HTML5 - 如何获取图像尺寸

Question

我有这个脚本,它用于获取浏览器上传图像的宽度和高度.

参考:http://renevier.net/misc/resizeimg.html

function createReader(file) {
    reader.onload = function(evt) {
        var image = new Image();
        image.onload = function(evt) {
            var width = this.width;
            var height = this.height;
            alert (width); // will produce something like 198
        };
        image.src = evt.target.result; 
    };
    reader.readAsDataURL(file);
}

for (var i = 0, length = input.files.length; i < length; i++) {
    createReader(input.files[i]);
}

我想从createReader函数外部访问值的宽度和高度.我怎样才能做到这一点？

Answer 1

更改"createReader",以便在图像可用时传入要调用的处理函数:

function createReader(file, whenReady) {
    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);
}

现在,当你调用它时,你可以传递一个函数来做你想要的图像尺寸:

  createReader(input.files[i], function(w, h) {
    alert("Hi the width is " + w + " and the height is " + h);
  });