从url获取远程图像的宽度高度 [英] Get width height of remote image from url

问题描述

因此警报为宽度和高度提供了未定义的值。我认为来自img.onload计算的图像的w和h值没有被传递给要返回的值，或者它可能会返回w和h 之前 onload计算它们：

So the alert gives undefined values for the width and height. I think the w and h values of the image from the img.onload calculation is not being passed to the values to return, or it may be returning w and h before the onload calculates them:

function getMeta(url){
 var w; var h;
 var img=new Image;
 img.src=url;
 img.onload=function(){w=this.width; h=this.height;};
 return {w:w,h:h}    
}

// "http://snook.ca/files/mootools_83_snookca.png" //1024x678
// "http://shijitht.files.wordpress.com/2010/08/github.png" //128x128

var end = getMeta("http://shijitht.files.wordpress.com/2010/08/github.png");
var w = end.w;
var h = end.h;
alert(w+'width'+h+'height');

如何让警报显示正确的宽度和高度？

How can I have the alert show the correct width and height?

http://jsfiddle.net/YtqXk/

推荐答案

使用jQuery获取图像大小

Get image size with jQuery

function getMeta(url){
    $("<img/>",{
        load : function(){
            alert(this.width+' '+this.height);
        },
        src  : url
    });
}

使用JavaScript获取图像大小

Get image size with JavaScript

function getMeta(url){   
    var img = new Image();
    img.onload = function(){
        alert( this.width+' '+ this.height );
    };
    img.src = url;
}

使用JavaScript （现代浏览器，IE9 +）获取图像大小

Get image size with JavaScript (modern browsers, IE9+ )

function getMeta(url){   
    var img = new Image();
    img.addEventListener("load", function(){
        alert( this.naturalWidth +' '+ this.naturalHeight );
    });
    img.src = url;
}

将上述内容简单地用作： getMeta（http ：//example.com/img.jpg）;

Use the above simply as: getMeta( "http://example.com/img.jpg" );

https://developer.mozilla.org/en/docs/Web/API/HTMLImageElement

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