我有以下代码。它在 Chrome 中工作得很好,正如预期的那样。但是,在 Firefox 中,它记录“CONVERT”但从不记录“LOADED”。没有 JS 错误或任何东西。 onload 只是不触发。我似乎无法在 google 或 stackoverflow 上找到太多。许多人说 onload 不会为缓存的图像触发,但这些不应该被缓存,即使它们被缓存,我也无法缓存它们(对吗?)
flattenImage: function(file, callback){
// Safari uses webkitURL
var URL = window.URL || window.webkitURL;
var canPreformat = !!(window.Blob && window.Uint8Array && URL && URL.createObjectURL);
// If we have all features we need to preformat on the client and the image
// isn't already flattened (jpeg), DO IT
if (canPreformat && !file.type.test(/jpe?g/i)) {
console.log('CONVERT');
var thiz = this;
var c = document.createElement('canvas');
var ctx = c.getContext('2d');
var img = new Image;
// Makes a blob URL from the file given.
img.onload = function() {
console.log('LOADED');
c.width = this.width;
c.height = this.height;
// Take the img that was added and copy it to the canvas
ctx.drawImage(img, 0, 0);
// Put the image on top of everything else
ctx.globalCompositeOperation = 'destination-atop';
// Any transparency should become white (instead of the default black)
ctx.fillStyle = "#fff";
ctx.fillRect(0, 0, this.width, this.height);
// Save canvas as a base64'd jpeg
var dataURL = c.toDataURL("image/jpeg");
// The following blob lines take the base64 encoded image and then
// convert it to a jpeg "file". This allows us to do a real file
// upload rather than needing to send a base64 string.
var blobBin = atob(dataURL.split(',')[1]);
var array = [];
for(var i = 0; i < blobBin.length; i++) {
array.push(blobBin.charCodeAt(i));
}
callback.call(thiz, new Blob([new Uint8Array(array)], {type: 'image/jpeg'}));
}
img.src = URL.createObjectURL(file);
}
// If we don't have all the features just return the same file given to us
else {
console.log('NOPE')
callback.call(this, file);
}
}
最佳答案
我通过不使用 createObjectURL 而是像这样使用 FileReader 来解决这个问题:
flattenImage: function(file, callback){
// Safari uses webkitURL
var URL = window.URL || window.webkitURL;
var canPreformat = !!(window.FileReader && window.Blob && window.Uint8Array);
// If we have all features we need to preformat on the client and the image
// isn't already flattened (jpeg), DO IT
if (canPreformat && !file.type.test(/jpe?g/i)) {
console.log('CONVERT');
var thiz = this;
var c = document.createElement('canvas');
var ctx = c.getContext('2d');
var reader = new FileReader();
var img = new Image;
// Once the image is loaded from FileReader set the src of the image to
// the base64'd result. This will trigger the img.onload
reader.onload = function (ev) {
img.src = ev.target.result;
};
// Makes a blob URL from the file given.
img.onload = function() {
console.log('LOADED');
c.width = this.width;
c.height = this.height;
// Take the img that was added and copy it to the canvas
ctx.drawImage(img, 0, 0);
// Put the image on top of everything else
ctx.globalCompositeOperation = 'destination-atop';
// Any transparency should become white (instead of the default black)
ctx.fillStyle = "#fff";
ctx.fillRect(0, 0, this.width, this.height);
// Save canvas as a base64'd jpeg
var dataURL = c.toDataURL("image/jpeg");
// The following blob lines take the base64 encoded image and then
// convert it to a jpeg "file". This allows us to do a real file
// upload rather than needing to send a base64 string.
var blobBin = atob(dataURL.split(',')[1]);
var array = [];
for(var i = 0; i < blobBin.length; i++) {
array.push(blobBin.charCodeAt(i));
}
callback.call(thiz, new Blob([new Uint8Array(array)], {type: 'image/jpeg'}));
}
reader.readAsDataURL(file);
}
// If we don't have all the features just return the same file given to us
else {
callback.call(this, file);
}
}
关于javascript - 在 Firefox 中,onload 未使用 createObjectURL img.src 触发,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20668351/