
auto sprite = Sprite::create( "test.png" );
sprite->setAnchorPoint( ccp( 0.0, 1.0 ) );  // 设置描点
sprite->setPosition( VisibleRect::leftTop() )  // 左上

只要上面代码，就能达到需求了，很方便~~（小白：哦哦~~）

本章到此结束，希望对大家有帮助~~~

作者使用 cocos2d-x 3.0 示例代码分析，未经作者允许，请勿转载！在此谢谢各位手下留情~~~

本文没有获得作者本人同意，不得转载，否则必追究相关责任。转载请注明出处！！~~

原文地址：http://www.cnblogs.com/wodehao0808/p/4087713.html