我正在创建一个jQuery插件。
我如何得到真实的图像宽度和高度与Javascript在Safari?
Firefox 3、IE7和Opera 9的操作如下:
var pic = $("img")
// need to remove these in of case img-element has set width and height
pic.removeAttr("width");
pic.removeAttr("height");
var pic_real_width = pic.width();
var pic_real_height = pic.height();
但在Safari和谷歌等Webkit浏览器中，Chrome的值为0。
当前回答
在github检查这个存储库!
使用Javascript检查宽度和高度的好例子
https://github.com/AzizAK/ImageRealSize
-编辑的要求从一些评论。
Javascript代码:
function CheckImageSize(){
var image = document.getElementById("Image").files[0];
createReader(image, function (w, h) {
alert("Width is: " + w + " And Height is: "+h);
});
}
function createReader(file, whenReady) {
var reader = new FileReader;
reader.onload = function (evt) {
var image = new Image();
image.onload = function (evt) {
var width = this.width;
var height = this.height;
if (whenReady) whenReady(width, height);
};
image.src = evt.target.result;
};
reader.readAsDataURL(file);
}
和HTML代码:
<html>
<head>
<title>Image Real Size</title>
<script src="ImageSize.js"></script>
</head>
<body>
<input type="file" id="Image"/>
<input type="button" value="Find the dimensions" onclick="CheckImageSize()"/>
</body>
<html>
其他回答
Webkit浏览器在图像加载后设置高度和宽度属性。我建议使用图像的onload事件，而不是使用超时。这里有一个简单的例子:
var img = $("img")[0]; // Get my img elem
var pic_real_width, pic_real_height;
$("<img/>") // Make in memory copy of image to avoid css issues
.attr("src", $(img).attr("src"))
.load(function() {
pic_real_width = this.width; // Note: $(this).width() will not
pic_real_height = this.height; // work for in memory images.
});
为了避免CSS对图像尺寸的影响，上面的代码在内存中复制了图像。这是FDisk提出的一个非常聪明的解决方案。
你也可以使用naturalHeight和naturalWidth HTML5属性。
根本问题是WebKit浏览器(Safari和Chrome)并行加载JavaScript和CSS信息。因此，JavaScript可能在计算CSS的样式效果之前执行，返回错误的答案。在jQuery中，我发现解决方案是等到文档。readyState == 'complete'，例如，
jQuery(document).ready(function(){
if (jQuery.browser.safari && document.readyState != "complete"){
//console.info('ready...');
setTimeout( arguments.callee, 100 );
return;
}
... (rest of function)
至于宽度和高度……根据你正在做的事情，你可能需要offsetWidth和offsetHeight，其中包括边界和填充。
您可以通过编程方式获取图像，并使用Javascript检查尺寸，而完全不需要处理DOM。
var img = new Image();
img.onload = function() {
console.log(this.width + 'x' + this.height);
}
img.src = 'http://www.google.com/intl/en_ALL/images/logo.gif';
我们如何在不眨眼的情况下获得正确的真实尺寸:
(function( $ ){
$.fn.getDimensions=function(){
alert("First example:This works only for HTML code without CSS width/height definition.");
w=$(this, 'img')[0].width;
h=$(this, 'img')[0].height;
alert("This is a width/height on your monitor: " + $(this, 'img')[0].width+"/"+$(this, 'img')[0].height);
//This is bad practice - it shows on your monitor
$(this, 'img')[0].removeAttribute( "width" );
$(this, 'img')[0].removeAttribute( "height" );
alert("This is a bad effect of view after attributes removing, but we get right dimensions: "+ $(this, 'img')[0].width+"/"+$(this, 'img')[0].height);
//I'am going to repare it
$(this, 'img')[0].width=w;
$(this, 'img')[0].height=h;
//This is a good practice - it doesn't show on your monitor
ku=$(this, 'img').clone(); //We will work with a clone
ku.attr( "id","mnbv1lk87jhy0utrd" );//Markup clone for a final removing
ku[0].removeAttribute( "width" );
ku[0].removeAttribute( "height" );
//Now we still get 0
alert("There are still 0 before a clone appending to document: "+ $(ku)[0].width+"/"+$(ku)[0].height);
//Hide a clone
ku.css({"visibility" : "hidden",'position':'absolute','left':'-9999px'});
//A clone appending
$(document.body).append (ku[0]);
alert("We get right dimensions: "+ $(ku)[0].width+"/"+$(ku)[0].height);
//Remove a clone
$("#mnbv1lk87jhy0utrd").remove();
//But a next resolution is the best of all. It works in case of CSS definition of dimensions as well.
alert("But if you want to read real dimensions for image with CSS class definition outside of img element, you can't do it with a clone of image. Clone method is working with CSS dimensions, a clone has dimensions as well as in CSS class. That's why you have to work with a new img element.");
imgcopy=$('<img src="'+ $(this, 'img').attr('src') +'" />');//new object
imgcopy.attr( "id","mnbv1lk87jhy0aaa" );//Markup for a final removing
imgcopy.css({"visibility" : "hidden",'position':'absolute','left':'-9999px'});//hide copy
$(document.body).append (imgcopy);//append to document
alert("We get right dimensions: "+ imgcopy.width()+"/"+imgcopy.height());
$("#mnbv1lk87jhy0aaa").remove();
}
})( jQuery );
$(document).ready(function(){
$("img.toreaddimensions").click(function(){$(this).getDimensions();});
});
<img class="toreaddimensions"…
无意中发现了这条线索，试图为我自己的问题找到答案。我试图在加载程序后的函数中获得图像的宽度/高度，并不断得到0。我觉得这可能就是你想要的，因为这对我来说很管用:
tempObject.image = $('<img />').attr({ 'src':"images/prod-" + tempObject.id + ".png", load:preloader });
xmlProjectInfo.push(tempObject);
function preloader() {
imagesLoaded++;
if (imagesLoaded >= itemsToLoad) { //itemsToLoad gets set elsewhere in code
DetachEvent(this, 'load', preloader); //function that removes event listener
drawItems();
}
}
function drawItems() {
for(var i = 1; i <= xmlProjectInfo.length; i++)
alert(xmlProjectInfo[i - 1].image[0].width);
}
