adapt.js

//
if (navigator.userAgent.indexOf('Firefox') > 0 || window.navigator.msPointerEnabled) {
    var head = document.getElementsByTagName('head');
    var viewport = document.createElement('meta');
    viewport.name = 'viewport';
    viewport.id = 'viewport';
    viewport.content = "width=640";
    head.length > 0 && head[head.length - 1].appendChild(viewport);
    $(window).resize(function () {
        resizeWindow();
    });
    function resizeWindow() {
        if ($(window).width() > $(window).height()) {
            $("#wrongLayer").show();
        } else {
            $("#wrongLayer").hide();
        }
    }

    $(function () {
        resizeWindow();
    });
} else {
    var adaptUILayout = (function () {
        //根据校正appVersion或userAgent校正屏幕分辨率宽度值
        var regulateScreen = (function () {
            var cache = {};
            //默认尺寸
            var defSize = {
                width: window.screen.width,
                height: window.screen.height
            };
            var ver = window.navigator.appVersion;
            var s = window.orientation;    //屏幕方向
            var _ = null;
            var check = function (key) {
                return key.constructor == String ? ver.indexOf(key) > -1 : ver.test(key);
            };
            var add = function (name, key, size) {
                if (name && key)
                    cache[name] = {
                        key: key,
                        size: size
                    };
            };
            var del = function (name) {
                if (cache[name]) {
                    delete cache[name];
                }
            };
            var cal = function () {
                if (_ != null) {
                    return _;
                }
                for (var name in cache) {
                    if (check(cache[name].key)) {
                        _ = cache[name].size;
                        break;
                    }
                }
                if (_ == null)
                    _ = defSize;
                return _;
            };
            return {
                add: add,
                del: del,
                cal: cal,
                s: s
            };
        })();

        //实现缩放
        var adapt = function (uiWidth) {
            var
                deviceWidth,
                devicePixelRatio,
                targetDensitydpi,
                initialContent,
                head,
                viewport,
                ua;
            ua = navigator.userAgent.toLowerCase();
            //whether it is the iPhone or iPad
            isiOS = ua.indexOf('ipad') > -1 || ua.indexOf('iphone') > -1;
            //获取设备信息,并矫正参数值
            devicePixelRatio = window.devicePixelRatio;
            devicePixelRatio < 1.5 ? 2 : devicePixelRatio;

            if (window.orientation == 0 || window.orientation == 180) {
                $("#wrongLayer").hide();
                $("#main").show();
                if (regulateScreen.s != 0) {
                    if (regulateScreen.cal().width < regulateScreen.cal().height) {
                        deviceWidth = regulateScreen.cal().width;
                    } else {
                        deviceWidth = regulateScreen.cal().height;
                    }
                } else {
                    deviceWidth = regulateScreen.cal().width;
                }
            } else {
                $("#wrongLayer").show();
                if (regulateScreen.s != 0) {
                    $(function () {
                        $("#wrongLayer").fadeIn();
                    });
                    if (regulateScreen.cal().width > regulateScreen.cal().height) {
                        deviceWidth = regulateScreen.cal().width;
                    } else {
                        deviceWidth = regulateScreen.cal().height;
                    }
                } else {
                    deviceWidth = regulateScreen.cal().height;
                }
            }

            if (devicePixelRatio == 2 && (deviceWidth == 320 || deviceWidth == 360 || deviceWidth == 592 || deviceWidth == 640)) {
                deviceWidth *= 2;
            }
            if (devicePixelRatio == 1.5 && (deviceWidth == 320)) {
                deviceWidth *= 2;
                devicePixelRatio = 2;
            }
            if (devicePixelRatio == 1.5 && (deviceWidth == 640)) {
                devicePixelRatio = 2;
            }

            //获取最终dpi
            targetDensitydpi = uiWidth / deviceWidth * devicePixelRatio * 160;
            initialContent = isiOS
                ? 'width=' + uiWidth + 'px, user-scalable=no'
                : 'target-densitydpi=' + targetDensitydpi + ', width=' + uiWidth + ', user-scalable=no';
            $("#wrongLayer").remove();
            head = document.getElementsByTagName('head');
            viewport = document.createElement('meta');
            viewport.name = 'viewport';
            viewport.id = 'viewport';
            viewport.content = initialContent;
            if (isiOS && window.orientation != 0 && window.orientation != 180) {
                viewport.content = 'width=1280';
                head.length > 0 && head[head.length - 1].appendChild(viewport);
            } else {
                head.length > 0 && head[head.length - 1].appendChild(viewport);
            }
        };
        return {
            regulateScreen: regulateScreen,
            adapt: adapt
        };
    })();

    adaptUILayout.adapt(640);

    $(window).bind('orientationchange', function (e) {
        adaptUILayout.adapt(640);
    });
}