cocos2d-js 3.0 屏幕适配方案 分辨率适应

cc.view.setDesignResolutionSize(1024, 768, cc.ResolutionPolicy.FIXED_WIDTH);

cc.ResolutionPolicy = {
    // The entire application is visible in the specified area without trying to preserve the original aspect ratio.
    // Distortion can occur, and the application may appear stretched or compressed.
    EXACT_FIT:0,
    // The entire application fills the specified area, without distortion but possibly with some cropping,
    // while maintaining the original aspect ratio of the application.
    NO_BORDER:1,
    // The entire application is visible in the specified area without distortion while maintaining the original
    // aspect ratio of the application. Borders can appear on two sides of the application.
    SHOW_ALL:2,
    // The application takes the height of the design resolution size and modifies the width of the internal
    // canvas so that it fits the aspect ratio of the device
    // no distortion will occur however you must make sure your application works on different
    // aspect ratios
    FIXED_HEIGHT:3,
    // The application takes the width of the design resolution size and modifies the height of the internal
    // canvas so that it fits the aspect ratio of the device
    // no distortion will occur however you must make sure your application works on different
    // aspect ratios
    FIXED_WIDTH:4,

    UNKNOWN:5
};

EXACT_FIT会拉伸游戏，充满整个屏幕，最简单最粗暴；
SHOW_ALL保持游戏原比例，让一边占满屏幕，另外一侧黑边；
NO_BORDER跟SHOW_ALL类似，但让短边占满屏幕，另外一侧超出屏幕，不显示黑边，一部分画面在屏幕外，无法显示；
FIXED_WIDTH和FIXED_HEIGHT都是NO_BORDER的升级版，指定那一侧充满屏幕，另外一侧超出屏幕。