How do I get natural dimensions of an image using javascript or jquery?

问题

I have this code so far:

var img = document.getElementById('draggable');
var width = img.clientWidth;
var height = img.clientHeight;

However this gets me the html attributes - css styles. I want to get dimensions of the actual image resource, of the file.

I need this because upon uploading an image, it's width gets set to 0px and I have no idea why or where this is happening. To prevent it I want to get the actual dimension and reset them. Is this possible?

Edit: Even when I try to get naturalWidth I get 0 as a result. I've added a picture. The weird thing is that it only happens when I upload new files and upon refresh it's working as it should.

http://oi39.tinypic.com/3582xq9.jpg

回答1:

You could use naturalWidth and naturalHeight, these properties contain the actual, non-modified width and height of the image, but you have to wait until the image has loaded to get them

var img = document.getElementById('draggable');

img.onload = function() {
    var width  = img.naturalWidth;
    var height = img.naturalHeight;
}

This is only supported from IE9 and up, if you have to support older browser you could create a new image, set it's source to the same image, and if you don't modify the size of the image, it will return the images natural size, as that would be the default when no other size is given

var img     = document.getElementById('draggable'),
    new_img = new Image();

new_img.onload = function() {
    var width  = this.width,
        heigth = this.height;
}

new_img.src = img.src;

FIDDLE

回答2:

There are img.naturalHeight and img.naturalWidth which give you the width and height of the image itself, and not the DOM element.

回答3:

You can use the following function I made.

Function

function getImageDimentions(imageNode) {
  var source = imageNode.src;
  var imgClone = document.createElement("img");
  imgClone.src = source;
  return {width: imgClone.width, height: imgClone.height}
}

html:

<img id="myimage" src="foo.png">

use it like this

var image = document.getElementById("myimage"); // get the image element
var dimentions = getImageDimentions(image); // get the dimentions
alert("width: " + dimentions.width + ", height: " + dimentions.height); // give the user a visible alert of the dimentions

来源：https://stackoverflow.com/questions/16342936/how-do-i-get-natural-dimensions-of-an-image-using-javascript-or-jquery

标签

javascript

jquery

image

dimensions