我在 IE8 中运行的 Windows7 IE9 上。这仅在 IE9 中有效，因为我可以使用画布，但在 IE8 中，它应该回退到 Flash 画布。这是我的来源http://blog.jackadam.net/2010/alpha-jpegs/现在看来我在 IE 中遇到了 context.drawImage 不绘制图像的问题？我已经在 flashcanvas 谷歌组上发帖，但他们似乎需要一些时间来回复，所以希望这里可能有 flashcanvas 大师。
;(function() {
var create_alpha_jpeg = function(img) {
var alpha_path = img.getAttribute('data-alpha-src')
if(!alpha_path) return
// Hide the original un-alpha'd
img.style.visiblity = 'hidden'
// Preload the un-alpha'd image
var image = document.createElement('img')
image.src = img.src + '?' + Math.random()
console.log(image.src);
image.onload = function () {
console.log('image.onload');
// Then preload alpha mask
var alpha = document.createElement('img')
alpha.src = alpha_path + '?' + Math.random()
alpha.onload = function () {
console.log('alpha.onload');
var canvas = document.createElement('canvas')
canvas.width = image.width
canvas.height = image.height
img.parentNode.replaceChild(canvas, img)
// For IE7/8
if(typeof FlashCanvas != 'undefined') FlashCanvas.initElement(canvas)
// Canvas compositing code
var context = canvas.getContext('2d')
context.clearRect(0, 0, image.width, image.height)
context.drawImage(image, 0, 0, image.width, image.height)
//context.globalCompositeOperation = 'xor'
//context.drawImage(alpha, 0, 0, image.width, image.height)
}
}
}
// Apply this technique to every image on the page once DOM is ready
// (I just placed it at the bottom of the page for brevity)
var imgs = document.getElementsByTagName('img')
for(var i = 0; i < imgs.length; i++)
create_alpha_jpeg(imgs[i])
})();