cocos2d-x 3.x（回头巩固基础知识之分辨率的适配(下)）

本文链接：https://blog.youkuaiyun.com/freshstraw/article/details/53763587

1.updateDesignResolutionSize（）函数

void GLView::updateDesignResolutionSize()
{
    if (_screenSize.width > 0 && _screenSize.height > 0
        && _designResolutionSize.width > 0 && _designResolutionSize.height > 0)
    {
        _scaleX = (float)_screenSize.width / _designResolutionSize.width;
        _scaleY = (float)_screenSize.height / _designResolutionSize.height;

        if (_resolutionPolicy == ResolutionPolicy::NO_BORDER)
        {
            _scaleX = _scaleY = MAX(_scaleX, _scaleY);
        }

        else if (_resolutionPolicy == ResolutionPolicy::SHOW_ALL)
        {
            _scaleX = _scaleY = MIN(_scaleX, _scaleY);
        }

        else if ( _resolutionPolicy == ResolutionPolicy::FIXED_HEIGHT) {
            _scaleX = _scaleY;
            _designResolutionSize.width = ceilf(_screenSize.width/_scaleX);
        }

        else if ( _resolutionPolicy == ResolutionPolicy::FIXED_WIDTH) {
            _scaleY = _scaleX;
            _designResolutionSize.height = ceilf(_screenSize.height/_scaleY);
        }

        // calculate the rect of viewport
        float viewPortW = _designResolutionSize.width * _scaleX;
        float viewPortH = _designResolutionSize.height * _scaleY;

        _viewPortRect.setRect((_screenSize.width - viewPortW) / 2, (_screenSize.height - viewPortH) / 2, viewPortW, viewPortH);

        // reset director's member variables to fit visible rect
        auto director = Director::getInstance();
        director->_winSizeInPoints = getDesignResolutionSize();
        director->createStatsLabel();
        //对视口(OpenGL渲染窗口大小)重新定义
        director->setGLDefaultValues();
    }
}

2.屏幕适配的函数setDesignResolutionSize（）

通过1中的代码可以看出：

//1.自适应:不管宽和高的缩放比例是否相同，只是缩放到铺满整个窗口（视口的大小）
//  优点:铺满整个屏幕窗口
//  缺点:图像拉伸明显
    glview->setDesignResolutionSize(1280, 720, ResolutionPolicy::EXACT_FIT);
//2.无黑边:以宽高的缩放比例中，较大的为准进行缩放（视口的大小）
//  优点:铺满屏幕窗口
//  缺点:缩放比小的一边有可能会超出屏幕窗口（相当于投影仪的影像超出了影布的范围），导致图像在屏幕中显示不全。
    glview->setDesignResolutionSize(1280, 720, ResolutionPolicy::NO_BORDER);
//3.完全显示:以宽高的缩放比例中，较小的为准进行缩放(视口的大小)
//  优点:图像在屏幕中显示完全
//  缺点:缩放比大的一边有可能会出现黑边
    glview->setDesignResolutionSize(1280, 720, ResolutionPolicy::SHOW_ALL);
//4.以高的缩放比例为准，进行缩放(视口的大小)
//  优点:高方向的图像在屏幕中显示完全
//  缺点:宽方向的图像在屏幕中显示不完全(有可能超出屏幕)
    glview->setDesignResolutionSize(1280, 720, ResolutionPolicy::FIXED_HEIGHT);
//5.以宽的缩放比例为准,进行缩放(视口的大小)
//  优点:宽方向的图像在屏幕中显示完全
//  缺点:高方向的图像在屏幕中显示不完全(有可能超出屏幕)
    glview->setDesignResolutionSize(1280, 720, ResolutionPolicy::FIXED_WIDTH);

3.容易弄混的函数getWinSize(),getVisibleSize()，getVisibleOrigin(),getFrameSize()

getWinSize()函数就是_designResolutionSize的大小，只要_designResolutionSize的大小没有重置，getWinSize()的值就不会变。
getVisibleSize()函数：

Size GLView::getVisibleSize() const
{
    if (_resolutionPolicy == ResolutionPolicy::NO_BORDER)
    {
        return Size(_screenSize.width/_scaleX, _screenSize.height/_scaleY);
    }
    else 
    {
        return _designResolutionSize;
    }
}

由上可以看出:只有NO_BORDER适配模式的时候，getVisibleSize()的大小会特殊，其他情况下，getVisibleSize()和getWinSize()可以理解为大小相同。

getVisibleOrigin()函数：

Vec2 GLView::getVisibleOrigin() const
{
    if (_resolutionPolicy == ResolutionPolicy::NO_BORDER)
    {
        return Vec2((_designResolutionSize.width - _screenSize.width/_scaleX)/2, 
                           (_designResolutionSize.height - _screenSize.height/_scaleY)/2);
    }
    else 
    {
        return Vec2::ZERO;
    }
}