JavaScript:当'user-scalable'设置为yes时,检测到缩放以缩放

Question

当meta name ="viewport"设置为user-scalable = yes时,如何检测缩放的缩放比例(或缩放距离)？

我已经在Android上进行了测试,但如果meta name ="viewport"设置为user-scalable = yes,则无法检测到缩放到缩放.如果meta name ="viewport"设置为user-scalable = no,则可以检测到缩放到缩放但是我无法放大文档.

这是我对jsFiddle的测试:

Hammer.js:http: //jsfiddle.net/pE42S/

var pziW = "test";
var viewport_width = $(window).innerWidth();
var zoom = 0;

var hammer = new Hammer(document.getElementById("touchme"));

hammer.ontransformstart = function(ev) {
    console.log("ontransformstart");
    console.log(ev);
    //pziW = $(window).innerWidth() / 2 * ev.scale;
    zoom = ev.scale;
    var msg = "ontransformstart " + pziW + " scale " + zoom;
    log(msg);
};
hammer.ontransform = function(ev) {
    console.log("ontransform");
    console.log(ev);
    zoom -= ev.scale;
    viewport_width+=viewport_width*zoom;
    zoom = ev.scale;
    pziW=viewport_width;
    //pziW = $(window).innerWidth() / 2 * ev.scale;
    jqUpdateSize();
    var msg = "ontransform " + pziW + " scale " + zoom;
    log(msg);
};
hammer.ontransformend = function(ev) {
    console.log("ontransformend");
    console.log(ev);
    var msg = "ontransformend " + pziW + " scale " + zoom;
    log(msg);
};

TouchSwipe:http: //jsfiddle.net/pE42S/1/

$(function() {      
    $("#touchme").swipe( {
        pinchStatus:function(event, phase, direction, distance , duration , fingerCount, pinchZoom) {
            console.log("pinchStatus");
            console.log(event);
            pziW=viewport_width - distance;
            $("#log").text(pziW);
            jqUpdateSize();
        },
        fingers:2,  
        pinchThreshold:0  
    });
});

有人有答案吗？

Answer 1

实现此目的的一种方法是使用通用 touchstart 处理程序：

• 等到用户开始触摸至少两个点 ( event.touches.length > 1)
• 记下两次触摸的 x 和 y 起始坐标，附加 touchend 侦听器
• 等到触摸结束。
• 删除触摸端侦听器并测量距离。

使用手势事件和 event.scale 属性会更简单，请参阅检测捏捏的最简单方法中的最佳答案以获取更多详细信息。