我有一个PHP脚本,可以将PNG图像编码为Base64字符串.
我想用JavaScript做同样的事情.我知道如何打开文件,但我不知道如何进行编码.我不习惯使用二进制数据.
我需要一种有效的(读取本机)方式将ArrayBuffer转换为需要在多部分帖子上使用的base64字符串.
我有一些UTF-8编码数据存在于Javascript中的一系列Uint8Array元素中.有没有一种有效的方法将这些解码为常规的javascript字符串(我相信Javascript使用16位Unicode)？我不希望当时添加一个字符,因为字符串concaternation将变为CPU密集型.
我需要将base64编码字符串转换为ArrayBuffer.base64字符串是用户输入,它们将从电子邮件中复制和粘贴,因此在加载页面时它们不存在.如果可能的话,我想在javascript中执行此操作而不对服务器进行ajax调用.
我发现这些链接很有趣,但他们没有帮助我:
这是相反的转换,从ArrayBuffer到base64,而不是相反
http://jsperf.com/json-vs-base64/2
这看起来不错,但我无法弄清楚如何使用代码.
是否有一种简单的(可能是原生的)方式进行转换？谢谢
我有一个ArrayBuffer包含使用UTF-8编码的字符串,我找不到将其转换ArrayBuffer为JS 的标准方法String(我理解使用UTF-16编码).
我已经在很多地方看到过这段代码,但我看不出它如何适用于长度超过1个字节的任何UTF-8代码点.
return String.fromCharCode.apply(null, new Uint8Array(data));
同样,我找不到从a String转换为UTF-8编码的标准方法ArrayBuffer.
我正在使用的业务应用程序angularJS.我的一个服务方法返回我byte[](包括PDF文件内容)现在我需要下载此文件作为PDF客户端机器使用JavaScript.
如何使用HTML5 Apis或任何JavaScript API？
我用过 window.atob(base64String)
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
但得到以下错误 Failed to execute 'atob' on 'Window': The string to be decoded is not correctly encoded.
该.charCodeAt函数返回caracter的unicode代码.但我想得到字节数组.我知道,如果charcode超过127,那么该字符将存储在两个或更多字节中.
var arr=[];
for(var i=0; i<str.length; i++) {
arr.push(str.charCodeAt(i))
}
在此页面 http://www.html5rocks.com/en/tutorials/file/dndfiles/,如果您向下滚动到示例"示例:切片文件.试试吧!" 您将看到使用readAsBinaryString API读取本地文件的字节.
我见过IE(我的情况是IE11)不支持readAsBinaryString.
甚至在HTML5文件API中提到的此代码也会在IE11 中的readAsBinaryString中读取为文本和二进制中断.
我在堆栈溢出中看到了一些帖子,它建议使用ReadAsArrayBuffer().但它也没有用.它返回undefined.
我的问题是如果我必须在IE11上运行它有什么选择？是否可以编写另一个IE兼容的JS函数,它将执行readAsBinaryString()的JOB.
给定一个带有图像的现有浏览器页面，有没有办法使用 Javascript 从元素中获取字节<img>？
我没有看到任何HTMLImageElement允许从图像元素获取字节数组的方法。
我尝试了以下方法，但这返回一个空字节数组。
var img = document.querySelector('.my_image');
var body = document.querySelector('body');
var canvas = document.createElement('canvas');
canvas.height = img.height;
canvas.width = img.width;
var context = canvas.getContext('2d');
context.drawImage(img, 0, 0);
body.appendChild(canvas);
var imageBytes = context.getImageData(img.width, img.height, 1, 1).data;
console.log(imageBytes);
基本上,我需要做这个,但是在Python而非JavaScript.我从socketio连接接收到base64编码的字符串,将其转换为uint8并对其进行处理,然后需要将其转换为base64字符串,以便我可以将其发回.
所以,到目前为止,我已经得到了这个(我data从socketio服务器获取字典):
import pickle
import base64
from io import BytesIO
from PIL import Image
base64_image_string = data["image"]
image = Image.open(BytesIO(base64.b64decode(base64_image_string)))
img = np.array(image)
我如何扭转这个过程从img回到base64_image_string？
更新:
我已通过以下方式解决了这个问题(从上面的代码片段继续):
pil_img = Image.fromarray(img)
buff = BytesIO()
pil_img.save(buff, format="JPEG")
new_image_string = base64.b64encode(buff.getvalue()).decode("utf-8")
有点令人困惑,new_image_string不一样,base64_image_string但是new_image_string看起来相同的图像,所以我很满意!