cocosCreator多种屏幕适配方案

cocosCreator2.2.0以上版本测试过，低版本未测试。适用多种屏幕（大屏，小屏，异形屏等）。

下面附上代码：

start(){

　　this.resetSize(this.node);

}

/**

     * 手机屏幕适配

     * @param cav 

     */

    resetSize(cav) {

        let frameSize = cc.view.getFrameSize();

        let designSize = cc.view.getDesignResolutionSize();

        if (frameSize.width / frameSize.height > designSize.width / designSize.height) {

            cav.width = designSize.height * frameSize.width / frameSize.height;

            cav.height = designSize.height;

            cav.getComponent(cc.Canvas).designResolution = cc.size(cav.width, cav.height);

        } else {

            cav.width = designSize.width;

            cav.height = designSize.width * frameSize.height / frameSize.width;

            cav.getComponent(cc.Canvas).designResolution = cc.size(cav.width, cav.height);

        }

        this.fitScreen(cav, designSize);

    }

    /**

     * 背景适配

     * @param canvasnode 

     * @param designSize 

     */

    fitScreen(canvasnode, designSize) {

        let scaleW = canvasnode.width / designSize.width;

        let scaleH = canvasnode.height / designSize.height;

        let bgNode = canvasnode.getChildByName('background');

        let bgScale = canvasnode.height / bgNode.height;

        bgNode.width *= bgScale;

        bgNode.height *= bgScale;

        if (scaleW > scaleH) {

            bgScale = canvasnode.width / bgNode.width;

            bgNode.width *= bgScale;

            bgNode.height *= bgScale;

        }

    }